Draw a generic engineering stress-strain diagram for a ductile metal and highlight the key strength.

Draw a generic engineering stress-strain diagram for a ductile metal and highlight the key strength points (yield, ultimate, and fracture strength) on the curve. (a) Schematically, show what happens if you load the specimen just below its yield point and then unload to zero. (b) Will the specimen behave differently if you load it again? Explain.