Optimization of laminate’s single lap joints by FSDT theory

Abstract

The focus of this paper was to optimize the interconnection mapping of the adhesive single-lap joints that are bonding composite laminates by utilizing the adherent’s layers’ arrangement method. In this work, as the first step, shear and peeling stress distributions in the adhesive layer of a single lap joint under tensional loading were determined by a 2-D first-order shear deformation theory (FSDT). Subsequently, the stacking sequence of the laminated adherents was optimized by the bees algorithm (BA) in order to reduce the maximum stresses in the adhesive layer. The adhesive layer was assumed to be isotropic while the laminated adherends were assumed to be made of orthotropic laminae. All stresses were determined by an improved closed-form solution based on the deduced displacement fields. The results of the analytical solution were compared with those of finite element solution using ANSYS software, version 13.0. Good agreements were observed between the results of both methods. The results of BA optimization technique were also provided. Results indicated that a decrease in orientation of fiber angles in the laminated adherends would decrease the maximum shear stress in the adhesive layer (and vice versa). Additionally, to decrease the maximum peeling stress, it is crucial that the outer laminae in each adherend layer have a low fiber angle. However, an increase in the fiber angles will increase the maximum peeling stress in the adhesive, causing possible damage to the joint. The presence of high fiber angles in the outer laminae of each adherend layer (away from adhesive-adherend interface) will reduce the peeling stress significantly. However, the presence of such laminae adjacent to the adhesive-adherend interface produces lower shear stress in the adhesive layer.