STRENGTH OF MATERIAL
BECE1053
CHAPTER 1: STRESS AND STRAIN
Prepared by:
Aqilah Binti Kamaruzaman
aqilah.Kamaruzaman@city.edu.my
Learning Outcomes

Understand the concept of stress and strain.

Solve the problem related to stress and strain.

Calculate the deformation caused by stress and strain.

Compare and contrast the normal and shearing stress and
strain.

Understand the relationship between shear stress and shear
strain.

Apply the factor of safety to the design material.
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Content

1.1 Introduction

1.2 Direct Stress and Strain

1.3 Shear Stress and Strain

1.4 Stress and Strain Diagram

1.5 Poisson Ratio and Factor Of Safety (FOS)

1.6 Stress, Strain and Deformation due to Applied Load
for Homogeneous Material

1.7 Stress, Strain and Deformation due to Applied Load
for Composite Material

1.8 Plane Stress and Strain

1.9 Mohrs Circle
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1.1 Introduction
What is Solid Mechanics
 Solid mechanics is the study of the
deformation and motion of solid materials
under the action of forces.
 It is one of the fundamental applied
engineering sciences.

It is used to describe, explain and predict
many of the physical phenomena around us.
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Application of the
Knowledge
How do you build a bridge which will
not collapse?
When will this cliff
collapse?
Strength of
the column?
Strength of the
signage
post?
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Your Future
Introduction
•
Before any engineering structure can be used, we have to
ensure that it is able to sustain the load acted on it throughout
its life.
•
Mechanics of material is studies on the relationship between
the external loads applied to a body and the internal forces
acting within the body.
•
The size of members, deflection and stability depend not only
on the internal loadings, but also the type of material used.
•
If the components or members are in equilibrium, the
resultant of the external forces will be zero.
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Type of Load
Roof
Slab
Column
Beam
Static or Dead Loads
Non fluctuating stationary loads
(generally caused by selfweight of structure).
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Type of Load
Lives Loads
Moving loads. Example: Vehicular
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loads on bridge.
Type of Load
Impact or Shock Loads
Loads caused sudden
blows
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Type of Load
Fatigue, Fluctuating or Alternating
Loads
Loads where magnitude and
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direction change with time
Type of Loading
Concentrated/Point Load
Uniform Loads
Triangular Load
Varying Uniform Loads
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Type of Support
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Types of Support
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Types of Support
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Class Activity 1
The picture shows a railway bridge. As a designer, you are required to
identify types of load, types of loading and types of support involve in the
structure.
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1.2 Direct Stress and
Direct Strain
Symbol
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Review Statics and
Dynamics
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Review Statics and
Dynamics
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Review Statics and
Dynamics
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Review Statics and
Dynamics
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Review Statics and
Dynamics
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Overview
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Direct Stress
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Direct Stress
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Example 1
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Example 2
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Example 3
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Example 3
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Direct Strain
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Direct Strain
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Example 4
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1.3 Shear Stress and
Shear Strain
Overview
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Comparisons of Direct
Stress and Shear Stress
DIRECT STRESS
SHEAR STRESS
Intensity of internal force
acting on a surface
perpendicular to the
direction of the internal
force.
Intensity of internal force
acting on a surface
parallel to the direction
of the internal force.
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Shear Stress
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Shear Stress
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Shear Stress
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Shear Stress
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Example 5
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Example 6
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43
Comparisons of Direct
Strain and Shear Strain
DIRECT STRAIN
SHEAR STRAIN
Deformation
(elongation/shortening) per
unit of the original length
Deformation involving a
change in shape/direction
(distortion).
It can defined as the
tangent of the angle (unit in
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radian) of distortion.
Shear Strain
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Example 7
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Example 7
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Example 7
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Example 7
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Thank you
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