Multiobjective optimization design of clinching joints between punches and dies

To resolve multiobjective conflicts among stress concentration, resonance risk, and lightweight demand for punch and die in electromagnetic pulse-driven high-speed impact clinching dies, this work develops a multiobjective optimization framework combining orthogonal test, response surface methodology (RSM), and NSGA-II. Key geometric parameters of punch and die are parameterized. Orthogonal tests with range and variance analysis are used to rank parameter effects on maximum equivalent stress, first-order natural frequency and mass. A second-order polynomial response surface surrogate model is established, with ( R ²  > 0.96) and average relative error below 3%. Pareto optimization via NSGA-II shows the punch’s maximum equivalent stress drops by 16.3% (1130–946 MPa), its first-order natural frequency rises by 10.3% (929–1025 Hz), while mass merely grows 3.2%. For the die, maximum equivalent stress decreases by 12.1% (621–546 MPa), first-order natural frequency increases by 3.9%, and mass rises 6.4%. The method effectively balances strength, dynamic stiffness, and lightweight targets, offering a practical route to enhance the performance of clinching dies.