BSC105C

Unit Description and General Aims

The objective in presenting this unit is to provide students with broad knowledge of the functions of machines/mechanisms – as a necessity for optimum machine design – and the fundamental principles of simple machine elements – which are frequently employed as devices in modern complex machines.

The subject matter covered in this unit will include: the different types of links and joints making up mechanisms; velocity and acceleration analysis; static and dynamic force analysis; design and analysis of cams, gears, drive trains, and flywheels; the characteristics of bearings, belt and chain drives, couplings, clutches, and brakes; balancing techniques for rotating and reciprocating masses; and, an overview of different governor types and their working principles and characteristics.

At the conclusion of this unit, students will have been imparted with relevant knowledge to assist them in analyzing, designing, selecting, and evaluating mechanisms for various applications.

Learning Outcomes

On successful completion of this Unit, students are expected to be able to:

1. Analyze, design, select, and evaluate mechanisms for various applications.
   Bloom's Level 5
2. Apply typical analytical and graphical techniques to a variety of mechanical engineering components and systems.
   Bloom's Level 3
3. Perform static and dynamic force analysis.
   Bloom's Level 3
4. Carry out performance evaluation of cams.
   Bloom's Level 5
5. Design and select gear, belt and chain drives, bearings, couplings clutches, and brakes for various applications.
   Bloom's Level 6
6. Perform balancing calculations for rotating and reciprocating machinery, and calculate the gyroscopic forces for rotating machines.
   Bloom's Level 3
7. Evaluate the characteristics of different governor types.
   Bloom's Level 5

Student assessment

Prescribed and Recommended readings

Suggested Textbook 

• D. H. Myszka, Machines and Mechanisms, Applied Kinematic Analysis, 4th ed. Prentice Hall. ISBN 9780132157803

 Reference Materials

• Wilson, CE, Sadler, JP 2003, Kinematics and Dynamics of Machinery, 3rd edn, Prentice Hall, ISBN-13: 978-0201350999
• Waldron KJ, Kinzel, GL 2003, Kinematics, Dynamics, and Design of Machinery, 2nd edn, John Wiley & Sons Inc., ISBN-13: 978-0471244172
• Peer reviewed Journals
• Knovel library: http://app.knovel.com
• IDC Technologies publications
• Other material and online collections as advised during the lectures

Unit Content

Topics 1 and 2

Introduction to Kinematics and Mechanisms

1. Kinematic pairs
2. Kinematic chains
3. Degree of freedom, mobility
4. Inversion
5. Kutzbach’s criterion
6. Gruebler’s criterion
7. Grashof’s Law
8. Inversions of four bar and slider crank chains
9. Description of common mechanisms - quick return mechanisms, straight line motion mechanisms, intermittent motion mechanisms
10. Pantograph

Topic 3

Velocity and Acceleration Analysis of Mechanisms

1. Velocity and acceleration analysis of four bar mechanism, slider crank mechanism, and simple mechanisms by vector polygons
2. Relative velocity and acceleration of particles in common and separate links
3. Coriolis component of acceleration
4. Angular velocity and angular acceleration of links
5. Velocity of rubbing
6. Analysis of four bar chain and slider crank chain using analytical expressions

Topic 4

Static and Dynamic Force Analysis

1. Static equilibrium
2. Free body diagrams
3. Static force analysis of four bar mechanism and slider-crank mechanism with and without friction
4. D'Alembert's principle
5. Inertia force, inertia torque
6. Dynamic force analysis of four-bar mechanism and slider crank mechanism

Topic 5

Theory of gears

1. Gear types – terms and definitions
2. Gear equations
3. Pressure angle, gear tooth force
4. Shaft loads, torque, power
5. Load factors, service factoring
6. Backlash and alignment
7. Speed ratio and performance evaluation of gear trains
8. Planetary gear case

Topic 6

Theory of Cams

1. Cam motions and dynamics
2. Types of cam follower mechanisms
3. Follower motion diagrams and design of cam profiles
4. Pressure angle and undercutting
5. Performance evaluation of cams

Topic 7

Bearings, Belts, Chains, Couplings, Brakes, Clutches

1. Bearings – types, loads, clearance, pre-loading
2. Belt and chain drives – principles, types, tension, loads
3. Couplings – types, load factors
4. Clutches and brakes – types, calculations
5. Introduction to Mesys software

Topic 8

Flywheels and gyroscopes

1. Flywheels
2. Turning moment diagram
3. Determination of size of flywheels
4. Gyroscopic forces and couple
5. Gyroscopic effect in aero planes, ship motion, and vehicles moving on a curved path

Topics 9 and 10

Balancing

1. Definition of balancing
2. Causes of unbalance
3. Shaft alignment
4. Balancing of rotating masses
5. Balancing of single rotating mass by balancing masses in the same plane and in different planes
6. Balancing of several rotating masses by balancing masses in the same plane and in different planes
7. Static and dynamic balancing
8. Field balancing of discs and rotors
9. Balancing reciprocating masses
10. Determination of out-of-balance forces

Topic 11

Governors

1. Need for governors
2. Types of governors
3. Stability, sensitivity, isochronism, effort, and power
4. Effect of friction
5. Hunting of governors

Topic 12

Unit Review

In the final week students will have an opportunity to review the contents covered so far. Opportunity will be provided for a review of student work and to clarify any outstanding issues. Instructors/facilitators may choose to cover a specialized topic if applicable to that cohort.

Software/Hardware Used

Software

• -        Software: MechAnalyser

  -        Version: 5

  -        Instructions: Free download: http://www.roboanalyzer.com/mechanalyzer.html

  -        Additional resources or files: N/A

Hardware

• N/A