Composite materials have emerged as a method of engineering high strength structures to specific tasks at a low weight cost. The strength to weight ratio makes composite materials ideal for replacing metal components in vehicles, but the plates have to be thick enough to withstand impacts during service use. Often, the weakest point of any composite panel is the point at which it is fastened to the vehicle frame. A bolting method is identified as the fastening mechanism of choice and is applied to a single-lap joint geometry for this study. Fastening parameters included bolt-to-hole clearance, and the use of insertsA combination of measurements taken using embedded fiber optic strain gages, digital image correlation, and stiffness data was used to determine the optimum design characteristics. It was seen that clearance had a negative effect on the stiffness of the joint, increased clearance from the zero percent clearance had an immediate effect on decreasing the stiffness of the joint. Also, the fiber optic strain gages found that there was a significant strain concentration just inside the interface between the overlap of the bolted composite to aluminum plates. Initial increase in clearance was seen to increase this concentration. Also, in studying the use of inserts it was found that an aluminum insert at the largest diameter tested of 0.75" outer diameter was the best performing geometry. Overall, the design recommendations were that there should be minimal to no clearance, with an aluminum insert with an outer diameter of 0.75".
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