Introduction to Engineering-Materials 2.1 Stress-Strain Curve Yielding and Yield Strength Yielding occurs in the region between B and C For small changes in stress,the rod experiences a large change in strain The rod stretched substantially even as the force grows only slightly For that reason,the onset of yielding is often taken by engineers as an indication of failure The value of stress in region B- D Yield E C defines a quantity called the stress Yielding yield strength,Sy Strain,a Shanghai Jiao Tong University 11 Introduction to Engineering H.ShaoIntroduction to Engineering Introduction to Engineering —— Materials Materials Shanghai Jiao Tong University Shanghai Jiao Tong University Introduction to Engineering Introduction to Engineering H. Shao 11 2.1 Stress-Strain Curve Yielding and Yield Strength Yielding occurs in the region between B and C – For small changes in stress, the rod experiences a large change in strain • The rod stretched substantially even as the force grows only slightly • For that reason, the onset of yielding is often taken by engineers as an indication of failure – The value of stress in region B￾C defines a quantity called the yield strength, Sy . Strain,ε Stress, σ A B C D E Yielding Yield stress