Evaluation of the adhesive bonding of laminated composite plate adherends under buckling loading using GDQM

Composite structures are susceptible to local instabilities such as compressive buckling, especially in the presence of joints. Due to geometric complexities and manufacturing constraints, structural connections are often unavoidable in large-scale composite systems. Adhesive bonding has gained significant traction over mechanical fasteners because of its uniform stress distribution, weight reduction, and enhanced fatigue performance. This study investigates the compressive buckling behavior of orthotropic rectangular laminated composite plates joined via adhesive bonding. The adhesive layer’s force response under buckling conditions is also evaluated. To determine the critical buckling loads under various boundary conditions, the Generalized Differential Quadrature Method (GDQM) is employed. The analysis is based on the First-Order Shear Deformation Theory (FSDT), incorporating compatibility conditions at the adhesive interface. The governing equations for the lap-joint configuration are derived using the principle of minimum potential energy. Parametric studies are conducted for composite laminates made of glass/epoxy, carbon/epoxy, and aramid/epoxy, with adhesives including epoxy, AV-138, and IPCO-9923. The influence of laminate lay-up, adhesive and composite material properties, overlap length, plate aspect ratio, adhesive-to-plate thickness ratio, and boundary conditions on the critical buckling load is thoroughly examined. Furthermore, adhesive failure is evaluated to ensure it does not occur prior to structural buckling. Results indicate that increasing the adhesive overlap ratio significantly enhances the buckling load capacity. Bidirectional carbon/epoxy laminates bonded with AV-138 adhesive exhibit the highest critical buckling loads. The analytical findings are validated through finite element simulations using ABAQUS commercial software, showing good agreement with the proposed model.