Compressive Stress - Definition, Formula, SI Unit, and FAQs

Stress is a force or combination of forces that are distributed throughout an object and act to deform it.
Compressive stress is the normal force per area that causes an object’s length to decrease. For instance, Pressure is the compressive stress (P = F/A) applied uniformly to all surfaces of an object.
Its formula is given as σ =F/A, where F is a force in Newtons and A is the area in the meter square.
Compressive strain is the fractional decrease in the length of an object caused by compressive stress.
The SI unit of compressive stress (same as of stress) is the pascal or newton per meter squared [Pa = N/m²].

Table of Contents

Daily Life Examples of Compressive Stress

A person standing on the ground experiences compressive stress in their feet and legs as the weight of their body is pushed downwards into the ground.
When you squeeze a stress ball, the rubber material inside is subjected to compressive stress.
When you sit on a chair, the seat of the chair experiences compressive stress as your weight pushes down on it.
When you squeeze a tube of toothpaste, the tube experiences compressive stress as you push the toothpaste out.
When you step on a floorboard, the board experiences compressive stress as your weight pushes down on it.
When you press down on a stack of books, the books experience compressive stress as they are pushed together.
When you carry a heavy backpack, the straps of the backpack experience compressive stress as the weight of the backpack pushes down on them.

Important Definitions

Ultimate compressive strength: Stress required to rupture a specimen.
Young’s modulus is the ratio of compressive stress to compressive strain.
Resilience modulus: This quantity is the ratio of the tensile stress and the double of the material’s Young’s modulus.
Elastic limit: The maximum stress that may be given to an item without causing permanent (plastic) deformation.

Difference between Tensile Stress and Compressive Stress?

The primary difference between tensile stress and compressive stress is that tensile tension causes elongation while compressive stress causes shortening. Some materials are strong when subjected to tensile stress yet weak when subjected to compressive stress.

Stress in Physics

Stress measures the magnitude of the forces that cause deformation. Stress is frequently expressed as force per unit area. Tensile stress occurs when forces are applied to an object, causing it to stretch, such as when stretching an elastic band. When forces compress an item, compression stress occurs. Bulk stress occurs when an object, such as a submarine in the deep ocean, is pressed from all sides (or volume stress). Shear stress occurs when two materials brush against or glide over each other. Please check the full article “Stress in Physics”.

Yield Point

The yield point of material occurs when it transitions from elastic behavior (in which releasing the applied force restores the material to its original shape) to plastic behavior (where deformation is permanent).

Strain energy

Strain energy is a type of potential energy stored in an item due to elastic deformation. When an item is deformed from its unstressed state, the external work done on it is turned into (and is considered equivalent to) the strain energy contained in it.

Frequently Asked Questions

1. The spring constant?

The spring constant, k, is a measure of the stiffness of the spring. It depends on the spring and the material. The bigger the spring constant, the stiffer and harder the spring is to extend.

2. What is a metal?

Metals have properties such as malleability, ductility, conductivity, brightness, – and solidity.
Metals are also unique materials found in rock.

3. What is Flexural strength?

A material’s flexural strength is the highest bending stress that can be applied to it before it yields.

4. What is fatigue testing?

Fatigue testing of thermoset composites entails applying cyclic force to a thermoset composite coupon. These tests are used to detect crack growth data, identify critical regions, and demonstrate the safety of fatigue-prone places.