Stress and strain are linked together by stress-strain curve. And stress-strain curve of each material is usually obtained by experimental tests (tension test).
Stress-strain curve can be separated to several stages which correspond to different states of the material:
When strain is small, elastic deformation occurs and linear material model is used.
When the strain is large enough, plastic deformation will occur and a nonlinear material model will have to be considered.
In the linear region, the stress-strain relation (Hook’s law) can be simplified into:
σ=Eε (σ: stress, E: modulus of elasticity, ε: strain)
Modulus of Elasticity (Young’s Modulus)
1) Description of an object’s tendency to be deformed elastically when a force is apply to it.
2) It is equal to the slope of the stress-strain curve within the elasticity region
The relative ratio of the change in length of an object in the direction to which force is applied to the change in length in the other two directions