Sophia YANG,
et al.
Metal Microlattice
Video
Photos
Patents
US2013303067
Ventilated Aero-Structures, Aircraft, and Associated
Methods
US2014272275
MICRO-TRUSS MATERIALS HAVING IN-PLANE MATERIAL PROPERTY
VARIATIONS
WO2014137924
ENERGY ABSORBING TRUSS STRUCTURES FOR MITIGATION OF
INJURIES FROM BLASTS AND IMPACTS
US2014252674
ARCHITECTED MATERIALS FOR ENHANCED ENERGY ABSORPTION
US9096722
A METHOD FOR CURING STRUCTURES USING A DUAL PHOTOINITIATOR
SYSTEM AND A STRUCTURE MADE USING THE SAME
US2015176132
STRUCTURES HAVING SELECTIVELY METALLIZED REGIONS AND
METHODS OF MANUFACTURING THE SAME
US8195023
FUNCTIONALLY-GRADED THREE-DIMENSIONAL ORDERED OPEN-CELLULAR
MICROSTRUCTURE AND METHOD OF MAKING SAME
US7382959
OPTICALLY ORIENTED THREE-DIMENSIONAL POLYMER
MICROSTRUCTURES
US8353240
Compressible fluid filled micro-truss for energy absorption
WO2015095617
STRUCTURES HAVING SELECTIVELY METALLIZED REGIONS AND
METHODS OF MANUFACTURING THE SAME
https://www.youtube.com/watch?v=k6N_4jGJADY
Boeing's micro lattice metal
Boeing's micro lattice metal -- Microlattice is the lightest
metallic structure ever made. At 99.99% air, it's light enough to
balance on top of a dandelion, while its structure makes it
strong. Strength and record breaking lightness make it a potential
metal for future planes and vehicles. Learn more about Boeing
Innovations at http://www.boeing.com/innovation/
PATENTS
http://worldwide.espacenet.com/advancedSearch?locale=en_EP
US2013303067
Ventilated Aero-Structures, Aircraft, and Associated
Methods
Ventilated aero-structures include a micro-lattice structure
operatively coupled to a honeycomb core. The interface between the
honeycomb core and the micro-lattice structure is configured to
permit air flow to and from the honeycomb core via the
micro-lattice structure. Aircraft include a ventilated
aero-structure and a ventilation system configured to circulate
air through the ventilated aero-structure. Some methods include
coupling a micro-lattice structure to a honeycomb core. Some
methods include utilizing a ventilated aero-structure to assemble
an aircraft...
BACKGROUND
[0002] Honeycomb structures are often used in the construction of
aircraft, because they typically have high strength to weight
ratios. Typically, honeycomb structures are sandwiched and bonded
between opposing panels, or face-sheets, resulting in closed
volumes of air within the cells of the honeycomb structures.
Closed cells are susceptible to collecting moisture and do not
permit airflow for venting, cooling, or heating applications.
Moisture ingress may contribute to failure of the bond between the
honeycomb structure and adjacent panels, as well as separation and
degradation of cells of the honeycomb structure. Unvented
honeycomb structures may be difficult to process in autoclave
bonding operations, which use gas pressure and/or vacuum to apply
forces to the structure to achieve bonding, because pressures can
build and collapse the honeycomb structure.
SUMMARY
[0003] Ventilated aero-structures according to the present
disclosure include a micro-lattice structure and a honeycomb core
operatively coupled to at least one side of the micro-lattice
structure. The interface between the honeycomb core and the
micro-lattice structure is configured to permit air flow to and
from the honeycomb core via the micro-lattice structure. Aircraft
according to the present disclosure include a ventilated
aero-structure and a ventilation system configured to circulate
air through the ventilated aero-structure.
[0004] Methods of constructing ventilated aero-structures
according to the present disclosure include coupling a
micro-lattice structure to a honeycomb core. Methods of assembling
aircraft according to the present disclosure include utilizing a
ventilated aero-structure to define a portion of the aircraft's
airframe...
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is an isometric view of an aircraft.
[0006] FIG. 2 is a schematic diagram representing ventilated
aero-structures according to the present disclosure.
[0007] FIG. 3 is a schematic plan view representing an
illustrative, non-exclusive example of a ventilated aero-structure
that includes a series of spaced-apart projections.
[0008] FIG. 4 is an isometric view of a portion of an
illustrative, non-exclusive example of an aero-structure according
to the present disclosure.
[0009] FIG. 5 is an isometric view of a micro-lattice structure
with an adherence grid.
[0010] FIG. 6 is a schematic plan view illustrating an interface
between an adherence grid and a honeycomb core structure.
[0011] FIG. 7 is a schematic side view illustrating an interface
between an adherence grid and a honeycomb core structure.
[0012] FIG. 8 is a schematic cross-sectional side view
representing illustrative, non-exclusive examples of
aero-structures according to the present disclosure that define a
leading edge of an airfoil.
[0013] FIG. 9 is another schematic cross-section side view
representing illustrative, non-exclusive examples of
aero-structures according to the present disclosure that define a
leading edge of an airfoil.
[0014] FIG. 10 is a flow-chart schematically representing
illustrative non-exclusive examples of methods according to the
present disclosure.
[0015] FIG. 11 is a schematic plan view representing illustrative
non-exclusive examples of masks that may be used to form an
adherence structure on a micro-lattice structure.
[0016] FIG. 12 is another schematic plan view representing
illustrative non-exclusive examples of masks that may be used to
form an adherence structure on a micro-lattice structure.
[0017] FIG. 13 is a schematic side view representing a curing step
of methods according to the present disclosure.
[0018] FIG. 14 is a schematic side view representing illustrative,
non-exclusive examples of molds that may be used to form an
adherence structure on a micro-lattice structure.
US2014272275
MICRO-TRUSS MATERIALS HAVING IN-PLANE MATERIAL PROPERTY
VARIATIONS
A micro-truss sheet having material properties varying across the
sheet. The sheet may include a plurality of truss members
intersecting at nodes. The diameter of the truss members at one
point in the sheet may differ from the diameter of the truss
members at another point in the sheet. In one embodiment the
spacing between adjacent truss members may be different in one
part of the sheet from the spacing between adjacent truss members
in another part of the sheet.
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application incorporates by reference in its entirety,
as if set forth in full, U.S. Pat. No. 8,195,023 (“the
'023 patent”), entitled “FUNCTIONALLY-GRADED THREE-DIMENSIONAL
ORDERED OPEN-CELLULAR MICROSTRUCTURE AND METHOD OF MAKING SAME”,
and U.S. Pat. No. 7,382,959 (“the '959 patent”), entitled
“OPTICALLY ORIENTED THREE-DIMENSIONAL POLYMER MICROSTRUCTURES”.
FIELD
[0002] The present invention relates to micro-truss materials, and
more particularly to micro-truss materials in sheet form, with
material properties varying across the sheet.
BACKGROUND
[0003] Polymer cellular materials or three-dimensional (3D)
microstructures, having the shape of a three-dimensional
micro-truss, have numerous applications, including applications as
mechanical structures for support, cushioning, and
shock-absorption, as heat or mass exchangers or components
thereof, and as flow-regulating devices or materials.
[0004] In these applications it may be desirable that the
properties of a piece of material not be uniform throughout the
piece, but varying. For example, in a flow control material, it
may be preferred to have a greater rate of flow through one
portion of the piece of material than another, or, in a piece of
material used as a cushion, it may be preferred that one portion
of the cushion be firmer than another portion.
[0005] Thus, there is a need for a micro-truss material with
non-uniform properties.
SUMMARY
[0006] The present invention relates to a micro-truss sheet having
material properties that vary across the sheet. The diameter of
the truss members, or their spacing, for example, may vary across
the sheet, providing a novel material suited to applications in
which a non-uniform sheet is preferred.
[0007] According to an embodiment of the present invention, there
is provided a micro-truss sheet, including: a plurality of first
truss members defined by a plurality of first self-propagating
polymer waveguides and extending along a first direction; a
plurality of second truss members defined by a plurality of second
self-propagating polymer waveguides and extending along a second
direction; and a plurality of third truss members defined by a
plurality of third self-propagating polymer waveguides and
extending along a third direction; the plurality of first truss
members, the plurality of second truss members, and the plurality
of third truss members being integrally provided as one continuous
body; the sheet having a length substantially greater than its
thickness, and the sheet having a first point and a second point
separated along the length of the sheet. Here the diameter of a
truss member of the plurality of first truss members, the
plurality of second truss members, and the plurality of third
truss members at the first point is at least 10% greater than the
diameter of a truss member of the plurality of first truss
members, the plurality of second truss members, and the plurality
of third truss members at the second point...
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] These and other features and advantages of the present
invention will become appreciated as the same become better
understood with reference to the specification, claims and
appended drawings wherein:
[0028] FIG. 1A is a perspective view of a micro-truss structure
forming a part of a micro-truss sheet according to an embodiment
of the present invention;
[0029] FIG. 1B is a perspective view of a unit cell of a
micro-truss sheet according to an embodiment of the present
invention;
[0030] FIG. 2A is a top-view photograph of a micro-truss sheet
having non-uniform properties across the sheet according to an
embodiment of the present invention;
[0031] FIG. 2B is a close-up photograph of a portion of the sheet
of FIG. 2A;
[0032] FIG. 2C is a close-up photograph of another portion of the
sheet of FIG. 2A;
[0033] FIG. 2D is a close-up photograph of another portion of the
sheet of FIG. 2A;
[0034] FIG. 3 is a top-view photograph of a non-rectangular sheet
having non-uniform properties across the sheet according to an
embodiment of the present invention;
[0035] FIG. 4 is a flowchart illustrating a process for forming a
micro-truss sheet having non-uniform properties across the sheet
according to an embodiment of the present invention; and
[0036] FIG. 5 is a schematic side view of a micro-truss sheet
having non-uniform properties across the sheet according to
another embodiment of the present invention.
WO2014137924
ENERGY ABSORBING TRUSS STRUCTURES FOR MITIGATION
OF INJURIES FROM BLASTS AND IMPACTS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0001] This invention was made with U.S. Government support under
Contract No. W91CRB-11-C-0112 awarded by the Defense Advanced
Research Projects Agency (DARPA) Defense Sciences Office. The U.S.
Government has certain rights to this invention.
CROSS-REFERENCE TO RELATED APPLICATION
[0002] The use of metallic lattice (truss) materials for energy
absorbing applications is discussed in U.S. Patent No.
7,382,959 ("Optically oriented three-dimensional polymer
microstructures"), U.S. Patent No. 8,353,240
("Compressible fluid filled micro-truss for energy absorption"),
and U.S. Patent Application Nos. 11/801,908, filed on May 10,
2007; 12/008,479, filed on January 11, 2008; 12/074,727, filed on
March 5, 2008; 12/075,033, filed on March 6, 2008; and 12/455,449,
filed on June 1, 2009, which are incorporated by reference herein
in their entirety. Various micro-truss structures and methods of
manufacturing micro-truss structures are described, for example,
in U.S. Patent Application No. 12/455,449, which discloses a
method of fabricating micro-truss structures having a fixed area,
U.S. Patent Application No. 12/835,276, which discloses a method
of continuously fabricating micro-truss structures according to a
continuous process (e.g., a strip of arbitrary length), and U.S.
Patent No. 8,353,240, which discloses a compressible fluid filled
micro-truss for energy absorption. Each of the above
cross-referenced applications is incorporated by reference herein
in its entirety.
FIELD OF THE INVENTION
[0003] The following description relates to energy-absorption
materials and more particularly to cellular materials with
periodic, ordered micro-micro-truss structures with enhanced
energy absorption capabilities for mitigation of injuries from
blasts and impacts.
BACKGROUND
[0004] Energy absorption materials are widely used to protect
people and goods from damaging impacts and forces. In an impact or
blast event these materials should reduce the impulsive load to a
level below a damage threshold by absorbing a maximum of energy
while not transmitting a stress in excess of the damage threshold.
Examples from the automotive, sporting and defense sectors include
crash absorbers, helmet pads and blast-mitigating foot pads.
Depending on the application, different performance
characteristics are required of the energy absorbing material. The
injury criterion or damage threshold athdetermines the maximum
allowable stress, atr, transmitted through the energy absorber,
i.e., to avoid damage is it necessary that atr< σ^. For energy
absorbers in direct contact with the human body the injury
criterion is generally on the order of 1 MPa.
[0005] Cellular materials are often used as energy absorption
materials because they can absorb energy on compression. Single
use energy absorption materials may be metallic and include closed
or open cell foams and pre-crushed honeycombs; multi-use materials
with reversible energy absorption are typically polymeric and
include visco-elastic closed or open cell foams, and thermoplastic
polyurethane (TPU) twin hemispheres. Lattice structures can be
composed of polymer or metallic materials and may consist of a
periodic arrangement of solid or hollow members (struts, trusses).
[0006] Figure 1 is a schematic plot illustrating the ideal
behavior of an energy absorption material. At low stress, the
strain increases linearly with stress, up to a stress of, e.g., 1
MPa. At this threshold stress, the strain of the material
increases rapidly at substantially constant stress, and the
material absorbs energy. Finally, when the material reaches a high
strain referred to as the densification strain, the stress again
increases. The maximum possible volumetric energy absorption for a
given material structure is calculated as the product of the peak
stress with 100% strain.
[0007J Real materials typically deviate from the ideal response
and have lower absorption efficiency. Figure 2 illustrates the
typical behavior of a lattice or truss structure with high
structural symmetry and internal connectivity. Here, after
reaching a peak initial stress (labeled as Max. transmitted stress
in Figure 2), the strain increases at a lower level of stress,
resulting in a reduction in energy absorption compared to the
ideal case illustrated in Figure 1. This is believed to be due to
the fact that the onset of buckling at a single point in such a
structure with high structural symmetry and internal connectivity
triggers buckling throughout the structure, which leads to an
abrupt loss of load-carrying capability and reduced impact energy
absorption efficiency. In such a case, the densification strain is
defined as the strain at which the stress- strain curve intersects
a horizontal line at the peak initial stress value. The volumetric
energy absorbed is calculated as the area under the stress-strain
curve between 0% strain and the densification strain. The energy
absorption efficiency of such a material is calculated as the
ratio of the volumetric energy absorbed to the maximum possible
volumetric energy absorption.
[0008] Figure 3 shows a compressive stress-strain response typical
of types of aluminum foam used as energy absorption materials.
Such materials have a plateau-like stress-strain curve and do not
exhibit the non-ideal behavior of an initial stress peak followed
by softening. However, such materials have a low densification
strain since the stress starts to rise at an increasing rate at
approximately 30% strain, which limits the energy absorption
efficiency to be about 35%. Figure 4 shows the compressive
stress-strain response of an aluminum honeycomb energy absorption
material. In this case, the material exhibits a large initial
stress peak followed by softening, which limits its energy
absorption efficiency to about 34%. Figure 5 shows the compressive
stress-strain response of a twin hemisphere energy absorption
material. The material exhibits softening after an initial stress
peak, which limits its energy absorption efficiency to about 47%.
[0009] Certain materials with a truss or lattice architecture have
constant architectural parameters through the thickness direction,
i.e., the energy absorbing direction of the truss or lattice
structure. In these materials, the high structural symmetry and
lack of disconnected internal members lead to simultaneous
buckling and a sharp loss of load transfer capability as shown in
Figure 2. This reduces the energy absorption efficiency of the
material as the stress level associated with compaction drops well
below the peak value. Figure 6 displays the compressive
stress-strain response of a typical hollow metallic micro-truss
structure with no enhancement on the structure. It exhibits a
large stress peak followed by softening, and additional stress
peaks. The energy absorption efficiency is about 15% - 30%.
[0010] Therefore, there is a need for micro-truss or lattice
architectures with the inherent structural and low mass benefits
of such architectures, yet with improved energy absorption
response.
SUMMARY
[0011] Aspects of embodiments of the present invention pertain to
architected materials with superior energy absorption properties
when loaded in compression. In several embodiments such materials
are formed from micro-truss structures composed of
interpenetrating tubes in a volume between a first surface and a
second surface. The stress-strain response of these structures,
for compressive loads applied to the two surfaces, is tailored by
arranging for some but not all of the tubes to extend to both
surfaces, adjusting the number of layers of repeated unit cells in
the structure, arranging for the nodes to be offset from alignment
along lines normal to the surfaces, or including multiple
interlocking micro-truss structures.
[0012] According to an embodiment of the present invention there
is provided a system for protection from impulsive loads as
generated by impacts and explosions, the system including: a first
micro-truss architecture, wherein the micro-truss architecture is
configured to have greater than 50% volume decrease while
transmitting nearly constant pressure in the range of 0.3 - 7 MPa
under dynamic loading at 1 - 20 m/s impact velocity. [0013] In one
embodiment, the first micro-truss architecture includes: a first
surface and a second surface parallel to each other with a
distance therebetween defining a thickness of the micro-truss
architecture; a plurality of angled struts extending along a
plurality of non-vertical directions each having a first end on
the first surface and a second end; a plurality of nodes where the
plurality of angled struts extending along a plurality of
directions interpenetrate one another; the plurality of angled
struts and the plurality of nodes defining a plurality of unit
cells each having an upper node among the plurality of nodes, a
lower node among the plurality of nodes, and a cell height, the
cell height being the distance between the upper node and the
lower node, wherein the second end of each angled struts is on the
lower node closest to the second surface at a distance away from
the second surface; and a vertical post extending from the first
surface in a normal direction having a first end on the first
surface and a second end extending past the lower node closest to
the second surface onto the second surface...
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Figure 1 is a schematic illustration of the compressive
stress-strain behavior of an ideal energy absorption material.
[0039] Figure 2 is a schematic illustration of the compressive
stress-strain behavior of a lattice or truss structure with high
structural symmetry and internal connectivity and defines the
terms used. [0040] Figure 3 shows the quasi-static stress-strain
performance of a commercial aluminum foam used as energy
absorption material.
[0041] Figure 4 shows the compressive stress-strain performance of
a commercial honeycomb material used as energy absorption
material.
[0042] Figure 5 shows the compressive stress-strain performance of
a commercial polyure hane twin hemisphere material blast
protection mat.
[0043] Figure 6 shows the compressive stress-strain performance of
a hollow metallic micro-truss material without enhanced structure.
[0044] Figure 7a is a perspective view photograph of a hollow
nickel micro-truss with vertical posts that extend past the lower
node, according to an embodiment of the present invention.
[0045] Figure 7b is a side view photograph of a hollow nickel
micro-truss with vertical posts that extend past the lower node,
according to an embodiment of the present invention.
[0046] Figure 8a is a photograph of, and quasi-static test results
of, an embodiment of the micro-truss architecture shown in Figures
7a and 7b.
[0047] Figure 8b is a photograph of, and quasi-static test results
of, a commercial energy absorption material with a twin hemisphere
structure.
[0048] Figure 8c shows an exemplary embodiment of two structures
stacked according to an embodiment of the present invention, and
the resulting stress-strain response.
[0049] Figure 9a is a side view photograph of an exemplary
1.5-cell tall hollow micro-truss with vertical posts extending
only across 1 cell according to an embodiment of the present
invention.
[0050] Figure 9b is a top view photograph of an exemplary 1.5-cell
tall hollow micro-truss with vertical posts extending only across
1 cell according to an embodiment of the present invention.
[0051] Figure 10 shows the stress-strain curve measured in
compression on the structure shown in Figures 9a and 9b. [0052]
Figure 11a is a perspective view photograph of an exemplary
standard electroless nickel octahedral hollow micro-truss about 5
unit cells tall according to an embodiment of the present
invention.
[0053] Figure l ib is a perspective view photograph of an
exemplary standard poly(p- xylylene) polymer octahedral hollow
micro-truss about 5 unit cells tall according to an embodiment of
the present invention.
[0054] Figure 11c is a close-up perspective view photograph
pictures of the poly(p- xylylene) polymer octahedral hollow
micro-truss of Figure 1 lb.
[0055] Figure 12 shows the stress-strain curve measured in
compression on the poly(p- xylylene) structure shown in Figures 1
lb and 11c.
[0056] Figure 13a shows an assembled view and an exploded view of
a micro-truss architecture with repeating periodic interlocking
unit cell structures according to an embodiment of the present
invention.
[0057] Figure 13b shows the simulated stress-strain response, for
dynamic compression at 1 m/s, of the embodiment of Figure 13 a.
[0058] Figure 14a shows an assembled view and an exploded view of
a micro-truss architecture with interlocked unit cell structures
according to an embodiment of the present invention.
[0059] Figure 14b shows the simulated stress-strain response, for
dynamic compression at 1 m/s, of the embodiment of Figure 13 a.
[0060] Figure 15a shows a micro-truss based energy absorber
combined with a flexible face sheet before a blast event.
[0061] Figure 15b shows a micro-truss based energy absorber
combined with a flexible face sheet during a blast event.
[0062] Figure 16 shows a micro-truss based energy absorber
combined with an armor plate according to an embodiment of the
present invention. {0063] Figure 17 is a schematic drawing of
micro-truss based body armor that incorporates air flow cooling
through the open-celled structure according to an embodiment of
the present invention.
[0064] Figure 18 is a schematic cross-sectional drawing of an
exemplary micro-truss structure according to an embodiment of the
present invention.
[0065] Figure 19a is a top view illustration of a micro-truss
structure with all nodes in an upper layer shifted by 0.1L in same
directions according to an embodiment of the present invention.
[0066] Figure 19b is a side view illustration of a micro-truss
structure with all nodes in an upper layer shifted according to an
embodiment of the present invention.
[0067] Figure 20a is a top view illustration of a micro -truss
structure with nodes in a bottom layer shifted according to an
embodiment of the present invention.
[0068] Figure 20b is a side view illustration of a micro-truss
structure with nodes in a bottom layer shifted according to an
embodiment of the present invention.
[0069] Figure 21a is top view of a micro-truss structure with
three-fold symmetry where all nodes in one plane sit in the center
between the nodes in the planes above and below, according to an
embodiment of the present invention.
[0070] Figure 21b is perspective view of a micro-truss structure
with three-fold symmetry where all nodes in one plane sit in the
center between the nodes in the planes above and below, according
to an embodiment of the present invention.
[0071] Figure 22 shows the simulated stress-strain response of the
micro-truss structure shown in Figure 19a and Figure 19b.
[0072] Figure 23 is a flow chart describing an exemplary method to
fabricate the micro- truss structure according to an embodiment of
the present invention.
US2014252674
ARCHITECTED MATERIALS FOR ENHANCED ENERGY ABSORPTION
A three-dimensional lattice architecture with a thickness
hierarchy includes a first surface and a second surface separated
from each other with a distance therebetween defining a thickness
of the three-dimensional lattice architecture; a plurality of
angled struts extending along a plurality of directions between
the first surface and the second surface; a plurality of nodes
connecting the plurality of angled struts with one another forming
a plurality of unit cells. At least a portion of the plurality of
angled struts are internally terminated along the thickness
direction of the lattice structure and providing a plurality of
internal degrees of freedom towards the first or second surface of
the lattice architecture.
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to and the benefit of U.S.
Provisional Application No. 61/775,330, filed on Mar. 8, 2013,
entitled ARCHITECTED MATERIALS WITH THICKNESS HIERARCHY, the
content of which is incorporated herein in its entirety by
reference.
[0002] The use of metallic lattice (truss) materials for energy
absorbing application is discussed in U.S. Pat. No. 7,382,959
(“Optically oriented three-dimensional polymer microstructures”)
and U.S. patent application Ser. No. 11/801,908 filed on May 10,
2007; Ser. No. 12/008,479 filed on Jan. 11, 2008; Ser. No.
12/074,727 filed on Mar. 5, 2008; Ser. No. 12/075,033 filed on
Mar. 6, 2008; Ser. No. 12/455,449 filed on Jun. 1, 2009; and Ser.
No. 12/928,947 filed on Dec. 22, 2010. Various micro-truss
structures and methods of manufacturing micro-truss structures are
described, in U.S. patent application Ser. No. 12/455,449, which
discloses a method of fabricating micro-truss structures having a
fixed area, U.S. patent application Ser. No. 12/835,276, which
discloses a method of continuously fabricating micro-truss
structures according to a continuous process (e.g., a strip of
arbitrary length), and U.S. patent application Ser. No.
12/928,947, which discloses a compressible fluid filled
micro-truss for energy absorption. Each of the above
cross-referenced patents and applications is commonly owned by the
assignee of the present application and incorporated by reference
herein in their entireties.
FIELD OF THE INVENTION
[0003] The following description relates to energy-absorption
materials and more particularly to architectured lattice materials
with enhanced energy absorption capabilities.
BACKGROUND
[0004] Energy absorption materials have been widely used to
protect people and goods from damaging impacts and forces. Energy
absorption materials can be divided into two categories: those
without truss architecture, and those with truss architecture. The
former category includes cellular materials such as metallic or
polymeric closed or open cell foams, crushed honeycombs, or other
commercial materials such as Skydex™. The latter category includes
micro-truss structures composed of solid or hollow members
(struts, trusses, or lattices) with constant architectural
parameters such as unit cell size, radius, length, or angles of
each member, through the thickness direction of the structure. For
the former category, the cellular materials dissipate kinetic
energy associated with impact via elastic and/or inelastic
deformation. The compression response of foam and pre-crushed
honeycomb materials approaches an ideal response (as shown in FIG.
1, which will be described in more detail afterwards), but the
ability of these materials is limited either by the low
densification strain in foams or the low load-bearing capability
in pre-crushed honeycombs. In either case, although the response
characteristics are ideal, the performance of the material suffers
due to non-ideal spatial arrangement of the microstructures.
[0005] Previous materials with truss or lattice architecture have
constant architectural parameters through the thickness direction,
i.e., the energy absorbing direction of the truss or lattice
structure. The high structural symmetry and lack of disconnected
internal members lead to simultaneous buckling and a sharp loss of
load transfer capability as shown in FIG. 2. This reduces the
energy absorption efficiency of the material as the stress level
associated with compaction drops well below the peak value.
[0006] Turning now to the behavior of a given energy absorption
material during impact or compression, architected materials
composed of truss- or beam-like elements experience collapse
mechanisms in which the incoming energy or external work is
absorbed in three stages: initial buckling, compaction at a
constant or near-constant stress plateau, and ultimately full
densification. FIG. 1 is a schematic plot illustrating the ideal
behavior of an energy absorption material. The initial response of
the material is a compressive strain that changes linearly with
the compressive stress corresponding to the material response
prior to the onset of buckling or plasticity. After reaching a
peak stress 101, the ideal material response switches from the
linear elastic stage to a constant stress plateau stage 102, where
the force transmitted through the material remains uniform and
constant, until the material reaches a densification stage in
which the strain increases rapidly, linearly or non-linearly, with
the stress again. The strain corresponding to the transition point
from the plateau stress to the densification stage is identified
as the densification strain 103. The maximum possible volumetric
energy absorption for a given material is calculated as the
product of the peak stress 101 with 100% strain. However, actual
architected materials will have deviation from the ideal response
and lead to a loss of absorption efficiency. FIG. 2 illustrates
the typical behavior of a lattice or truss structure with high
structural symmetry and internal connectivity. Here, after
reaching a peak stress 201 at the onset of buckling, rather than
staying at the peak stress level, the compressive stress drops to
a lower plateau stress 202. This is believed to be due to the fact
that the onset of buckling at a single point in a structure with
high structural symmetry and internal connectivity will trigger
buckling throughout the structure, which leads to an instantaneous
loss of load-carrying capability and reduced energy absorption
efficiency. In such a case, the densification strain 203 is
defined as the strain level corresponding to the interception of a
horizontal line at the peak stress value with the stress-strain
curve. The actual volumetric energy absorbed is calculated as the
area under the stress-strain curve between 0% strain and the
densification strain. The energy absorption efficiency of such a
material is calculated as ratio of the actual volumetric energy
absorbed to the maximum possible volumetric energy absorption.
[0007] Therefore, there is still a demand for lattice
architectures with the inherent structural and low mass benefits,
yet with improved energy absorption response.
SUMMARY
[0008] Aspects of embodiments of the present invention pertain to
architected materials with superior energy absorption properties
when loaded in compression. The materials possess a truss or
lattice configuration with hierarchy through the thickness
direction, i.e., the primary energy absorption direction, of the
material, which provides enhanced energy absorption functionality
versus lattice architectures in prior art while retaining their
inherent structural and mass benefits. The added dimension of
architectural control can be introduced to a standard lattice
structure in two different embodiments.
[0009] In one embodiment of the invention, a three-dimensional
lattice architecture with a thickness hierarchy includes a first
surface and a second surface separated from each other (along a
normal direction to at least one of the first and second surfaces)
with a distance therebetween defining a thickness of the
three-dimensional lattice architecture; a plurality of angled
struts extending along a plurality of directions between the first
surface and the second surface; a plurality of nodes connecting
the plurality of angled struts with one another forming a
plurality of unit cells. At least a portion of the plurality of
angled struts are internally terminated along the thickness
direction of the lattice structure and providing a plurality of
internal degrees of freedom towards the first or second surface of
the lattice architecture...
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic illustration of the ideal compressive
stress-strain behavior of an energy absorption material, with or
without a lattice architecture.
[0015] FIG. 2 is a schematic illustration of the typical
compressive stress-strain behavior of a lattice or truss structure
with high structural symmetry and internal connectivity.
[0016] FIGS. 3a and 3b are schematic drawings illustrating a
lattice architecture with architected thickness hierarchy
introduced through the use of an architected template.
[0017] FIG. 4 is a schematic illustration of a lattice
architecture with two different lattice structures stacked
together.
[0018] FIG. 5a is a schematic drawing illustrating one embodiment
of the process of making a lattice architecture using an
architected template.
[0019] FIG. 5b is a schematic drawing illustrating another
embodiment of the process of making a lattice architecture using
an architected template.
[0020] FIG. 6a shows a bottom view of one exemplary lattice
architecture prior to the introduction of interrupted internal
members.
[0021] FIG. 6b shows the bottom view of the exemplary lattice
architecture shown in FIG. 6a with an architected template
superimposed on the lattice architecture.
[0022] FIG. 6c shows the bottom view of the exemplary lattice
architecture shown in FIG. 6a after the introduction of
interrupted internal members formed by using the architected
template shown in FIG. 6b.
[0023] FIG. 6d shows a cross-sectional view of the lattice
architecture shown in FIG. 6c along the line a-a′.
[0024] FIG. 7 shows another exemplary lattice architecture with
interrupted internal members.
[0025] FIG. 8 shows one exemplary lattice architecture with
interrupted internal members attached to structural facesheets at
the top and bottom surfaces of the structure.
[0026] FIG. 9 shows the comparison of a simulated compressive
stress-strain response of the exemplary lattice architecture shown
in FIG. 7 versus a similar lattice structure without the
interrupted members.
[0027] FIG. 10 shows the comparison of a simulated compressive
stress-strain response of the exemplary lattice architecture shown
in FIG. 8 versus a similar lattice structure without the
interrupted members.
[0028] FIG. 11 is a schematic drawing illustrating one embodiment
of the process of making a lattice architecture with multiple
lattice structures stacked together.
[0029] FIG. 12 is a photograph of an actual lattice architecture
with two different lattice structures stacked together.
[0030] FIG. 13 is a schematic illustration of a lattice
architecture with three different lattice structures stacked
together including facesheet materials at the interfaces between
lattices with dissimilar architectures
[0031] FIG. 14 shows the compressive stress-strain response of the
material shown in FIG. 12 under compression.
[0032] FIG. 15 shows photographs of the lattice architecture of
FIG. 12 composed of two different layers of lattice structures
stacking together under compression.
US9096722
A METHOD FOR CURING STRUCTURES USING A DUAL PHOTOINITIATOR
SYSTEM AND A STRUCTURE MADE USING THE SAME
Inventor(s): YANG SOPHIA, et al.
A monomeric formulation for fabrication of microlattice
structures, the monomeric formulation including a plurality of
monomers, a first photoinitiator configured to substantially
activate above a wavelength of light, and a second photoinitiator
configured not to substantially activate above the wavelength of
light and to substantially activate below the wavelength of light.
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims priority to and the benefit of U.S. Patent
Application No. 61/893,001, filed on Oct. 18, 2013, the entire
content of which is incorporated herein by reference.
This application is related to a U.S. patent application entitled
“Net-Shape Structure with Micro-Truss Core” (U.S. application Ser.
No. 13/312,952), filed on Dec. 6, 2011, is related to a U.S.
patent entitled “Functionally Graded Three-Dimensional Ordered
Open-Cellular Microstructure and Method of Making the Same” (U.S.
Pat. No. 8,195,023), issued on Jun. 5, 2012, and is also related
to a U.S. patent entitled “Optically Oriented Three-Dimensional
Polymer Microstructures” (U.S. Pat. No. 7,653,279), issued on Jan.
6, 2010, the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
The present invention relates to methods for curing structures in
a net shape, and, more particularly, to methods for curing the
structure utilizing a dual photoinitiator system, and to
structures produced thereby.
BACKGROUND
Lightweight sandwich structures, that is, structures including a
core sandwiched between two facesheets, are utilized for a variety
of purposes including heat exchangers, padding (e.g., in seats,
cushions, helmets, shoe insoles, mattresses, etc.), advanced armor
applications (e.g., blast protection), high impact/low weight
applications (such as bumper beams, battery trays, wings), and/or
the like. In some applications, it may be beneficial to shape
lightweight sandwich structures into particular curvatures that
conform to a surface where the structure will be utilized. In some
instances, framing a sandwich structure into a particular shape
may require costly manufacturing techniques.
Generally, the materials utilized for lightweight sandwich
structures dictate how the structure is formed and whether it can
be formed to have complex curvatures. Existing materials utilized
as cores for lightweight sandwich structures include foams,
honeycomb, and metal lattice structures. Each of these materials
has limitations in its ability to conform to particular
curvatures.
Foams can be either open-cellular or closed cellular and are
available in a variety of materials including, but not limited to,
polymers, metals, and ceramics. Open-cellular foams generally have
limited strength and stiffness, which limits their usefulness in a
variety of applications. Open-cellular foams also have tortuous,
non-uniform paths for fluid flow, in which high pressures are
often utilized to force fluid through the structure.
Closed-cellular foams have greater strength and rigidity than
open-cellular foams, making them more suitable as cores for
sandwich structures. However, closed-cellular foams do not permit
fluid to freely flow through the material, which limits their
usefulness in applications where fluid flow is required, such as
heat transfer applications. Generally, machining is utilized to
form foam into a particular curvature.
Honeycomb structures are also available in a number of different
materials including, but not limited to, aluminum, and
thermoplastic polymers. Generally, honeycomb structures are
closed-cellular. In order to achieve a particular curvature with a
honeycomb structure a specific corresponding unit cell shape is
generally utilized. This approach may work for a structure
requiring a single radius of curvature; however, it is less
effective for complex curvatures which have more than one radius
of curvature.
Metallic lattice structures have good strength and stiffness
properties and may also function as fluid heat exchanges because
the structures allow low pressure drop fluid flow through the
material. However, to form a metal lattice structure into a
particular curvature, the structure is generally plastically
deformed or machined.
As such, what is desired is a lightweight structure that can be
easily formed to have a particular curvature without resorting to
pre- or post-production manufacturing, which may be time
consuming, expensive, and/or may damage the structural integrity
of the sandwich structure.
SUMMARY
Aspects of embodiments of the present invention are directed to
curing structures in net shape by utilizing a combination of
different photoinitiators and different wavelength light sources.
Aspects of embodiments of the present invention are directed
toward forming and curing a microlattice structure by forming a
compliant (e.g., pliable) precursor structure through activating a
first photoinitiator of a resin formulation by a light (e.g.,
ultraviolet (UV) light) of a first wavelength and first intensity,
shaping the precursor structure, if desired, and post-curing the
precursor structure through activating a second photoinitiator of
the resin formulation by a light (e.g., UV light) of a second
wavelength and a second intensity, where the second wavelength is
shorter than the first wavelength and the second intensity is
greater than the first intensity.
According to embodiments of the present preset invention, there is
provide a monomeric formulation for fabrication of microlattice
structures, the monomeric formulation including: a plurality of
monomers; a first photoinitiator configured to substantially
activate above a wavelength of light; and a second photoinitiator
configured not to substantially activate above the wavelength of
light and to substantially activate below the wavelength of
light...
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features and advantages of the present invention
will be better understood by reference to the following detailed
description when considered in conjunction with the following
drawings, in which like elements are referenced with like
numerals. These drawings should not be construed as limiting the
present invention, but are intended to be illustrative only.
FIG. 1 is a schematic cross-sectional diagram illustrating a dual
photoinitiator system (e.g., a dual cure system) for forming a
three-dimensional structure, according to an illustrative
embodiment of the present invention.
FIG. 2A illustrates the UV absorption spectra of example
photoinitiators that are active at longer wavelengths utilized as
the first photoinitiators of the resin formulation, according to
an illustrative embodiment of the present invention. FIG. 2B
illustrates the UV absorption spectra of example photoinitiators
that are active at shorter wavelengths utilized as the second
photoinitiators of the resin formulation, according to an
illustrative embodiment of the present invention.
FIG. 3 illustrates the light absorption spectra of the first and
second photoinitiators and the wavelengths of lights utilized
during the dual curing stages of the dual photoinitiator system,
according to an embodiment of the present invention.
FIGS. 4A-4B respectively illustrate a cross-section of a flat
unconstrained microlattice structure, and one that is shaped
utilizing a method of net-shaping, according to an illustrative
embodiment of the present invention.
FIG. 5 is a flow diagram of a process for curing microlattice
materials by utilizing the dual cure system, according to an
illustrative embodiment of the present invention.
US2015176132
STRUCTURES HAVING SELECTIVELY
METALLIZED REGIONS AND METHODS OF MANUFACTURING THE SAME
Methods of manufacturing a structure having at least one plated
region and at least one unplated region. The method includes
plating a metal on a polymer structure having a first region
accepting the metal and a second region unreceptive to the metal
plating. The first region may include fully-cured polymer optical
waveguides and the second region may include partially-cured
polymer optical waveguides. The first region may include a first
polymer composition and the second region may include a second
polymer composition different than the first polymer composition.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of U.S.
Provisional Application No. 61/918,540, filed Dec. 19, 2013, the
entire content of which is incorporated herein by reference.
FIELD
[0002] The present invention relates generally to polymer
structures and, more particularly, to partially metallized polymer
structures.
BACKGROUND
[0003] Metallized components are ubiquitous. Components are
commonly metallized for aesthetic, structural, conductive, and/or
corrosion resistance purposes. Related processes for metallizing
components include painting, dipping, electroplating, electroless
plating, spraying, sputtering, and laser activation. Processes for
metallizing components are typically directed at uniformly coating
the component. Non-metallized portions of the component are
typically the result of uncontrollable variation, which is
indicative of an unsuccessful process and therefore such partially
metallized components are typically discarded.
[0004] Additionally, related processes for metallizing components
are typically limited to line-of-sight coverage of the component.
For instance, related metallizing processes may be limited to
metallizing only external surfaces of the component. Additionally,
related metallizing processes may be restricted to components
having limited sizes and geometries (e.g., related metallizing
techniques may be limited to the two-dimensional coating of flat
components, such as circuit boards). Thus, related metallizing
processes may be suitable only for components having limited sizes
and architectures.
SUMMARY
[0005] Aspects of embodiments of the present disclosure are
directed toward various methods for manufacturing a structure
having at least one plated region and at least one unplated
region. In one embodiment, the method includes plating a metal on
a polymer structure having a first region accepting the metal and
a second region unreceptive to the metal. The polymer structure
may include a plurality of interconnected polymer optical
waveguides arranged in a unitary lattice structure. Plating the
polymer structure may include conditioning the polymer structure,
etching the polymer structure, neutralizing the polymer structure,
catalyzing the polymer structure, immersing the polymer structure
in an accelerator, and immersing the polymer structure in an
electroless bath. Plating the polymer structure may include a
catalyst poisoning method, an inhibition of metal reaction method,
an over-etched polymer surface method, an increased etch rate-post
process method, an uncured surface inhibition of plating method,
or an etch resistant polymer-prevention of catalyst deposition
method. The first region may include fully-cured, cross-linked
polymer optical waveguides and the second region may include
partially-cured polymer optical waveguides. The first region may
include a first polymer composition, and the second region may
include a second polymer composition different than the first
polymer composition.
[0006] The method may also include immersing the polymer structure
in a catalyst inhibitor that deposits onto the second region of
the polymer structure and is repelled by the first region of the
polymer structure. The method may also include immersing the
polymer structure in a reaction inhibitor that deposits onto the
second region of the polymer structure and is repelled by the
first region of the polymer structure. The method may also include
etching the polymer structure. The first region of the polymer
structure may etch at a first rate and the second region of the
polymer structure may etch at a second rate different than the
first rate. The method may also include forming the polymer
structure by irradiating one or more photo-monomers with a series
of light beams. The polymer structure may include a series of
interconnected polymer optical waveguides arranged in a unitary
lattice structure. The method may also include forming the polymer
structure by irradiating a volume of a first photo-monomer with a
series of light beams to form the first region of the polymer
structure and irradiating a volume of a second photo-monomer with
a series of light beams to form the second region of the polymer
structure. The method may also include forming the polymer
structure by an additive manufacturing process, such as
stereolithography, digital light processing, fused deposition, or
selective laser sintering.
[0007] In another embodiment, the method includes irradiating a
volume of a first photo-monomer with a series of light beams to
form a first region of a polymer structure and irradiating a
volume of a second photo-monomer different than the first
photo-monomer with a series of light beams to form a second region
of the polymer structure coupled to the first region of the
polymer structure. One of the first and second regions of the
polymer structures accepts metal plating and the other one of the
first and second regions of the polymer structure rejects metal
plating. The method may also include plating the first or second
region of the polymer structure that accepts metal plating. The
method may also include metal plating the other one of the first
and second regions of the polymer structure and removing the
polymer structure by etching to form a plurality of interconnected
hollow struts...
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] These and other features and advantages of embodiments of
the present disclosure will become more apparent by reference to
the following detailed description when considered in conjunction
with the following drawings. In the drawings, like reference
numerals are used throughout the figures to reference like
features and components. The figures are not necessarily drawn to
scale.
[0012] FIGS. 1A-1K are side views of partially metallized
three-dimensional structures according to various embodiments of
the present disclosure;
[0013] FIGS. 2A-2C illustrate tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to one
embodiment of the present disclosure;
[0014] FIG. 3 is a flowchart illustrating tasks of metallizing the
one or more regions of the polymer structure of FIG. 2C that are
receptive to metal plating according to one embodiment of the
present disclosure;
[0015] FIG. 4 is a partial side view of a series of interconnected
hollow struts according to one embodiment of the present
disclosure;
[0016] FIGS. 5A-5C illustrate tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to another
embodiment of the present disclosure;
[0017] FIG. 6 illustrates tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to a further
embodiment of the present disclosure;
[0018] FIGS. 7A-7D illustrate tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to another
embodiment of the present disclosure; and
[0019] FIGS. 8A and 8B illustrate tasks of forming a polymer
structure having one or more regions receptive to metal plating
and one or more regions unreceptive to metal plating according to
one embodiment of the present disclosure.
US8195023
FUNCTIONALLY-GRADED THREE-DIMENSIONAL ORDERED OPEN-CELLULAR
MICROSTRUCTURE AND METHOD OF MAKING SAME
A method for creating or forming a functionally graded 3D ordered
open-cellular microstructure, and a functionally graded 3D ordered
open-cellular microstructure. In one embodiment, the
functionally-graded three-dimensional ordered open-cellular
microstructure includes a first three-dimensional interconnected
pattern of polymer waveguides having a first three-dimensional
pattern; a second three-dimensional interconnected pattern of
polymer waveguides having a second three-dimensional pattern
differing from the first three-dimensional pattern; and an
interface connected with the first three-dimensional
interconnected pattern of polymer waveguides and the second
three-dimensional interconnected pattern of polymer waveguides.
Here, the term "functionally graded" refers to a spatial variation
in the physical microstructure-and thus the properties-through the
thickness of the material.
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application relates to U.S. patent application Ser. No.
11/580,335, filed on Oct. 13, 2006, entitled “Optically Oriented
Three-Dimensional Polymer Microstructures” and to U.S. patent
application Ser. No. 11/801,908, filed on May 10, 2007, entitled
“Three-Dimensional Ordered Open-Cellular Structures.” The entire
contents of each of the above-referenced applications are
incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to a three-dimensional (3D) ordered
open-cellular microstructure and a method to fabricate such a
material. In particular, the present invention relates to a
functionally graded 3D ordered open-cellular microstructure and a
method of making the same.
BACKGROUND OF THE INVENTION
A three-dimensional (3D) ordered open-cellular microstructure is
an ordered 3D structure at the micrometer scale. Aspects of
embodiments of the present invention are directed toward a
functionally graded 3D ordered open-cellular microstructure and a
method of making the same. Here, the term “functionally graded”
refers to a spatial variation in the physical microstructure—and
thus the properties—through the thickness of the material.
A 3D ordered open-cellular microstructure can be formed, for
example, by using a stereolithography technique, which relies on a
bottom-up, layer-by-layer approach. This process usually involves
a platform (substrate) that is lowered into a photo-monomer
(photopolymer) bath in discrete steps. At each step, a laser is
scanned over the area of the photo-monomer that is to be cured
(polymerized) for that particular layer. Once the layer is cured,
the platform is lowered a specific amount (determined by the
processing parameters and desired feature/surface resolution) and
the process is repeated until the full 3D structure is created.
One example of such a stereolithography technique is disclosed in
Hull et al., “Apparatus For Production Of Three-Dimensional
Objects By Stereolithography,” U.S. Pat. No. 4,575,330, Mar. 11,
1986, which is incorporated by reference herein in its entirety.
Modifications to the above described stereolithography technique
have been developed to improve the resolution with laser optics
and special resin formulations, as well as modifications to
decrease the fabrication time of the 3D structure by using a
dynamic pattern generator to cure an entire layer at once. One
example of such a modification is disclosed in Bertsch et al.,
“Microstereolithography: A Review,” Materials Research Society
Symposium Proceedings, Vol. 758, 2003, which is incorporated by
reference herein in its entirety. A fairly recent advancement to
the standard stereolithography technique includes a two-photon
polymerization process as disclosed in Sun et al., “Two-Photon
Polymerization And 3D Lithographic Microfabrication,” APS, Vol.
170, 2004, which is incorporated by reference herein in its
entirety. However, this advance process still relies on a
complicated and time consuming layer-by-layer approach.
Previous work has also been done on creating polymer optical
waveguides. A polymer optical waveguide can be formed in certain
photopolymers that undergo a refractive index change during the
polymerization process. If a monomer that is photo-sensitive is
exposed to light (typically UV) under the right conditions, the
initial area of polymerization, such as a small circular area,
will “trap” the light and guide it to the tip of the polymerized
region due to this index of refraction change, further advancing
that polymerized region. This process will continue, leading to
the formation of a waveguide structure with approximately the same
cross-sectional dimensions along its entire length. The existing
techniques to create polymer optical waveguides have only allowed
one or a few waveguides to be formed and these techniques have not
been used to create a self-supporting three-dimensional structure
by patterning polymer optical waveguides.
In addition, functionally graded foams with random cell
configurations have been fabricated through various techniques and
are discussed in Lefebvre et al., “Method Of Making Open Cell
Material,” U.S. Pat. No. 7,108,828, Sep. 19, 2006; in Lauf et al.,
“Method Of Making A Functionally Graded Material,” U.S. Pat. No.
6,375,877, Apr. 23, 2002; and in Vyakarnam et al., “Porous Tissue
Scaffoldings For The Repair Or Regeneration Of Tissue,” U.S. Pat.
No. 6,534,084, Mar. 18, 2003; the entire contents of each of which
are incorporated herein by reference. However, these functionally
graded structures with specifically designed and ordered
microstructures rely on layer-by-layer approaches similar to the
above discussed stereolithography techniques, an example of which
is also discussed in Keicher et al., “Forming Structures From CAD
Solid Models”, U.S. Pat. No. 6,391,251, May 21, 2002, which is
incorporated herein by reference in its entirety. These above
cited references do not, however, disclose or discuss a
manufacturing technique for 3D patterning of self-propagating
polymer optical waveguides to form functionally graded
open-cellular microstructures.
As such, there continues to be a need for 3D patterning of
self-propagating polymer optical waveguides to form functionally
graded 3D ordered open-cellular microstructures (or open-cellular
materials) on a large and useful scale using a simple technique...
SUMMARY OF THE INVENTION
An aspect of an embodiment of the present invention is directed
toward a method for creating or forming a functionally graded 3D
ordered open-cellular microstructure.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, together with the specification,
illustrate exemplary embodiments of the present invention, and,
together with the description, serve to explain the principles of
the present invention.
FIG. 1 is a perspective schematic view of a portion of a structure
according to an embodiment of the present invention.
FIG. 2 is a perspective schematic view of a structure according to
an embodiment of the present invention.
FIG. 3 is a schematic diagram of a system for forming a structure
of an embodiment of the present invention from multiple waveguides
created using a single collimated beam or multiple collimated
beams through multiple apertures.
FIG. 4a illustrates an example of a square mask pattern (or a
square mask aperture pattern) according to embodiments of the
present invention.
FIG. 4b illustrates an example of a hexagonal mask pattern (or a
hexagonal mask aperture pattern) according to embodiments of the
present invention.
FIG. 5 is a process flow diagram for forming one or more polymer
waveguides of a structure according to an embodiment of the
present invention.
FIG. 6 is a perspective schematic view showing respective
directions along which truss elements of a structure of an
embodiment of the present invention extend.
FIG. 7 is schematic diagram of a system for forming a functionally
graded 3D ordered open-cellular microstructure according to an
embodiment of the present invention.
FIG. 8 illustrates a top view schematic of a system for forming a
functionally graded 3D ordered open-cellular microstructure
according to an embodiment of the present invention.
FIGS. 9a, 9b, and 9c represent 2D schematics of three-dimensional
functionally graded microstructures according to embodiments of
the present invention.
FIG. 10 is a process flow diagram for forming a functionally
graded 3D ordered open-cellular microstructure according to an
embodiment of the present invention.
US7382959
OPTICALLY ORIENTED THREE-DIMENSIONAL POLYMER
MICROSTRUCTURES
A method and system of creating one or more waveguides and/or
patterning these waveguides to form a 3D microstructure that uses
mask and collimated light. In one embodiment, the system includes
at least one collimated light source selected to produce a
collimated light beam; a reservoir having a photo-monomer adapted
to polymerize by the collimated light beam; and a mask having at
least one aperture and positioned between the at least one
collimated light source and the reservoir. Here, the at least one
aperture is adapted to guide a portion of the collimated light
beam into the photo-monomer to form the at least one polymer
waveguide through a portion of a volume of the photo-monomer.
FIELD OF THE INVENTION
The present invention relates to patterning one or more polymer
waveguides to form an ordered three-dimensional (3D)
microstructure and/or a system and method to fabricate the one or
more polymer waveguides.
BACKGROUND OF THE INVENTION
An ordered three-dimensional (3D) microstructure is an ordered 3D
structure at the micrometer scale. Currently, polymer cellular
materials that are mass produced are created through various
foaming processes, which all yield random (not ordered) 3D
microstructures. Techniques do exist to create polymer materials
with ordered 3D microstructures, such as stereolithography
techniques; however, these techniques rely on a bottom-up,
layer-by-layer approach which prohibits scalability.
A stereolithography technique is a technique that builds a 3D
structure in a layer-by-layer process. This process usually
involves a platform (substrate) that is lowered into a
photo-monomer (photopolymer) bath in discrete steps. At each step,
a laser is scanned over the area of the photo-monomer that is to
be cured (polymerized) for that particular layer. Once the layer
is cured, the platform is lowered a specific amount (determined by
the processing parameters and desired feature/surface resolution)
and the process is repeated until the full 3D structure is
created. One example of such a stereolithography technique is
disclosed in Hull et al., "Apparatus For Production Of
Three-Dimensional Objects By Stereolithography," U.S. Pat. No.
4,575,330, Mar. 11, 1986, which is incorporated by reference
herein in its entirety.
Modifications to the above described stereolithography technique
have been developed to improve the resolution with laser optics
and special resin formulations, as well as modifications to
decreasing the fabrication time of the 3D structure by using a
dynamic pattern generator to cure an entire layer at once. One
example of such a modification is disclosed in Bertsch et al.,
"Microstereolithography: A Review," Materials Research Society
Symposium Proceedings, Vol. 758, 2003, which is incorporated by
reference herein in its entirety. A fairly recent advancement to
the standard stereolithography technique includes a two-photon
polymerization process as disclosed in Sun et al., "Two-Photon
Polymerization And 3D Lithographic Microfabrication," APS, Vol.
170, 2004, which is incorporated by reference herein in its
entirety. However, this advance process still relies on a
complicated and time consuming layer-by-layer approach.
3D ordered polymer cellular structures have also been created
using optical interference pattern techniques, also called
holographic lithography; however, structures made using these
techniques have an ordered structure at the nanometer scale and
the structures are limited to the possible interference patterns,
as described in Campbell et al., "Fabrication Of Photonic Crystals
For The Visible Spectrum By Holographic Lithography," NATURE, Vol.
404, Mar. 2, 2000, which is incorporated by reference herein in
its entirety.
Previous work has also been done on creating polymer optical
waveguides. A polymer optical waveguide can be formed in certain
photopolymers that undergo a refractive index change during the
polymerization process. If a monomer that is photo-sensitive is
exposed to light (typically UV) under the right conditions, the
initial area of polymerization, such as a small circular area,
will "trap" the light and guide it to the tip of the polymerized
region due to this index of refraction change, further advancing
that polymerized region. This process will continue, leading to
the formation of a waveguide structure with approximately the same
cross-sectional dimensions along its entire length. The existing
techniques to create polymer optical waveguides have only allowed
one or a few waveguides to be formed and these techniques have not
been used to created a self-supporting three-dimensional structure
by patterning polymer optical waveguides.
As such, there continues to be a need to create polymer cellular
materials with ordered microstructures on a large and useful scale
using a simple technique.
SUMMARY OF THE INVENTION
An aspect of the present invention provides a method and system of
fabricating polymer cellular (porous) materials with an ordered
three-dimensional (3D) microstructure using a simple technique.
These cellular materials are created from a pattern of
self-propagating polymer waveguides, which are formed in an
appropriate photopolymer. This method and system can create truly
3D microstructures without building the structures layer-by-layer
as with stereolithography and other prototyping techniques.
Another aspect of the present invention creates polymer cellular
materials with ordered microstructures on a large and useful
scale.
In an embodiment of the present invention, a system for forming at
least one polymer waveguide is provided. The system includes at
least one light source selected to produce a light beam; a
reservoir having a photo-monomer adapted to polymerize by the
light beam; and a patterning apparatus adapted to guide a portion
of the light beam into the photo-monomer to form the at least one
polymer waveguide through a portion of a volume of the
photo-monomer.
In one embodiment of the system, the at least one light source
includes at least one collimated light source, the light beam is a
collimated light beam, the patterning apparatus includes a mask
having at least one aperture and positioned between the at least
one collimated light source and the reservoir, and the at least
one aperture is adapted to guide the portion of the collimated
light beam into the photo-monomer to form the at least one polymer
waveguide through the portion of the volume of the
photo-monomer...
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, together with the specification,
illustrate exemplary embodiments of the present invention, and,
together with the description, serve to explain the principles of
the present invention.
FIG. 1 is a schematic diagram of a system to form a single
waveguide from a single collimated beam through a single aperture
pursuant to aspects of the present invention;
FIG. 2 illustrates examples of different aperture shapes pursuant
to aspects of the present invention;
FIG. 3 is a schematic diagram of a system to form multiple
waveguides from a single collimated beam or multiple collimated
beams through a single aperture pursuant to aspects of the present
invention;
FIG. 4 is a schematic diagram of a system to form a 3D structure
(e.g., a 3D ordered polymer microstructure) formed from multiple
waveguides created using a single collimated beam or multiple
collimated beams through multiple apertures pursuant to aspects of
the present invention;
FIG. 5a illustrates an example of a square mask pattern (or a
square mask aperture pattern) pursuant to aspects of the present
invention;
FIG. 5b illustrates an example of a hexagonal mask pattern (or a
hexagonal mask aperture pattern) pursuant to aspects of the
present invention;
FIG. 6 is a process flow diagram for forming one or more polymer
waveguides pursuant to aspects of the present invention;
FIGS. 7a, 7b, 7c, and 7d are SEM micrographs of a sample 3D
polymer microstructure pursuant to aspects of the present
invention;
FIG. 8 is a 3D diagram for illustrating a formation of a 3D
ordered polymer microstructure pursuant to aspects of the present
invention; and
FIG. 9 is another 3D diagram for illustrating a formation of a 3D
ordered polymer microstructure pursuant to aspects of the present
invention.
US8353240
Compressible fluid filled micro-truss for energy
absorption
A kinetic energy and blast energy absorbing material includes: a
micro-truss structure including: a plurality of first struts
extending along a first direction; a plurality of second struts
extending along a second direction; and a plurality of third
struts extending along a third direction; and a compressible fluid
comprising a liquid or gel and a nanoporous material, wherein the
micro-truss structure contains the compressible fluid.
BACKGROUND
Cellular, or porous, materials have the ability to absorb
significantly more energy than solid structures because of their
ability to become denser (e.g., “densify”) in response to impacts.
As such, cellular materials such as metallic or ceramic foams have
been proposed as an energy absorbing layer in armor-type systems.
However, the random microstructure of these materials severely
diminishes their mechanical properties. The deformation of a
cellular foam is dominated by the bending behavior of the cell
struts. Simple mechanics dictates that bending dominated
structures are less efficient in load carrying capacity than
compression dominated behavior exemplified by a truss structure.
Due this mechanical inefficiency, some fraction of the mass in the
foam does not participate in energy absorption and represents
added or parasitic weight.
U.S. Pat. Nos. 6,698,331 and 7,128,963, which are
incorporated by reference herein in their entirety, propose blast
protection material systems that incorporate random cellular
ceramic or metallic foam as an energy absorbing layer. However,
these patent disclosures do not provide an ordered micro-truss
structure. The use of metallic lattice (truss) materials for
energy absorbing application is discussed in U.S. Pat. No.
7,382,959 and U.S. patent application Ser. Nos. 11/801,908;
12/008,479; 12/074,727, 12/075,033, and 12/455,449 which are
incorporated by reference herein in their entirety. Methods of
manufacturing a micro-truss structure are described, for example,
in U.S. patent application Ser. No. 12/455,449, which discloses a
method of fabricating micro-truss structures having a fixed area,
and 12/835,276, which discloses a method of continuously
fabricating micro-truss structures according to a continuous
process (e.g., a strip of arbitrary length), which are
incorporated by reference herein in their entirety. However, there
is still a demand for an impact or blast energy absorbing material
that is light weight.
Compressible fluids have the ability to absorb a significant
amount of energy. U.S. patent application Ser. No. 11/720,784,
which is incorporated by reference herein in its entirety,
describes a compressible fluid which may include a nanoporous
material immersed in a non-wetting liquid which is compressed when
external forces push the liquid into the nanopores of the
material.
An explosive blast typically comprises an air pressure wave
characterized by an overpressure P0 in excess of the ambient
pressure Pa (and where P0/e and ti indicate that the pressure
drops exponentially) with an associated impulse per unit area, as
illustrated, e.g., in FIGS. 11a and 11b. In order for an
intervening medium to protect a structure against the overpressure
P0, the medium must reduce the pressure below the structure's
damage threshold σth. This can be achieved by the intervening
medium's undergoing a large volume decrease at a constant
pressure, thereby extending the duration of the impulse.
The above information disclosed in this Background section is only
for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person skilled in the art.
SUMMARY
Aspects of embodiments of the present invention relate to a
micro-truss based structural apparatus with compressible fluid for
absorbing energy from impacts or pressure waves (e.g., a fluidic
micro-truss based impact or blast protection apparatus).
Aspects of embodiments of the present invention are directed
toward a fluidic micro-truss based blast protection apparatus
which is capable of absorbing energy from an impact or a pressure
wave. Aspects of embodiments of the present invention are directed
toward a fluidic micro-truss blast protection system which may be
used as a component of personal armor, a component of vehicle
armor (e.g., on a Humvee), or a component of a blast protection
wall (e.g., a Bremer wall) in order to provide additional
protection against collisions, projectiles (e.g., bullets), and
blasts (e.g., from improvised explosive devices (IEDs)).
Aspects of embodiments of the present invention are also directed
toward a fluidic micro-truss blast protection system which may be
used on internal surfaces of a vehicle to provide additional
protection for passengers.
According to embodiments of the present invention, polymer
micro-truss structures, which are formed by interconnecting
self-propagating polymer waveguides (or struts), are converted to
lightweight, high-strength materials such as carbon, metals,
ceramics, or polymers (e.g., high toughness polymers) or
composites thereof, that are utilized by the micro-truss based
protection apparatuses for high velocity impact or pressure wave
applications. According to embodiments of the present invention,
these micro-truss structures are combined with a compressible
fluid, e.g., a suspension of nanoporous particles in a liquid or
gel (which may be referred to as a
“nanoporous-materials-functionalized (NMF) fluid”), to provide
additional energy absorbing characteristics.
According to one embodiment of the present invention, a kinetic
energy and blast energy absorbing material includes: a micro-truss
structure including: a plurality of first struts extending along a
first direction; a plurality of second struts extending along a
second direction; and a plurality of third struts extending along
a third direction; and a compressible fluid comprising a liquid or
gel and a nanoporous material, wherein the micro-truss structure
contains the compressible fluid.
The compressible fluid may be a compressible nano-porous materials
functionalized (NMF) fluid. The NMF fluid may be a liquid or a
gel. The NMF fluid may include a nanoporous material and an
infiltration fluid, wherein the infiltration fluid is nonwetting
to the nanoporous material. The nanoporous particles may be silica
based nanoporous particles. The nanoporous particles may be a
hydrophobic zeolite. The nanoporous particles may be a nanoporous
carbon. The nanoporous carbon may be a mercaptohexadecanoic acid
(MHA) treated nanoporous carbon.
The nanoporous particles may have a surface area at 100
m<2>/g or 2000 m<2>/g or between 100 m<2>/g and
2000 m<2>/g.
The infiltration fluid may include water, an aqueous solution of
electrolytes, a viscous liquid, a liquid metal, a gel, a polymer,
or a combination thereof.
The struts of the kinetic energy and blast energy absorbing
material may be hollow.
The compressible fluid may be located within the hollow struts.
Each of the hollow struts may have a diameter from 10 microns to
10 mm.
A wall of each of the struts may have a thickness from 1 micron to
1 mm.
The compressible fluid may be located between the struts.
The kinetic energy and blast absorbing material may be configured
to be part of a protective piece of clothing.
The kinetic energy and blast energy absorbing material may be
configured to be part of a wall of a building.
The first, second, and third struts may include a metal. The metal
may be nickel, aluminum, titanium, steel, or alloys thereof.
The first, second, and third struts may include a polymer. The
polymer may be a polycarbonate, an aramid, a high impact
polystyrene, a nylon, an ultra-high molecular weight polyethylene,
and combinations thereof.
The micro-truss structure may fill 0.5% to 30% of a volume of the
material and the NMF fluid may fill 5% to 95% of the volume.
The first, second, and third directions may be at a first angle
between 45° and 70° with respect to a facesheet attached to a
plurality of first ends of the first, second, and third struts.
The kinetic energy and blast absorbing material may further
include a plurality of fourth struts extending in a fourth
direction substantially perpendicular with respect to a facesheet
attached to a plurality of first ends of the first, second, and
third struts.
The plurality of first, second, third and fourth struts may be
hollow and may comprise metal and the first, second, third and
fourth struts may each have a diameter of 2 mm and a wall
thickness of 0.1 mm, wherein the micro-truss structure has a unit
cell height of 15 mm, wherein each of the first, second, and third
directions is at an angle of 60° with respect to the facesheet,
wherein the compressible fluid may be an aqueous suspension of 40%
by weight hydrophobic nanoporous silica gel and may be located
within the hollow portions of plurality of first, second, third
and fourth struts, and wherein the micro-truss structure may fill
5% of the volume of the kinetic energy and blast energy absorbing
material and the compressible fluid may fill 25% of the volume of
the kinetic energy and blast energy absorbing material.
The plurality of first, second, third and fourth struts may be
hollow and may comprise metal and the first, second, third and
fourth struts may each have a diameter of 2 mm and a wall
thickness of 0.1 mm, wherein the micro-truss structure has a unit
cell height of 15 mm, wherein each of the first, second, and third
directions is at an angle of 60° with respect to the facesheet,
wherein the compressible fluid may be an aqueous suspension of 7%
by weight hydrophobic nanoporous silica gel in polyacrylic acid
gel and may be located within the hollow portions of plurality of
first, second, third and fourth struts, and wherein the
micro-truss structure may fill 5% of the volume of the kinetic
energy and blast energy absorbing material and the compressible
fluid may fill 25% of the volume of the kinetic energy and blast
energy absorbing material...
BRIEF DESCRIPTION OF THE DRAWINGS
The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawing(s) will be provided by the Office
upon request and payment of the necessary fee.
The accompanying drawings, together with the specification,
illustrate exemplary embodiments of the present invention, and,
together with the description, serve to explain the principles of
the present invention.
FIG. 1 is a perspective view of a portion of an ordered 3D
micro-truss structure according to aspects of the present
invention.
FIG. 2 is a perspective view of an ordered 3D micro-truss
structure according to aspects of the present invention.
FIG. 3a is a schematic cross-sectional diagram at an exposure area
of a channel of a system for forming a structure from multiple
waveguides created using a single collimated beam or multiple
collimated beams passing through multiple apertures located at the
bottom of the channel.
FIG. 3b is a schematic cross-sectional diagram at an exposure area
of a channel of a system similar to that of FIG. 3a, but where the
collimated beam or beams pass through multiple apertures located
above the channel.
FIG. 4a illustrates a square mask pattern (or a square mask
aperture pattern) according to an embodiment of the present
invention.
FIG. 4b illustrates a hexagonal mask pattern (or a hexagonal mask
aperture pattern) according to an embodiment of the present
invention.
FIG. 5 is a schematic representation of a system for forming an
ordered 3D micro-truss structure according to an embodiment of the
present invention from multiple waveguides created using a single
collimated beam or multiple collimated beams through multiple
apertures and a moving mask.
FIG. 6 is a photograph of a micro-truss structure according to one
embodiment of the present invention.
FIG. 7 is a graph comparing compressive stress as a function of
nominal strain for micro-truss structures with and without 90°
truss members (as depicted) having relative densities of 1.8% and
1.4% respectively, according to one embodiment of the present
invention.
FIG. 8a is a graph comparing sorption isotherm curves for zeolite
based NMF fluids including a solution of NaCl at a variety of
concentrations according to one embodiment of the present
invention.
FIG. 8b is a graph comparing sorption isotherm curves for carbon
based NMF fluids in which the carbon surface treating carbon
surfaces with mercaptohexadecanoic acid (MHA) according to one
embodiment of the present invention.
FIG. 8c is a graph comparing sorption isotherm curves of a silica
based NMF fluid in glycerin-water mixtures having a variety of
concentrations of glycerin according to one embodiment of the
present invention.
FIG. 8d is a graph comparing sorption isotherm curves of a
nanoporous carbon in polypropylene during first and second
loadings according to one embodiment of the present invention.
FIG. 8e is a graph comparing sorption isotherm curves of a silica
based gel matrix NMF fluid during successive infiltration cycles
according to one embodiment of the present invention.
FIG. 8f is a graph comparing sorption isotherm curves of a carbon
based NMF fluid in mercury during first and second loadings
according to one embodiment of the present invention.
FIG. 8g is a graph comparing sorption isotherm curves of a silica
based NMF fluid in which the silica particles have been treated
for various amounts of time according to one embodiment of the
present invention.
FIG. 9 is a graph illustrating a relationship between pressure and
specific volume change for an NMF fluid during a plurality of
cycles according to one embodiment of the present invention.
FIGS. 10a and 10b illustrate the effect of a blast on a
micro-truss structure according to one embodiment of the present
invention (figure adapted from A. G. Evans, M. Y. He, V. S.
Deshpande, J. W. Hutchinson, A. J. Jacobsen, W. B. Carter,
“Concepts for enhanced energy absorption using hollow
micro-lattices,” Int. Journal of Impact Engineering 37 (9), p.
947-959 (2010)).
FIG. 11 illustrates the effect the effect of a blast on a fluidic
micro-truss structure in which an NMF fluid is located within
hollow struts of the micro-truss structure according to one
embodiment of the present invention.
FIG. 12 is a graph comparing the energy absorbed per unit mass
versus transmitted stress for a variety of energy absorbing
materials in a non-dimensional form that distinguishes topology
effects from the influence of material properties. The projected
best performance of a fluidic micro-truss structure according to
one envisioned embodiment of the present invention is included.
(Figure adapted from A. G. Evans, M. Y. He, V. S. Deshpande, J. W.
Hutchinson, A. J. Jacobsen, W. B. Carter, “Concepts for enhanced
energy absorption using hollow micro-lattices,” Int. Journal of
Impact Engineering 37 (9), p. 947-959 (2010).)
FIG. 13 illustrates the effect of a blast on a fluidic micro-truss
structure in which an NMF fluid is located between the struts of
the micro-truss structure according to one embodiment of the
present invention.
FIG. 14 illustrates an application of a fluidic micro-truss
structure according to one embodiment of the present invention in
which the fluidic micro-truss structure is used to provide blast
protection for a vehicle.
WO2015095617
STRUCTURES HAVING SELECTIVELY METALLIZED REGIONS AND
METHODS OF MANUFACTURING THE SAME
Methods of manufacturing a structure having at least one plated
region and at least one unplated region. The method includes
plating a metal on a polymer structure having a first region
accepting the metal and a second region unreceptive to the metal
plating. The first region may include fully-cured polymer optical
waveguides and the second region may include partially-cured
polymer optical waveguides. The first region may include a first
polymer composition and the second region may include a second
polymer composition different than the first polymer composition.
FIELD
[0001] The present invention relates generally to polymer
structures and, more particularly, to partially metallized polymer
structures.
BACKGROUND
[0002] Metallized components are ubiquitous. Components are
commonly metallized for aesthetic, structural, conductive, and/or
corrosion resistance purposes. Related processes for metallizing
components include painting, dipping, electroplating, electroless
plating, spraying, sputtering, and laser activation. Processes for
metallizing components are typically directed at uniformly coating
the component. Non-metallized portions of the component are
typically the result of uncontrollable variation, which is
indicative of an unsuccessful process and therefore such partially
metallized components are typically discarded.
[0003] Additionally, related processes for metallizing components
are typically limited to line-of-sight coverage of the component.
For instance, related metallizing processes may be limited to
metallizing only external surfaces of the component. Additionally,
related metallizing processes may be restricted to components
having limited sizes and geometries (e.g., related metallizing
techniques may be limited to the two-dimensional coating of flat
components, such as circuit boards). Thus, related metallizing
processes may be suitable only for components having limited sizes
and architectures.
SUMMARY
[0004] Aspects of embodiments of the present disclosure are
directed toward various methods for manufacturing a structure
having at least one plated region and at least one unplated
region. In one embodiment, the method includes plating a metal on
a polymer structure having a first region accepting the metal and
a second region unreceptive to the metal. The polymer structure
may include a plurality of interconnected polymer optical
waveguides arranged in a unitary lattice structure. Plating the
polymer structure may include conditioning the polymer structure,
etching the polymer structure, neutralizing the polymer structure,
catalyzing the polymer structure, immersing the polymer structure
in an accelerator, and immersing the polymer structure in an
electroless bath. Plating the polymer structure may include a
catalyst poisoning method, an inhibition of metal reaction method,
an over-etched polymer surface method, an increased etch rate-
post process method, an uncured surface inhibition of plating
method, or an etch resistant polymer- prevention of catalyst
deposition method. The first region may include fully-cured,
cross-linked polymer optical waveguides and the second region may
include partially-cured polymer optical waveguides. The first
region may include a first, polymer composition, and the second
region may include a second polymer composition different than the
first polymer composition.
[0005] The method may also include immersing the polymer structure
in a catalyst inhibitor that deposits onto the second region of
the polymer structure and is repelled by the first region of the
polymer structure. The method may also include immersing the
polymer structure in a reaction inhibitor that deposits onto the
second region of the polymer structure and is repelled by the
first region of the polymer structure. The method may also include
etching the polymer structure. The first region of the polymer
structure may etch at a first rate and the second region of the
polymer structure may etch at a second rate different than the
first rate. The method may also include forming the polymer
structure by irradiating one or more photo-monomers with a series
of light beams. The polymer structure may include a series of
interconnected polymer optical waveguides arranged in a unitary
lattice structure. The method may also include forming the polymer
structure by irradiating a volume of a first photo-monomer with a
series of light beams to form the first region of the polymer
structure and irradiating a volume of a second photo-monomer with
a series of light beams to form the second region of the polymer
structure. The method may also include forming the polymer
structure by an additive manufacturing process, such as
stereolithography, digital light processing, fused deposition, or
selective laser sintering...
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] These and other features and advantages of embodiments of
the present disclosure will become more apparent by reference to
the following detailed description when
considered in conjunction with the following drawings. In the
drawings, like reference
numerals are used throughout the figures to reference like
features and components. The figures are not necessarily drawn to
scale.
[0011] FIGS. 1 A-1K are side views of partially metallized
three-dimensional structures 15 according to various embodiments
of the present disclosure;
[0012] FIGS. 2A-2C illustrate tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to one
embodiment of the present disclosure;
[0013] FIG. 3 is a flowchart illustrating tasks of metallizing the
one or more regions of the polymer structure of FIG. 2C that are
receptive to metal plating according to one embodiment of the
present disclosure;
[0014] FIG. 4 is a partial side view of a series of interconnected
hollow struts according to one embodiment of the present
disclosure;
J [0015] FIGS. 5A-5C illustrate tasks of forming a polymer
structure having one or more regions receptive to metal plating
and one or more regions unreceptive to metal plating according to
another embodiment of the present disclosure;
[0016] FIG. 6 illustrates tasks of forming a polymer structure
having one or more regions 0 receptive to metal plating and one or
more regions unreceptive to metal plating according to a further
embodiment of the present disclosure;
[0017] FIGS. 7A-7D illustrate tasks of forming a polymer structure
having one or more regions receptive to metal plating and one or
more regions unreceptive to metal plating according to another
embodiment of the present disclosure; and
[0018] FIGS, 8A and 8B illustrate tasks of forming a polymer
structure having one or more regions receptive to metal plating
and one or more regions unreceptive to metal plating according to
one embodiment of the present disclosure.
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