Evaluating Material Performance Between High-Current Contacts

A high-current test fixture (HiCTF) was developed to examine material response to repulsive forces generated between electrically conducting material pairs during short pulses of high current, similar to conditions experienced in Electromagnetic Launch applications. Based upon Holm´s contact theory with additional preload and pressure distribution parameters, this test fixture was designed to use a loading press to apply preload to the test specimens while conducting current through the specimen contact interface. The fixture uses an aligned mechanical loading device to provide a preload across the contact interface of the specimen. The HiCTF will allow for investigation of contact response sensitivity as a function of its degradation, impact of geometry variation, surface conditions, material pairing, preload, and contact integrity. Statistically based experimental designs have been constructed and analysis methodologies developed that incorporate likelihood ratio analysis and the Neyer method. The Neyer D-optimal design method, used in sensitivity testing of explosives, shows promise as an appropriate test method for HiCTF results and will be used to provide sufficient information for comparisons and developmental thresholds. Results from HiCTF testing provide insight into the electrical contact phenomenon and high-current material response. This paper provides an overview of the HiCTF, its motivation, analysis methodology, results, observations, and lessons learned.