What is stress and strain- Stress Strain Graph
Stress-strain are very important terms of solid mechanics. Strength of materials is a branch of engineering which deals with the material's properties to resist its failure. This topic also discusses about the behavior of materials under different level of forces.
When a body is subjected to external forces, equal and opposite internal forces are developed at the various sections of that body. This resisting force is known as unit stress or stress.
Stress = Force / Cross sectional are = P/A
Stress is generally denoted by the Greek letter sigma .
IN system international (S.I) the unit of stress is Pascal (Pa) .
1 Pa = 1 Newton /1 square meter.
In practical calculation, bigger units like megapascal (Mpa) or gigapascal (Gpa) is used. I hope that meaning of stress is very much clear now.
Strain = Change in the length of the body / Original length
Strain is generally expressed by the Greek letter epsilon .
For understanding the stress strain relationship we can explain the stress-strain diagram for mild steel which is under tensile load.
From the stress strain graph we can find the yield stress, ultimate stress and breaking stress. After passing the yield point plastic deformation occurs.