Fatigue Life Estimation of Cold Expanded and Bolt Clamped Al-Alloy Plates in Double Shear Lap Joints Using Different Plasticity Models

Abstract

Finite element method was used to analyze cold expansion levels (1.5% and 4.7%) under a bolt torque of 4 N.m to estimate fatigue life of 2024-T3 aluminum in double-shear lap joints. To model the material response, three different plasticity hardening approaches were employed to predict the resulting stress and strain fields in the joint under the influence of cold expansion and bolt preload. The multi-linear isotropic and multi-linear kinematic hardening models were calibrated using monotonic tensile test data, whereas the nonlinear combined hardening model was developed based on cyclic tests. The fatigue crack initiation life was estimated using Kandil–Brown–Miller, Fatemi–Socie, and Glinka criteria. The AFGROW software was adopted for estimating fatigue crack propagation life. The overall fatigue life was determined by summing the crack initiation and propagation stages and was compared against previously published experimental fatigue results. The nonlinear model provided the most accurate fatigue life estimations across all three fatigue assessment criteria.