Experimental study and DEM modelling of bolted composite lap joints subjected to tension

This paper presents a numerical approach using the discrete element method to predict strength and damage propagation of plates and bolted lap joints subjected to axial tension. Tensile tests on GFRP plates and bolted joints are carried to obtained their overall stiffness and strength. A new three-dimensional discrete element model constructed by a 19-ball assembly is proposed and the relationships between the macro and the micro mechanical properties of FRP is established through calibrations using the test results. The calibrated DEM model is then used to reproduce the test results. Excellent agreements are achieved between the numerical and the experimental results in terms of not only the overall failure loads, but also the detailed failure modes, including cracking and delamination. The research shows great potential of the DEM model in predicting strength of composite materials and presenting detailed local damage and damage propagation at micro-scale, which represents a significant advantage over the conventional numerical methods, such as the finite element method.