Sandia Labs FY22 Laboratory Directed Research & Development Annual Report

FY22 ANNUAL REPORT

UNDERSTANDING THE COUPLING BETWEEN HEAT GENERATION AND MECHANICAL WORK IN LARGE DEFORMATION PLASTICITY.

Accurately predicting material failure is of high value to any number of applications including accident/ crash scenarios. When metals deform plastically, a large amount of energy is generated, which is classically understood to be either stored in the metal or dissipated, usually as heat (described by a single, constant parameter β). The dissipation as heat leads to a temperature rise, increasing the local strain rate in a feedback loop, until ductile failure. The key impacts from this LDRD project include a comprehensive thermomechanical dataset, simulation development (including a functional form for β), and a mechanism to quantitatively compare coupled mechanical behavior to simulation. The dataset includes use of emerging microstructural analysis tools to quantify energy stored in the microstructure and full-field diagnostics. The wide range of states interrogated allows careful evaluation of model form error, which will lead to predictive thermomechanical models. This project resulted in one patent, numerous conference presentations (including the 16 th

International Conference on Advances in Experimental Mechanics [the British Society for Strain Measurement] where it won a Best

Paper Award, a proceedings paper at the ASME Conference in 2021, and two journal publications ( Measurement Science and Technology , Strain, An International Journal for Experimental Mechanics ). (PI: Amanda Jones) Coupling between heat generation and mechanical work with high amounts of generated energy shows plastically deformed metals.

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