A multi-variable parametric study on the performance of bolted busbar contacts

The reliability of bolted joints is a concern for high-powered devices as the generated heat and thermal expansion could loosen the connections over many actuation cycles. There currently appears to be relatively little information on what material combinations, surface finish, etc. would be beneficial. This work experimentally evaluates the reliability of bolted contacts over 100 cycles and develops theoretical models to predict the relative bolted contact performance. The experimental test arrangement includes eight busbar pairs connected in series, while a power supply cycles current so that the busbars reach a desired temperature rise. A variety of cases are tested that vary the busbar material and thickness, washers, torque, bolt property class, diameter, and head types, in 60 different combinations. Each combination is tested three times, and then the cases are compared to each other using statistical methods. As expected, the electrical and thermal cycling fatigues the bolts, and in some cases the limitations of the joint were exceeded.