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Traumatic Brain Injury Reducing

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					Traumatic Brain Injury Reducing Army Combat Helmet
                            By:
                    Damian Frankiewicz
                      Kristin Ohanian
                       Jim Veronick


              Client Contact: Denise Panosky
         University of Connecticut School of Nursing
                    Storrs Hall, Room 208
              231 Glenbrook Road, Unit 2026
                      Storrs, CT 06269
                       (860) 486-0549
Executive Summary


        The following is a proposal to create a helmet specifically designed to decrease the risk
of traumatic brain injury in a soldier working under combat situations. Because one of the
clients is a member of the National Guard, most of the data collected pertains to experience
obtained in Iraq under responsibilities shared with the Army. Because military helmet
manufacturing and development has become privatized, the company Gentex and its helmet
designs are first scrutinized. From there, appropriate specifications are highlighted and altered in
order to satisfy the requirements of the client, a nursing instructor worried about the current
Gentex Advanced Combat Helmet and its lessened protection in the back and side of the head as
well as its relatively complicated and uncomfortable neck strap that has been reported to be worn
improperly or not at all by soldiers in the field.
        When fulfilling the client’s requirements, helmets engineered for different tasks are
referenced, specifically in the field of motocross racing. While other sports helmets may provide
insight into helmet structure or padding design, many sports do not require an integrated chin
guard into the helmet itself but rather a metal or plastic mesh that is attached to protect the face,
such as in football or hockey. On the other hand, motocross helmets have built in chin guards as
well as excellent padding protection designed to prevent the movement of the head inside the
helmet, according to the second client, who is a nursing student and an avid motocross rider.
        In order to fully understand the helmet specifications and how to change them, the
purchase of an Advanced Combat Helmet is necessary for testing. In addition, a motocross
helmet will also be useful in the understanding of how exactly its design and padding is an
improvement over the current Army helmet. As for the building of the actual prototype helmet,
kevlar material, and especially its weave, is an important part of the budget because it will most
likely have to be shipped, as well as the molding of the hard outer helmet casing.
1. Introduction


1.1 Background


       A redesign for an army helmet project was brought to the Biomedical Engineering
program by the School of Nursing. During a lecture on traumatic brain injuries, a nursing student
who was a former soldier in the US Army inquired upon the helmets he used in Iraq. An avid
motocross rider, the nursing student was curious as to why the helmets used in motocross
provided better protection from traumatic brain injury (TBI) than those used in combat in Iraq. It
is estimated that almost 90% of military personnel treated for injuries in Iraq were injured by
IED (Improvised Explosive Device) explosions. Almost half of those injuries were incurred on
the head.
       Research and experience shows that the greatest cause for traumatic brain injuries are due
to blasts or explosions from IEDs, vehicle accidents, and falls. Fewer TBIs were caused by
bullets, fragments, or shrapnel. The effect of IED blasts is of growing concern for the military.
IEDs alter atmospheric pressure rapidly, producing waves of shear and stress forces on the body.
Organs of different densities accelerate at different rates with these energy waves and ultimately
result in displacement, stretching, and shearing forces. The brain is very susceptible to these
atmospheric changes, which is why TBI is the common result of an IED blast.


1.2 Purpose of the project


       The current military design for helmets is most effective at protecting a soldier’s head
from bullets, fragments, or shrapnel penetration; however, the risk of TBI is still present. The
purpose of the project will be to research TBIs, forces from explosions, shock resistant materials,
and other areas in order to ultimately design a more protective military helmet to prevent TBIs.
To account for TBIs, the new helmet design will incorporate the protective features of the current
Advanced Combat Helmet, but also will include ideas from the common protective motorcyclist
helmet which is more successful at preventing head injuries from impact forces. The new helmet
will provide better protection against TBIs from explosions, vehicle accidents, and falls.
1.3 Previous Work Done by Others


1.3.1   Products


        While most helmets used by the United States Army were created internally by Army
engineers, in recent years helmet design and manufacturing have been awarded to the Gentex
Corporation, who has recently created three helmets used by different branches of the military.
The Lightweight Helmet, or LWH, was initially used by the Marines. The Modular Integrated
Communications Helmet, or MICH, and the Advanced Combat Helmet, or ACH, have been used
by the Army. All three of these designs by inspection are seen to have much less protection than
older helmets, partly due to the fact that they cover much less of the back and sides of the head
as opposed to the older Personal Armor System Ground Troops, or PASGT helmet, which was
used in the eighties and nineties and was developed by the United States Army Aeromedical
Research Laboratory. Before this design, the Army used a generic M1 helmet in Vietnam.


1.3.2   Patent Search Results


        Although the Army developed older models of helmets, no patents pertaining to
protective helmets can be found under the holder the United States of America as Represented by
the Secretary of the Army, or other such military branches. The following two tables show a
search of all patents pertaining to the project at hand. Table A is a compiled list of protective
combat helmets held by private companies. Most of these patents are held by Gentex, who owns
the patents pertaining to the helmet being studied and improved upon. Table B is a list of patents
pertaining to motocross helmets, which are held by several leading companies in this
industry. These patents are important in order to ensure that no infringements occur in the areas
of the chin straps, padding, or chin guard.
             Table A: Patents Pertaining to Privatized Military Helmets
Patent Number                     Description                      Patent Holder
   RE32569                     Protective Helmet                      Gentex
   7316036                Padset for Protective Helmet                Gentex
   7225471         Removable Optical Assembly for Helmet              Gentex
   6292953               Interchangeable Latch System                 Gentex
   6279172           Custom Fitting Assembly for Helmet               Gentex
   5584073                 Integrated Helmet System                   Gentex
   5522091                Sighter’s Protective Helmet                 Gentex
   5396661            Helmet Visor Operating Mechanism                Gentex
   5226181         Mounting Design for Night Vision Mount             Gentex
                             and Goggle Assembly
   4908877                   Ballistic Helmet Body                    Gentex
   4884301             Combination Chinstrap-Natestrap                Gentex
                              Assembly for Helmet
   4847920              Dual-Visor Assemly for Helmet                 Gentex
   4778638            Method of Making Ballistic Helmet               Gentex
   4748694          Spring Device for Earcup Assemblies of            Gentex
                               Protective Helmet
   4713844            Protective Helmet with Face Mask                Gentex
                                 Sealing Means
   4700410         Pneumatic Adjustment Means for Earcups             Gentex
                                   in Helmets
   4596056         Helmet Shell Fabric Layer and Method of            Gentex
                               Making the Same
   4432099              Individually Fitted Helmet Liner              Gentex
   4412358           Individually Fitted Helmet Liner and             Gentex
                          Method of Making the Same
   4145338           Custom-Fitted Helmet and Method of               Gentex
                               Making the Same
   4290149         Method of Making and Individually Fitted           Gentex
                                     Helmet
  42392106         Individually Fitted Helmet and Method of           Gentex
                     and Apparatus and Making the Same
   4170042          Readily Releasable Powered Visor-and-             Gentex
                           Lock Assembly for Helmet
   6804829            Advanced Combat Helmet System               Lineweight LLC
                      Table B: Patents Pertaining to Motocross Helmets
  Patent Number                        Description                     Patent Holder
    D5545502                             Helmet                      Troy Lee Designs
     D499213                       Helmet with Visor                  Troy Lee Design
     7181777               Shield Mounting Device for Helmet            HJC Co. Ltd.
     6892400                Helmet Having opening Type Chin             HJC Co. Ltd.
                                      Protection Bar
      6763526                 Air Vent Structure for Helmet             HJC Co. Ltd.
      6748607              Breath Guard Assembly for Helmet             HJC Co. Ltd.
      6598238              Jaw Protecting Apparatus of Helmet           HJC Co. Ltd.
      D495838                            Helmet                         Arai Helmet
      7207071                   Ventilated Helmet System              Fox Racing, Inc.
      D476779                            Helmet                        Shoei, Co., Ltd.
      D471675                      Helmet Chin Cover                   Shoei, Co., Ltd.
      D460219                            Helmet                        Shoei, Co., Ltd.
      D457691                            Helmet                        Shoei, Co., Ltd.
      D446357                            Helmet                        Shoei, Co., Ltd.
      6910228                            Helmet                        Shoei, Co., Ltd.
      6421841            Inside Pad for Helmet Using this Inside       Shoei, Co., Ltd.
                                           Pad
      6417491                   Shield Panel and Helmet                Shoei, Co., Ltd
      9256797             Helmet and Method of Removing the            Shoei, Co., Ltd
                                          Same
      6226803                            Helmet                        Shoei, Co., Ltd.
      6105172                            Helmet                        Shoei, Co., Ltd.


2. Project Description


2.1 Objective


       The basic design of the proposed traumatic brain injury reducing helmet encompasses
much of what currently exists in the Advanced Combat Helmet. This helmet will provide the
same ballistic protection as the current ACH, but will also provide greater protection against
traumatic brain injuries cause by improvised explosive device detonations. TBI protection will
encompass protecting against three types of blast injuries; from blast wave-induced changes in
atmospheric pressure (primary injury), from objects put in motion by the blast hitting people
(secondary injury), and from people being put in motion by the blast (tertiary injury).
       Protection from the three types of blast-induced injuries will be implemented in several
ways. The current pad suspension system offers more padding than previous designs, but still
does not provide proper protection when the user is thrown during an IED blast. One category of
TBIs is coup-contrecoup injuries that are sustained when acceleration changes or an impact to
the head injures the brain at the point of impact and at the side of the brain opposite that point.
Many other types of TBI are also caused from an impact due to the user being thrown or an
object being thrown at the user. The effects of these impacts would reduce significantly if there
was more padding inside the helmet that would absorb most of the impact energy.
       Protection against TBIs caused by rapidly changing atmospheric pressures was initially
going to be implemented in this design. A layer of protective material was going to be placed
beneath the Kevlar shell to decrease the effect of atmospheric pressure changes on the brain
tissue, as the current ACH does not provide any such protection. However, after much research it
has been determined that this objective is beyond the capabilities of the senior design program.
The focus will be placed on preventing TBIs from impact forces.
       Many components of the current ACH will remain in the design of this helmet. The
Kevlar outer shell of the ACH will continue to be used, as it provides excellent ballistic
protection. A helmet retention system in the form of a chin strap and neck strap will continue to
be utilized, but with slight improvements over the current design. These improvements will assist
in situations when noise generated from clipping the plastic buckle could reveal the user’s
location and place them in danger of being discovered by the enemy.
       Several innovative designs may also be incorporated into the helmet design. The current
ACH does not offer any facial protection. A chin guard similar to what appears on motocross and
BMX helmets would prevent many injuries occurring on the lower face. The chin guard could
have several practical features such as an implanted microphone connected to a radio unit. If the
chin guard was movable, the user could lift it up or down to accommodate for comfort and
various combat or non-combat situations. In addition to a chin guard, a neck guard would also
provide comfort and in turn, protection not offered by the ACH. The client expressed interest in
this idea, as many soldiers turn their helmets around under combat conditions that require them
to lie on their stomachs. They complained the helmet dug into their necks, but repositioning the
helmet on the head reduces its protection. Therefore, the neck guard would need to be adjustable
based on the position of the user.
2.2 Methods


       In order to make the prototype helmet, a projectile protective Kevlar helmet shell will be
molded from the Fibre Glast epoxy molding kit. The Kevlar and carbon fiber layers will be
layered on top of this mold which will result in the shell. The shell will serve as the base of the
prototype design. Next, a layer of expanded polystyrene (EPS) will be inserted into the shell,
followed by another layer of padding for comfort and to provide a proper and sturdy fit for the
helmet. The protection from impact will thus be in form of the three protective layers as shown
in Figure 1.
       The helmet from Gentex Corporation can be viewed in Figure 2. The protective shell
made from the mold will have the same general shape, but will be slightly larger than what is
shown in the images, to allow for the padding support system. The protective shell’s main
purpose is for ballistic protection. The shell also provides protection from environment
conditions such as rain and sun. In addition, camouflage can be added to the shell via an outer
netting than can provide the soldier with cover in dangerous situations.




                      Figure 1. View of helmet and inner padding design.
                       Figure 2. Gentex Advanced Combat Helmet. [1]


       Next, appropriate holes will be drilled into the helmet to provide the proper positioning
for the helmet padding to be inserted. The EPS padding will be custom made and purchased
from Universal Foam Products. The EPS padding is a common padding used in bike and
motorcycle helmets which provides a very inexpensive, light weight and impact protective
solution in crashes. An EPS mold can be designed and formed into an appropriately fitting mold
for the shell. Because the EPS unit typically breaks on impact while protecting the user’s head,
the design will be made removable so that the soldier can replace it after a crash or heavy impact
incident. EPS has been studied to be a very good impact resistant cushion. Figure 3 shows an
example of a removable EPS inner shell from a motorcycle helmet. The prototype design will
follow a similar design as the one in the image.




            Figure 3. Removable EPS inner shell from a motorcycle helmet. [3]
               Figure 4. A typical football helmet with viscoelastic foam pads.


       The final inner layer of padding will be composed of a viscoelastic foam found
commonly in football helmets. This foam padding will be ordered, cut to size, and applied
within the EPS shell. The pads will be removable separately from the EPS shell. This will
provide customization for the particular soldier using the helmet. An example of viscoelastic
foam pads can be seen in the football helmet in Figure 4.
       The last design on the prototype is the lockable chin guard system. The chin guard will
be in a resting upright position on top of the helmet shell. When combat situations approach, the
soldier can lower the chin guard over his or her face towards the chin where it will lock in
position. This chin guard will provide protection to the soldier’s face from ballistics but more
importantly from impact incidents. The protective chin guard can prevent traumatic impacts to
the head coming at the face and chin. In addition, the chin guard provides a better stability
system for the helmet to fit over and around the soldier’s head, ridding the need to secure a chin
strap and wobbly helmet in time limiting situations. The total prototype can be viewed from
different directions in Figures 5 and 6.
Figure 5. Side view of helmet with chin guard down (left) and up (right).




         Figure 6. Front view of helmet with chin guard down.
       After making the prototype helmet, a motocross helmet and an Advanced Combat Helmet
will be purchased to perform comparison testing. The brand and model of motocross helmet that
is purchased will be highly rated by the US Department of Transportation and the Snell
Memorial Foundation, two organizations highly regarded for rating helmet safety. The Advanced
Combat Helmet that is purchased will be manufactured by Gentex Corp. and will possess the
same quality and specifications required by the US Army.
       A drop test will be used to simulate impacts on various surfaces and shapes. Testing
equipment will be modeled after equipment used by various helmet testing laboratories and
research centers, as outlined in the US Department of Transportation National Highway Traffic
Safety Administration Laboratory Test Procedure [2]. A headform will be mounted inside the
helmet to simulate the presence and weight of a human head. An accelerometer will also be
placed inside the helmet and attached to a National Instruments DAQ. Acceleration data will be
recorded using a LabVIEW program. A test apparatus using a vertical metal pole will be set up
with an attached pulley and cable system. An anvil, a cement block, and various other surfaces
will be placed beneath the apparatus. The helmet will be attached to the cable then dropped onto
the surfaces from various heights. A variation of this test setup is shown in Figure 7. This test
will simulate the acceleration and forces experienced by a human head inside a combat helmet
being propelled onto buildings, vehicles, and other surfaces after being thrown from an IED
explosion.
                             Figure 7. Example test apparatus. [3]


       After testing the prototype helmet, motocross helmet, and Advanced Combat Helmet, g-
force data will be compared and analyzed. According to DOT, the “accelerations in excess of
400 g or cumulative dwell times in excess of 2.0 ms above 200 g or 4.0 ms above 150 g shall be
recorded as failures.” [2] If the prototype helmet does not meet the 150 g specification, it will be
considered a failure. Adjustments will then be made and testing will be performed again. The
prototype should have the lowest g-force that is obtainable, so several adjustments and tests will
be performed.
3. Budget


       The purchase of both an Advanced Combat Helmet and a motocross helmet would be
very beneficial to the creation of the prototype. These helmets would be inspected to see how
the materials are fastened together. In addition, the Tinius Olson Tensile tester in the
Biomaterials laboratory could be used to test forces that these helmets may withstand. More
importantly, a comparison of the padding between these two helmets would be of great interest
to our client. Buying an individual Advanced Combat Helmet comes to about $500 while a
motocross helmet made by a top motocross helmet company costs about $300.
       As for the creation of the prototype, because the majority of the materials are composites,
the Fibre Glast Developments Corporation is a great resource for these types of materials. First,
an epoxy resin is chosen due to its superior characteristics over polyester resins and also due to
its superior adhesive compatibility with kevlar. The Fibre Glast website has an epoxy molding
kit for $330, which includes the resin, hardener, mold polish, glaze and buffering pads, some
surface coating, and fabric to place on the outside of the composite so it stays within the fabric
shell. The inner shell of the helmet will be made of kevlar with the epoxy resin. Fibre Glast
sells kevlar in sheets of fifty inches by one yard by .01 inches thick for $50. Currently in this
stage the amount of kevlar layers have not yet been determined, so for estimation purposes five
sheets of kevlar totaling about five yards of the material will be bought for $250. The outer
covering of the helmet requires a composite with larger tensile strength, so carbon fiber is an
ideal choice. It is sold for $60 a yard, and it will be assumed that two yards will be used for now
totaling $120.
       Motocross chinstraps have been shown to be less complicated, more reliable, and quieter
by the client and for now have been chosen as a replacement to the current military chinstrap
used. These motocross chinstraps retail for about $50, but the straps in the helmet may or may
not be used for the prototype helmet depending on circumstances such as dimensions. The
expanded-polystyrene layer will be custom made by Universal Foam Products for approximately
$250. Lastly, the viscoelastic foam padding to be used has not yet been determined. However,
based on current padding kits used in military helmets, the budget will be set to $100. Lastly,
any remaining testing equipment to test the strengths of the helmets, such as pulleys, cables, and
a pulley system, can be set to about a $150 budget.
       When factoring in the cost of the two test helmets as well as all of the component
materials as well as the mold components, the total budget hovers around $2000. Not including
the price of the helmets, the cost of the prototype is around $1200. When scaling this cost to
about 35%, the final product would be about $420. Compared to bulk costs of the Advanced
Combat Helmet bought by the army for about $350 or the motocross helmet for the same price,
the new helmet may be both economically feasible and better at preventing traumatic brain
injuries than anything in the market.


4. Conclusion


       Current helmets used by the United States military are not specifically made to prevent
traumatic brain injuries. In addition, the recent Advanced Combat Helmet used by the Army
raises several criticisms for its decrease in head protection in the back and side of the head as
well as a large reported rate of discomfort by soldiers in Iraq. With the creation of a replacement
helmet that may offer more protection against impacts that is more comfortable to wear at the
same time, a product that may be both economically viable as well as one with a higher chance
to save a human life is a large possibility.
       Padding material and design are important aspects in the prevention of traumatic brain
injuries. This material must absorb a large amount of the energy produced by a high force
impact to the helmet which may move the brain in its own skull and damage it due to this sudden
and violent movement. A large part of this design includes a helmet that fits very snugly on the
head it is protecting, so that the head and helmet move as one unit with no unnecessary spacing
in between. The material of the hard shell of helmets is pretty much standardized at this point,
with the primary composites used being fiberglass, carbon fiber, or kevlar, with either an epoxy
or polyester resin depending on the material it must bind to. However, the layering of these
materials may help in the absorption of energy when constructing the prototype.
       Overall, the proposed prototype will cost about $1000, which can make it economically
viable when produced on a larger scale and standardizing and cutting the cost of manufacturing.
However, the decision to purchase a motocross helmet and an Advanced Combat Helmet for
about $800 more may provide invaluable insight into industry practices such as composite
layering and overall shell design and layout, which may be of great help in the final prototype
design. In addition, if this new product can be shown to absorb more energy and effectively
protect the brain, those in areas of conflict may be very interested in such a device when
comparing it to others on the market.


References
[1] United States of America. Army Aeronautical Research Laboratory. Blunt Impact
Performance Characteristics of the Advanced Combat Helmet and the Paratrooper and Infantry
Personnel Armor System for Ground Troops Helmet, 2005.

[2] United States of America. Department of Transportation National Highway Traffic Safety
Administration. Laboratory Test Procedure for FMVSS No. 218 Motorcycle Helmets. TP-218-
06. Washington, DC: Office of Vehicle Safety Compliance, 2006.

[3] “Motorcycle Helmet Performance: Blowing the Lid Off,” Motorcyclist, June 2005.

				
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