Strategies for Incorporating Micro-Computed Tomography into Homogenized Ductile Damage Models

Stephen Cabel Foster, PhD
Post Doctoral Fellow
DEVCOM Army Research Laboratory

Abstract:
aterial damage behavior is not well understood in high strain-rate environments. Developing materials for these regimes demands an understanding of the relationships between real microstructures and time-dependent properties. Although advanced material characterization methods, e.g., micro-computed tomography (micro-CT), have enabled high-resolution reconstruction of relevant microstructural features, many investigations into material behavior and damage use idealized microstructures, which generally do not accurately represent the as-processed material. This research proposes strategies to model material behavior by incorporating realistic microstructural morphology into homogenized damage models and then implementing these models in high strain-rate investigations. The material data consists of micro-CT scans of different alloys that resolve second-phase particle and void distributions, both of which highly affect the ductile damage process. First, we propose a tool that converts a realistic, highlyanisotropic second-phase particle morphology to an idealized, periodic microstructure. The efficacy of this tool is determined by comparing finite element (FE) simulations of the idealized microstructures to direct numerical FE simulations. We then use a reduced version of this methodology to convert a set of realistic void distributions to a set of idealized microstructures. The idealized microstructures are then spatially varied around the circumference of a rapidly-expanding ring in a FE simulation to model the fragmentation behavior in a parametric study. We compare the model to experiments of similar rings and find improved agreement over current modeling techniques.

Biography:
Caleb Foster is a postdoctoral fellow at the DEVCOM Army Research Laboratory where he currently works on modeling anisotropic and heterogeneous materials. Caleb obtained a B.S. in Mechanical Engineering from Mississippi State University in 2019 and subsequently graduated with a Ph.D. in the same field from Texas A&M University in 2024. As a student, he conducted solid mechanics research at both national and international institutions, including Sandia National Laboratories, and the Universidad Carlos III de Madrid. Caleb’s work has been recognized and supported by several awards, including the National Defense Science and Engineering Graduate (NDSEG) Fellowship, the National Science Foundation (NSF) Graduate Research Fellowship, the Materials in Extreme Dynamic Environments (MEDE) – Materials for Strategic Advantage (MSA) Research Fellowship, and the J. Mike Walker ’66 Impact Award. His research interests lie at the interface of solid mechanics and materials science, with an emphasis in damage mechanics across length- and time-scales. He is particularly interested in developing computational tools that use microstructural information to predict rate-dependent damage and fracture.