Understanding Fragment Impact on Responding Surfaces

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software; Advanced Materials OBJECTIVE: Develop techniques for characterization of dust and debris from fragment impacts on responding structures. DESCRIPTION: Real world CWMD strike kinetic weapons often encounter responding structures such as concrete walls. Fragments from weapons striking responding walls generate dust and debris. It has been shown that dust and debris quench the late-time chemistry that is necessary for agent defeat. The mass, geometry and velocity of fragments are anecdotally believed to change the amount of dust and debris generated; however, no good data sets exist to develop models. Well-characterized experiments and accompanying modeling and simulation (M&S) are needed to determine the amount of dust and debris generated in weapon strike scenarios. Uncertainty quantification and statistical analysis is critical in understanding the stochastic fragmentation process and the accompanying debris generation. This topic looks to develop new diagnostics, experimental techniques, and modeling to understand fragment impact on responding surfaces such as walls made from concrete, dry wall, geo-materials, or other materials found in target sets as required. This effort would address the impact, fragment-structure interaction, and response including ejected dust and debris. The goal of this effort is the characterization of dust and debris from building surfaces as a function of different impacts. This effort should be able to scale from single lab size fragments and velocities to generic fielded weapons with multiple fragments and post detonation weapon environments. Prior and concurrent efforts by DTRA and others can and should be utilized for efforts but expectation for this topic is that novel diagnostics, M&S, and experimental techniques will be developed to optimize understanding of fragment impact. This effort will be linked with other efforts on understanding the effect of dust and debris on the late-time chemistry. PHASE I: Initial M&S, diagnostics, and experiments Initial experiments and modeling of fragmentation expectation is Phase I will be at the laboratory scale with characterized materials to scope out techniques. Develop plans for more complex scenarios with different materials. PHASE II: Prototype M&S program characterized with complex conditions Model able to provide statistical range (particle size, velocity, direction) of dust and debris ejected from a provided generic fragment size and velocity. Model capable of multiple impacts from different fragments incorporating pre-damaged scenarios. Model the interaction of the ejected solid with the surrounding environments. Develop experimental technique(s) to validate model over a range of fragment and impact velocities that can be used to evaluate weapon effects. PHASE III DUAL USE APPLICATIONS: Full-scale tests and accompanying model perditions Capability to predict dust and debris from various weapons and target scenarios. Diagnostics and testing protocol for characterizing dust and debris in full-scale weapon testing. Linking this effort with Agent Defeat mission and planning codes such as IMEA. Marketing of capability across DoD/DOE. REFERENCES: Collins A, Chapman, D., and Proud, W. Front face spall of concrete. Shock Compression of Condensed Matter - 2007, p 497 -500 (2007); Wu, C.T., Wu, Y., Crawford, J.E. & Magallanes, J.M. Three-dimensional concrete impact and penetration simulations using the smoothed particle Galerkin method. Int. J. Impact Eng. 106, 1 17 (2017); H Wang, J Xiao, Y Zheng, Q Yu, Failure and ejection behavior of concrete materials under internal blast. Shock and Vibration, 2016; Meyers, M.A., Dynamic Behavior of Materials. J. Wiley, 1994 KEYWORDS: Dust; Debris; M&S; Responding Surfaces; Testing; Fragment Impact; Diagnostics; Concrete