# Deformation of Solids

By Deepak Yadav|Updated : October 6th, 2022

Before getting into insights into the deformation of solids, let's understand some fundamental concepts. The three states of matter are solids, liquids, and gases. Ions, molecules, and atoms are arranged differently in each of them. Solids are distinguished by their densely packed particles, which are restricted in their ability to move.

Pressure has the power to alter the shape of a solid. The change may be very large for some objects, like a spring, whereas it might be very small for some structures, like a building. The definition of deformation and the many kinds of deformation of solids will be discussed in this article.

## What is the Deformation of Solids?

An object's shape can be described geometrically as the area of space it occupies, as specified by its external limits. Deformation of solids is the term for a change in shape brought on by applying force. It is recognized that even tiny forces can result in some deformation: thus, it occurs when an external force acts on an object.

The Deformation could involve crumpling, twisting, ripping, or tearing the object apart. In physics, the terms "strain" and "stress" describe the force acting on things that are deforming.

## Stress in Deformation of Solids

Stress is a term used to describe the magnitude of force per unit area that lead to the Deformation. There are various forms of stress as follows:

• Tensile Stress: When forces pull on an object and cause it to elongate, such as when a rubber band stretches, it is called tensile stress.
• Compressive stress: when an object is compressed due to forces, it is called compressive stress.
• Bulk stress: when something is confined from all sides like a submarine is when it is submerged in the ocean.
• Shear Stress: It is a kind of stress in which the deforming stress acts perpendicular to the object's surface.

## Strain in Deformation of Solids

Strain is the term used to describe the distortion that occurred. A fractional change in the length, geometry, or volume is used to represent strain. Strain is a dimensionless number. The strain increases with increasing stress. The elastic modulus is the constant of proportionality in this relationship. Following is the relationship between stress and strain:

Stress = Elastic Modulus × Strain

When an object's elastic modulus is high, the impact of stress is minimal. Similarly, a low elastic modulus indicates that stress causes observable Deformation. For example, applying pressure to a rubber band results in a greater strain than a steel band of the same size. This is because the elastic modulus of a steel band is greater than that of a rubber band. Different materials' elastic modulus is measured following physical parameters, such as temperature variations, and compiled into engineering data tables for reference. These tables are useful resources for businesses, as well as for those working in engineering or construction.

## Young's Modulus

Young's modulus The mechanical property known as E, also known as the Young modulus or the modulus of elasticity in tension or compression (i.e., negative tension), evaluates the tensile or compressive stiffness of solid material when a force is applied longitudinally. The relationship between axial strain (proportional Deformation) and tensile/compressive stress (force per unit area) in a material's linear elastic region is measured using the formula.

## Types of Deformation

There are two distinct types of Deformation:

• Permanent Deformation : It is irreversible and is also referred to as plastic Deformation. It is a deformation that remains even after the applied forces are removed.
• Temporary Deformation: It is reversible and also known as elastic Deformation. It is a deformation that goes away as the applied forces are removed.

A material deforms under the action of forces in two stages: elastic deformation and plastic deformation. How quickly a material may transition from an elastic to a plastic state depends on its yield strength. There are several mechanisms for plastic Deformation in both crystalline and amorphous materials. For example, the slip process involves dislocations' movement and is used to distort crystalline materials. In contrast, the random movement of atoms and ions causes amorphous materials to distort.

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## FAQs about Deformation of Solids

• Deformation is the effect of external forces stretching, compressing, or shearing a solid. There are two types of deformation, Elastic deformation, and plastic deformation.

• Deformation in materials science refers to changes in an object's size or shape brought on by applied forces or a shift in temperature. Typically, forces like tensile (pulling), compressive, and shear (pushing).

• Plastic deformation is defined as the transformation of a substance into a new shape with the application of force. Elastic deformation occurs when a material returns to its initial shape after the removal of external forces. Every time an object experiences plastic deformation, mechanical energy is lost.

• The bonds are stretched during this type of deformation, but the atoms do not slide past one another. When the metal is sufficiently stressed to undergo permanent distortion, it undergoes a process known as plastic deformation.

• When a material changes shape by bending or flowing, it is said to exhibit ductile deformation. During this process, chemical bonds may break and then reform into new ones.

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