Masters Theses

Date of Award

12-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Reza Abedi

Committee Members

Reza Abedi, Stephanie TerMaath, Brett Compton

Abstract

Microstructural heterogeneity governs the strength, stiffness, and fracture behavior of materials. Predicting its influence requires linking local variability to macroscopic behavior while retaining the governing mechanisms that link behavior across scales.

A statistical volume element (SVE) framework is developed to connect microstructural variability and residual stresses to apparent material behavior. The approach is first established using a metallic microstructure from selective laser melting to quantify scale effects in elasticity and fracture, then extended to a multiphase ceramic composite where thermal mismatch generates internal residual fields. Building on prior experimental characterization of these stresses, the analysis incorporates them into a phase-field formulation that couples elasticity and fracture to compare thermally influenced and mechanical-only responses.

Residual stresses reduce peak strength but promote post-peak stability, reflecting how stored energy is redistributed between tensile inclusions and a compressive matrix. Anisotropy and variability diminish with increasing SVE size, revealing a common mechanism through which apparent homogeneity emerges from microstructural disorder. Variability follows a consistent scaling trend, with residual fields extending the length required for convergence in strength-related metrics. These findings demonstrate that effective properties are not fixed material constants but scale-dependent outcomes shaped by geometry, boundary conditions, and microstructural history.

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