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METALLIC MICROLATTICE: USING LIGHTWEIGHT STRUCTURES TO
MAKE IMPROVEMENTS IN THE TRANSPORTATION INDUSTRY
Joseph Morgan, jdm163@pitt.edu, Vidic, 2:00, Lucas DiCioccio, lad118@pitt.edu, Mahboobin, 4:00
Abstract — Metallic microlattices are being seen as the next
generation of lightweight and robust materials. Despite the
fact that the microlattice is composed of hollow metal tubes
about 1000 times thinner than a human hair, and 99.99% of
its volume is air, it is a remarkably strong material. This
material is so strong in fact, that it can hold about 1000 times
its weight without being permanently damaged. Its strength
does not come from the type of material it is made from,
instead it is a result of the structure itself. This structure can
be easily altered during the manufacturing process to provide
optimal strength for almost any use. Microlattices were also
shown to be effective at damping sounds and vibrations.
Sophia Yang, a researcher at HRL Laboratories, believes that
if an egg wrapped in metallic microlattice were to be dropped
from 25 stories high, it would not crack. Due to its strength
and ability to absorb high amounts of energy, metallic
microlattices can be used in a variety of applications, ranging
from sound and vibration absorption, to increasing the
strength of structures. Replacing current structural
components that undergo great stresses and strains in
airplanes and automobiles with metallic microlattices will
increase their strength and reduce their weight.
Keywords—Energy Absorption, Materials Science, Metallic
Microlattice, Strain, Stress, Ultralight Materials
One example of this would be metallic microlattices. The
metallic microlattice is currently the lightest material in the
world. Despite being made of metal, the metallic microlattice
is actually comprised of 99.99% air [1]. It can even withstand
forces of up to 1000 times its own weight. The reason it can
do this is not because scientists discovered a new blend of
materials like many other new materials, but rather because
of its structure. Metallic microlattice is made of thin hollow
tubes (usually nickel) woven together to form a structurally
strong material. There are several different methods to
produce microlattices. Each of these have their advantages
and disadvantages, however, there are more advanced
techniques that are more efficient, and generally faster than
conventional methods.
Structural and shock absorbing components in both
automobiles and airplanes could be replaced by metallic
microlattice. The reduction in weight, would cause these
vehicles to be more efficient. This would also allow engineers
to relocate this weight to other parts of the vehicle, if
necessary. The decreased overall weight provides a
tremendous amount of options for the designers and
manufacturers of the car or airplane to be able to improve its
performance. This would also have a significant impact on the
fuel consumption of airplanes and automobiles, thus also
affecting the cost of travel.
WHY THE WORLD NEEDS METALLIC
MICROLATTICES
HOW METALLIC MICROLATTICES CAN
CHANGE THE FUTURE
For centuries, it has been human nature to search for
smarter and more efficient answers to complex problems. One
example of this can be found in cars. Originally it was thought
that the way best way to make a car safer was to put more
metal between the driver and the accident. However as human
knowledge increased, it was realized that creating a car frame
that crumpled around the driver and passengers was safer than
making the car bulkier. The genius of crumple zones was that
they did not even need to rely on large amounts of materials
because they were structurally smart. While crumple zones
were incorporated into cars decades ago, this is the same
principle is still being used today.
DEVELOPMENT OF METALLIC MICROLATTICES
University of Pittsburgh Swanson School of Engineering
2016/03/03
In the aerospace and automobile industries, there is a
constant need to innovate and improve the design and
construction of these vehicles. We are always trying to find
ways to get from one place to another as fast, comfortable,
and efficient as possible. One of the most effective ways to do
this is to find a new material, which is lighter and generally
better suited to its application. In the area of transportation,
materials are needed that are light, structurally sound, and
good at absorbing energy. In years past, manufacturers have
used honeycomb panels to reinforce structural components,
while also saving weight [2]. The use of these honeycomb
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Joseph Morgan
Lucas DiCioccio
panels has been effective in saving weight, however, as our
world becomes increasingly conscious of our effects on the
environment, manufacturers have been looking for materials
or structures that could further improve the efficiency of
airplanes and automobiles. By decreasing the overall weight
of the vehicle, less fuel is necessary to power the vehicle.
Even small decreases in weight can have a very large impact
on fuel consumption over a long period of time.
With so much research being done on new materials for
the aerospace and automobile industries, it is no surprise,
then, that a research laboratory co-owned by General Motors
and Boeing discovered one such material. Researchers at
HRL Laboratories first created the metallic microlattice in
2007 [3]. The reasoning behind the metallic microlattice is the
exact same reasoning behind the Eiffel Tower. The
symmetrical structure allows it to hold up to much larger
forces than usual [4]. In some respects, the metallic
microlattice is just an extremely small scale version of the
Eiffel Tower. It has the same type of symmetrical truss system
which gives this material its strength.
Deformation forming is a process in which hexagonal or
diamond shapes are punched out of a sheet of metal. The
metal can then be bended at the nodes to form the lattice
shape. This method can produce either tetrahedral or
pyramidal shapes. To be able to bend the metal, it first needs
to be softened, which is usually done by an annealing
treatment. To perform an annealing treatment, the metal is
heated to around fifty degrees celsius, and then is cooled at a
rate of twenty degrees celsius per hour [8]. Even though the
heat treating process does take several hours, this process is
faster than investment casting because of the fewer number of
steps in this process. The only disadvantage is the amount of
material that is wasted due to perforating the metal sheet.
The next conventional manufacturing process is woven
metal textiles. This is a very simple technique to make
microlattices. As the name implies, wires are simply woven
together into the desired shape. Using this technique, virtually
any arrangement or structure is feasible. Because of the
simplicity of this technique, it is one of the least time
consuming processes. It is also very inexpensive because
there are virtually no wasted materials [7]. The only
disadvantage to this material, is that as it was simply bent to
the shape of the lattice, the trusses only cross over each other
at the nodes. This means that their strength is slightly
decreased when compared to over types of microlattice
construction.
Non-woven metal textiles are very similar to woven metal
textiles. In this technique, layers of wires or tubes are stacked
together and joined through brazing. Brazing is when the
metal is melted at the joint and a filler metal is inserted and
allowed to cool. When it does dry, what is left is one solid
piece of metal [9]. This process, like woven metal textiles, is
very cheap and fast. The difference between the two is that
the non-woven textile is more limited in the possible
arrangements.
CONVENTIONAL MANUFACTURING PROCESSES
The two main categories of manufacturing processes for
metallic microlattices are the conventional and advanced
methods. The conventional methods for manufacturing
include investment casting, deformation forming, woven
metal textiles, and non-woven metal textiles [5]. These
methods are generally slower and less efficient than advanced
methods.
Investment casting is a process in which liquid metal is
poured into a mold to create the desired structure. This
process has been used for hundreds of years to create copies
of metal components. The first step of this process is to create
the mold itself. There are actually two different molds that
need to be made. The first is created out of metal. They are
usually made using a CNC milling machine, which follows a
computer model to create the mold. Then, the second mold
can be made. They are generally made of either wax or a
volatile polymer. A volatile polymer is a type of polymer that
can be melted into a liquid form. The polymer or wax is
heated to convert it to a liquid form. It is poured into the metal
mold, and allowed to dry. This results in a finished mold,
which can be filled with the liquid metal. Once the metal has
solidified, the outer mold is removed, leaving only the desired
material. The problem with this method is that it is very time
consuming, expensive and wastes several different
intermediate materials [6]. Since the walls of the microlattices
are so thin (around 100 nanometers), the mold also has to be
very close together. At these thicknesses, it is very difficult to
make the liquid metal flow through the whole mold.
Therefore, the smallest density currently achievable with this
technique is around two percent [7]. While this is still a very
low density, it is not as low as manufacturers would like it to
be in some circumstances.
ADVANCED MANUFACTURING PROCESSES
In addition to the conventional methods of manufacturing,
there are also some more advanced methods. These include
selective laser melting, electron beam melting, and selfpropagating photopolymer waveguide technique. In general,
these advanced methods are faster, but more expensive than
the conventional methods.
Selective laser melting and electron beam melting are
essentially the same techniques. Both of these techniques are
forms of additive manufacturing. This means that they are
built by adding layer upon layer of metal powder. The powder
is then melted either by a laser or electron beam to form the
solid microlattice structure. Using additive manufacturing,
there is virtually no wasted materials, because the metal
powder is first deposited in the exact structure and orientation
of the finished microlattice. Therefore, there is no need to cut
off excess material like in investment casting or deformation
forming [7].
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The final method for producing metallic microlattices is
called the self-propagating photopolymer waveguide
technique. This is the technique that the researchers at HRL
Laboratories used to create their microlattice in 2007. The
basic idea of this technique is to shine ultraviolet light on a
photopolymer, causing it to solidify. The photopolymer used
by T.A. Schlaeder et al, was a thiol-ene liquid monopolymer
[10]. To create the microlattice shape, the light is shone at a
specific angle through a grid. This prevents the light from
hitting certain areas of the photopolymer, thus keeping it as a
liquid, while causing the areas struck by the light to solidify.
The result is the interconnected microlattice shape. This
template can then be coated in a metal such as nickel using a
process known as autocatalytic electroless plating. The
electroless plating process allows very specific amounts of
nickel to be deposited on the polymer. This is because the
thickness of the nickel coat depends on the length of time it is
allowed to react in the nickel solution. Once the metal coat
has been added, the polymer can be dissolved by putting it in
a basic solution. This leaves behind the finished metallic
microlattice [4]. This is one of the most popular techniques to
produce microlattices, as it is very easy to produce many
different orientations and geometries of microlattices.
The problem with simply comparing these three values to
those of other materials, is that microlattices would not just
be used on their own. In practice, metallic microlattices would
be made into sandwich panels similar to honeycomb panels
that are currently used in the aerospace and automobile
industries. There has not been enough public testing of simple
microlattice arrays to honeycombs with reliable data, for
example. Therefore, we can simply analyze the properties of
microlattices, or compare the strength of these materials per
unit mass. By comparing the materials’ strength per mass, we
are able to see a better representation of how strong the
microlattices are even though they are so light.
In these stress versus strain curves, the highest peak
signifies the first compression test. In figure 4A, six
compressions were performed. The first peak represents the
point where the microlattice begins to buckle at a few
locations. After this peak, the stress decreases slightly which
is representative of the whole microlattice compressing and
absorbing the pressure evenly across the material. The curve
then decreases sharply, back to its original position. In tests
two through six, the curve never reaches a peak like in test
one, instead, there is a more gradual increase. This is because
in a sense, the microlattice has already been “broken in”, so
that it will flex under a smaller force. This happens with all
materials, but what is special about microlattices is that there
is very little degradation between the second and sixth tests.
This is also shown in figure 4B. This shows how different
physical properties of the microlattice change over the course
of the six cycles. The maximum stress experienced by the
microlattice stays relatively constant throughout the test. The
Young’s Modulus, which is very similar to the compressive
modulus, decreases after the first trial, but then stays constant.
This is the same pattern for the yield stress, and energy loss.
Energy loss is a very important value for determining the
effectiveness of microlattices and other materials designed to
absorb impacts. The amount of energy lost is equivalent to the
amount of energy that the microlattice absorbed. While
having a high energy loss is desirable, it is perhaps even more
desirable to have a consistent energy loss value over the
course of many compressions. This is important because
automobiles and airplanes are exposed to repeated impact
over the lifetime of these vehicles. If shock absorbers or
structural components broke after only a few impacts, the cost
of maintenance would be completely impractical. Figure 5
shows how microlattices compare in terms of energy
absorption capacity per gram to honeycomb materials. This
shows that depending on the specifications of the microlattice,
they can be equally as efficient and even more efficient that
honeycomb panels.
In order for these materials to be used, the original shape
also has to be maintained even if they are exposed to large
forces. Researchers at HRL Laboratories have found that
when nickel microlattice is compressed to half of its original
height, the microlattice recovers nearly completely. It only
results in a residual strain of two percent, and recovers to its
original shape.
ENERGY ABSORPTION
The main property that researchers at HRL Laboratories
wanted to achieve in their search for a new material was the
ability to absorb energy, while still being able to retain its
original shape after an impact. To quantitatively analyze
energy absorption properties of the microlattice, we will look
at three different values change as the dimensions of the
microlattice change. We will also compare these values to
those of other materials.
The compressive modulus, E, is a relationship between the
amount a material has been compressed, also known as the
strain, and the force per unit area, or the stress. The higher the
compressive modulus, the larger the force needed to deform
the material. Also, the more a material is deformed by a given
force, the smaller the compressive modulus is. In data table 1,
all of the microlattice samples are made out of nickel. We
cannot accurately compare the compressive moduli for solid
nickel and nickel microlattices,
The compressive strength is the maximum stress a
material can withstand before permanently deforming.
Therefore the compressive strength can be found using the
formula: =FA where F is the force, and A is the crosssectional area. A larger compressive strength signifies that the
material can absorb a large force, thus it can also absorb a
large amount of energy.
The residual strain is the amount that the material was
permanently deformed as a result of the force. To find the
residual strain, the change in height of the microlattice is
divided by the original height: =LL. The change in height is
the difference between the initial height and the height after a
full compression cycle has been performed.
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Joseph Morgan
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There are two main theories to explain why exactly
microlattices are so good at absorbing energy despite their
extremely low density. The possible reason is because as the
microlattice compresses, the trusses bend, buckle, and in
extreme cases, may snap. Even though the structure is slightly
weakened when this happens, it also absorbs a lot of energy
in the process. The second reason is because of the force of
friction caused by each truss rubbing against each other. The
former is more likely because for large arrays of microlattices,
each truss is supported by those around it, which allows them
to undergo a controlled and stable compression.
Metallic microlattices are very good candidates for
structural components and other components that need to
absorb vibrations or impact. This is because of the
combination of their durability, energy absorption, and
resilience to permanent damage.
kilo-pascals to pounds per square inch, using the conversion
rate of 1 kpa = .145 psi, we were able to compare the the
compressive strength of metallic microlattices to the
compressive strengths Hexcel’s honeycombs. Viewing the
data side by side shows that the strongest metallic microlattice
is stronger than most of the aluminum alloy honeycombs.
According to the information given in table 1, the
compressive strength of microlattice sample A is 8510 kPa,
when converted to psi (8510 kpa * .145) exhibits a
compressive strength of 1234.2 psi. When comparing the
strength of to the compressive strengths of Hexcel
honeycombs the data shows that only two honeycomb
formations manage to have a higher compressive strength
than the tested metallic microlattice. This shows that for the
most part metallic microlattices are just as strong as or even
stronger than aluminum honeycombs [12].
In addition to being generally stronger than honeycombs,
metallic microlattices are also more customizable than
honeycomb products. While more dense microlattice can be
built to be stronger than honeycombs while sacrificing
weight, metallic microlattices can also be configured to be the
lightest material in the world, sacrificing strength. By
adjusting the hollow tube thickness, strut length and strut
angle, metallic microlattices can fit almost any need. When
using the self-propagating photopolymer technique, all that
needs to be done in order to adjust the thickness or angle of
the trusses is to adjust the angle that the ultraviolet light hits
the polymer. This is a very simple adjustment that is also very
inexpensive. This makes them the ideal to replace Hexcel’s
honeycomb and other honeycomb products in airplanes.
While honeycombs are rigid in their design, metallic
microlattices can be fine-tuned to the exact specifications
required of the job. This will allow aircraft manufacturers to
customize the strength and density of their aircraft’s structural
components, using denser microlattices in areas that require
higher energy absorption and lighter microlattices in areas
that do not need to absorb enough energy. Designers can build
their own microlattice to be as strong or as light as necessary.
While metallic microlattices are a new technology it is clear
that they will soon make structural components like
honeycombs obsolete.
THE ROLE OF METALLIC MICROLATTICES IN
THE AEROSPACE INDUSTRY
One of the biggest problems in the aerospace industry is
weight management. The most obvious obstacle to airplanes
is gravity. To fight gravitational forces airplane
manufacturers try to create lighter and lighter airplanes. A
large challenge for airplane designers is finding the right
balance between lightweight and strong materials, making the
plane light enough to fly and strong enough to stay stable.
Until recently, the most efficient materials to use for paneling
in airplanes were honeycomb panels. Honeycomb panels are
made of an inner insulating layer shaped in a honeycomb
pattern with two layers of metal paneling on either side.
Honeycomb panels are extremely efficient in situations where
it will have to absorb vibrations. However, metallic
microlattices might soon replace honeycomb paneling in
planes. Metallic microlattices are not only lighter than
honeycomb panels, but microlattices are also more than
capable of absorbing energy. Energy absorption in planes is
important to keeping passengers comfortable. Planes shake
and tremble when varying air pressures lead to turbulence that
absorbs more energy, will absorb more vibrations, leading to
less vibrations inside the cabin. The weight of the metallic
microlattice also makes it an ideal choice for any component
on an aircraft that requires an ultralight material. Science
Magazine states that for a material to be ultralight, it must
have a density of 10 mg/cc or less [11]. While metallic
microlattices are not always made to be ultralight materials,
they can be made to be extremely lightweight. According to
Table 1, located above, metallic microlattices can be made to
be as dense as only .017 mg/cc, making this particular type of
metallic microlattice one of the lightest materials in the world.
One structural material that is currently being used in
airplanes are HexWeb honeycomb cells. As listed on the
parent company Hexcel’s website, HexWeb honeycombs are
used in 19 key components of airplanes from ailerons to
stabilizers. However, by converting the compressive strength
values for the metallic microlattices tested on table one from
ADVANCEMENTS IN THE AUTOMOBILE
INDUSTRY
As with planes, an easy way to increase efficiency is to
conserve weight. Automobiles, however, are exposed to many
more impacts than airplanes, because of their constant contact
with the ground, as well as more frequent high energy impacts
with other cars. This means that metallic microlattices could
also increase the safety of cars [13]. Because metallic
microlattices are so good at absorbing high amounts of
energy, they would fit well in areas such as the bumpers as
well as structural components. In addition to making cars
safer metallic microlattices could also be used to create a more
comfortable ride. Placing microlattices underneath seat
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Joseph Morgan
Lucas DiCioccio
cushions and in various other places in the interior could
create an extremely smooth ride. In addition to these
functions, Hexcel honeycombs, a product with similar
applications to metallic microlattice, can be used to protect
drivers and passengers in accidents. As in the aerospace
industry, metallic microlattices could prove to be just as
effective as and more efficient than the Hexcel honeycomb.
be used to dampen noise and vibrations in addition to being a
lightweight structural component. Because they are so light
and good at absorbing energy, there has also been discussion
of using microlattices in football and crash helmets. Although
there have been no such products incorporating microlattices
yet, they would be a good fit. While metallic microlattices
may not be a flashy new invention, they are important none
the less. Stronger and lighter materials will not only let us
make existing technologies more efficient, but will be
necessary to the inception of creations that have not even been
thought of yet.
As the amount of research on the applications of metallic
microlattices increases in the future, the cost of producing
microlattices will decrease. This is because the methods for
producing them will become more and more efficient,
replacing older and more wasteful techniques. This will
further incentivize transportation companies to make the
transition away from honeycomb panels, to metallic
microlattice sandwich panels. Because the manufacturing of
metallic microlattices results in little to no waste, metallic
microlattices are not only a smart option, but an economical
as well. However the benefits of metallic microlattices also
surpass just manufacturing, since incorporating metallic
microlattices into vehicles makes them more efficient and in
turn, makes them require less energy or fuel to use.
AFFCTS OF METALLIC MICROLATTICES ON THE
ENVIRONMENT AND ECONOMY
Raw materials such as metal ores are becoming increasingly
harder to attain. Therefore it makes sense to try to conserve as
much materials as possible. Because over 99% of the metallic
microlattice is air, very little raw materials are needed to
create it. This also lowers manufacturing costs as well as
pollution that results from extracting ores from the earth [5].
Metallic microlattices manufacturing results in such little
manufacturing waste it is estimated that manufacturing
titanium microlattices instead of blocks of raw material could
extend the longevity of Australia’s titanium reserve tenfold.
However the environmental impact of metallic microlattices
far exceeds the amount of metals used to create the material
itself. By incorporating metallic microlattices into the design
of airplanes, these vehicles can be made to weight much less.
Lighter airplanes and cars are able to be more fuel and energy
efficient. In airplanes, even small reductions in weight can
have a large impact on the fuel economy. According to
Lufthansa German airlines, even small reductions in weight
can lead to large overall savings. Lufthansa airlines claimed
that shedding one kilogram on all of their aircrafts, the airline
managed to save 30 tons of fuel [14]. Replacing current sound
and energy insulators and sandwich panels with microlattices
could lead to a significant reduction in weight and
incorporating microlattices into every plane in a fleet could
not only save fuel, but money for the airlines. Microlattices
could also replace the already commonly used honeycomb
fillers such as Hexcel honeycomb. In addition to being strong
and lightweight, metallic microlattices are also beneficial for
sustainability.
METALLIC MICROLATTICES: THE
FUTURE OF TRANSPORTATION
While metallic microlattices are a new creation, it is clear
they will have a large impact on the transportation people use
every day. Despite being the lightest material ever created,
metallic microlattices are surprisingly strong and are able to
resist large amounts of stress and maintain their shape. This
new material can be used in almost any situation that requires
a lightweight structural component. Another benefit of
metallic microlattices is that it does not require many raw
materials to make. Considering that metallic microlattices can
be built to be 99.99% air, they require an incredibly small
amount of alloy to develop. Factor in the number of different
manufacturing processes that create little to no material waste,
metallic microlattices are one of the most sustainable
materials on the planet. The weight reduction is not without
effect either. Using the ultralight microlattices in vehicles
such as airplanes and automobiles will cut down on the weight
of the vehicle, increasing its efficiency. Despite being the
lightest material ever created, metallic microlattices can
actually withstand large stresses and strains and can even
support 1000 times its own weight. This is especially
remarkable because of their consistency and dependability
over time. After the microlattice is “broken in”, its properties
will stay constant over time even when subject to large forces.
The extreme weight saving possibilities provided by the use
of microlattices allow engineers and designers more options
to further improve the performance and efficiency of vehicles
THE IMPORTANCE OF METALLIC
MICROLATTICES IN THE TRANSPORTATION
INDUSTRY
Metallic microlattices stand to make a rather large impact
on the transportation industry. Their sheer number of
applications makes them useful in almost any situation. In
planes, metallic microlattices could replace current sandwich
panel fillers like Hexcel, or other honeycomb panels. In cars,
metallic microlattices can be incorporated to absorb energy or
to help protect the driver and passengers from a collision.
Metallic microlattices will be able to reduce the weight of any
structure they are used in and will increase their efficiency. In
addition to being lightweight, metallic microlattices are able
to absorb large amounts of energy, which means they can also
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Joseph Morgan
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Metallic microlattices are an example of structural
engineering on the microscopic scale, that will help to reduce
both the cost of travel, and its environmental impact.
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Joseph Morgan
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APPENDIX
Figure 1 [7]
This figure shows the steps of deformation forming.
Figure 2 [5]
This shows the layers of metal powder before it is melted either by a laser or electron beam used to create
microlattices through advanced processes.
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Joseph Morgan
Lucas DiCioccio
Figure 3 [10]
This figure shows the steps for the self-propagating photopolymer waveguide technique.
Figure 4 [10]
This figure shows the stress strain curves for three different microlattices. 4A is the curve for a microlattice
with a density of 14 mg/cc. 4B shows how different physical properties change after six compressions for
the microlattice in 4A. 4C has a density of 1 mg/cc, and 4D has a density of 43 mg/cc.
Table 1 [15]
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Lucas DiCioccio
This table includes values for compressive strength, compressive modulus and residual strain for several different
microlattice samples.
Figure 5 [16]
This graph shows the energy absorption capacity of several different microlattice shapes as well as honeycombs.
Figure 6 [17]
This figure compares the impact energies of several aluminum microlattices to an aluminum honeycomb panel.
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Joseph Morgan
Lucas DiCioccio
[14] “Fuel Efficiency at the Lufthansa Group.” (2012).
Lufthansa
Group.
(online
article).
https://www.lufthansagroup.com/fileadmin/downloads/en/L
H-fuel-efficiency-0612.pdf
[15] T.A Schaedler, A. Torrents, et al. (2012).
“Characterization of nickel-based microlattice materials with
structural hierarchy from the nanometer to millimeter scale.”
Acta
Materialia.
(online
article).
DOI:
10.1016/j.actamat.2012.03.007
[16] G. Kooistra, V.S. Deshpande, H. N. G. Wadley.
“Compressive Behavior of Age Hardenable Tetrahedral
Lattice Truss Structures Made From Aluminum.” (2004).
Acta
Materialia.
(online
article). https://www.researchgate.net/publication/22270060
8_Compressive_behavior_of_age_hardenable_tetrahedral_la
ttice_truss_structures_made_from_aluminium
[17] R. A. W. Mines, S. Tsopanos, Y. Shen, et al. “Drop
Weight Impact Behavior of Sandwich Panels with Metallic
Microlattice Cores.” (2013). International Journal of Impact
Engineering.
(online
article).
http://www.sciencedirect.com/science/article/pii/S0734743X
13000912
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10
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ACKNOWLEDGEMENTS
We would like to thank our parents for funding our college
research. In addition, we would like to thank our writing
instructor Amanda Brant, our co-chair Kaitlin Keene, our
professional chair, Michael Elisco, for reviewing our work
thus far and David Nero for helping us analyze data.
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