An elastoplastic material with strain hardening has the stress–strain relationship shown in Figure . The yield point corresponds to 600 MPa stress and 0.003 m/m strain.
a. If a bar made of this material is subjected to a stress of 650 MPa and then released, what is the permanent strain?
b. What is the percent increase in yield strength that is gained by the strain hardening shown in part (a)?
c. After strain hardening, if the material is subjected to a stress of 625 MPa,how much strain is obtained? Is this strain elastic, permanent, or a combination of both?
Extracted text: 1000 800 600 400 200 0.02 0.04 0.06 0.08 Strain, m/m Stress, MPa