PROJECT STRESS & STRAIN

1. PRESENTED BY
SHAHZADALAMANSARI
UniversityRollNo.-15800721104
Year:2022 Semester:5th
Subject:SolidMechanics(PC-ME502)
AcademicYear:2022-2023
Approved by AICTE & Affiliated to MAKAUT)
MECHANICAL STRESS

2. Mechanical stress
• Mechanical stress is a measure of internal resistance exhibited by a body of material when an
external force is applied to it.
• It denoted by sigma(σ)
Stress= σ = Resistive force/Unit area= R/A.
• S.I unit of stress is N/m2. But in material datasheet it is written as Mpa.
• Type of Mechanical Stress:
• Mechanical stress acts on the cross-sectional area of a body
• Types of mechanical stress

3. Normal Stress:
• Normal stress is a stress that acts perpendicular to the area. The formula for the normal stress is
given by
• The normal stress is again subdivided into two parts.
• Tensile Stress: The stress-induced in a body when it is subjected to two equal and opposite pulls as
shown in the figure given below is called tensile stress.
•Due to the tensile stress there is an increase in the length of
the body and decrease in the cross section area of the body.
•Tensile stress is a type of normal stress, so it acts at 90
degree to the area.
•The strain which is induced due to tensile stress is called
tensile strain. It is equals to the ratio of increase in the length
to the original length.

4. Compressive Stress:
• The stress which induced in a body when it is subjected to two equal and opposite pushes as shown in the
figure given below is called compressive stress.
• Due to the compressive stress, there is a decrease in the length and increase in the cross section area of the
body.
• Compressive stress is also a type of normal stress and so it also acts at 90 degree to the area.
• The strain which is induced due to compressive stress is called compressive strain. It is equals to the ratio of
decrease in the length to the original length.

5. Shear Stress:
• Shear stress induced in a body when it is subjected to two equal and opposite forces that acts
tangential to the area.
• The strain produced due to the shear stress is called shear strain.
• The shear stress is denoted by the symbol τ (tau). It is a Greek letter.
• It is defined as ratio of shear resistance to the shear area.
• The formula for the shear stress is given below.
• Shear stress is responsible for the change in the shape of the body. It does on affect the volume of
the body.

6. Strains and its types
Strain is the amount of deformation experienced by the body in the direction of force applied, divided
The following equation gives the relation for deformation in terms of the length of a solid:
Types of Strain
Strain experienced by a body can be of two types depending on stress
application as follows:
Tensile Strain
The deformation or elongation of a solid body due to applying a tensile for
body increases in length as applied forces try to stretch it.
Compressive Strain
Compressive strain is the deformation in a solid due to the application of
compressive stress. In other words, compressive strain is produced when
a body decreases in length when equal and opposite forces try to
compress it.

7. Stress-Strain Curve
• When we study solids and their mechanical properties, information regarding their elastic properties is most important.
We can learn about the elastic properties of materials by studying the stress-strain relationships, under different loads, in
these materials.
• The material’s stress-strain curve gives its stress-strain relationship. In a stress-strain curve, the stress and its
corresponding strain values are plotted. An example of a stress-strain curve is given below

8. Explaining Stress-Strain Graph
• The different regions in the stress-strain diagram are:
(i) Proportional Limit
• It is the region in the stress-strain curve that obeys Hooke’s Law. In this limit, the stress-strain
ratio gives us a proportionality constant known as Young’s modulus. The point OA in the graph
represents the proportional limit.
(ii) Elastic Limit
• It is the point in the graph up to which the material returns to its original position when the load
acting on it is completely removed. Beyond this limit, the material doesn’t return to its original
position, and a plastic deformation starts to appear in it.
(iii) Yield Point
• The yield point is defined as the point at which the material starts to deform plastically. After the
yield point is passed, permanent plastic deformation occurs. There are two yield points (i) upper
yield point (ii) lower yield point.
(iv) Ultimate Stress Point
• It is a point that represents the maximum stress that a material can endure before failure.
Beyond this point, failure occurs.
(v) Fracture or Breaking Point
• It is the point in the stress-strain curve at which the failure of the material takes place.

9. Hooke’s law
• Hooke’s law states that the force required to extend or compress a spring by some distance is
directly proportional to that distance. The stiffness of the spring is a constant factor characteristic.
The property of elasticity states that it takes twice the much force to stretch a spring twice as long.
This linear dependence of displacement on stretching is known as Hooke’s law. This law is named
after 17th-century British physicist Robert Hooke.
• It says that the amount of stress we apply on any object is equal to that amount of strain is
observed on it, which means Stress ∝ Strain.
• Hooke’s Law Formula is given as
• F = -K x
Where,
F is the amount of force applied in N,
x is the displacement in the spring in m,
k is the spring constant or force constant.
Hooke’s law formula can be applied to determine the force constant, displacement, and force in a stretched spring.

10. • THANK YOU