Improved SIF calculation in riveted panel type structures using numerical simulation

Abstract

As damage tolerance methods continue to evolve it has become possible to evaluate the interaction of riveted connections on the predicted SIF values in airframe structures. This current work is focused on the prediction of SIF values and crack growth paths in riveted structural members subject to complex loading, taking into account the influence of contact loading in the rivet hole, by-pass loading and changes to the load path which occur when a growing crack causes a rivet to completely cease transferring load. The SIF calculation and simulated crack growth trajectory are performed using a boundary element based fatigue and crack growth toolset. Newly developed modelling tools and analysis capabilities are applied to demonstrate how load transfer between different structural members may influence the calculated SIF values and crack growth direction. The results from analysis of different airframe type models are presented. The first study examines the effects of changing the rivet geometry, using perfect fit rivets, clearance fit rivets and push fit rivets, and determining the effect on SIF values calculated for a half-penny shaped crack. A second study looks at load transfer between more complex riveted components, including effects of the significant load redistribution which occurs when a rivet is lost as a result of ligament failure.