Fundamental Study on Improvement in Frontal Crashworthiness by Application of High-Strength Sheet Steels

For the improvement in the frontal crash resistance of automotive body, the application of high-strength sheet steels are considered. At first the authors conducted the high speed tensile test by Split Hopkinson Bar Method to clarify the mechanical property of various sheet steels at a high strain rate. Secondary the authors conducted dynamic and static compression tests of the columns of various sheet steels to evaluate the energy absorption at the frontal crash. Results clarified that the energy absorption by column collapse is estimated only by tensile test. It was also clarified in comparison with the sheet steels with the same tensile strength, that the absorbed energy can be increased 5 - 15% by the adoption of a proper sheet steel. In case of the sheet steels with tensile strength of 590MPa, a tri-phase sheet steel of ferrite, bainite and retained austenite exhibited the largest energy absorption than others of similar tensile strength.