Mechanics of Solids is the combination of physical, mathematical, and computer laws and techniques to predict the behavior of solid materials that are subjected to mechanical or thermal loading. It is the branch of mechanics that deals with the behavior of solid matter under external actions. The external actions may be:

- External Force
- Temperature Change
- Displacement

## Topics covered in Mechanics of solids

- INTRODUCTION TO MECHANICS OF SOLIDS
- FUNDAMENTALS OF STATICS
- TRUSSES
- DISTRIBUTED FORCES, CENTRE OF GRAVITY AND MOMENT OF INERTIA
- FRICTION
- SIMPLE MACHINES
- PHYSICAL AND MECHANICAL PROPERTIES OF STRUCTURAL MATERIALS
- SIMPLE STRESSES AND STRAINS
- BEAMS
- STRESSES IN BEAMS
- PRINCIPAL STRESSES AND STRAINS

## Books for Mechanics of Solids

Mechanics of solid by RK Bansal

## Some Important Definitions in Solid Mechanics

## Stress

When an external force is applied on a body, it undergoes deformation which is resisted by the body. The magnitude of the resisting force is numerically equal to the applied force. This internal resisting force per unit area of the body is known as stress.

- Stress = Resistive Force/Area
- In equation form: σ = P/A,
**Units are**- – N/m
^{2}, kN/m^{2}MPa (Mega Pascal) - – Psi (lb/in
^{2}), psf (lb/ft^{2}) - – Ksi (kips/in
^{2}), ksf (kips/ft^{2})

- – N/m

## Strain

When a body is subjected to an external force, there is some change of dimension in the body. Numerically the strain is equal to the ratio of change in length to the original length of the body.

- Strain = Change in length/Original length
- In equation form: ε= δL/L
**Units**- m/m, mm/m
- In/in, in/ft

## Primary Strain/Longitudinal Strain/Direct Strain

It is the ratio of the change in longitudinal length (dimension parallel to the direction of applied force) to the original longitudinal length.

Longitudinal Strain = **δL **/ **L**

## Objective Questions