general information - ishik · mechanics of material 11/29/2017 1 general information assistant...
TRANSCRIPT
Mechanics of Material 11/29/2017
1
General Information
Assistant Lecturer: Asmaa Ab. Mustafa
Email : [email protected]
Department : Civil Engineering
Course Title : Engineering Mechanics I
Code : Credit : 2
Office Hour : Monday 15:00 – 16:00
or by appointment
Website : http://www.sul.ishik.edu.iq/asmaa-abdulmajeed/
Grade : 1st
Year : 2017 - 2018
1
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
Required Textbook :
*Engineering Mechanics-Statics
by R.C.-Hibbeler, 12th Edition
Additional Reference :
*Engineering Mechanics-Statics
by Meriam & Kraige, 7th Edition
2
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
Mechanics of Material 11/29/2017
2
Evaluation Criteria :
Weekly Quizzes : 10%
Assignments : 10%
Bonus Quizzes : 5%
Project : 5%
Mid-term Exam : 30%
Final Exam : 40%
Assignments :
Approximately (10) homework assignments will be given
during the term. These assignments are very important. Their
purpose is to promote your understanding of the course
material, and to provide needed practice with example
problems that are too lengthy to discuss in class. It is your
responsibility to complete each homework assignment within
one week of distribution. 3
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
Weekly Quizzes :
Except for the week corresponding to the midterm, weekly quizzes will be given once per week, during the first fifteen minutes of lecture. In the Quiz, you will be expected to solve one of the questions from the previous week’s subject (possibly with slight alterations in the numbers). The weekly quizzes will be completely closed book although calculators will be allowed.
Midterms and Exam :
One midterms will be scheduled in addition to the final examination. Midterm and the final exam will be closed book. You will also be allowed to use a non-communicating calculator.
Prerequisites :
Mathematics and Physics
4
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
Mechanics of Material 11/29/2017
3
Class Attendance and Absences :
Students are strongly encouraged to attend class since some course material may only appear in lectures. Students that miss class are responsible for obtaining class notes from a classmate. Also students whom their absent percentage pass 20% will fail in that course automatically.
Conduct :
Students are expected to arrive at lectures on time, and to conduct themselves during class in a professional and respectful manner that is not disruptive to others. Please put your cell phone in silent mode before coming to class, quiz or exam.
Course Format :
There will be daily lectures. Your active participation is essential in making the class a success. Read the material before class and come equipped with questions.
5
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
6
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
Manner Guideline in this Lecture Course
Be reasonable and act politely.
Turn off your mobile phone. If you have urgent calls to
make or answer, kindly leave the room.
No food. Only water and candy are allowed.
No noisy chat and all other activities that can distract
the lecture should be avoided.
Do not disturb your classmates.
Mechanics of Material 11/29/2017
4
7
Mechanics ?
Mechanics
Statics
Dynamics -Equilibrium
-Selected Topics
Kinematics Kinetics
-Particles
-Rigid Bodies
-Particles
- Rigid Bodies
A branch of physical science
which deals with ( the states of
rest or motion of ) bodies
under action of forces
Dynamics: Motion of bodies
Statics:
Equilibrium of bodies
(no accelerated motion)
under action of Forces
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
8
Engineering Mechanics
• Statics – Equilibrium Analysis of particles and
bodies.
• Dynamics – Accelerated motion of particles and
bodies Kinematics and Kinetics.
• Mechanics of Materials…
• Theory of Vibration…
Mechanics of Material 11/29/2017
5
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
9
Static Analysis
Force and Equilibrium
Force System Resultants
Structural Analysis
Internal forces
Friction
Centroid and Moments of Inertia
Virtual Work and Stability
Dynamic Analysis
Kinematics of a Particle
Kinetics: Force and Acceleration
Work and Energy
Impulse and Momentum (Impact)
Planar Kinematics and Kinetics
3-D Kinematics and Kinetics
Vibrations
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
10
Contents of Engineering Mechanics – Static
Chapter -1- General Principles
Chapter -2- Force Vectors
Chapter -3- Equilibrium of a Particle
Chapter -4- Force System Resultants
Chapter -5- Equilibrium of a Rigid Body
Chapter -6- Structural Analysis
Chapter -7- Internal Forces
Chapter -8- Friction
Chapter -9- Center of Gravity and Centroid
Chapter -10- Moments of Inertia
Chapter -11- Virtual Work
Mechanics of Material 11/29/2017
6
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
11
Chapter -1-
General Principles
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
12
Chapter -1-
General Principles
1.1 Mechanics
1.2 Fundamental Concepts
1.3 Units of Measurement
1.4 The International Systems of Units
1.5 General Procedure for Analysis
Mechanics of Material 11/29/2017
7
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
13
1.1 Mechanics
Mechanics is the physical science which deals with the
effects of forces on objects. No other subject plays a
greater role in engineering analysis than mechanics.
Mechanics
Statics
Dynamics
Mech. of Materials
Fluid Mechanics
Vibration
Fracture Mechanics
Etc.
Structures
Automotives
Robotics
Spacecrafts
MEMs
Etc.
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
14
Mechanics : Generally are subdivided in to three branches:
1- Rigid-body Mechanics
2- Deformable-body Mechanics
3- Fluid Mechanics
• In this course we will study rigid-body mechanics since it
is a basic requirement for the study of the mechanics of
deformable bodies and the mechanics of fluids.
• Furthermore rigid-body mechanics is essential for the
design and analysis of many types of structural members,
mechanical components or electrical devices encountered
in engineering.
Mechanics of Material 11/29/2017
8
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
15
• Rigid-body mechanics is divided into two areas: statics
and dynamics.
• Statics deals with the equilibrium of bodies, that is those
that are either at rest or move with a constant velocity.
• Whereas dynamics is concerned with the accelerated
motion of bodies.
• We can consider statics as a special case of dynamics, in
which the acceleration is zero.
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
16
1.2 Fundamental Concepts
Before we begin our study of engineering mechanics, it is important
to understand the meaning of certain fundamental concepts and
principles.
Basic Quantities; The following four quantities are used throughout
mechanics.
• length. meter [m]
• time. second [s]
• mass. gram [g]
• force. newton [N]
Mechanics of Material 11/29/2017
9
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
17
Space : Collection of points whose relative positions can be
described using “a coordinate system”
Length : Is used to locate the position of a point in space and
thereby describe the size of a physical system.
Time : Although the principles of statics are time
independent. This quantity plays an important role in the
study of dynamics.
Mass : Is a measure of a quantity of matter.
Force : is considered as a "push" or "pull" exerted by one
body on another. This interaction can occur when there is
direct contact between the bodies, such as a person pushing
on a wall. A force is completely characterized by its
magnitude, direction, and point of application.
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
18
Particle : Has a mass, but it size can be neglected.
A rigid body can be considered as a combination of a large
number of Particles.
Concentrated Force : a concentrated force is a
representation of loading as a single point force. This is
justified if the load is applied to an area which is small com-
pared to the overall size of the body
Mechanics of Material 11/29/2017
10
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
19
Particle: Body of negligible dimensions
Rigid body: Body with negligible deformations
Non-rigid body: Body which can deform
In Statics, bodies are considered rigid
unless stated otherwise.
Before considering whether
the body can be assumed
rigid-body or not,
you need to estimate the relevant force first.
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
20
Newton‘s Three Laws of Motion
• First law
equilibrium
if ∑F = 0 then v = const.
FAB
FBA
• Second law
accelerated motion
F = m · a
• Third law
action = reaction
FAB = - FBA
Mechanics of Material 11/29/2017
11
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
21
Newton's Law of Gravitational Attraction: Shortly after
formulating his three laws of motion. Newton postulated a law
governing the gravitational attraction between any two particles.
Stated mathematically.
Where;
F: Force of gravitational between the two particles.
G: Universal constant of gravitation, according to experimental
evidence.
m1, m2: Mass of each of the two particles.
r: Distance between the two particles.
22
Weight : Refers to the gravitational attraction of the earth on
a body or quantity of mass. The weight of a particle having a
mass is stated mathematically.
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
*Therefore, a body of mass 1 kg has a weight of 9.81 N, a 2
kg body weights 19.62 N, and so on.
g = 9.81 m/s² = 32.2 ft/ s²
Mechanics of Material 11/29/2017
12
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
23
1.3 Units of Measurement
1. SI units:
• The international System of units.
• Abbreviated SI is a modern version which has received worldwide
recognition.
• The SI system defines length in meters (m), time in seconds (s), and
mass in kilograms (kg).
• In the SI system the unit of force, the Newton is a derived unit.
• Thus, 1 Newton (N) is equal to a force required to give 1 kilogram of
mass and acceleration of 1 𝑚 /𝑠².
1 N = (1 kg)(1 m/ s²)
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
24
2. US customary:
• In the U.S. Customary system of units (FPS) length.
• Is measured in feet (ft), time in seconds (s), and force in
pounds (lb).
• The unit of mass, called a slug.
• Thus, 1 slug is equal to the amount of matter accelerated
at 1 𝒇𝒕/𝒔² when acted upon by a force of 1 Ib.
1 slug = 1 lb s2 /ft = m
Mechanics of Material 11/29/2017
13
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
25
SI system
basic units • meters [m]
• seconds [s]
• kilogram [kg]
derived unit • Newton [N = kg · m /s2]
FPS system
basic units • feet [ft]
• seconds [s]
• pounds [lb]
derived unit • slug [slug = lb · s2/ft]
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
26
Conversion from one System of Units to Another:
1 ft = 0.3048 m
1 lb = 4.448 N
1 slug = 1 lb s² /ft = 14.59 kg
𝟏 𝐟𝐭 = 𝟏𝟐 𝐢𝐧
𝟏 𝐦𝐢𝐥𝐞 = 𝟓𝟐𝟖𝟎 𝐟𝐭
𝟏 𝐤𝐩 𝐤𝐢𝐥𝐨 𝐩𝐨𝐮𝐧𝐝 = 𝟏𝟎𝟎𝟎 𝐥𝐛
𝟏 𝐭𝐨𝐧 = 𝟐𝟎𝟎𝟎 𝐥𝐛
Mechanics of Material 11/29/2017
14
27
28
When a numerical quantity is either very Large or very small, the units used to
define its size may be modified by using a prefix. Some of the prefixes used in
the SI system are shown in Table 1.3. Each represents a multiple or submultiples
of a unit which, if applied successively, moves the decimal point of a numerical
quantity to every third place. For example, 4000000N=4000kN (kilonewton)
=4MN (mega-newton), or 0.005m=5mm (milli·meter).
Prefixes:
Mechanics of Material 11/29/2017
15
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
29
SCALARS AND VECTORS
We use two kinds of quantities in mechanics-scalars and
vectors.
Scalar quantities are those with which only a magnitude
is associated.
Examples of scalar quantities are time, volume, density,
speed, energy.
Scalars: associated with “Magnitude” alone
- mass, density, volume, time, energy, …
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
30
PRINCIPLES OF MECHANICS
Some principles that governs the world of Mechanics:
1. Newton’s First Law discussed
2. Newton’s Second Law discussed
3. Newton’s Third Law discussed
4. Newton’s Law of Gravitation discussed
5. The Parallelogram Law
6. The Principle of Transmissibility
Mechanics of Material 11/29/2017
16
31
The Parallelogram Law
The two vectors V1 and V2, treated as free vectors, can be
replaced by their equivalent V, which is the diagonal of the
parallelogram formed by V1 and V2 as its two sides.
2V
1V1V
2V V
1 2V V V
1V2V
V
1 2(generally )V V V
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
32
The Principle of Transmissibility
“A force may be applied at any point on its given line of action
without altering the resultant effects external to the rigid body
on which it acts.”
We can slide the force along its line of
action.
(force can be considered as sliding
vector)
F
F
= ?
If we concerns only about the
external resultant effects on rigid
body.
Mechanics of Material 11/29/2017
17
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
33
Summation of Force
1F
2F 1 2F F
1F
2F
1F
2F 1 2F F
if there are sliding vectors
concurrent forces
non-concurrent
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
34
Exercise 1.1:
Mechanics of Material 11/29/2017
18
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
35
Exercise 1.2:
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
36
Exercise 1.3:
Mechanics of Material 11/29/2017
19
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
37
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
38
Determines the mass in kilograms of an object that has a
weight of:
(a) 20 mN
(b) 150 kN
(c) 60 MN
Homework 1:
Mechanics of Material 11/29/2017
20
Ish
ik U
niv
ersity
- Su
laim
an
i
Assis
tan
t Le
ctu
rer - A
sm
aa
Ab
.
Mech
an
ics o
f Ma
teria
ls
39
References:
1. Engineering Mechanics -Statics, Twelfth Edition, R. C.
Hibbeler, 2009.
2. Engineering Mechanics-Statics by Meriam & Kraige, 7th
Edition.
3. Dr. Daniel C. Deckler, , The University of Akron, Wayne
College.
4. Lecture Notes and Exercises on Statics, by Dr.
Abdulwahab Amrani