OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR) TECHNOLOGY AREA(S): Bio Medical OBJECTIVE: Develop and demonstrate technologies capable of measuring complex surface response kinematics at the interface between the torso and body armor system. DESCRIPTION: Body armor systems can be comprised of hard and soft materials which are designed to prevent ballistic projectile penetration into underlying surfaces and improve armor performance. Defeat of ballistic threats are typically accompanied with armor system back face deformation (BFD) into the underlying torso. Current armor system performance requirements include deformation depth limits, measured by the residual deformation impression in a clay substrate backing. While penetration of the ballistic threat may be stopped by the armor system, the ballistically induced BFD could induce injury to the wearer. Advanced material development advancements have produced armor systems capable of defeating increased threats, but with various BFD characteristics. Unfortunately, the backing material obscures visual observation of back face surfaces. To establish human injury risk due to blunt insults, the Medical Research & Development Command research laboratories need the ability to accurately characterize the high-rate response surface kinematics which occur at the outer body armor system and underlying tissue interface when ballistic threats are defeated (i.e., no tissue penetration). An innovative approach is needed to measure and record these kinematics during ballistic exposures. This technical solution would provide medical researchers with a critical tool needed to define human injury mechanisms and tolerances associated with blunt exposures. The approach should be independent of backing material used, and should not influence the armor's performance or deformation response. The measurement system should provide a time-history surface deformation response along with associated kinematic parameters. The surface response parameters should include deformation depths, velocities, and accelerations, cross-sectional areas of deformations at variable deformation depths, deformation volumes, and their change rates. Analytical data post-processing techniques are required to extract and provide the response kinematic parameters and a computational visualization of data collected during dynamic test events. Due to the high speed of ballistic induced insult onto the armor system, the data acquisition rate should be greater than 100 kilohertz (kHz). Deformation depth measurement resolution should be at least 1 millimeter (mm) with a sensitivity of 0.5 mm. The sensing surface should cover a minimum area of 400 by 400 mm; a single sensing array should cover the surface area of the armor systems. Sensing array spacing should be less than 5 mm. The sensing material should be flexible to account for the complex curvature of armor surfaces and backing materials. Unless the armor system fails to prevent ballistic threat penetration, the ideal measurement system should recover and be reusable. Current rigid armor testing protocols require ballistic impacts at three distinct locations. The deformation measurement system should capture these three events without need for removal. During exploratory and developmental testing, armor systems could be tested in more than three distinct locations. Methods to calibrate and verify system operation will be needed. If successful, this innovative technology will allow researchers to ascertain injury risk associated with individual armor system BFD during successful ballistic defeat. Use of this system could be employed in multiple medical research programs and armor systems research, development, and acquisition by the military, law enforcement organizations, etc. PHASE I: The main goal of Phase I is a feasibility study in the development of a high-rate surface response sensor system. Initially, to prove feasibility, a physical, electronics, optical and circuit design of the sensor system should be completed as the first deliverable. The electronic and circuit designs should include commercially available electronic, computer, and optical components, or components that can be fabricated easily and without extraordinary expense. The physical design of the surface response sensor should not exceed 2 mm thickness and cover a 400 mm by 400 mm area. The material should be lightweight and highly flexible in order to conform to complex and rapidly changing surface profiles, without altering the performance of armor systems and their deformations. The sensing array spacing within the sensor element should be less than 5 mm. A second deliverable is a data acquisition system and software capable of operating and sampling the surface response sensor system at a sample rate of 100 kilohertz. Appropriate anti-aliasing filters should be integrated into the data acquisition system. The associated software should provide ability to control power to the sensor system and provide data collection trigger options (manual, external source, and sensor threshold activated), and ability to store and view the collected data. A third deliverable is a data processing software capable of performing the needed post-processing of the sensor system data to extract the surface response kinematic metrics and provide imaging algorithms for displaying digital visualization animations of the surface response at various playback speeds. The response metrics include parameters such as, deformation distance, velocity, accelerations, strain rate, area, and volume at various surface points. The animation files should be easily recorded and exportable in commercial video formats to other commercial software programs. The post-processing software should provide a means for exporting the surface response kinematics data into commercially compliant software files. The fourth deliverable is a description of the surface response sensor system, the accompanying data acquisition system and supporting software systems. This is necessary because if the innovative technologies anticipated to accomplish the high-rate surface response data acquisition and associated data density. A detailed software schematic must be produced to indicate the computational path and logic in sensing, triggering, data acquisition, metric extraction, and data visualization algorithms. Specific existing software, or a plan to program new software, must be identified that can accomplish each step involved in the software path. PHASE II: The overall objective of Phase II is to produce a fully operational prototype high-rate surface response sensor system, and required data acquisition and software system(s), capable of collecting high-rate surface response kinematics of a ballistically driven surface and through data post-processing, extract the surface response kinematic metrics and visually display response surface animations of the collected data. Testing of improvements and changes is then encouraged in order to take advantage of the state-of-the-art in electronics, optics, data acquisition technologies, computers, and software. At this early stage, data can be generated by testing with inanimate phantoms such as placing the sensor system over a heavily padded surface (flat and curved) and striking the sensor material with a blunt object of known and different surface geometries such a baseball bat or other projectile. The aim is to mature the software programming and data post-processing algorithms to identify the known surface geometry and to test the robustness of the surface sensor technology and the required electrical wiring harnesses and connectors. This system and software should be tested extensively with inanimate phantoms. Modifications to the sensor system electronics, optics, data acquisition function, software and/or data post processing algorithms should be made at this point. Next, the focus should shift to the production of a fully functional prototype high-rate surface response sensor system in the desired form factor, complete with the computer software needed to perform data acquisition and all functions for collecting, archiving, retrieving the acquired data, extracting surface response kinematics, and data visualization animations. This system should be demonstrated to acquire high-rate surface response data (such as, deformation distance, velocity, accelerations, strain rate, area, and volume) collected with inanimate phantoms when struck by blunt surfaces of known surface geometries. The system data acquisition system and associated software should have the ability to detect sensor system faults and to verify system functionality prior to data collection events. Sensor calibration techniques should be investigated and demonstrated, and calibration hardware and methodologies developed. One fully functional prototype will constitute the third deliverable, accompanied by user manuals, calibration procedure, validation test reports and other relevant reports and designs. PHASE III DUAL USE APPLICATIONS: During a Phase III award, the awardee will work towards maturing the technology, software and manuals for system commercialization. This product is envisioned to be a stand-alone sensor technology capable of being integrated with other test systems to record complex, high-rate surface deformations. The final product is envisioned to consist of three major components, the sensing element(s), the data acquisition module, and software. Users may require multiple sensing elements as they may sustain damage in harsh test environments. Along with the accompanying software, this data will be processed to provide surface response kinematics such as, distance, velocity, accelerations, strain rate, area, and volume. Commercially, this technology and capability could be utilized in the automotive testing and development market, by recording structural deformations during crash testing, seating system development to capture seat surface deformations for improved comfort, endurance, and to investigate chronic back pain in at-risk populations such as long distance truck drivers. New developments in anthropometric test dummies could utilize this technology to record surface deformations of various body regions (abdomen, chest, etc) to record deformations during automotive crash testing in order to document injury risks. Current test dummy instrumentation systems measure chest deformation in discrete locations. This technology is directly applicable to military medical research, such as the Military Operational Medicine Research Program at the Medical Research and Development Command in their research efforts on human tolerance, specifically blunt trauma, as well as utility in the Military materiel research, development, and acquisition in the areas of non-lethal weapon and personal protective equipment development. If this technology is successful, it could be embedded into procurement and testing requirements for the research, development, testing, and acquisition of body armor systems. As such, this technology could be adopted by the National Institute of Justice for integration into their performance specifications for body armor systems used by law enforcement personnel. Commercially, this technology would then be widely used by commercial industries that develop and produce personal armor systems for the military, law enforcement, and private citizens, as well as companies that produce protective equipment such as torso and chest protectors used in numerous sporting activities. REFERENCES: Cameron R. Bass, Robert S. Salzar, Scott R. Lucas, Martin Davis, Lucy Donnellan, Benny Folk, Ellory Sanderson & Stanley Waclawik (2006) Injury Risk in Behind Armor Blunt Thoracic Trauma, International Journal of Occupational Safety and Ergonomics, 12:4, 429-442, DOI: 10.1080/10803548.2006.11076702 Hanlon, E & Gillich, P. (2012). Origin of the 44-mm Behind-Armor Blunt Trauma Standard. Military Medicine, Volume 177, Issue 3, March 2012, Pages 333 339, https://doi.org/10.7205/MILMED-D-11-00303. Prather RN, Swann CL, Hawkins CE, 1977. Backface signatures of soft body armors and the associated trauma effects. U.S. Army Armament Research and Development Command Tech. Report ARCSL-TR-77055. Aberdeen Proving Ground, Maryland. The National Academies of Science, Engineering, and Medicine. (2012). Testing of Body Armor Materials: Phase III. Washington, D.C.: National Academy of Sciences. US Congress, Office of Technology Assessment. Police Body Armor Standards and Testing: Volume I. OTA-ISC-534. 1992. KEYWORDS: Body armor, Back face deformation, Instrumentation, Kinematics, Complex surfaces, Dynamic response, Behind armor blunt trauma (BABT)
