The tensile stress-strain curve of a certain material is best represented by a saturation model, = − exp(−. a) derive an expression for the true strain at maximum load in terms of the constants a and . b) in a tension test, the maximum load occurred at an engineering strain of = 21% and the tensile strength was 350 mpa. determine the values of the constants a and for the material. [remember that the tensile strength is the maximum engineering stress.]