Tensile strength and failure simulation of simplified spot weld models

• A simple strategy to design a spot weld joint nugget on a test coupon is presented.
• Six simplified spot weld joint finite element model is developed.
• Model performances are verified with experimental results.
• Material strength based failure criterion was implemented in the spot weld models.
• Considering computational costs the best spot weld model was recommended.

A simple model for spot weld joints is desirable in body-in-white automotive structures which contains thousands of them. Hence, comparative performance and failure prediction study of six simplified spot weld models in terms of their geometric and constitutive properties are presented in this paper. The stiffness characteristics of these models under tensile loading condition were compared with the experimental results. It was found that the current spot weld modelling practice in the automotive industry predict the strength with 45.33% of error. To simulate the joint failure a material damage criterion correlating ultimate tensile strength of material was implemented in the developed models. The comparative study with respect to the accuracy was also related with the computational cost incurred by the different models. Hence, suitable modelling conditions to design a finite element model for spot welded joints are established which is very simple to develop, relatively cheap in terms of computational costs but yet predicts reasonably accurate results.