Development of Techniques for the Joining of Composite Tubes

Manufacturing and Testing techniques were investigated for the development of efficient joining of composite tubes. The stepped lap joining arrangements were studied. Finite element models were developed using ANSYS finite element code for predicting the stress distribution of the joint under the applied loads. Tubes made of graphite/epoxy were considered. The tubes were tested under both tension and torsion. The joining technique developed provides an average joint strength of 69% of the strength of the substrate when tensile tests were conducted. Reinforcement of the joint with overlay layers improves the joint strength efficiency in tension to 81%. In torsion, the average torsional joint strength is 70% of the torsional strength of a tube with no joint. Reinforcement of the tubular joint with overlay improves the torsional behavior to 86% of the torsional strength of the tube with no joint.