OBJECTIVE: Develop, optimize, and demonstrate the use of high-throughput, sub-scale ballistic test setup that incorporates automated or autonomous functionality to maximize both data output and fidelity relative to full-scale ballistic testing. DESCRIPTION: Data-driven materials design is a burgeoning field with the potential to rapidly accelerate new materials development, provided that large volumes of data can be efficiently generated and analyzed. The Department of Defense (DoD) is interested in data-driven design of next-generation protection materials. However, ballistic evaluation of protection materials presents a significant bottleneck: due to safety concerns and stringent testing requirements (e.g., the V50 ballistic test for armor as described by DoD MIL-STD-662F), full-scale ballistic tests are expensive and generate data at a very low rate, on the order of 10 samples/day. Sub-scale ballistic testing (e.g., laser-driven micro-projectiles, air gun-driven microbeads, electric-discharge-driven flyer plates) offers a potential route around these limitations, with the ability to use dramatically smaller projectiles and smaller samples to improve safety, expense, and significantly increase throughput. Nonetheless, sub-scale ballistic data collection is still relatively slow alignment and calibration are exhaustively hands-on processes that could benefit from automation and analysis is still done manually and post mortem. For example, fragmentation analysis, a valuable proxy for impact performance of brittle protection materials, is still done by manually collecting and analyzing each fragment that results from the subscale ballistic impact. Importantly, the accuracy of sub-scale methods against full-scale ballistic tests must be further evaluated: equivalent testing standards do not yet exist, and sub-scale techniques are only valuable so far as they provide accurate information about the real-world ballistic performance of a protection material. This situation warrants a concerted effort to enable high-throughput sub-scale ballistic testing and carefully evaluate its fidelity. The goal for this effort is to develop a sub-scale ballistic testing platform as a critical tool for data-driven, high-throughput design and characterization of next-generation protection materials. PHASE I: Define and develop an approach for high-throughput sub-scale ballistic testing of macroscale protection materials. The specific sub-scale method is not prescribed, but must be capable of creating ballistic, high loading rate (i.e. between 104 and 107 s-1) mechanical testing conditions that serve as an accurate proxy for a full-scale ballistic test. Specific capabilities that are desired include: in situ quantitative characterization and analysis capabilities that provide as good or better determination of ballistic performance as traditional post mortem manual analysis or conventional failure probability analyses, like V50. The approach should also be capable of automation (e.g., in sample preparation/loading, alignment, data processing, etc.) to maximize testing and data throughput: the concept must demonstrate a 10-fold improvement in the rate of experimentation over manual subscale ballistic testing, and a 100-fold improvement over full scale ballistic testing conventionally used to satisfy V50/MIL-STD-662F. Note that the approach is not intended to replace ballistic testing standards, but rather shall complement existing standards by enabling rapid screening of materials. The method should be tailored for research and development of next-generation hard protection materials based on ceramics, composites, and/or metals (as opposed to soft materials like polymers, or low-dimensional materials like graphene), and must serve as an accurate surrogate for full-scale ballistic testing while simultaneously enabling safe, high-throughput data generation and collection for data-driven design of advanced protection materials. The concept must also outline an approach for qualifying the accuracy of the method with respect to predicting material performance under full scale ballistic testing based on MIL-STD-662F. If awarded the Phase I option, the small business will demonstrate the feasibility of the proposed concept/approach. Develop a Phase II plan. PHASE II: Based on Phase I results, develop, demonstrate, and validate the proposed high-throughput test apparatus for sub-scale ballistic testing. The accuracy of the automated in situ approach will be quantified relative to a manual post mortem approach to data analysis, using the same sub-scale ballistic technique. The test must demonstrate a 10-fold improvement in the rate of experimentation with respect to manual subscale ballistic testing, and a 100-fold improvement over full scale ballistic testing to satisfy V50/MIL-STD-662F. The technique should encompass one or more of the following projectile geometries: highly planar flyer plates, spheres, and/or projectiles with ogived noses. The technique should enable various angles of target obliquity with respect to the vector of projectile velocity. High throughput data generation should be leveraged to facilitate data-driven inferences about the behavior and design of protection materials. The fidelity of the sub-scale technique and these inferences will be evaluated with select full-scale ballistic tests for V50/MIL-STD-662F. It is recommended that the performer work with government laboratories and/or established testing agencies to perform these select ballistic tests. It is also recommended that the performer work with bulk material vendors/Original Equipment Manufacturers (OEMs) and/or ballistic testing agencies to facilitate transition for Phase III. Successful completion of Phase II shall include a demonstration to DEVCOM Army Research Laboratory scientists and engineers engaged in ballistic testing of protection materials. PHASE III DUAL USE APPLICATIONS: The completion of this effort would provide an automated tool that receives, prepares, assesses, and analyzes the ballistic performance of subscale samples in a way that accurately reflects the global behavior of the bulk material. Phase III will transition high throughput sub-scale ballistic testing techniques to commercial suppliers through bulk material vendors, OEMs, or other partnering agreement(s). Commercialization of this technology may be through the development of kits or modules for retrofitting existing subscale ballistic testing apparatus, or through the development of full turn-key systems. If successful, this technology would provide DoD engineers with a platform for rapidly assessing the ballistic performance of next generation armor materials. REFERENCES: 1. MIL-STD-662F, Department of Defense Test Method Standard: V50 Ballistic Test for Armor (18 December 1997), http://everyspec.com/MIL-STD/MIL-STD-0500-0699/MIL-STD-662F_6718/; 2. NIJ Standard-0101.06, Ballistic Resistance of Body Armor (July 2008), https://www.ncjrs.gov/pdffiles1/nij/223054.pdf; 3. ASTM E3110 / E3110M 19, Standard Test Method for Collection of Ballistic Limit Data for Ballistic-resistant Torso Body Armor and Shoot Packs; 4. Mallick, Debjoy D., and Ramesh, K.T. Dynamic Fragmentation of Boron Carbide Using Laser-Driven Flyers. International Journal of Impact Engineering, Vol. 136 (2020), 103416, https://www.sciencedirect.com/science/article/pii/S0734743X19307304; 5. Hassani, Mostafa, Veysset, David, Nelson, Keith A., and Schuh, Christopher A. Material Hardness at Strain Rates Beyond 106 s-1 via High Velocity Microparticle Impact Indentation. Scripta Materialia, Vol. 177 (2020), 198-202. https://www.sciencedirect.com/science/article/pii/S1359646219306256; 6. Lee, Jae-Hwang, Loya, Phillip E., Lou, Jun, and Thomas, Edwin L. Dynamic Mechanical Behavior of Multilayer Graphene via Supersonic Projectile Penetration. Science, Vol. 346 (2014), 1092-1096. https://science.sciencemag.org/content/346/6213/1092 KEYWORDS: Ballistic test, armor design, subscale testing, data-driven design, protection material, automation, machine learning, autonomous experimentation, high-throughput experimentation
