Stress strain diagram

1. STRESS -STRAIN

2. STRESS Stress The resistance offered by the material under the application of load is known as stress . It is denoted by ‘sigma’. Stress = force/Area It’s unit is N/m 2

3. Diagram of stress

4. STRAIN Strain it is the ratio of change in dimension to the original dimension Strain = Change in dimension /original Dimension It is unit and dimension less .

5. Diagram of strain

6. HOOKE’S LAW Robert Hooke discovered experimentally that “ within elastic limit, stress is directly with the strain’’ Stress α Strain Stress/strain = constant Stress/strain = E Here ‘E’ is a constant which is called “Modulus of Elasticity”

7. Stress-strain diagram of mild steel (Ductile material )

8. Here oa =elastic limit bc =yield point b = upper yield point c= lower yield point d=ultimate strength e=Breaking point

9. Elastic Limit it is the maximum stress at which stress is directly with the strain( i,e obey Hooke’s Law) . Within the elastic limit when the load is removed the body regain its original shape . in above graph ‘ oa ’ is elastic limit. Yield point Yield point is the stress at which there increase a strain without an increasing in stress . in above graph the point ‘b’ and ‘c’ is yield point .

10. Ultimate Strength ultimate strength is defined as the maximum value of stress in the plastic region . in above graph the point ‘d’ is the ultimate strength. Breaking point The point at which body can break of after the application of load. in above graph the point ‘e ’ is breaking point .

11. Stress-strain diagram of brittle Material(cast iron)

12. The point ‘a’ represents the elastic limit. The point ‘b’ represents the ultimate stress point . The point ‘c’ represent the breaking point.