KY Space Grant GF-25-038: Constitutive and Fracture Modeling of Additively Manufactured Aerospace Alloys Across Temperature and Strain Rate Regimes

Constitutive and fracture modeling of additively manufactured aerospace alloys across temperature and strain rate regimes Madhav Baral, Ph.D. (PI) Department of Mechanical Engineering University of Kentucky - Paducah ABSTRACT Additive manufacturing (AM) is emerging as a transformative technique in the fabrication of aerospace components, including those developed for NASA hardware. In particular, dispersion- strengthened (DS) alloys produced via AM are being explored for their superior mechanical performance and suitability for ultra-high temperature environments. Despite demonstrated improvements in strength and ductility over baseline alloys, the constitutive and fracture behaviors of these materials remain insufficiently characterized across a broad range of conditions, including variations in temperature, strain rate, and stress states. This research aims to systematically evaluate and model the mechanical response and fracture behavior of AM and DS aerospace alloys under varying strain rate and temperature regimes. The study will incorporate advanced experimental techniques, including Digital Image Correlation (DIC) for full-field strain measurements and Acoustic Emission (AE) sensing for real-time monitoring of damage initiation. These complementary methods will be employed to identify strain localization, capture dynamic damage events, and correlate surface deformation with subsurface fracture activity. Experimental data from uniaxial and notched specimen testing will be used to calibrate a rate- and temperature- dependent constitutive and damage model (e.g., Johnson-Cook model), enabling accurate finite element (FE) simulations of material behavior under complex loading conditions. The model will be validated through comparison with observed flow stresses and fracture strains across multiple temperatures and strain rates. Triaxial stress states at the onset of failure will be determined to inform the fracture criteria. Ultimately, this work aims to establish a robust framework for predicting the performance of additively manufactured structural alloys, supporting their accelerated certification and integration into NASA missions and other demanding aerospace applications. The integration of AE and DIC in this modeling approach enhances the understanding of deformation and failure mechanisms, leading to more reliable and damage-tolerant component designs.