A study of dynamic pull-through failure of composite bolted joints using the stacked-shell finite element approach

Abstract

Pull-through failure of bolted joints in composites is due to the relatively low through-thickness properties of laminated materials. Recently it has been identified that pull-through failure also plays an important role in the ultimate bearing load and total energy absorption of bolted joints, especially under dynamic conditions. It has been previously found that bolted joints loaded in bearing exhibit rate sensitivity whereas bolts loaded in pull-through experience very little sensitivity, for nearly identical joint configurations. The primary focus of this paper was to use explicit finite element simulation of pull-through failure to shed light on discrepancies between experimentally observed rate sensitivity for seemingly similar tests. The paper uses the stacked-shell modelling approach to efficiently model the interaction of delamination and ply failure under the complex dynamic load state. The results of the simulation indicated that the properties of the interface susceptible to loading rate sensitivity, Mode I and II strain energy release rates (SERR), did not have a great effect on the overall joint response; despite the prevalence of delamination during the failure process. A weak relationship between Mode II SERR and joint response was discovered which was consistent with experimental observations.