Research and multi-objective optimization of forming quality of SPR joint using Taguchi–gray relational analysis

This study proposes a systematic approach for predicting and optimizing the forming quality of self-piercing riveting (SPR) joint between aluminum alloy sheets. First, the finite element (FE) model of the forming of SPR joint was built to monitor the forming process and assess the joint’s forming quality, which was then experimentally validated. Second, based on FE numerical simulation, a parameter study was implemented to explore the action laws of forming process parameters (rivet shank thickness, rivet shank inner diameter, die pip height and die inner diameter) on the joint’s forming quality. Third, taking above forming process parameters as design variables, a hybrid Taguchi–gray relational analysis (GRA) method was employed to conduct a multi-objective optimization of the joint’s forming quality for maximizing interlock value (IV) and bottom thickness (BT) simultaneously, which are two primary evaluation indicators of forming quality of SPR joint. Finally, the multi-objective optimization results were validated. According to the outcomes, the SPR joint achieves increases of IV by 7.41% and BT by 40.63% simultaneously, indicating a good multi-objective optimization of forming quality of SPR joint is obtained. The present study provides an effective new method for predicting and optimizing the forming quality of SPR joint.