Effects of Laminate Thickness and Tapering on the Behavior of FRP Composite Multibolt Joints

Abstract

This paper presents a numerical study to show the effects of laminate thickness and tapering on the performance of composite bolted joints made of carbon fiber–reinforced polymer (CFRP) materials. Major weight savings can be achieved by using tapered joints while compromising little in joint stiffness and strength compared to joints having uniform thickness. A numerical investigation is carried out to minimize the weight of a double-lap CFRP composite multibolt joint considering different tapering configurations. The proposed tapering configurations can be useful for designing efficient lightweight aerospace structures, in which weight savings are a great concern. The present analysis is carried out using a novel three-dimensional (3D) finite-element-based progressive damage model developed using the FE software ABAQUS. The material constitutive relations and the progressive damage algorithms are integrated with ABAQUS using the user subroutine UMAT. In addition to the stiffness and strength of the joints, out-of-plane displacements are also calculated for each case in order to determine the effect on secondary bending.