Three-dimensional strain analysis of single-lap bolted joints in thick composites using fiber-optic strain gages and finite element method

Bolted joints involving composite plates used to be almost entirely dedicated to aero-space applications. As the need for energy conservation increases, the field of composite bolted joints finds new application in ground armored vehicles. Thick panels able to withstand large in-plane and impact loads are critical. This study was concerned with the evaluation of strain fields in thick composite plates used in single-lap bolted joints. The area of interest was the bearing plane region close to the bolt hole. Both experimental and finite element analyses were performed to evaluate possible failure causes and three-dimensional effects present in thick composite bolted joints. Experiments were performed for pin connection and bolted joint configurations. Experimental data for the pin connection and the bolted joints were recorded by embedded fiber-optic strain gages. The fiber-optic strain gages were embedded in the bearing plane of the composite plate. The numerical analysis was performed using both ANSYS and LS-DYNA finite element codes. The finite element analysis correlated reasonably well with the experiments.