U.S. patent application number 14/636630 was filed with the patent office on 2015-09-03 for macro-patterned materials and structures for vehicle arresting systems.
The applicant listed for this patent is Engineered Arresting Systems Corporation. Invention is credited to Michael Galbus, Youhong Li, Yijian Shi, Silvia C. Valentini, Marcos Villa-Gonzalez, Hong Zou.
Application Number | 20150247298 14/636630 |
Document ID | / |
Family ID | 52814180 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150247298 |
Kind Code |
A1 |
Li; Youhong ; et
al. |
September 3, 2015 |
MACRO-PATTERNED MATERIALS AND STRUCTURES FOR VEHICLE ARRESTING
SYSTEMS
Abstract
Embodiments of the present disclosure relate generally to
macro-patterned materials and methods of their use in connection
with vehicle arresting systems. Certain embodiments provide 3-D
folded materials, honeycombs, lattice structures, and other
periodic cellular material structures, that can be used for
arresting vehicles. The materials can be engineered to have
properties that allow them to reliably crush in a predictable
manner under pressure from a vehicle. The materials can be formed
into various shapes and combined in various ways in order to
provide the desired properties.
Inventors: |
Li; Youhong; (Cherry Hill,
NJ) ; Villa-Gonzalez; Marcos; (Cherry Hill, NJ)
; Valentini; Silvia C.; (West Chester, PA) ; Shi;
Yijian; (Swedesboro, NJ) ; Zou; Hong; (Chadds
Ford, PA) ; Galbus; Michael; (Middletown,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Engineered Arresting Systems Corporation |
Aston |
PA |
US |
|
|
Family ID: |
52814180 |
Appl. No.: |
14/636630 |
Filed: |
March 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61947194 |
Mar 3, 2014 |
|
|
|
Current U.S.
Class: |
428/116 ;
428/174 |
Current CPC
Class: |
E01C 9/007 20130101;
Y10T 428/24149 20150115; Y10T 428/24628 20150115; E01F 15/145
20130101; B64F 1/025 20130101; B21D 13/04 20130101 |
International
Class: |
E01F 15/14 20060101
E01F015/14 |
Claims
1. A vehicle arresting system, comprising: a plurality of
macro-patterned structures formed of a material that reliably
crushes in a predictable manner.
2. The system of claim 1, wherein the macro-patterned structures
comprise three dimensional folded structures.
3. The system of claim 2, wherein the three dimensional folded
structures are formed by pressing a sheet of material with one or
more sets of rollers to form a desired raised pattern on the
sheet.
4. The system of claim 2, wherein the three dimensional folded
structures comprise a chevron pattern.
5. The system of claim 2, wherein the three dimensional folded
structures are combined into a block, with one or more structures
separated by an intermediate layer.
6. The system of claim 1, wherein the macro-patterned structures
comprise a uniform geometry throughout each structure.
7. The system of claim 1, wherein the macro-patterned structures
comprise a honeycomb cell structure bordered by one or more outer
panels.
8. The system of claim 7, wherein the honeycomb structure comprises
a cell size of from about 0.25 inch to about five inches.
9. The system of claim 7, wherein the one or more outer panels
comprise one or more scores or cuts.
10. The system of claim 7, wherein the honeycomb structure
comprises cells having axes, wherein the cell axes are arranged in
a non-perpendicular manner with respect to an arresting bed
surface.
11. The system of claim 1, wherein the macro-patterned structures
comprise a raw material thickness of from about 0.003 inches to
about 0.016 inches.
12. The system of claim 1, wherein the macro-patterned structures
comprise a height of about 0.3 inch to about 2 inches.
13. The system of claim 1, wherein the macro-patterned structures
comprise sheet metal, aluminum, copper, stainless steel, metal
foil, plastic, paper, fire resistant-paper, paperboard, fiberboard,
corrugated material, fiberglass, reinforced composite, carbon
fiber, reinforced composite material, thermoplastic materials,
ceramics, cementitious materials, polymers, or combinations
thereof
14. The system of claim 1, comprising a block formed from a
plurality of macro-patterned structures, wherein the
macro-patterned structures at the top of the block have a lower
strength than the macro-patterned structures at the bottom of the
block.
15. The system of claim 1, wherein the macro-patterned structures
comprise lattice structures having a density in the range of about
2-50 pcf and a compressive strength in the range of 3-100 psi.
16. The system of claim 1, wherein the macro-patterned structures
comprise lattice structures having a component diameter or
component cross-section feature size of about 0.001 to about 1.5
inches.
17. A vehicle arresting system, comprising: a plurality of
macro-patterned structures formed as three dimensional folded
structures that are stacked with respect to one another and
separated by one or more intermediate layers, wherein the material
of the structures comprises a material that reliably crushes in a
predictable manner, and wherein the macro-patterned structures
comprise a raw material thickness of from about 0.003 inches to
about 0.016 inches and a patterned layer height of about 0.3 inch
to about 12 inches.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/947,194, filed Mar. 3, 2014, titled "The
use of Macro-patterned materials structures for vehicle arresting
systems," the entire contents of which are hereby incorporated by
reference.
FIELD OF THE DISCLOSURE
[0002] Embodiments of the present disclosure relate generally to
macro-patterned materials and methods of their use in connection
with vehicle arresting systems. Certain embodiments provide 3-D
folded materials, honeycombs, lattice structures, and other
periodic cellular material structures, that can be used for
arresting vehicles. The materials can be engineered to have
properties that allow them to reliably crush in a predictable
manner under pressure from a vehicle. The materials can be formed
into various shapes and combined in various ways in order to
provide the desired properties.
BACKGROUND
[0003] Aircraft can and do overrun the ends of runways, raising the
possibility of injury to passengers and destruction of or severe
damage to the aircraft. Such overruns have occurred during aborted
take-offs or while landing, with the aircraft traveling at speeds
up to 80 knots. In order to minimize the hazards of overruns, the
Federal Aviation Administration (FAA) generally requires a safety
area of one thousand feet in length beyond the end of the runway.
Although this safety area is now an FAA standard, many runways
across the country were constructed prior to adoption of this
standard. These runways may be situated such that water, roadways,
or other obstacles prevent economical compliance with the one
thousand foot overrun requirement.
[0004] In order to alleviate the severe consequences of overrun
situations, several materials, including existing soil surfaces
beyond the runway, have been assessed for their ability to
decelerate aircraft. However, soil surfaces are not the best
solution for arresting moving vehicles (i.e. aircraft), primarily
because their properties are unpredictable.
[0005] Another system that has been explored is providing a vehicle
arresting system or other compressible system that includes
material or a barrier placed at the end of a runway that will
predictably and reliably crush (or otherwise deform) under the
pressure of aircraft wheels traveling off the end of the runway.
The resistance provided by the compressible, low-strength material
decelerates the aircraft and brings it to a stop within the
confines of the overrun area. Specific examples of vehicle
arresting systems are called Engineered Materials Arresting Systems
(EMAS), and are now part of the U.S. airport design standards
described in FAA Advisory Circular 150/5220-22B "Engineered
Materials Arresting Systems (EMAS) for Aircraft Overruns" dated
Sep. 30, 2005. EMAS and Runway Safety Area planning are guided by
FAA Orders 5200.8 and 5200.9.
[0006] A compressible (or deformable) vehicle arresting system may
also be placed on or in a roadway or pedestrian walkway (or
elsewhere), for example, for purposes of decelerating vehicles or
objects other than aircraft. They may be used to safely stop cars,
trains, trucks, motorcycles, tractors, mopeds, bicycles, boats, or
any other vehicles that may gain speed and careen out of control,
and thus need to be safely stopped.
[0007] Some specific materials that have been considered for
arresting vehicles (particularly in relation to arresting
aircraft), include phenolic foams, cellular cement, foamed glass,
and cellular chemically bonded phosphate ceramic (CBPC). These
materials can be formed as a shallow bed in an arrestor zone at the
end of the runway. When a vehicle enters the arrestor zone, its
wheels will sink into the material, which is designed to create an
increase in drag load.
[0008] However, some of the materials that have been explored to
date can be improved upon. For example, phenolic foam may be
disadvantageous in that is has a "rebound" characteristic,
resulting in return of some energy following compression. Cellular
concrete has density and compressive strength properties that may
vary with time and that could be difficult to maintain in
production due to the innate properties of its variable raw
materials and subsequent hydration process. Foamed glass can be
difficult to control in uniformity. It is thus desirable to develop
improved materials for vehicle arresting beds.
BRIEF SUMMARY
[0009] Embodiments of the invention described herein thus provide
systems and methods for designing vehicle arresting systems using
macro-patterned materials or structures that can be engineered to
have properties that allow them to reliably crush in a predictable
manner under pressure from a vehicle. The materials can be formed
into various shapes and combined in various ways in order to
provide the desired properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a top perspective view of one embodiment of a
macro-patterned material, specifically a 3-D folded structure in a
chevron pattern on an aluminum alloy sheet.
[0011] FIG. 2 shows a top perspective view of one embodiment of a
macro-patterned material that is a 3-D folded structure in a
chevron pattern on a different aluminum alloy material.
[0012] FIG. 3 shows a top perspective view of another embodiment of
a macro-patterned material.
[0013] FIG. 4 shows a side perspective view of one embodiment of a
machine that may be used to form folds or patterns on a material
sheet.
[0014] FIG. 5A shows blocks formed from a plurality of
macro-patterned material structures.
[0015] FIG. 5B shows a panel made from a plurality of blocks formed
from a plurality of macro-patterned material structures.
[0016] FIG. 6 shows a block formed from a plurality of
macro-patterned material structures.
[0017] FIGS. 7A-7H show alternate structure shapes that are within
the scope of this disclosure.
[0018] FIG. 8 shows one embodiment of a honeycomb pattern.
[0019] FIG. 9 shows a schematic of a honeycomb pattern with outer
panels on both sides of the honeycomb core.
[0020] FIG. 10 shows one embodiment of a honeycomb sandwich
panel.
[0021] FIG. 11 shows one embodiment of a honeycomb sandwich panel
with scored outer panels.
[0022] FIGS. 12A and 12B show a schematic of an aircraft wheel
contacting the honeycomb embodiments, having varying orientation of
cell axes.
[0023] FIG. 13 shows a schematic of stacked honeycomb blocks or
panels.
[0024] FIG. 14 shows a schematic of adhesive layers that may be
positioned between various structures that form a block.
[0025] FIGS. 15A and 15B show fire testing results for a honeycomb
core and a honeycomb panel.
[0026] FIG. 16 shows various types of lattice structures that are
within the scope of this disclosure.
DETAILED DESCRIPTION
[0027] Embodiments of the present invention provide materials that
are designed in a way that renders them useful for arresting
vehicles. In one aspect, the materials are provided as
macro-patterned materials. As used herein, the phrase
"macro-patterned materials" or "macro-patterned structures" is used
to mean structures that are made of repetitive units in three
dimensional ("3-D") spaces. They may include minimum feature sizes
for each unit that are equal to or larger than about 1 millimeter.
The materials or structures may include 3-D folded materials,
lattice structures, honeycomb structures, and any other type of
periodic cellular structures.
[0028] As used herein, "periodic cellular material structures"
refers to materials that have similar structures to those of
periodic cellular metals (for example, those described in Haydn N.
G. Wadley, "Multifunctional periodic cellular metals", Phil. Trans.
R. Soc. A (2006) 364, 31-68), but they are not limited to metallic
materials. Such periodic cellular material structures can be made
of any viable materials including metallic materials, ceramics,
plastics, papers, and composites thereof, or combinations thereof.
Furthermore, non-periodic cellular materials having the feature
size defined above also fall into the scope of macro-patterned
materials and structures.
[0029] In one example, the materials are folded three-dimensional
structures. The structures may be formed by being folded or pressed
or tessellated or otherwise engineered. These materials can be
formed in any number of optional shapes and configurations and
layers. In other embodiments, the materials are formed as lattice
structures, a geometrical arrangement of objects or points, rods,
sticks, inflatable structures, or any other structure, such as
interlaced structures and patterns, honeycombs, and folded
honeycombs.
[0030] The macro-patterned materials or structures described herein
can be made of metals and alloys thereof, foils, plastics, paper,
related materials, or combinations thereof More options are
provided in the below description. Such materials or structures may
be manufactured so that they exhibit energy absorbing capacities
when tailored for use as vehicle arresting systems. By generating a
dragging force from a vehicle wheel or other vehicle structure upon
interaction with the materials, the kinetic energy of the moving
vehicle can be absorbed so that the vehicle can be decelerated or
stopped with minimal damage to the vehicle and with reduced to no
injury to the vehicle occupants. By changing the geometric
configurations and material properties of various materials or
structures, moving vehicles of different weights can be safely
stopped within predetermined ranges. (The vehicles that may be
stopped include any land-based, wheeled moving systems, such as
cars, trucks, bicycles, aircraft after landing or before
taking-off, and so forth.)
[0031] Vehicle arresting systems refer to systems for installation
at the ends of aircraft runways or other vehicle safety areas. They
provide an external source of energy absorption. They are separate
from the vehicle structure itself. Vehicle arresting systems are
generally effective to safely decelerate vehicles entering the
systems. They may be provided as a bed, a raised barrier, an
indented area on a runway that is filled with materials, or any
other appropriate system. The arresting systems disclosed are
generally assembled of the macro-patterned materials and structures
described herein.
[0032] The materials and structures may be engineered so that
failure mode will meet desired performance requirements. For
example, the pieces of material deform or break upon application of
a force in a controlled way, such that they do not pose a severe
hazard to the vehicle or its occupants. The materials are generally
engineered to have desired properties for a wheel of an overrun
aircraft to penetrate the material so that aircraft is stopped. In
some examples, the materials may be considered "brittle."
[0033] Additionally, federal regulations may dictate that the size
of the resulting pieces from the broken or crushed materials or
structures be such that they are small enough to not cause safety
issues on a runway. Another example is that materials and
structures may be engineered or treated to meet non-flammability
requirements.
[0034] In one specific example, folding of flat sheets of materials
into intricate 3-D structures has been found to provide a strength
to density ratio that can be useful in arresting vehicles. As
background, folded material structures and honeycombs have been
developed and used for other applications, such as for acoustic
applications for noise reduction, for protection in air drop of
relief and aid supplies to reduce impact force (e.g., as an air
drop cushion), as elastic shock absorbers, as building skeletons,
or in packaging perfumes and other fragile items. The goal for each
of these uses, however, is for the material to withstand an impact
and to not shatter or break. By contrast, the desired intent of the
materials described in this application is that they are designed
to reliably crush in a controlled manner under impact from a
vehicle so as to safety stop the vehicle, while minimizing injury
to the vehicle occupants and damage to the vehicle.
[0035] One folding theory that may be used to provide the
structures described herein is a sheet of material that is folded
into a 3-D pattern. This can create a core structure 10, examples
of which are shown in FIGS. 1-3. Once formed, the core structure 10
may be combined with other core structures 10 in various geometries
and arrangements and patterns in order to provide the desired
compressive strength, as outlined further below.
[0036] Scientists have developed mathematical theories that
generate repetitive geometric patterns that can be folded from flat
sheets. The theories generate an extensive variety of patterns, all
of which are considered within the scope of this disclosure. (Many
of these theories were developed and pioneered by D. H. Kling of
Rutgers University, and are outlined in related literature
published by Dr. Kling and his team. For example, processes for
generating different patterns for various structures are described
in the paper titled "Applications of Folding Flat Sheets of
Materials Into 3-D Intricate Engineering Designs" by E. A. Elsayed
and B. B. Basily of Rutgers University, the entire contents of
which are incorporated by reference.)
[0037] Any type of folding technology may be used to form the core
structures 10 described. Some examples include but are not limited
to continuous folding using rollers, discrete folding using die,
and vacuum folding. One example of a potential folding process is
shown in FIG. 4. In this example, a sheet of material 12 may be
pressed by rollers 14 in order to provide a raised pattern 16 or a
creased pattern on the sheet. The sheet with a raised pattern may
then be sent through another set of rollers--cross folding
rollers--that are engraved with a pattern to create additional
folds and patterns. More specifically, the sheet 12 may be
pre-folded by being sent through a set of sequential
circumferentially grooved rollers. The pre-folded sheet may then be
sent through a set of cross folding rollers engraved with a
specific pattern. This continuous folded sheet may they be cut into
the desired dimensions. In some examples, the specific pattern may
be a chevron-like or triangular pattern. The raised pattern 16 that
is formed may be a chevron pattern, such as that shown in FIGS.
1-3. The chevron pattern may generally provide a series of nested
V-shape features. In other examples, the raised pattern may be a
mating surface ("MS") pattern, as shown in FIG. 7A. The MS patter
generally provides offset triangular faces. In other examples, the
specific pattern may be a box pattern or a castellated pattern
(FIGS. 7B and 7C), a curved or sin wave-like pattern, a chevron
with flat surfaces (rather than points) (FIG. 7D), reflective (or
star-like) surfaces (FIG. 7E), bearing surfaces reflector (FIG.
7F), or any other pattern. Additional non-limiting examples are
shown in FIGS. 7G and 7H. Any other patterns are possible and are
considered within the scope of this disclosure. Other examples of
potential raised surfaces include but are not limited to a chevron
pattern. Other patterns may include a honeycomb pattern and any
other pattern that provides the desired energy absorbing
properties.
[0038] In another example, a die may be created by forming and
arranging desired tessellation units. Once the die is formed, a
sheet of material having a specific dimension may be pressed
against the die to form the desired folded shape. The resulting
structure has the desired folded pattern.
[0039] In another example, a sheet of material may be subjected to
heat and stretched. This method is particularly useful for
polymeric, plastic, or composite material sheets. A vacuum may then
be applied to force the malleable sheet against a die engraved with
the desired folded pattern. Combinations of these techniques may
also be used. Other methods of 3-D folding or forming 3-D folded
structures are possible and considered within the scope of this
disclosure.
[0040] The criteria to consider when determining what raised
pattern to use include but are not limited to the desired impact
strength, energy absorption, crush strength, compressive gradient,
and any other factors. The material may be modified as desired as
well. For example, materials may be selected having certain density
and corrosion resistance, and may be formed with specific
geometries and heights.
[0041] The properties of the final materials and the structure
selected may be tailored through engineering. Changes may be made
to the raw sheet materials, their thickness, folded pattern, and
pattern geometry. Flexibility in design for selecting property and
performance characteristics can allow better and more
cost-effective use of materials for various applications.
[0042] For example, the sheet of material may be a sheet metal. The
sheet of material may be a foil, a metal foil such as a foil of
aluminum or copper or their alloys. The sheet of material may be
paper, such as paperboard, fiberboard, corrugated material, fire
resistant paper, or fiberglass reinforced composites. The material
may be a plastic, such as thermoplastic materials, other polymers
composite material, thermoplastic materials, polymers (including
but not limited to polyethylene, polypropylene, polyvinyl chloride,
polystyrene, acrylonitrile butadiene styrene), or a composite
material, such as reinforced plastic or combinations thereof. The
material may be a reinforced composite, a carbon fiber, a
reinforced composite material, ceramic, cementitious materials, or
combinations thereof
[0043] That material may be any combination of the above materials.
It is also envisioned that other materials are possible and
considered within the scope of this disclosure. Inflatable
materials may also be explored and are considered within the scope
of this disclosure. The material may be any appropriate material
that can be deformed upon application of appropriate pressure,
heat, or other means. The raw material properties may be selected
to provide the desired crush strength. Parameters such as yield
strength, ultimate strength, heat treating history, and chemical
stability may be considered. In a specific example, 1100 series
aluminum alloy has been tested and has shown good performance in
various vehicle arresting applications.
[0044] One concept that the present inventors have identified is
that for the structure (or a plurality of structures in
combination) to reliably crush, it may be desirable for the pattern
selected to be less anisotropic, such that it is generally uniform
in most, if not all, directions. The core structure 10 may be
formed so that its folds and other dimensions are generally similar
across various cross-sections of the structure 10.
[0045] The structures are generally stacked or formed into larger
structures that form the vehicle arresting system. In one example,
the macro-patterned lattice, honeycomb or 3-D structured material
is formed into a body that has a defined structure formed by the
individual pieces. The macro pieces (which may be any shape, such
as spheres, folded sheets, rods, flat panels, honeycomb panels, and
so forth) may be placed in a set volume. This may be a box, a cube,
stacked to form a certain body, assembled in layers, positioned in
a bed, or any other option. They may have a defined position, such
that there is a repetitive pattern. This repetitive pattern may be
formed by stacked structures that may be oriented in different
ways. In another example, the individual pieces or structures can
be loose or attached by any means, such as being glued, welded,
interlocked, or any other appropriate option. In short, the
assembling is generally not random. The structures are not combined
in any way, but are generally architected to create repeating
patterns. This can assist with providing a system that provides
reliable crushing from many directions.
[0046] The present inventors have also determined that certain
thicknesses of the material also lend to its use as a vehicle
arresting system. In one example, the thicknesses of the material
prior to folding may range from about 0.003 inch to about 0.016
inch. In another example, the thickness of the material prior to
folding may be from about 0.005 to about 0.015. In another example,
the thickness of the material prior to folding may be less than
about 0.5 millimeter, and particularly less than about 0.3
millimeter.
[0047] In one example, the height of the raised patterns 16 formed
on the folded material may be from about 0.3 inch to about 2
inches. Specific ranges may be from about 0.4 inch to about one or
11/2 inches. It is generally advantageous for this height to be
uniform or otherwise generally consistent across the entire
structure 10. This can allow the structure to reliably crush, no
matter what part of it receives the impact. Providing an evenly
distributed pattern can assist with the desired reliability of
crushing upon impact.
[0048] As outlined above, the resulting structure 10 that is formed
may also be stacked or layered with other structures to form a
block 18 of core structures. Examples of a plurality of blocks or
units of core structures are shown in FIGS. 5 and 6. The block 18
of core structures may be formed of structures 10 having the same
materials and the same or similar geometry. In another example, the
block 18 of core structures may be formed of structures having
different materials and the same or similar geometry. In another
example, the block 18 of core structures may be formed of
structures having the same materials and different geometries. Any
combination of these features may be used. As mentioned, one
specific example provides structures 10 that have similar
geometries, such that the block 18 of core structures is less
anisotropic.
[0049] The structures 10 may be layered in any number of
orientations. For example, in the example shown in FIG. 5A, the
structures may be stacked on top of one another longitudinally. In
another embodiment, they may be aligned in a side-by-side
vertical-like arrangement, as shown in FIG. 6. An insert layer 20
may be inserted between each layer of stacked structures, as shown
in FIG. 5A. Alternatively, the structures may be stacked directly
against one another. In a further embodiment, the structures 10 may
be twisted or rolled into a rounded unit or block. Any other
configuration option is possible and is considered within the scope
of this disclosure. The structures may have different top and/or
bottom layers, different intermediate layers, or the layers may all
be similar.
[0050] In one example, the structures 10 forming the layers may be
glued to one another. In another example, the structures 10 forming
the layers may be welded to one another. In another example, the
structures 10 forming the layers may be cemented (using e.g.,
crushable nonflammable materials) to one another. Intermediate
layers 20 may be glued and/or welded in place. It is possible to
incorporate filler materials (not shown) in any areas of gaps in
the folded structures 10. The filler materials may include but are
not limited to stable, crushable, and non-flammable materials.
Examples include a very lightweight ceramic foam. Further examples
include a loose powder, a weak ceramic cement, a jelly, a foam,
various types of sand, combinations thereof, and any other
appropriate options. The filler may fill cavities of the
macro-patterned structure, which may improve its performance and/or
change the response behavior of the resulting vehicle arresting
system.
[0051] In one specific embodiment, a block 18 may be made by
orienting a plurality of the folded layers/structure 10 alternately
in two different directions. These 2 directions may be
perpendicular to one another. An intermediate layer, un-folded flat
sheet 20 may be added between structures 10. This can help build
(with adhesive or other means of bonding) block units 18. In one
specific aspect, the block units 18 are about five cubic inches
each. Other dimensions are possible and considered within the scope
of this disclosure. For example, the blocks may range from 1 cubic
inch to about 12 cubic inches in size.
[0052] These block units 18 can have less anisotropic compressive
yield strength. For example, the strength difference in different
directions may be less than 30%. Less anisotropy in compressive
yield strength can be desirable in vehicle arresting performance.
(It is anticipated that the vehicle may approach and contact the
block 18 from one of any number of different directions). The block
units 18 may then be arranged in a level and bonded with adhesive
or other means of bonding with unfolded face sheet(s) 20. These
intermediate layer sheets 20 may have a thickness of about
0.003-0.016 inches at top and/or bottom. In one aspect, the
thickness of the intermediate layer 20 can be similar to or
different from the thickness of the initial sheet used to make the
folded structure 10.
[0053] Different levels of bonded units or blocks 18 can be bonded
further, adding one level above another to form larger blocks.
These blocks may be rectangular in shape, square, or any other
appropriate dimension or shape.
[0054] FIG. 5A shows a plurality of units 18 that were built with
folded structures 10, unfolded intermediate layers 20, a top layer
22 (unfolded), a bottom layer 24 (unfolded), and adhesives. In this
example, each unit 18 is generally cube shaped and has one or more
flat inter-layers or intermediate layers 20 in between any two
adjacent folded structure 10 layers. The orientations of the folded
structure 10 layers were alternate as described previously to
achieve the same strength in two mutually perpendicular directions.
Because materials may have different strengths in different
directions, it may be desirable to reduce the strength difference
by alternating layer orientations. The height of the folded
structure layer is also determined from testing and achieved by
selecting and using appropriate folding tools to minimize the
difference in strength between lateral and vertical directions.
Adjusting the parameters, such as thickness of the raw material
sheet, the material of the sheet, height of the folds, interlayer
thickness, and other parameters to obtain the desired material
strength and reduced anisotropy of strength in different directions
can be achieved. For example a range of folded layers may be from
0.3 to about 1.5 inches.
[0055] FIG. 5B shows a larger block 26 made of thirty six cube
units 18, each of which is a cube 18 of 5 inch.times.5 inch.times.5
inch. For this example, adhesives are used to bond the cubes 18
together. In addition, face sheets 28 were bonded to the top and
bottom of two levels of cube units 18. In between the two levels of
cubes 18, there is also a large flat sheet 30 used to bond the two
levels of cube units together. Apart from the large face sheets 28
and the large flat sheet 30 in between any two levels of the cubes,
no additional bonding was used between adjacent cube units 18. It
should be understood, however, that bonding adhesives or other
securing materials may be used if desired. Higher blocks 26 may be
made by adding more levels and a flat sheet 30 in between any
adjacent levels. It should be understood that the heights and other
aspects of the units 18 used in the block 26 need not be the same.
For example, blocks of varying materials, varying geometries, and
varying designs may be used. However, one benefit of using blocks
18 of similar materials, geometries, and designs may be that the
larger block 26 that is formed is less anisotropic and may crush
reliably and predictably.
[0056] FIG. 6 shows an embodiment in which the structures 10 are
positioned vertically with respect to one another, so that there is
a larger space between each intermediate layer than when they are
positioned horizontally as shown in FIGS. 5A and 5B.
[0057] It should also be understood that the thicknesses of the
face sheets 28 and flat sheets 30 may be varied to provide varying
crush profiles. This can allow the units 18 or larger block 26 to
be designed to meet various performance requirements, for example,
in the case of the desired vertical strength change with height.
The concept of using units 18 of certain sizes to build larger
blocks 26 and controlling the bonding between units 18 in the
blocks 26 can help ensure good failure mode during vehicle
arrestment.
[0058] In the examples shown, a chevron pattern was tested.
Although this pattern was found to provide test results that show
good energy absorption characteristics for the intended application
in vehicle arresting systems, it should be understood that other
patterns may be used and are considered within the scope of this
disclosure.
[0059] In other embodiments, the macro-patterned materials may be
formed as lattice structures, honeycombs, folded honeycombs, or
other periodic cellular structures. For example, a honeycomb
structure 32 may be formed as a honeycomb-shaped cell structure 34
being sandwiched between two outer panels 36. An example of a
honeycomb cell structure 34 is illustrated in FIG. 8. The cell
sizes may range from about 1/4 inch up to about one inch. It is
possible for the cell sizes to be even larger, depending upon the
materials used. The cell types may be rectangular, hexagonal, or
any other appropriate shape. Honeycomb core structures typically
have a load bearing capacity in one dimension and are extremely
anisotropic in terms of mechanical properties. However, through
engineering (such as, by adding face panel and adjusting the core
height, or using folded honeycomb structures so that the final
honeycomb structures can withstand load from different directions),
the material can become less anisotropic.
[0060] The cell axes may be designed or oriented so that they have
a crush strength that is similar from different directions. In one
example, the material for the honeycomb-shaped cell structure 34
may be sheet or foil of metal or alloys such as aluminum or other
metal alloy. The material may be plastic. The material may be
paper, such as aramid paper, cardboard, or other options. The
material may be ceramics, cementitious materials, composites,
combinations thereof, or other appropriate material that may have
the desired crushability aspects.
[0061] A schematic example of a honeycomb structure 32 with outer
panels 36 is illustrated in FIG. 9. An actual example of a
honeycomb structure 32 is shown in FIG. 10. The outer panels 36 may
be made of the same or different material as the cell structure 34.
The outer panels 36 provide a "skin" to the honeycomb structure 32
that provides a more rigid panel.
[0062] The gauge of the material(s) and/or the thickness of the
material(s) may be optimized to provide the desired crushability of
the resulting structure. For example, the gauge of the material may
range from a thin aluminum foil thickness to a rigid sheet of
metal. The thickness of the assembled honeycomb panels may range
from about 1/4 inch to about 40 inches in height H. In a specific
embodiment, the panels are about 24 inches high. In another
embodiment, assembled blocks of multiple panels may be up to about
40 inches high. It should be understood that the height can be
varied to meet the needs, and heights higher than 40 inches are
possible.
[0063] As shown in FIG. 11, the outer panels 36 may be scored or
have one or more cuts 38 made in the skin of the panel 36. This can
help enhance the energy absorbing features of the structures 32,
either alone or as a combined structure 32. The scores 38 may be
generally parallel as shown, or they may be random or at various
directions. The scores or cuts have been shown to provide a desired
drag load in testing.
[0064] FIG. 12 shows various options for the directions of the cell
axes 40. In FIG. 12A, the cell axes 40 are angled at 22.degree..
FIG. 12B, the cell axes 40 are angled at 45.degree.. Tests have
been conducted on 90.degree. (vertical cell axis), 45.degree., and
22.degree.. Under certain tests conditions, it was found that
45.degree. worked well. However other angles may be used depending
upon the expected engagement angle of the vehicle wheel. Scientific
literature has established strength as a function of cell axis
angle. It has been found that the strength of the honeycomb
structure 32 may be a function of the cell axis 40. In these
examples, the honeycomb structure 32 may be secured to a base panel
B via any appropriate means. In one example, they may be secured to
the base panel B via as adhesive. One or more honeycomb structures
32 may be placed end to end.
[0065] In another example, FIG. 13 shows that a plurality of honey
comb structures 32 may be stacked to form a combined structure 42.
In this example, the structures 32 may be stacked so that they
create a raised area further along the runway. In one aspect, the
stacked honeycomb structures 32 may be designed to have similar
strengths. In another aspect, the stacked honeycomb structures 32
may be designed to have varying strengths. For example, there may
be provided weaker honeycomb structures 32A on top for arresting
lighter aircraft. Stronger honeycomb panels 32B may be provided as
bottom or lower layers. All of the layers may be glued or otherwise
adhered to one another via one or more adhesive layers 42.
[0066] FIG. 15 shows a series of fire testing results. FIG. 15A
shows a honeycomb cell structure 34 without panels. FIG. 15B shows
the structure 34 of FIG. 15A with panels 36 secured thereto. These
results show that the honeycomb structure 32 provides the desired
fire resistance. It is possible, however to provide a further fire
resistant coating to the panel, such as, for example, a coating of
Temprotex.RTM. or other fire or corrosion resistant material.
[0067] Another example of a macro-patterned material that may be
used according to this disclosure is a 3-D printed material that is
printed in layers. The desired macro-patterned material shape may
be computer generated and then printed using any appropriate
material(s). Additional materials may be useable with the 3-D
printing option. For example, sand or loose pumice (when combined
with a suitable binder) may be printed into the desired forms. The
materials used should generally have the crushability parameters
described, such that wheels of a moving aircraft will cause the
material to crush or otherwise deform.
[0068] A further example of a macro-patterned material that may be
used according to this disclosure is a lattice material that is
formed via sticks that are connected to one another at various
points to create a structure. Non-limiting examples of such
lattice-type structures are shown in FIG. 16.
[0069] The material properties of the lattice structure can be
tailored by changing lattice structure itself, the raw materials,
or the size of the material components. Changes may also be made in
the length, width or diameter of the sticks, the bonding strength
at the joint points, as well as other parameters. For example, the
compressive strength may be controlled to be about 3-100 psi,
depending on the specific requirements for a vehicle arresting
system application. For example, the density may range from about
2-50 pcf. For example, the lattice structure may have a component
diameter or component cross-section feature size of about 0.001 to
about 1.5 inches. One example of a possible lattice structure is a
lattice truss structure.
[0070] Whether the vehicle arresting system is made from the 3-D
folded materials or the honeycomb structures described, the
macro-patterned materials may be stacked so that varying layers
have varying levels of crushability. In one example, core
structures may be arranged in a way that allows varying
crushability at varying levels of the structure. For example, an
outer layer may crush more easily than an inner layer, so that much
of the damage to the structure occurs externally. As another
example, the outer panel or layer may be scored more heavily or
deeply, so that it creates more drag load. As another example, an
outer layer of the system may be provided of different layers of
materials having different strengths from lower materials in the
same system. An optimal combination of these parameters may result
in the maximum effectiveness of the structure as a vehicle
arresting system. These features may be tailored for different
airport requirements, runway sizes, and/or expected size of
aircraft to be safely stopped.
[0071] The resulting structures and blocks of bodies formed
therefrom may be formed into panels, blocks, beds, or any structure
that can positioned at the end of a runway or road. The resulting
vehicle arresting system may be secured in any appropriate way. The
resulting vehicle arresting system may be covered or coated with
any materials for such purpose.
[0072] Changes and modifications, additions and deletions may be
made to the structures and methods recited above and shown in the
drawings without departing from the scope or spirit of the
disclosure or the following claims.
* * * * *