Draw a generic engineering stress-strain diagram for a ductile metal. a) in the figure, highlight the key points: yield, tensile, and fracture strengths. b) annotate the loading-unloading path if you load the specimen just before reaching its tensile strength and then unload to zero. c) point out the total, elastic and plastic strains. d) when loading beyond the yield strength, explain why permanent deformation occurs. e) will the deformed specimen behave differently in terms of stiffness, yield strength and ductility if you load it again? justify your reasons.