Intermediate Strain Rate Bar
Background in Intermediate Strain Rate Testing
The intermediate strain rate regime (5 /s to 500 /s) is a relatively uncharted field in mechanical testing. This is despite many phenomena in everyday occurrences happening within this regime. Car accidents, metal forming, and sporting collisions are just a few of the many examples of these. The main reason for this lack of research is due to the lack of technology able to accurately gather this data. Most intermediate strain rate tests are currently performed on Hopkinson bars with a very long transmitted bar. The length of this bar directly impacts the maximum length of the specimen as well as the minimum speed the specimen can be tested. Intermediate strain rate testing also mandates high accelerations to achieve desired speeds during testing. Some machines use a modified servo-hydraulic actuator with a slack adapter in order to allow for more time to reach testing speeds. Although this can drive intermediate strain rate tests, this methodology can require multiple iterative calibration tests to find the correct stand off distance for testing.