Finite Element Micromechanical Modelling of Strain-Rate-Dependent Behavior of Al-Al2O3 Composite Coatings Via Cold-Spray Additive Manufacturing

This study investigated the uniaxial compressive behavior of Al-Al₂O₃ composite coatings fabricated by cold-spray additive manufacturing for strain rates of 0.001 to 3000 s^-1. A split-Hopkinson pressure bar (SHPB) setup coupled with digital image correlation (DIC) was employed to conduct the high strain rate experiments. Scanning electron microscope images of the material were captured to characterize the microstructural features (e.g., porosity, Al₂O₃ weight fraction, and size). Microstructure-informed representative volume elements (RVEs) were generated by using Digimat software. Rate-dependent constitutive material models were incorporated into the RVEs for the Al metal matrix and the Al₂O₃ reinforcing particles by using VUMAT subroutines in Abaqus software. The FE models were validated with experimental stress-strain curves and lateral versus axial strain histories. Additionally, the failure mechanisms such as ductile failure in the Al matrix, interfacial failure, and damage accumulation in the Al₂O₃ ceramic particles were quantified as volumetrically averaged parameters and compared to the experimental observations. The results revealed that the computational model reasonably predicts the rate-dependency of stress versus strain behavior, compressive strength, and strain hardening behavior of the material. The outcomes of this study have implications for the computational design and optimization of metal-ceramic composite coatings for clean technology and aerospace applications.