Development of spot weld failure parameters for full vehicle crash modelling

A cost and time effective process was developed to create spot weld failure parameters for crash models implemented in LS-DYNA. The process includes a design of experiment (DOE) approach for coordinating data collection, welding and testing, finite element modelling, statistical analysis, validation, and implementation. The DOE approach was used to coordinate testing of a reduced set of samples over a large range of material strengths and gauges. This testing included cross-tension, lap shea, and coach peel type evaluations. Computer models for each metal combination and sample geometry were developed to obtain normalised tensile, shear and bending stress at the incidence of weld failure. These normalised loads were then regressed to extend these results to all possible material combinations within the DOE space. These results were then used to estimate the spot weld failure parameters for all the stack-ups of interest. A set of multiweld T-section samples were then welded, physically tested and computer modelled to validate the failure parameters developed from the small single weld tests.