Effects of Load Angles on Stress Distribution in I-Shaped and L-Shaped Structures Under Uniaxial and Multiaxial Loadings: A Numerical Analysis

The mechanical integrity of multi-material interfaces in advanced electronic packages is critically governed by nanoscale stress localization. Yet, the interplay between geometric discontinuities and multiaxial loadings in governing nano-interfacial stress transmission remains insufficiently resolved. This study conducts nanoscale finite element simulations of GaN/resin/SiC tri-material joints subjected to systematically varied uniaxial and multiaxial loading orientations to elucidate these mechanisms. The analyses reveal an almost consistent trend: nano-interfacial stress magnitudes diminish progressively as loading angles approach the normal (90°), a behavior observed in both symmetric (I-shaped) and asymmetric (L-shaped) configurations. It was also demonstrated how geometric asymmetry is a primary driver of stress concentration, with L-shaped interfaces exhibiting a 1.6-fold higher stress concentration factor and a pronounced sensitivity to load direction orientations. Critical load-angle thresholds inducing stress singularity states were identified, providing insights into failure precursors. The visualized stress concentration, distribution, and localization patterns under combined loading can furnish a robust framework for predicting nanointerface-dominated failure. Collectively, these findings can advance the understanding of stress singularity at multi-material nanointerfaces and establish design principles for mitigating nano-interfacial delamination in high-performance surface-engineered systems. • Nanoscale finite element model analyzes uniaxial and multiaxial loads on electronic joints. • Stress drops as the load angle approaches the normal (90°) direction. • Study identifies critical load-angle thresholds for stress singularity. • L-shaped joints have 1.6-fold higher stress than symmetric I-shapes. • Geometric asymmetry is a primary driver of nanoscale stress concentration.