A Low-Cost, Laboratory-Scale Method to Identify Regions of Microstructural Changes in Response to Dynamic Loading Conditions

This proposal outlines a plan to develop an innovative and effective laboratory based method to support first-principles modeling of structural material responses under a range of energetic loadings, including explosions and high velocity impact. The range of strain rates posed by these dynamic loadings is similar to that experienced in metals in advance of a cutting tool. This provides a low-cost laboratory-scale experiment which covers the range of strain rates of interest to generate test specimens. Important to the various stress versus strain relationships are identifying regions of constant microstructure. Metal cutting technology has focused on the conditions required for a particular metal to drive shear band formation leading to chip fracture and breakup. By characterizing the chips formed at the varying shear strain rates, regions of microstructural changes can be readily identified. This provides key conditions for specialized dynamic tests to provide the stress versus strain curves of interest. This material response would be constant for a constant microstructure. Once the behavior response to the dynamic loading changes, the material response also changes. Approved for Public Release | 17-MDA-9219 (31 May 17)