For a given material, the tensile tests were conducted at the crosshead speeds of 1mm/sec and 10 mm/sec, respectively. The corresponding hardening laws related to the stress strain responses are given by (i) 500 ( + 0.05)0.25 (1mm/sec) and (ii) 520 ( + 0.05)0.25 (10 mm/sec), respectively. What is the value of strain-rate sensitivity index. Does it vary with strain in the present case. If the hardening laws of the stress-strain curves are changes by 500 &0.20 at 1 mm/sec and 550 0.25 at 10 mm/sec, respectively, then find the new value of strain rate sensitivity index in terms of strain. For a given stress-strain curve as shown in Fig. 1, stress value at point A is 500 MPa, if the curve is unload at point A, then find the value of strain at point B. 100 Mpa B 0.5 Strain Fig. 1 Stress