Metals test type only. Stressing rate is a rate specified in terms of a stress rate, but run under position control. The initial speed is calculated by dividing the value of the stressing rate by the nominal modulus of elasticity, then multiplying this quotient by the specimen gauge length.
Initial speed = (Target Stress Rate / Nominal Modulus of Elasticity) * Specimen Gauge (Parallel) Length
Note: The Nominal Modulus for the material you are testing should be available. If you do not know the nominal modulus of the material you are testing, you should run a test on a specimen to determine a modulus. The desired stressing rate is converted into an equivalent strain rate using the above calculation. The strain rate is controlled using the Straining Rate algorithm.
The modulus is only effective in the linear elastic region, where stress is proportional to strain. When the linear relationship between stress and strain breaks down (which occurs during yielding), this control mode is no longer capable of maintaining the desired stress rate. As a result, the stressing rate control mode should only be used in the elastic region prior to yielding, typically in Ramp 1 of the test.