This document provides an overview of basic concepts in strength of materials including definitions of mass, weight, area, volume, force, and Newton's laws of motion. It defines stress as resistive force per unit area and strain as the ratio of deformation to original dimensions. Examples of basic mechanical properties like elasticity, plasticity, and ductility are described. Stress is defined using the formula of resistive force over cross-sectional area and strain is defined as the change in dimensions over original dimensions. Common stress units like Pascal, kiloPascal, megaPascal, and gigapascal are also outlined.

1. B Y- M R . A S H I S H R AV I N D R A L A N D E
M . E ( C A D M E )
L E C T U R E R AT D E PA RT M E N T O F M E C H A N I C A L
E N G I N E E R I N G K . K . WA G H P O LY T E C H N I C ,
N A S H I K .
Lecture Series on
Strength of Materials
Lecturer:1

2. Basic of Subject
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 Mass
 Weight
 Area
 Volume
 Force
 Newton’s Laws of Motion

3. Basic Terms
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 Mass: It is amount of matter contained in the body.
 Weight: it is gravitational force exerted by earth on
the object.
 Area: It is amount of matter contained in two
dimensions.
 Volume: It is amount of matter contained in three
dimensions.

4. Newton's laws of Motion
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 1stLaw-Law of inertia.
 2nd Law-Law of conservation of momentum. It gives
the definition of force, the most important in the
study of strength of materials.
 3rd Law-Law of Action and Reaction

5. Force
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 Its is defined as the external agency which change the
state of the object.
 It is defined as per the Newton's second law of motion.
 Force=Mass(m)× Acceleration due to gravity(a)
 Force=m×a
 Depending on the application the force may be tensile,
compressive or shear.
 Unit=Kg-m/s2 =Newton(N)
 Tensile Force-It is pull force.
 Compressive Force-It is push Force.
 Shear Force-It is force in parallel or perpendicular
direction

6. Basic Mechanical Properties
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 Elasticity
 Plasticity
 Ductility
 Malleability
 Hardness
 Toughness
 Brittleness
 Fatigue
 Creep.

7. Very Basic Mechanical Properties…
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 Elasticity-It is defined as the ability of material to
regain its original shape and size when force is
removed.
 Plasticity-Its partial elasticity.
 Ductility-It is ability of material to be drawn into
thin wires.
 Malleability-It is ability of material to be drawn into
thin sheets.

8. Stress
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 Stress-It is defined as resistive force upon area.
Stress=(Resistive force/Cross sectional area)
It is denoted by “σ-Sigma”
(σ=P/A)
 It is intensity of force acted over the given section.
 Unit- N/m2 called as Pascal(Pa)
 1KPa= 103N/m2
 1MPa= 106N/m2 = N/mm2
 1 GPa= 109N/m2 = 103N/mm2

9. Strain
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 Deformation=Change in dimensions
 It may be along the length (Linear)or other than
length (lateral).
 The ratio of change in dimensions to the original
dimensions is called as strain.
 It is denoted by “e”
 Strain=(Change in dimension/Original Dimensions)
 Unit-As it is ratio of two similar quantities in has no
unit.

10. T H A N K Y O U