[Physics Class Notes] on Compressive Stress Pdf for Exam

When force is applied to an elastic band it stretches and when it does stretch it tends to undergo stress during the stretching. When the stress on the elastic band has reached its limit it tends to break and hence releasing the stress that was held by the elastic band. This stress is one of the factors that give it a shape. However, not every object is elastic in nature. Some are rigid and hence cannot be easily malleated even after providing an ample amount of stress to the material. One of the typical examples is a ping-pong ball which is quite brittle as it is made of plastic. Under stress, it tends to break and now holds a shape.

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Compressive stress is the restoring strain developed because of pressure or force applied on a material to deform it, thereby causing a reduction of its volume. This capability of materials to withstand such compression is known as compressive strength. Here, we will discuss these two essential terminologies in detail. 

What Is Compressive Stress?

It is the measure of restoring stress developed in a body as a result of force applied on a material for the intention of deforming it. The maximum force at which materials deform and their volume is reduced, is known as compressive stress. The value of stress may differ from one element to another. Let us understand this by taking two scenarios –

1. In case this force is applied to brittle materials, the material breakdowns into smaller particles because of the sudden release of energy. 

2. In case the material is ductile, it can be compressed easily. 

What is Compressive Strength?

It is the measure of the capacity of a material to withstand the external force applied to it with an intention to deform it. Once the compressive strength limit of a substance is attained, it may fracture or deform. 

Therefore, as per compressive strength meaning, brittle materials are more likely to have higher compressive strength than ductile ones. 

Kinds of Stress

One can deform a solid by applying external force. However, it is possible by only three ways as mentioned below. 

1. Tensile Stress – It is the equal force applied on a body perpendicular to its cross-sectional area to deform it. 

2. Compressive Stress Definition – The solid is compressed by applying an external force. In response, the restoring force is produced in the body, which is known for compressive stress. 

3. Shearing Stress – A tangential force developed in the solid body because of the application of two equal & opposite external forces parallel to its cross-sectional area is known as the shearing stress. 

Formula 

The compressive stress formula can be written as 

σ = F/A 

Where, 

• σ is compressive stress. 

• A is the unit area of a solid body. 

• F is a compressive force. 

This can also be used as the compressive strength formula as it is the limit at which the solid material deforms. 

Units and Dimensions 

SI units for compressive stress or compressive strength units can be expressed as Nm-2 or Pascal (Pa). 

The dimensional formula for the same will be [M L-1 T-2].

Tensile Stress vs Compressive Stress