An experimental method for characterizing friction properties of sheet metal under high contact pressure

Contact friction is present on interacting surfaces of steel thin-walled structural members under axial folding during vehicle crash, and often occurs under relatively high contact pressure (∼100 MPa) and sliding velocity (∼6 m/s). The contact friction could affect structural deformation mode and kinetic energy absorption capacity, and yet has not received sufficient attention in the area of automotive crashworthiness. The lack of knowledge on contact friction behavior and friction data of sheet metal has long affected the reliability and predictability of vehicle crash simulations. The objective of this study is to develop an appropriate experimental method for friction measurement on self-paired sheet metal under high contact pressure conditions. A fixture is designed for applying clamping pressure of 1–100 MPa on contact interfaces, under which sliding friction is generated by additional loading devices. Using a standard material test machine and a drop tower, two experimental configurations are set up for measuring the friction properties of steel sheet couples under the pressures of 1–100 MPa and the sliding velocities of 0–6 m/s. The test method is proved to be valid and viable in friction tests on a typical high-strength steel sheet. The results show distinct friction behaviors of the high steel under different loading conditions, which has also been discussed.