Effects of Hole Perpendicularity Error on Mechanical Performance of Single-Lap Double-Bolt Composite Joints

Static tensile experiments and numerical simulations were carried out to study effects of hole perpendicularity error on mechanical performance of single-lap double-bolt composite joints. Hole tilting angle, varying from 1 to 4 degrees, and hole tilting direction to account for anisotropic properties of composite material were investigated. Progressive damage model (PDM) based on ChangLessard type criterion with an extension by Olmedo was created, which involved seven failure modes and made material properties be a direct function of predefined field variables. The model was implemented in ABAQUS/Standard using a UMAT subroutine. Good agreement was found when comparing numerical simulation results with experimental outcomes. In addition, the results demonstrate that, with increasing of hole tilting angle, damage is prone to arise and the load path of the composite bolted joints alters with changing of hole tilting direction, which result in severe stress concentration around the edge of hole and joint failure in advance.