Shape optimization methodology of clinching tools based on Bezier curve

The purpose of this paper is to propose a methodology for the strength optimization of mechanical clinched joint. To this end, a mathematical optimization model which introduces ductile damage constraint to prevent the onset of fracture during the clinch joining of thin metal sheets is proposed. Meanwhile, Bezier curve is used to describe the outline shape of the clinching die, which can be used to search a lot of potential shapes by changing the location of the control point. In addition, a new solving method based on the direct communication between FE-analysis and genetic algorithm (GA) is proposed. The results indicate that the shape of the die groove can be replaced by arc curve to simplify the structure of the clinching tools for general applications. If the requirement of the joint strength is not very high or the ductility of the sheet is good, the clearance between the lower sheet and the die groove is not necessarily equal to zero, but if the requirement is very high or the ductility is poor, the zero clearance is very necessary.