. The critical stress intensity factor KIC for a particular material is 1.5MPa m1/2 and its Poisson ratio is 0.3. A thin tensile specimen of the material has an edge crack, as depicted. If the...

. The critical stress intensity factor KIC for a particular material is 1.5MPa m1/2 and its Poisson ratio is 0.3. A thin tensile specimen of the material has an edge crack, as depicted. If the specimen fails under a tensile stress of 230MPa, what is the size of the edge crack? Suppose now that there is some misalignment of the grips such that the specimen experiences some twist about its long axis. This twist results in an antiplane shear stress t=50MPa. What tensile stress would cause failure in the presence of the shear? (You may assume for the purposes of this question that the criterion for failure is that the strain energy release rate must reach some critical value Gc such that under mixed-mode loading the crack extends in its own plane and KIIIC=KIC.)