Optimization design of cylindrical rivet in flat bottom riveting

Abstract

Light weight material is used more and more extensively in automotive industry due to its high mechanical properties and low density. The joining of light weight material, such as mechanical clinching, is attracting much attention. The application of mechanical clinching is greatly restricted because of the protrusion produced on lower side of sheet. A new joining method, flat bottom riveting, is presented in this paper. Lower surface of riveted joint is flat and smooth, with no protrusion formed. Simulation was conducted to optimize geometrical parameters of rivet. Proper rivet length and rivet diameter were obtained. There is a circular groove on lower edge of rivet. Geometrical parameters of groove, such as groove inner diameter, groove length, groove height, groove bottom width and fillet radius have great influence on tensile load of joint. Finite element simulation and orthogonal test were carried out, and groove inner diameter was found to be the most important factor that affects joint tensile load. The results of simulation and experimental tests had high consistency, indicating that conclusion drawn was convincible.