Reference no: EM13610123

A strain-rate dependence test is conducted on samples of Al 6061-T6. Two identical bars are tested. The first bar is pulled at a constant strain rate to generate a baseline performance result. The second bar is pulled at the same strain rate until it reaches a strain of 0.020. Then, a higher strain rate is imposed, and after a brief transient, the flow curve at this higher strain rate is established at a strain of 0.030. This higher strain rate is maintained throughout the rest of the experiment. The graphs above are generated as a result, which illustrate the stress-strain response for each strain-rate case. The same information is shown in both plots, but the second plot shows a closer view of the transient strain-rate region. Assuming the strain rate in the initial experiment was 0.0020 S^-1 and the increased rate in the second experiment was 0.008 s^-1, calculate the strain-rate sensitivity (or m value) for Al 6061-T6 based on this data. Perform this evaluation at an engineering strain of 0.030. Assume the effective elastic modulus of the sample and the loading system is 50 GPa.