4. (25pts) The engineering stress-strain curve is shown below, with the lower curve being a magnification of the elastic region and the upper curve being the entire engineering stress-strain curve. A metal bar made from this material is loaded to an engineering stress of OENG-65ksi and EENG 0.07in/in. a. What are the true stress TRUE and true strain ETRUE? Give answers to 4 significant figures. Refer to the notes. b. The true stress and strain at the proportional limit are OTRUE =50.25ksi and ETRUE =0.0049875. Assuming that the elastic (proportional) region of the true stress strain curve is also linear from zero to the proportional limit, what is the calculated elastic modulus E using true stress and strain values and slope fit? What is the % difference, (Etrue-Eeng)/Eeng*100%? C. (ksi) 70 60 50 40 30 20 10 0 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.2 0 0.0025 0.0050.0075 0.01 0.0125 0.015 0.0175 0.02 0.0255 0.025 e (in./in.)