A self-clinching fastener for hidden lap joints

Sampaio, R.F.V.; Pragana, J.P.M; Bragança, I.M.F.; Silva, C.M.A.; Martins, P.A.F.

Key information

Authors:

Sampaio, R.F.V. (Rui Filipe Vieira Sampaio); Pragana, J.P.M (João Pedro da Fonseca Matos Pragana); Bragança, I.M.F. (Ivo Manuel Ferreira de Bragança); Silva, C.M.A. (Carlos Manuel Alves da Silva); Martins, P.A.F. (Paulo António Firme Martins)

Published in

May 1, 2022

Abstract

This paper presents a new self-clinching fastener to connect two sheets (or plates), made from similar or dissimilar materials, placed over one another by means of a mechanical form-closed joint that is hidden inside the sheets. The development of the fastener, the definition of its main design variables and the identification of its workability limits are carried out by means of a combined experimental and numerical simulation work based on finite elements. It is shown that self-clinching by pressing the two overlapped sheets against each other to displace material around the annular groove of the fastener shank and create undercuts in both sheets requires an appropriate choice of the design variables. Wrong values of the design variables resulting in lack or excess of material displaced by plastic flow gives rise to inappropriate lap joints that cannot be used in production. The new proposed fastener allows, for the first time ever, joining by forming with the use of auxiliary elements that are harder than the sheet materials to fabricate invisible joints with no material protrusions in applications requiring minimum installation space.