The following can be concluded from this study: The servo-hydraulic system can produce stress-strain data for a wide range of strain rates useful for automotive crashworthiness, from quasi-static to 500/second. The stress-strain data produced by tension SHB at strain rates higher than 500/second match better with the servo-hydraulic results than the compression SHB. In the servo-hydraulic tests, attaching strain gauges can produce high quality strain data up to 2 percent. This method may be used in combination with other methods of strain measurement, such as displacement or optical extensometer until better methods are proved successful. There is no obvious change of the modulus of elasticity with strain rate in the strain rate range tested. All seven steels show positive strain rate dependence for YS and UTS. However, the strain rate sensitivity, defined as the percentage increase of flow stress due to the increase of strain rate, decreases with the strength of the steel grade. Steels in the same group exhibit the similar strain rate sensitivity. The steels in the Group I (BH300, 440W and HSLA350), exhibit higher strain rate sensitivity than the steels in Group III (DP800) exhibits the lowest strain rate sensitivity. However, the absolute increase of flow stress is almost constant for all steels tested, on average, about a 22 MPa increase of UTS for each increase of strain rate on the order of magnitude.
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