<p style="margin: 0in">The development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel, which could result in training constraints and possibly expensive upgrades to improve the safety of existing facilities. New training ammunition manufactured from novel structural materials, are needed to allow for safe live-fire shoot house use. The goal of this project is to characterize three sintered metal powders and develop experimentally validated models suitable for simulation in support of numerical design. Samples of pressed and sintered blends of Copper-Tin, Copper-Fumed Silica, and Copper-Stainless Steel were selected as potential suitable materials for this application. Each material was tested in uniaxial tension under quasi-static conditions up to a strain rate of 5/s and at elevated temperatures. Dynamic strain rates up to a rate of approximately 10<sup>3</sup>/s and at elevated temperatures were tested in compression using a split-Hopkinson bar. The results of these tests were then used to develop Johnson-Cook and Zerilli-Armstrong strength models of the materials. The models were fit by selecting five points from test data at different strain rates and elevated temperatures. This system of equations was then solved for each model, ensuring that each was developed from the same data and were a fair comparison of the results of each. Four different notch conditions were then tested to assess the fracture characteristics of each material and to develop a Johnson-Cook fracture model for each. The unnoted quasistatic testing used for the strength model was also included in the damage model to estimate the strain rate and temperature parameters of the model. A Mie-Gruneisen equation of state for each material was estimated using a rule of mixtures and existing shock and particle velocity data. Taylor cylinder tests were conducted on each material and the change in length and area were recorded over time and measured using high speed video. Simulation of the Taylor tests was conducted using the developed strength, fracture, and equation of state models and compared to the experimental results for model validation, comparison, and selection. The more physically based Zerilli-Armstrong model was found to provide better agreement with the physical testing and is the model recommended for future studies. These material models will inform the further development of these materials for use in high strain rate applications.</p>

Constitutive Modeling and Validation of Sintered Metal Powders Subjected to Large Strains and High Strain Rates

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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