Thanks a lot for your help and sharing the knowledge. Also, it is concluded that the maximum true stress values are almost 15 higher than that of the maximum engineering stress values while the maximum true strain failure values are 1.5 smaller than the maximum engineering strain failure values. The area changes in tension test due to the process of necking. Modulus of Elasticity) and Ultimate Tensile Strength and Yield Strength for materials like steel, glass, wood and many more.
What Stress Strain curve is used for Elastic Plastic analysis in ANSYS, if Engineering Stress Strain data is used with negative Tangent Modulus (E), does the analyis continuous and solution converges after Tangent Modulus (E) becoming zero or True Stress Srain curve based upon the True Stress is used. True stress and engineering stress are terms which are calculated as a result of tension test.The engineering stress is calculated by F/A(here F is the force applied and A is the actual area)wheras true stress is calculated by F/A0 A0 is the instantaneous area. We can calculate this change in diameter of the rod at the neck using true and engineering strain. True stress and true strain are based upon instantaneous values of cross. While True stresses calculation based upon the current/decreased cross section area continuous to increase after the Ultimate Tensile Stress value is reached until the fracture occurs, it means the Tangent Modulus (E) does not become negative after the ultimate tensile stress value. True Strain vs Engineering Strain When an external tensile force is applied to a metal rod, its diameter keeps on decreasing with the application of the external force and breaks ultimately. Mechanical Design in Optical Engineering. To define the non linear portion of the material after yield stresses, Engineering Stress continuous to increase up to the Ultimate Tensile stress and then stress value starts to decrease until the fracture of the material occurs, it means the Tangent Modulus (E) becomes negative after the Ultimate Tensile Stress.