A presentation provided by Xiao Wu, Siva Vayugundla, and Hong-Tae Kang, A/SP Fatigue Committee Members, at the 2019 Great Designs in Steel. Project objective was to develop and validate a fatigue life prediction model for welded joints.
This presentation describes a new method called generalized stress parameter (GSP) to predict fatigue life of gas metal arc weld joints (GMAW). GSP is based on the structural stress and the stress intensity factor and is based on a modified version of the Maddox equation. The structural stress accounts for the effect of global weldment geometry and the stress intensity factor captures the local effect of the weld angle and weld toe radius. Stress versus fatigue life (S-N) curve is developed using GSP and fatigue test results of various specimen configurations, material grades and thickness combinations. The developed S-N curve along with the GSP approach is used to predict the GMAW’s fatigue life of an actual OEM’s production control arm link subjected to variable amplitude loading. Laboratory tests of the above component subject to the same variable loading history are conducted. Comparison of the analysis results based on GSP and the test results revealed excellent correlation.