Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions

Abstract

Composite materials are attractive for aerospace vehicles due to their low weight and high performance; however, predictive computational models are needed to lower the costs associated with their design and certification process. Furthermore, because aircraft structures are built up from many components fastened together, it is critical to understand and predict the mechanical behavior bolted joints introduce. The goal of this thesis is to advance the state of the art in fiber reinforced polymer composite bolted joint computational modeling and prediction using the multiscale reduced order computational model known as the Eigendeformation-based Homogenization Method (EHM). Preliminary blind predictions were performed for laminated [44/44/11] IM7/977-3 composite specimens in single-lap straight hole and countersunk bolt joints under static tension tests. To address stiffness and post-peak behavioral issues, an in-depth blind prediction study was conducted for open hole, filled hole, and single shear bearing configurations of countersunk laminated [44/44/11] IM7/977-3 specimens under static tension and compression tests. EHM performed very well in the open and filled hole cases, and the single shear bearing results show promise of EHM as a reliable choice for composite bolted joint damage analysis.