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