Analytical and Numerical Study of Percussive Riveting Process

Abstract

Percussive riveting is a dependable assembly method that produces high-quality joints in the aerospace industry. Its successful application is derived from its ease to implement in an assembly floor environment. The rivets are formed on the shank end of the rivet using a forming tool like a bucking bar and the head is constrained and impacted with a rapid succession of hits using a pneumatic gun with a special purpose die head. Research studies focused on the dynamics modeling of the percussive riveting process for robotic automation have not delivered an understanding of the temporal evolution of stress and strain fields in the vicinity of the rivet and the rivet hole. No modeling efforts have been published up to this point in time. This understanding is important to produce joints of predictable strength. In this work, squeeze riveting and percussive riveting numerical analysis was performed using finite element method. Inner skin region adjacent to the rivet button was observed to be most critical location for crack nucleation by compression-induced shearing. For a good quality percussive rivet joint, friction coefficient and rivet hammer impact energy need to be maintained high, and skin thickness ratio needs to be comparatively low. In three-dimensional percussive riveting numerical analysis performed in this work using finite element method, bucking bar (under asymmetric motion) dwell time was observed to impact magnitude of rivet deformation.