Dynamic Material Tests of Steel Sheets for an Auto-body Using the High Speed Material Testing Machine

Abstract

The dynamic behavior of sheet metals must be examined to ensure the impact characteristics of auto-body by a finite element method. Since the strain-rate in the crash analysis of auto-body is under 500 /s, an appropriate experimental method to acquire the material properties at the corresponding strain-rate has to be developed. In this study, a high speed material testing machine was manufactured for tension tests of sheet metal under 500/s. Dimensions of a specimen for sheet metal need to be determined for tension test of sheet metal at intermediate strain rate because there is not a standard tension specimen for the dynamic test. Numerical simulations are carried out to determine dimensions and the shape of the specimen. Tensile tests of steel sheets in auto-body are performed at several kinds of strain rates. Fast Fourier transform smoothing method is used to fit the oscillation of load caused by the ringing phenomenon of a jig.