An Al bar has length=4ft and diameter=1inch. Modulus of elascity=10x10^6psi. The bar is loaded by a tensile force 24k and then unloaded. what is the permanenet set of the bar. welll stress=F/A=210.77MPa with this value I made a dot on the corresponding stress strain curve. Then I shifted the linear part of the curve to the right until it hit the point. A vertical line at the 210.77Mpa is drawn on the graph and the small gap between the shifted line to this vertical line represents the elastic recovery strain. (sorry if its hard to understand I tried my best). So this elastic recovery strain region is calculated e.g to be 0.001. I know permanent set= elastic recovery strain x intial length........wouldn't this then state that permanent set is a representation of contraction length? thanks in advance.