U.S. patent application number 17/175735 was filed with the patent office on 2021-06-03 for system optimization using compressed reticulated foam structures.
This patent application is currently assigned to ERG Aerospace Corporation. The applicant listed for this patent is ERG Aerospace Corporation. Invention is credited to Mark BENSON, Mitchell HALL, Denver SCHAFFARZICK.
Application Number | 20210164072 17/175735 |
Document ID | / |
Family ID | 1000005404408 |
Filed Date | 2021-06-03 |
United States Patent
Application |
20210164072 |
Kind Code |
A1 |
HALL; Mitchell ; et
al. |
June 3, 2021 |
SYSTEM OPTIMIZATION USING COMPRESSED RETICULATED FOAM
STRUCTURES
Abstract
Heterogeneously dense (relative density) continuous one-piece
insoluble reticulated foam material with a continuous relative
density gradient and/or distinct and marked relative densities and
methods of manufacture.
Inventors: |
HALL; Mitchell; (Reno,
NV) ; SCHAFFARZICK; Denver; (Pacifica, CA) ;
BENSON; Mark; (Carmel, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ERG Aerospace Corporation |
Oakland |
CA |
US |
|
|
Assignee: |
ERG Aerospace Corporation
Oakland
CA
|
Family ID: |
1000005404408 |
Appl. No.: |
17/175735 |
Filed: |
February 15, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16679166 |
Nov 9, 2019 |
10920299 |
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17175735 |
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PCT/US2018/032468 |
May 11, 2018 |
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16679166 |
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62504946 |
May 11, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 70/00 20141201;
C22C 1/08 20130101 |
International
Class: |
C22C 1/08 20060101
C22C001/08; B33Y 70/00 20200101 B33Y070/00 |
Claims
1.-19. (canceled)
20. A heterogeneously dense continuous one-piece insoluble
reticulated open-celled foam metal or alloy material comprising (a)
partially collapsed open cells ranging in size and having a maximum
diameter of 4 mm and a minimum diameter of 0.35 mm; (b) ligaments
having a width of 0.025 mm to 0.7 mm; (c) pores formed by the
ligaments; and (d) a relative density gradient within the
heterogeneously dense one-piece insoluble reticulated open celled
foam metal or alloy material ranging from at least 3% in density at
a least dense point to 85% density at a most dense point.
21. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient is continuous across the one-piece
insoluble reticulated open-celled foam metal or alloy material.
22. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient is formed from the collapsing of the
cells.
23. The heterogeneously dense foam material of claim 20, wherein
pores formed by the ligaments are deformed.
24. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient occurs along a single direction.
25. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient occurs across two directions.
26. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient occurs across three dimensions.
27. The heterogeneously dense foam material of claim 20, wherein
the relative density within the foam material is a continuous
gradient that ranges from 10% to 33% and all values
therebetween.
28. The heterogeneously dense foam material of claim 20, wherein
the relative density within the foam material is a continuous
gradient that ranges from 25% and 70%, and all values
therebetween.
29. The heterogeneously dense foam material of claim 20, wherein
the relative density gradient within the foam has distinct and
marked differences.
30. The heterogeneously dense foam material of claim 29, wherein
the relative density within the foam is 10%, 25%, and 33%.
31. The heterogeneously dense foam material of claim 29, wherein
the relative density within the foam is 25% and 33%.
32. The heterogeneously dense foam material of claim 20, wherein
the cell diameters have a maximum diameter of 3.72 mm and a minimum
diameter of 0.55 mm.
33. The heterogeneously dense foam material of claim 20, wherein
the ligament width is 0.028 mm to 0.65 mm.
34. The heterogeneously dense foam material of claim 20, wherein
the pore size is 0.025 mm to 0.65 mm.
35. A blunt trauma foam protection barrier comprising the
heterogeneously dense foam material of claim 20.
36. A heat exchanger comprising the heterogeneously dense foam
material of claim 20.
37. An energy absorber comprising the heterogeneously dense foam
material of claim 1.
38. A filter comprising the heterogeneously dense foam material of
claim 1.
Description
TECHNICAL FIELD
[0001] Embodiments of the present invention relate to the technical
field of reticulated foam structures. More particularly, the
embodiments of the present invention are directed toward
heterogeneous reticulated foam structures.
BACKGROUND OF THE INVENTION
[0002] DUOCEL.RTM. foam is a material manufactured by ERG Aerospace
Corporation (www.ergaerospace.com). The material has been
manufactured, engineered to meet end user applications, and sold by
ERG Aerospace Corporation since 1967. The original manufacturing
patent for DUOCEL.RTM. is listed as U.S. Pat. No. 3,616,841 and
advances in manufacturing methods have progressed the use of
DUOCEL.RTM. as a material solution for a broad number of
applications.
[0003] DUOCEL.RTM. is an open celled foam structure that takes on
the characteristics of a base organic alloy. These base alloys
typically consist of low temperature alloys such as aluminum,
copper, zinc, and other refractory metals. The advantages of an
open celled foam structure is that the material offers high surface
areas and outstanding strength to weight ratios. Unlike closed cell
foams, gases, liquids, and other mediums may pass through the pores
of the material. This enables the material to be used in
applications such as heat exchangers, energy absorbers, baffles,
structural support members, and other applications that take
advantage of the homogeneous open celled framework of the
material.
[0004] DUOCEL.RTM. is manufactured in a range of pore sizes. These
sizes include 5 pores per inch (PPI), 10 PPI, 30 PPI, and 40 PPI.
The advantage of having different pore sizes is that the material
may be optimized for different applications. As an example, if high
pressure gas diffusion is a primary requirement of an end user,
then the 40 PPI material can be chosen to provide adequate pressure
drop given the higher surface area. Conversely, a 5 PPI material
may provide less pressure drop but the material may weigh less.
Therefore, there is a weight and performance consideration for the
specific PPI chosen. Specific examples of where this applies is
with the design of filtration systems where flow rates and pressure
drops are primary input parameters for optimizing the performance
of a pump. Other applications include heat exchangers, energy
absorbers, and other mechanical systems where there may exist a
unique and single optimized system solution.
[0005] It is also possible to control the relative density of
DUOCEL.RTM. for each of the pore sizes referred to above. In other
words, it is possible to add material to the individual ligaments
of DUOCEL.RTM. to create relative density ranges. As an example, a
5 PPI piece of DUOCEL.RTM. may be modified at the individual
ligament level to achieve relative density ranges anywhere from 3
to 20 percent relative density (relative to the weight of the solid
alloy). The relative density, much like the PPI, may be modified as
a design parameter to meet end user requirements. A DUOCEL.RTM.
part or insert that maintains the same porosity and relative
density is considered homogeneous.
[0006] Another unique feature of DUOCEL.RTM. is that the material
is composed of interconnected solid ligament structures or cells.
Conversely, open celled foam materials that are manufactured using
a chemical vapor deposition (CVD) type processes utilize a host
structure as a base for additive materials. These host structures
are typically plastic or other materials that do not mirror the
same composition as the CVD additive. The result is that CVD type
manufactured foams are considered hollow and result in lower yield
stresses (or lower foam modulus). In other words, the individual
ligaments lack a homogeneous make up and fail when loading the
material at lower thresholds then DUOCEL.RTM.. This material
disadvantage reduces the yield stress of parts manufactured
utilizing the CVD technique, reduces thermodynamic properties of
the material, creates non-homogeneous boundary layers between the
CVD layers, and limits the design power of using CVD parts for
unique engineering solutions when compared to DUOCEL.RTM..
[0007] Other additive manufacturing processes, to include 3-D
printing, are also at a disadvantage when compared to the
versatility of DUOCEL.RTM.. As mentioned above, inconsistent
temperature profiles during the additive manufacturing process
create degraded boundary layer affects when compared to
DUOCEL.RTM.. Most 3-D printing techniques also create slip planes
in between layers. These factors cause additive manufacturing
processes to be weaker (have a lower yield stress) and limits their
energy absorption capabilities and pressure drop design
capability.
[0008] One advantage that 3-D printing has over DUOCEL.RTM. is that
the porosity and relative density of a supporting matrix may be
varied across the entire part, validated, and then printed during
the build process. Currently, 3-D printers are unable to print the
complex geometries that DUOCEL.RTM. provides.
[0009] In addition, open celled foam structures that are
manufactured using additive processes, to include CVD and 3-D
printing, often fail when compressed due to the lower yield stress
(foam modulus) and are therefore limited to being densified to
ranges below 30% relative density. The limit in the ability to
compress these types of materials reduces their ability to meet
unique design solutions.
BRIEF SUMMARY OF THE INVENTION
[0010] Therefore, there is a need to create heterogeneous relative
density open celled DUOCEL.RTM. structures or inserts from an
original homogeneous relative density part in order to provide
optimized system performance Doing so would enable DUOCEL.RTM. the
ability to directly compete with 3-D printed structures where
relative density and porosity may be modified across an entire
part.
[0011] Furthermore, there is a need to create customized
DUOCEL.RTM. parts where relative density ranges anywhere from 3-85%
for a single part in order to provide engineers with versatile
system solutions. These relative density ranges may be created by
densifying the material along a single direction (along the
x-axis), across two directions (along the x-y axes), or across the
material in three dimensions (along the x-y-z axes).
[0012] It is a further objective of the present invention to create
heterogeneous DUOCEL.RTM. structures where the relative density
range differs throughout the structure when densified. These types
of structures offer a versatile material solution where each zone
of DUOCEL.RTM. is densified to meet any number of system
requirements within a zone or presents a progressive range of
relative densities across the structure.
[0013] It is yet a further objective of the present invention to
introduce methods of manufacturing that creates heterogeneous foam
structures and densified foam structures utilizing presses and
dies. These types of manufacturing procedures are inexpensive and
tight tolerances can be held. Reduced setup time for the dies and
presses, the simplicity of a hydraulic press when compared to
tooling machines, and overall throughput makes this approach
inexpensive and more efficient when compared to CNC machinery or
3-D printing.
[0014] It is a further objective of the present invention to use
heterogeneous DUOCEL.RTM. parts or inserts as energy absorbers,
filters, heat exchangers or other applications where system
performance may be optimized through heterogeneous relative
densification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will become more fully understood from
the detailed description given herein below and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0016] FIG. 1 is a perspective view of a homogeneous relative
density continuous one-piece insoluble reticulated open celled foam
material (1).
[0017] FIG. 2 is a perspective view of a single cell (2) of a
homogeneous relative density continuous one-piece insoluble
reticulated open celled foam material (1).
[0018] FIG. 3 is a perspective view of a heterogeneous relative
density continuous one-piece insoluble reticulated open celled foam
material (5).
[0019] FIG. 4 is a perspective view of a single cell (2) of a
heterogeneous relative density continuous one-piece insoluble
reticulated open celled foam material (5) after densification.
[0020] FIG. 5A is a table that provides data points from
stress-strain relationships from densification of a heterogeneous
relative density continuous one-piece insoluble reticulated open
celled foam material (5).
[0021] FIG. 5B is a stress strain curve that demonstrates the
different relative density properties of a single heterogeneous
relative density continuous one-piece insoluble reticulated open
celled foam material (5) when assessed for different sections of
the material (L1-L3).
[0022] FIG. 6A is a perspective view of an application where a
single heterogeneous relative density continuous one-piece
insoluble reticulated open celled foam material (5) is used to
demonstrate energy absorption system optimization.
[0023] FIG. 6B is a perspective view of the same system above.
[0024] FIG. 7 is a perspective view of an example of a die set for
manufacturing heterogeneous relative density continuous one-piece
insoluble reticulated open celled foam material.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0025] The present invention will now be described in detail with
reference to the accompanying drawings, wherein the same reference
numerals will be used to identify the same or similar elements
throughout the several views. It should be noted that the drawings
should be viewed in the direction of orientation of the reference
numerals.
[0026] FIG. 1 illustrates a homogeneous relative density continuous
one-piece insoluble reticulated open celled foam material (1). The
part has a relative density of 10%.
[0027] FIG. 2 illustrates a single cell (2) of a homogeneous
continues one-piece insoluble reticulated open celled foam material
(1) where each cell (2) is generally characterized as a bubble
shaped 14 sided polyhedral or solid shape tetrakaidekahedron.
Within each cell (2) is a series of pores (3) that create the open
celled architecture and each pore (3) is defined by a number of
solid ligaments (4). These ligaments (4) take on the properties of
the base alloy and examples include aluminum, titanium, copper, and
other metals. Typically, the ligament width is 0.025 mm to 0.65 mm,
such as 0.028 mm to 2.8 mm, 0.05 mm to 2.8 mm, 0.05 mm to 0.5 mm,
0.05 to 0.65 mm, 0.1 mm to 0.5 mm, 0.1 mm to 0.7 mm, or any range
of values falling between 0.025 mm and 0.7 mm. For example, a 10
PPI material can have a mean value ligament thickness of 0.41 mm or
a 20 PPI material can have a mean value ligament thickness of 0.31
mm, while a 40 PPI material can have a mean value ligament
thickness of 0.18 mm.
[0028] Ligament (4) thickness differs based on the density of the
homogeneous continuous one-piece insoluble reticulated open celled
foam material (1). As shown in FIG. 2, a 10% relative dense
ligament that consists of 10 pores (3) per inch (approximated) has
a mean value thickness diameter or width of approximately 0.041 mm.
This creates an average cell (2) diameter for the material shown to
be approximately 2.2 mm.
[0029] FIG. 3 illustrates a single heterogeneously dense (relative
density) continuous one-piece insoluble reticulated foam material
(5) that has been fabricated from a homogeneous relative density
continuous one-piece insoluble reticulated open celled foam
material (1). The part has an overall width w, height h, and length
L and, in this example, the density varies along the length L of
the part. In fact, average relative densities vary across and along
three different sections of the part. Section one (6) of the part
remains at 10 pores (3) per inch, 10% relative density, and remains
unchanged along the length L1. Section two (7) of the part remains
at 10 pores (3) per inch but the relative density over the length
L2 has increased to an average of 25% where cell size diameter is
approximately 1.2 mm. Likewise, section three (8) has increased
relative density to an average of 35% along length L3 and a cell
size diameter of approximately 0.8 mm.
[0030] Typically, average cell diameters in heterologous relative
density continuous one-piece insoluble reticulated foam material
(5) range from about 0.35 mm to about 4 mm, such as 0.8 mm to 0.38
mm. If the densification process is continuously gradual across the
heterologous relative density continuous one-piece insoluble
reticulated foam material (5), then all intervening fractions
between the relative density of the least dense portion and the
relative density of the most dense portion are represented. If,
however, a part made from the particular heterologous relative
density continuous one-piece insoluble reticulated foam material
(5) is desired to have a number of set relative densities that
occur within the part in some type of a step-wise manner, then the
average cell diameters associated with only those relative
densities will be present. For example, if the part requires a
portion with a relative density of 10%, that is adjacent to a
portion with a relative density of 33%, that is adjacent to a
portion with a relative density of 25%, then the average cell size
diameters present in the part will be about 2.8 mm (10% relative
density), 0.8 mm (33% relative density), and 1.2 mm (25% relative
density).
[0031] FIG. 4 illustrates the changes of the ligament (4) after
densification reaching the 35% relative density of section three
(8). While the ligament (4) is shown to have buckled, the overall
structural integrity of the deformed pores (16) remains intact and
therefore provides strength to the heterogeneously dense (relative
density) continuous one-piece insoluble reticulated foam material
(5). Likewise, the collapsing of the cell (2) volume provides
increased fluid impedance when compared to the original relative
density. The changes made therefore afford one to modify the stress
strain performance characteristics and the impedance ability of the
foam to enhance system optimization.
[0032] Laboratory experimentation has confirmed stress-strain
relationships of the single heterogeneously dense (relative
density) continuous one-piece insoluble reticulated foam material
(5) for each of the sections (6-8) illustrated as a demonstration.
More specifically, experimentation was conducted and load vs.
deflection readings were obtained in the following manner: During
the first 100 mils of deflection, readings were taken at intervals
of 10 mils; thereafter, readings were recorded every 50 mils until
either a deflection of 500 mils was reached, or 150 mils with a
load in excess of 1000 pounds was reached, or 150 mils with a load
in excess of 10000 pounds was reached, or 10000 pounds was reached
after 150 mils, but before 500 mils. Data points collected are
presented in FIG. 5A.
[0033] FIG. 5B shows the stress-strain curves associated with each
section (6-8) of the single heterogeneously dense (relative
density) continuous one-piece insoluble reticulated foam material
(5). This loading distribution across the entire length L of the
single heterogeneously dense (relative density) continuous
one-piece insoluble reticulated foam material (5) is done to
demonstrate how a single part can meet versatile design
requirements where complex and different energy absorbing
properties throughout the length L might be required.
[0034] One example of the value of a single heterogeneously dense
(relative density) continuous one-piece insoluble reticulated foam
material (5) is the design and fabrication of a blunt trauma foam
protection barrier (11) as shown in FIG. 6. While body armor (10)
provides protection for soldiers and first responders against
bullets, the protective plate characteristically used in such
devices cannot alone reduce backside spalling that occurs when a
bullet strikes the protective plate. In other words, people who are
shot when wearing body armor typically experience blunt trauma due
to the backside effects of the protective plate.
[0035] Utilizing a single heterogeneously dense (relative density)
continuous one-piece insoluble reticulated foam material (5) within
a body armor (10) system, one may reduce the energy translated from
the body armor (10) to the individual. Furthermore, by changing the
relative density of that additional foam protection barrier (11),
vital organs (such as the heart that which is centered near the
middle of the chest) are protected with a thicker foam protection
barrier (11) where needed most. Likewise, the thinner foam located
at the edges of the protection barrier (11) within the body armor
(10) provides ample protection but also allows the individual to be
unencumbered in movement due to the low volume of the device.
[0036] FIG. 7 illustrates an example of a die set (12) that
manufactures the foam protective barrier (11) mentioned above. The
die set (12) consists of a male press (13), a female press (14),
and a place to insert a homogeneous (relative density) continuous
one-piece insoluble reticulated open celled foam material (1) in
order to transform it into a single heterogeneously dense (relative
density) continuous one-piece insoluble reticulated foam material
(5). To accomplish this, a series of manufacturing steps must be
implemented.
[0037] First, the homogeneous relative density continuous one-piece
insoluble reticulated open celled foam material (1) must be
structurally weakened through a heating process if the parts
measure thicker than 6 mm Typically, homogeneous relative density
continuous one-piece insoluble reticulated open celled foam
material (1) that is equal to or greater than 6 mm thick is heated
to 20-200.degree. C. Heating and weakening the structure may not be
needed for parts less than 6 mm thick because small parts tend to
have few cells (2) and thereby have adequate space to densify
without interference. In other words, a thin 10 pores (4) per inch
part with an original 10% relative density is limited in its
ability to reach high relative densities simply because the lack of
material present prevents it. As an example, a thin part might only
be able to reach a maximum density of only 20 to 25% relative
density.
[0038] For larger parts, a heating process, heat treatment, or
annealing process is undertaken to change the material properties
of the host alloy, as mentioned above. Ideally, this process
softens the material and enables it to become less brittle and more
ductile thereby ensuring uniform ligament (4) buckling during
densification. After the densification process, strength is
returned to the product by subjecting the heterogeneously densified
(relative density) foam material (5) to a heat treatment according
to ASTM International standards appropriate for the metal or alloy
used in the homogeneous relative density continuous one-piece
insoluble reticulated open celled foam material (1).
[0039] Once the material has been modified, the press and die
procedure may begin. This is initiated by first placing the
homogeneous relative density continuous one-piece insoluble
reticulated open celled foam material (1) within a female die set.
Once in position, a male die set is placed on top of the part and
pressing is slowly initiated. This rate is typically no faster than
100 mils/second. The amount of pressure will vary depending upon
the thickness of the homogeneous relative density continuous
one-piece insoluble reticulated open celled foam material (1) used
and/or the PPI of that material. Pressures range from 1,000 psi to
40,000 psi, such as 5,000 psi to 20,000 psi, but can include any
range of pressures falling within 1,000-40,000 psi.
[0040] It should also be noted that this process must be done in
stages when achieving higher relative density levels is desired.
More specifically, when parts are pressed and the densities
approach 20% relative density, the parts are removed, cleaned, and
then loaded into secondary presses and dies which further densify
the material as needed. This treatment with secondary presses
addresses the spring-back memory action of the material and
provides a more uniform overall compression.
[0041] In addition to a stepped press approach, it should also be
noted that the material may only be compressed up to levels of 70%
relative density when heating in the 20-200.degree. C. range.
Further densification is possible, but temperatures within the part
must be nearing the molten state of the base alloy to reach
relative densification levels of more than 70%, such as 72.5%, 75%,
77.5%, 80%, 82.5%, 85%, 87.5% or more.
* * * * *