Lecture 01.ppt mgechanics of materials ehf

mechanics

1. Mechanics of Materials – I
(ME – 113)

2. Lecture 01
08
th
September 2025

3. Mechanical properties of materials; tensile, compressive and shear stress
and strain
Hooke’s law and Stress-strain relationship, Elastic Constants, and their
Relationships
Analysis of Statically Indeterminate Problems
Thermal stresses
Torsion of Circular Bars
Pure Bending of Beams, Moment of Inertia
Shear Stresses in Beams
Shearing Force and Bending Moment
Shear Force Diagram and Bending Moment Diagram
Thin Walled Pressure Vessels
Course Contents

4. Discuss the Course Contents, Recommended Books, Marks Distribution,
CLOs, and CLOs Mapping with PLOs
Discuss the Aim, Objectives and Applications of the Subject / Course
Define Types of Loading
Explain Sectioning of a Member
Draw Free Body Diagram
Use Equations of Equilibrium
Intended Learning Outcomes

5. Recommended Books
1.Ferdinand P. Beer, E. Russell Johnston Jr., John T. DeWolf, David F.
Mazurek, Mechanics of Materials, 6th edition, ISBN: 978-0-07-338028-5,
McGraw-Hill, 2012.
2. R.C. Hibbeler, Mechanics of Materials, 8th edition, ISBN: 978-0-13-
602230-5, Prentice Hall, 2011.
3.Andrew Pytel, Ferdinand L. Singer, Strength of Materials, 4
th
edition,
ISBN: 0060453133, Harpercollins College Div, 1987.
Reference Books
1.James M. Gere, Mechanics of Materials, 6th edition, ISBN 0-534-41793,
Bill Stenquist, 2004.
2.P. P. Benham & R. J. Crawford, Mechanics of Engineering Materials, ISBN:
0582251648 Pearson; 2nd edition, 1996.
3.Popov, Mechanics of Materials, 2nd edition, ISB: 0135713560, Prentice
Hall, 1976.
Course Books

6. Midterm Examination: 30 %
Final Examination: 50 %
Quizzes (No. 03): 10 %
Assignments (No. 03): 10 %
Attendance Requirement
Attendance of 75% is mandatory to sit in the final examination.
Marks Distribution

7. Course Learning Outcomes (CLOs)
Upon successful completion of the course, the student will be able to:

8. What is Mechanics?
•Mechanics is the branch of science which describes
and predicts the conditions of rest or motion of
bodies under the action of forces.
1 - 8
•Categories of Mechanics:
-Rigid bodies
-Statics
-Dynamics
-Deformable bodies
-Fluids
•Mechanics is the foundation of most engineering sciences
and is an indispensable prerequisite to their study.
•What are the subjects related to Mechanics in your
curriculum of Mechanical Engineering ?

9. Mechanics of Materials requires a deformable solid body subjected to
the action of an external applied load(s).
Mechanics of Materials is a branch of Mechanics that deals with the
internal effect (stress and strain) in a body subjected to an external force.
Stress is associated with strength of the material of which the body is
made while strain is associated with the deformation produced in a body.
What is Mechanics of Materials ?

10. Suitability of a structure or machine may depend on the deformations in
the structure as well as the stresses induced under loading. Statics
analyses alone are not sufficient.
Considering structures as deformable allows determination of member
forces and reactions which are statically indeterminate.
Determination of the stress distribution within a member also requires
consideration of deformations in the member.
Stress and strain are most important concepts for a comprehension of
the mechanics of solids. They permit the mechanical behavior of load-
carrying components to be described in terms fundamental to the
engineer.
List at least ten (10) load-carrying components that you know.
Objectives of MoM

11. Both the analysis and design of a given structure involve the
determination of stresses and deformations.
Therefore, it is necessary to study the subject of Mechanics of Materials
to learn the same.
The main objective of the study of the Mechanics of Materials is to
provide the future Engineer with the means of analyzing and designing
various machines and load bearing structures.
What are the different terminologies used for MoM in the literature?
Objectives of MoM (Contd.)

12. Why You Want to Learn MoM ?
As a student, you will use the knowledge of MoM in ……………… ?
After graduation, you will use the knowledge of MoM in ……………… ?
What is the difference between ME student and CE student with respect
to the study of MoM ?
Applications of MoM

13. Applications of MoM

14. Mechanics of Materials in Engineering
Design

15. Forces are vector quantities, thus having direction and magnitude.
Normal force is force acting normal (perpendicular) to a plane. It has
two types:
a)Compressive force is a normal force that acts normal to the plane
and directed toward the plane;
b)Tensile force is a normal force that acts normal to the plane and
directed away from the plane
Normal Force
Figure. Normal forces
FF
Force Force
Plane
Plane

16. 2 - 16
Axial Force and Normal Force
Examples
P is axial force as it is acting along axis of the body.
P is also normal force as it is acting normal to the lower face of the
body.
P is called tensile force as direction of the force is away from the
lower face / plane of the body.
Axis

17. 2 - 17
Axial Force and Normal Force Examples
2P, P and 4P are axial forces and also normal forces.
Axis

18. Shear force acts parallel to the plane as shown in the Figure.
Pair of oppositely directed forces produce twisting effect called
moment.
Shear Force
F
Force
Plane

19. Bending Force
2 - 19
Bending force is a force acting perpendicular to the axis of a body. It
tends to bend the body.
R1 and R2 are support reactions.
30 kN and 60 kN are transverse loads, called bending loads.
Axis of beam
(Bending
force)
(Bending
force)
(Support reaction 1) (Support reaction 2)

20. Torsional Moment or Torque
2 - 20
Torque (T) is the twisting force that tends to cause rotation.
It is the measure of how much a force acting on an object causes that
object to rotate.
= Torque

21. 1- 21
Sectioning of a Member
Cutting plane is used to section a given body.
When we section a given body, inner section / face / surface of the
body is made visible. This inner face or section is called cross section.
Internal or Resistive Forces are acting at the cross section.
External Loads are applied to the given body at given points.
Free Body Diagram (FBD) is a diagram of a part of the body drawn in
isolation (after sectioning the body) showing all the forces (known or
unknown) acting on the part of the body.
Equations of Equilibrium are used to find out unknown quantities
acting at the cross section.

22. 1- 22
Axial forces acting on a member result in only normal stresses on a plane
cut perpendicular to the member axis.
Sectioning of a Member
Cutting plane
L R
L
= resistive force
= applied force
: FBD
FBD stands for Free Body Diagram
P is acting parallel to Face or plane or cross section
Face or plane or cross section

23. 1- 23
Transverse forces on bolts and pins result in only shear stresses on the
plane perpendicular to bolt or pin axis.
Sectioning of a Member
(a) (b): FBD
Cutting plane
B
T
B
= resistive force
= applied force
(P is acting parallel to cross section)
Face or cross section
(Lower half of the bolt)

24. 1- 24
Sectioning of a Member
Case 1:
Case 2:
Pls refer to the next
slide.
Pls refer to the next
slide.

25. Sectioning of a Member
1- 25
(a) (b): FBD
(a) (b): FBD
Cutting plane
Cutting plane 1
Cutting plane 2
= resistive force 1
Applied force =
= resistive force 2
= resistive force 1
(P is acting parallel to cross section)
(P is acting parallel to cross section)
Case 1:
Case 2:

26. Sectioning of a Member
1- 26
L R
L
= resistive force
= applied force
(a)
(b): FBD
Cutting plane
(P is acting parallel to cross section)

27. 1- 27
Sectioning of a Member
Cutting plane
= resistive torque by differential element
= resistive torque by the cross section
Face or cross section
Face or cross section
(dF is acting parallel to cross section)
Applied torque =
Applied torque =
Applied torque =

28. Equations of Equilibrium
2 - 28
These are used to find out the unknown forces at a cross section
section.
(Used to find out resistive force acting along x – axis at a cross section )
(Used to find out resistive force acting along y – axis at a cross section )
(Used to find out resistive moment, M acting at a cross section )

29. 1.Ferdinand P. Beer, E. Russell Johnston Jr., John T. DeWolf, David F.
Mazurek, Mechanics of Materials, 6th edition, ISBN: 978-0-07-
338028-5, McGraw-Hill, 2012.
2.R.C. Hibbeler, Mechanics of Materials, 8th edition, ISBN: 978-0-
13-602230-5, Prentice Hall, 2011.
3.Andrew Pytel, Ferdinand L. Singer, Strength of Materials, 4th
edition, ISBN: 0060453133, Harpercollins College Div, 1987.
References

30. THANKS
Questions, if any