A material is under a state of stress such that the following relationship holds for the principal stresses: 1=32=23. Plastic flow starts when 2=140MPa. a) Calculate the yield stress of the material, using the Tresca criterion. b) If the loading of the material changes so that 1=3 and 2=0, calculate the values of 3 for which plastic flow will occur using the Tresca and von Mises criteria. A material is under a state of stress such that the following relationship holds for the principal stresses: 1=32=23. Plastic flow starts when 2=140MPa. a) Calculate the yield stress of the material, using the Tresca criterion. b) If the loading of the material changes so that 1=3 and 2=0, calculate the values of 3 for which plastic flow will occur using the Tresca and von Mises criteria