1.The following truestresses produce the corresponding true plastic strains for a brassalloy:
True Stress(psi) True Strain
60,000 0.15
70,000 0.25
What true stressis necessary to produce a true plastic strain of 0.21?
2.A coal mine's entry and breakthrough centers are set at 60ft with 20ft-wide openings. The 6ft coal seam lies 1,000ft below the suface, and the specific gravity of the overburden is 2.4. If the compressive strength of 4in. cubic coal specimens is 5,000psi, dtermine the safety factor for compressive failure of the pillers utilizing the Holland-Gaddy relationship.