Numerical Study of Knife Edge Effects in Flash Riveted Single Lap Joint

Abstract

The purpose of this work is to describe the effects of the countersink depth on the residual hoop stress in a flash riveted single lap joint. In this research instead of three dimensional finite elements, a force-controlled two-dimensional axisymmetric finite element analysis has been carried out to simulate the rivet installation. Results from this analysis show that with decrease in countersunk portion of the outer sheet, the rivet expansion is larger in the upper skin, leading to an increase in the compressive residual hoop stress near the hole edge. Furthermore the countersink depth must not exceed 60% of the skin thickness and anything beyond that will cause the skin to become knife edged. Using press countersinking instead of machine countersinking is highly recommended for sheet thickness less than 0.032 inch