Mechanical Behavior of metallic Materials Section 1: Deformation of metals Stress and strain ● Definition: engineering eng true stress. true stress. engineering true strain: 8 In eng true strain. ③大季Mechanical Behavior of Metallic Materials Stress and Strain ⚫ Definition: Section 1: Deformation of Metals engineering stress: 0 eng P A  = engineering strain: 0 0 f eng l l l  − = true stress: true i P A  = true strain: 0 ln f true l l  =