A Predictive Model for Fatigue Performance in Spot Welded and Bolted Joints

Abstract

This study examines the fatigue behavior of spot-welded and bolted single-lap joints through an integrated framework combining experimental testing, finite element analysis (FEA), and regression modeling. The investigation focuses on how geometric parameters-such as plate width, length, thickness, and overlap length-affect fatigue life under variable loading conditions. Fatigue tests serve as the foundation for developing a predictive model for low-cycle fatigue, while FEA provides detailed insights into stress concentrations at critical regions like weld nuggets and bolt holes. Results show that bolted joints, particularly those using M4 fasteners, exhibit superior fatigue performance due to more uniform stress distribution and reduced localization. Submodel-based FEA confirms these findings, revealing that bolted configurations better disperse stresses compared to the high gradients observed near spot welds. This combined approach enhances fatigue life prediction accuracy and offers practical guidance for optimizing joint geometry in automotive, aerospace, and mechanical engineering applications.