Effect of Metallic Insert Design Parameters on the Load-Carrying Capacity of GFRP Bolted Connection

Abstract Threaded metallic inserts can be embedded between laminates to avoid drilling and prevent the bearing stresses on the hole boundaries. In the present work single lap joint configuration was used to evaluate the joint strength using embedded metallic inserts. The parameters were selected using the Design of Experiment (DOE) to facilitate and control the variables that will be tested. Parameters such as the tightening torque, the specimen length (L), fiber orientation, and loading rate were kept fixed for all tests. Other design parameters such as edge distance to hole diameter (E/D) using 3 levels and the thickness of the specimen (t) were evaluated using 2 levels, 3 replicates for each. Finite element analysis using ABAQUS was conducted to simulate the experiment, and the results of the experimental work were used to validate the FEA model. The failure was initiated in the matrix at the composite-insert contact surfaces. The fiber failure begins in the laminate which is in contact with the metallic insert surface. Progressive delamination and fiber failures led to several peaks in the load-displacement curve before total failure by shear-out. It was found that the joint strength tends to increase with a lower E/D ratio in both single and double layers of fabrics.