Theory of Machines, MT 317

Engr. Akhtar Khurshid

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SUBJECT: MT-317 THEORY OF MACHINES

CREDIT HOURS: 2-0

CONTACT HOURS: 2 Hrs per Week

INSTRUCTOR: Assistant Professor Engr. Akhtar Khurshid

TEXT BOOK: R. Norton, Design of Machinery,. An introduction to

Synthesis and Analysis of Mechanisms and Machines, McGraw-Hill,

Latest Edition.

REFERENCE BOOK: . J.E. Shigley and Uicker, Theory of

Machines and Mechanisms, Laest Edition, McGraw-Hill. Mechanisms

and dynamics of machinery, Hamilton H Mabie, McGraw-Hill, Laest

Edition.

PREREQUISITE: a. Calculus: Basic

b. Engineering Statics

c. Engineering Dynamics.

MODE OF TEACHING: Lectures/Demonstrations

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COURSE OBJECTIVES: The objective of the course is to introduce the

preliminary concepts of mechanisms and to present methods of analysis for the

motion and force transmission in mechanism. After this course the students are able to

understand the various independent technical approaches that exist in the field of

mechanisms, kinematics and machine dynamics.

GRADING:

a. Midterm Exam 30%

b. Quizzes 10%

c. Assignments 5%

d. Project 10%

e. Final: 45%

STUDY PLAN

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DETAILS OF SYLLABUS

Kinematics, Kinetics, Mechanisms and Machines, Design Process

Degrees of Freedom, Types of Motion, Links and Joints, Kinematic chain, Grashof

Conditions

Graphical Linkage Synthesis, Limiting Conditions, Two Position and three position

synthesis

Position Analysis, Coordinate systems, Translation, Graphical position analysis

Velocity Analysis, graphical velocity analysis, Instant center of velocity

Cam Design and Gear Trains

Balancing, static balancing and dynamic balancing

STUDY PLAN

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In this text we will explore the topics of

Kinematics and dynamics of machinery in

respect to the Synthesis of mechanisms in order to

accomplish Desired motions or tasks, and also the

analysis of Mechanisms in order to determine

their rigid-body dynamic behavior.

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Theory of machines may be defined as

that branch of engineering science which

deals with the study of relative motion

between the various parts of machines

and the forces which act on them. The

knowledge of this subject is very essential

for an engineer in designing the various

parts of a machine.

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Kinematics and Kinetics

Kinematics: The study of motion without regard to forces.

Kinematics is that branch of theory of machines which is

responsible to study the motion of bodies without reference

to the forces which cause this motion, i.e. it relates the

motion variables (displacement, velocity, acceleration) with

the time.

Kinetics: The study of forces on systems in motion.

Kinetics is that branch of theory of machines which is

responsible to relate the action of forces on bodies to their

resulting motion.

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Virtually any machine or device that moves contains one or more

kinematic elements such as linkages, cams, gears, belts, chains.

Bicycle is a simple example of a kinematic System that contains a

chain drive to provide torque multiplication and simple cable-

operated linkages for braking.

In an automobile there are steering systems, wheel

suspension, piston engine which contains linkages, engine valves

open/close with cams, transmission is through gears.

The windshield wipers are linkage-driven. Construction

equipment such as tractors cranes and backhoes all use

linkages. Exercise equipment also uses linkages.

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It is the process of applying the various

techniques and scientific principles for the

purpose of defining a device, a process or a system

in sufficient detail to permit its

realization.

Design may be simple or enormously complex, easy

or difficult, mathematical or nonmathematical; it

may involve a trivial problem or one of great

importance.

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Design process has following steps:

Identification of need

Background Research

Goal Statement

Performance Specification

Ideation and Invention

Analysis

Selection

Detailed Design

Prototyping and Testing

Production

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Identification of need

First step in design is What we need? This may be

an unstructured problem statement or a structured

problem statement. It requires brainstorming to

identify the needs.

For example if we say we need a better lawn

mower.

This statement is brief and lacking in details. e.g. Is

it Automatic, Semiautomatic or Manual?, Expensive

or cheap, motor driven or engine driven, etc.

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Background Research

This is the most important phase in the process, and

is unfortunately often the most neglected. The term

research is used in this context, which is to collect

the background information on different aspects of

problem. If the similar problem is solved before then

it is no point to reinvent the wheel. The patent

literature and technical publications in the subject

area are the obvious sources of information.

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Goal Statement

After understanding the background, recast the

problem statement to a goal statement. This should

be concise, be general and be uncolored. The goal

statement clearly define the functional visualization

of the design.

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Performance Specifications

After the goal is clearly stated, formulate the set of

performance specifications. The difference between

performance specifications and design specifications

is that former define what the system must do

while the later define how the system must do. The

purpose of performance specifications is to carefully

define and constrain the problem so that it both can

be solved and can be shown to have been solved

after the fact.

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Ideation and Invention

This phase is much critical for most designers. It

consists of brainstorming process, idea generation

process and creative process.

Brainstormings rules require that no one is allowed

to make fun of or criticize anyones suggestions, no

matter how ridiculous it is.

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Analysis

By applying analysis techniques the performance of

the design is examined

Selection

When the technical analysis indicates that you have

some potentially viable designs, the best one available

must be selected for detailed design and drawing,

prototyping and testing. A decision matrix is made

which helps to identify the best solution after

considering a variety of factors in a systematic way.

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Detailed Design

This step usually includes the creation of a complete set of assembly and detailed drawings or computer aided design(CAD) of each part. Each detailed drawing must specify all the dimensions and the material specifications necessary to make that part.

Prototyping and Testing

Although a mathematical model is very useful yet it can never be as complete and accurate as a physical model. Prototypes are often very expensive but may be the most economical way to prove a design, short of building the actual, full scale device. Testing of prototype is done for observing the functionality of design.

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Production

Finally with enough time, money and persistence the

design will be ready for production.