General Information - ISHIK · Mechanics of Material 11/29/2017 1 General Information Assistant Lecturer: ... by R.C.-Hibbeler, ... Kinematics Kinetics -Particles -Rigid Bodies

Mechanics of Material 11/29/2017

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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

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Required Textbook :

*Engineering Mechanics-Statics

by R.C.-Hibbeler, 12th Edition

Additional Reference :

*Engineering Mechanics-Statics

by Meriam & Kraige, 7th Edition

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mailto:[email protected]

http://www.sul.ishik.edu.iq/asmaa-abdulmajeed/





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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

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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

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https://www.google.iq/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwirwJyUusDPAhVHtBQKHWYdASUQjRwIBw&url=http://www.chesskids.me.uk/ckbook/quizzes.htm&psig=AFQjCNEDj8DzFgi1jtBQ6iK0udjz3-gOgQ&ust=1475646605422281


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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.

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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.


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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

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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…


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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

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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


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Chapter -1-

General Principles

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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


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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.

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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.


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• 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.

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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]


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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.

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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


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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.

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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


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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.

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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.

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*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


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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)

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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


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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]

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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


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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:


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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, …

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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


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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

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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.


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Summation of Force

1F

2F 1 2F F

1F

2F

1F

2F 1 2F F

if there are sliding vectors

concurrent forces

non-concurrent

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Exercise 1.1:


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Exercise 1.2:

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Exercise 1.3:


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Determines the mass in kilograms of an object that has a

weight of:

(a) 20 mN

(b) 150 kN

(c) 60 MN

Homework 1:


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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

General Information - ISHIK · Mechanics of Material 11/29/2017 1 General Information Assistant Lecturer: ... by R.C.-Hibbeler, ... Kinematics Kinetics -Particles -Rigid Bodies

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