Effect of Bolt Tightness on the Behavior of Composite Joints

This study provides an experimental and analytical investigation of the behavior of a double bolted single lap shear composite joint. Various scenarios of bolt tightness are considered for composite-to-composite and composite-to-aluminum bolted joints. Progressive damage analysis is provided for the composite coupons in two regions; namely, the surface under bolt heads and near the contact with the shank of the bolt; the damage analysis is performed using an optical microscope. Four tightening configurations are used in the testing of each double bolted joint. These configurations permit each of the two bolts to be either tight or loose. The analytical part of the study utilizes a 3-D finite element model that simulates the bolt tightness and the multilayered composite coupons. The experimental and finite element results are correlated.