Mechanical Engineers Portal

## Saturday, June 17, 2017

Stress: It is defined as the ration of force per unit area. In other word it is the resistance offered by the material or body during application of load or force.
Mathematically stress is defined as,

Unit of Stress:
The SI unit of stress is Newton per square meter, which is also called Pascal.
1 Pascal or 1 Pa = 1 N/m2
Generally stress is expressed in terms of MPa.
1 MPa = 106 N/m2 = 1 N/mm2
Sometime stress is also expressed in terms of Gpa.

1 GPa = 1000 Mpa

Types of Stress:
1. Tensile and Compressive Stress
2. Shear Stress

1. Tensile and Compressive Stress:When we pull the body then tensile stress is developed and when we push or compress the body then compressive stress is developed within the body.

\begin{align*}&space;Compressive&space;\quad\textrm{stress},&space;\quad&space;\sigma_{c}&space;=&\frac{load}{Original\quad\textrm{area}}&space;\\&space;\sigma_{c}&space;=&\frac{P}{A}\end{align*}

2. Shear Stress: When two force acting on a body in opposite in direction but equal in magnitude then one layer of body try to slide over other layer, then resultant stress is Shear Stress.

\begin{align*}&space;Tensile&space;\quad\textrm{stress},&space;\quad&space;\tau&space;=&\frac{load}{Original\quad\textrm{area}}&space;\\&space;\tau&space;=&\frac{P}{A}\end{align*}

Strain:
Deformation per unit length is know as strain.
Mathematically it is expressed as,