Determination of Crash-Relevant Material Properties for High-Strength Steels and Constitutive Equations

This work reports on the results of tensile testing of Dual-Phase steels at different strain rates in the range 0.0001/s-1000/s. This type of steel is a strong candidate for use in crash-absorbing automotive components. An understanding of material behaviour at relevant strain rates is needed as well as constitutive equations suitable for use in analytic and numerical calculations. Mechanical properties are determined from tensile tests using flat sheet specimens. Quasi-static and high strain rate tests were performed on servo-hydraulic machines and a Hopkinson bar. The test results were used to compare and validate constitutive equations intended to provide a mathematical description of strain rate dependence. Cowper-Symonds, Johnson-Cook and Modified Johnson-Cook constitutive equations were examined.