# What is Stress? What are main Types of Stress?

In my last lecture we have learnt about strain and types of strain. Today we will learn about types of stress. We know that when a body is under loading some kind of stress developed in it. Mathematically this stress is the ratio of the applied force to cross section area of the body. If this stress reaches its ultimate limit or failure limit for particular object, it breaks it into two half. If this stress is under a certain limit (Elastic Limit), the body gets its actual dimension after removal loading. So the stress play very important role for designing any object.

There are various kinds of stress induced in the body due to loading.

Let’s learn them one by one.

## Types of Stress:

### Tensile Stress:

When a body is under tensile load or pull loading, the stress induce in it is known as tensile stress. The ultimate limit under tensile loading is called ultimate tensile stress.

### Compressive Stress:

When a body is under compressive load or push loading, the stress induce in it is known as compressive stress. The ultimate limit under compressive loading is known as ultimate compressive stress.

### Shear Stress:

When two equal and opposite forces acted on parallel faces of a body, the stress induce in it is called shear stress. This stress tends to deform the shape of a body without changing its volume.

### Thermal Stress:

When a body is resisted to expand and there is change in its thermal condition, some stress developed in it, is known as thermal stress. Thermal stress set up only when the body is not allowed to expand.