Strain Stress Curve For Mild Steel

Before entering the main topic of the Stress Strain Curve we have to know about stress and strain.

What is stress?

The term stress (s) is used to express the loading in terms of force applied to a certain cross-sectional area of an object. From the perspective of loading, stress is the applied force or system of forces that tends to deform a body.

Stress is defined as the Force per unit cross-section area.

Stress = F/A


σ = stress,

F = force applied, and

A= cross sectional area of the object.

Units of s : Nm-2 or Pa.

What is strain ?

Change in the dimension with respect to the original dimension due to stress is known as strain. It is denoted by the symbol epsilon.

Strain is defined as extension per unit length.

Strain = extension / original length


ε = strain,
lo = the original length
e = extension = (l-lo), and
l = stretched length

Strain has no units because it is a ratio of lengths.

What is stress-strain curve?

The stress-strain curve could be a behavior of fabric once it’s subjected to load. during this diagram stresses area unit aforethought on the vertical axis and as a result of these stresses, corresponding strains area unit aforethought on the horizontal axis. As shown below within the stress-strain curve.

Stress strain curve has different regions and points. These regions and points are:

  • Proportional limit
  • Elastic limit
  • Yield point
  • Ultimate stress point
  • Fracture or breaking point

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