|Unit Name||Mechanical Design|
|Unit Duration||1 Semester|
Bachelor of Science (Engineering)
Duration 3 years
|Unit Creator / Reviewer||N/A|
Total Course Credit Points 81 (27 x 3)
|Mode of Delivery||Online or on-campus.|
|Unit Workload||(Total student workload including “contact hours” = 10 hours per week; 5 hours per week for 24 week delivery)
Pre-recordings / Lecture – 1.5 hours
Tutorial – 1.5 hours
Guided labs / Group work / Assessments – 2 hours
Personal Study recommended – 5 hours
Unit Description and General Aims
The objective in presenting this unit is to provide students with an in-depth knowledge of the principles and practices of mechanical design, and the design process.
The subject matter covered in this unit will include basic design concepts such as stress; strain; a factor of safety; failure analysis; endurance; and, fracture mechanics. There will also be a systematic examination of the design and selection process involving mechanical system elements such as fasteners power screws; riveted and welded joints; keys; couplings; shafts; pulleys; flywheels; belts; ropes; chains; gears; bearings; springs; clutches; and brakes.
Students will have the opportunity to discuss at length all design related issues including designing for strength, rigidity, and stiffness, and design based on varying load conditions; they will also complete a detailed analysis involving the design of internal combustion (IC) engine parts such as piston; cylinder; connecting rod; and, crank shaft. The students will further learn to perform design calculations using simulation software. Students will also undertake project work involving designing a simple mechanical system.
At the conclusion of this unit, students will have been imparted with detailed knowledge of mechanical design concepts and the design process, and being equipped with the skills to design mechanical components.
On successful completion of this Unit, students are expected to be able to:
- Demonstrate relevant knowledge of design-related concepts such as stress, strain, a factor of safety, endurance, and fracture mechanics.
Bloom’s Level 3
- Design threaded fasteners and power screws for different load conditions.
Bloom’s Level 6
- Detail the design procedures involving riveted and welded joints.
Bloom’s Level 6
- Design cotters, keys, couplings, and shafts for varying loads.
Bloom’s Level 6
- Evaluate the design requirements for pulleys, flywheels, belts, ropes, and chains.
Bloom’s Level 5
- Outline the design procedures for gears, bearings, springs, clutches, and brakes.
Bloom’s Level 6
- Explain the design methodology for IC engine parts such as piston, cylinder, connecting rod, and crankshaft.
Bloom’s Level 4
|Assessment Type||When assessed||Weighting (% of total unit marks)||Learning Outcomes Assessed|
Type: Multi-choice test
Example Topic: Stress, strain, a factor of safety, failure analysis, fracture mechanics, design of threaded fasteners and power screws.
Students will complete a quiz and solve simple problems on stress-strain and failure analysis. They will also be required to describe how threaded fasteners and power screws are designed for different loads.
|Due after Topic 3||10%||1, 2|
Type: Mid-semester test
Example Topic: Riveted and welded joints, keys, cotters, couplings, shafts, pulleys, belts, ropes, chains.
Students will provide answers to essay type questions and perform simple calculations using simulation software related to the design of shafts, pulleys, belt, rope and chain drives.
|Due after Topic 6||25%||3, 4, 5|
Example Topic: Gear and bearing design or Springs, clutches, brakes.
Students will provide evidence of their understanding of the principles of gear and bearing design, by solving design-based problems showing evidence of their understanding of the design of springs, clutches, and brakes.
|Due after Topic 10||15%||6|
Example Topic: Mechanical system design.
Students will be given a project work that involves designing a simple mechanical system. The assessor will specify the format.
|Final Week||40%||1 to 7|
Tutorial attendance + Weekly homework*
* Tutorial attendance will be 5% and weekly homework submission will be 5% out of the total 10%. Weekly homework will be discussed and assigned during the live tutorials.
|Continuous||10%||1 to 7|
Prescribed and Recommended Readings
- R. Budynas, K. Nisbett, Shigley's Mechanical Engineering Design, 11th Edition. McGraw-Hill Education, 2020. ISBN-13: 978-0073398211
- Deutschman, AD, Michels, WJ & Wilson, CE 1975, Machine Design; Theory and Practice, 1st edn (Digitized 2007), Prentice Hall, ISBN: 978-23290008
- Robert, LN 2013, Machine Design, 5th edn, Prentice Hall, ISBN: 978-0133356717
Peer-reviewed journals and websites (advised during lectures)
Notes and Reference Texts
IDC notes and Reference texts as advised
Other material advised during the lectures
Introduction and General Considerations
1. Engineering materials, their mechanical properties, and selection
2. Principal stresses
3. Stress-strain diagrams, stress analysis
4. Design stress and a factor of safety
5. Stress concentration factor in tension, bending, and torsion
6. Theories of failures
7. Design for variable and repeated loadings
8. Fatigue stress concentration factor, endurance diagrams
9. Fracture mechanics
Threaded Fasteners and Power Screws
1. Geometry of thread forms
2. Terminology of screw threads and thread standards
3. Stresses in threaded fasteners
4. Effect of initial tension
5. Relation between bolt tension and torque
6. Design of threaded fasteners under static, dynamic, and impact loads
7. Design of bolted joints due to eccentric loading
8. Mechanics and stresses of power screw
9. Efficiency of thread
10. Design of power screw
Riveted and Welded Joints
1. Types of rivet heads and riveted joints
2. Strength of rivet joint
3. Failure of riveted joint
4. Design of riveted joint
5. Eccentrically loaded riveted joint
6. Types of welded joints
7. Stresses in butt and fillet welds
8. Strength of welded joints
9. Eccentrically loaded joint
10. Welded joint subjected to bending moment
11. Fillet welds under varying loads
Design of Basic Elements, Couplings and Shafts
1. Design of Cotter and Knuckle joints
2. Design of keys and splines
3. Design of rigid, flexible and flange couplings, compression coupling, muff coupling, bush and pin type coupling, Oldham’s coupling
4. Transmission shafts
5. Torsion of shafts
6. Design against static load
7. Design for strength, rigidity, and stiffness
8. Design under continuous loading for fatigue
Pulleys, Flywheels, Belts, Ropes and Chains
1. Flywheel inertia
2. Stresses in flywheels and pulleys
3. Failure criteria
4. Design of flat and round belt drives, V-belts, timing belts, and wire ropes
5. Chain drives
6. Roller chains
7. Geometric relationships
8. Dimensions of chain components
9. Power rating of roller chains
Topics 6 and 7
Design of Gears
1. Spur gear terminology and definitions
2. Types of failure
3. Stress concentration
4. Lewis equation and form factor
5. Design for strength, dynamic, and wear loads
6. Helical gear definitions
7. Effective load on gear tooth
8. Helical gear design based on strength, dynamic, and wear loads
9. Bevel ear definitions
10. Effective load on gear tooth
11. Bevel gear design based on strength, dynamic, and wear loads
12. Worm gear definitions
13. Worm gear design based on strength, dynamic, wear loads
14. Efficiency of worm gear drives
1. Types of ball and roller bearings
2. Rolling contact bearings – selection of bearings for radial and axial loads, bearing life
3. Design procedure
4. Mounting and lubrication for rolling contact bearings
5. Plain or journal bearings – types of lubrication, viscosity, hydrodynamic theory of lubrication
6. Somerfield number
7. Heat balance
8. Design procedure
1. Types of springs
2. Stresses in helical coil springs of circular and non-circular cross sections
3. Equation for stress and deflection
4. Tension and compression springs
5. Springs under fluctuating loads
6. Stresses in leaf springs
7. Equalized stresses
8. Energy stored in springs
9. Torsion, Belleville, and rubber springs
Clutches and Brakes
1. Introduction to clutches
2. Friction materials
3. Torque transmitting capacity
4. Design of single plate, multiple plate, centrifugal, and cone clutches
5. Introduction to brakes
6. Design procedure for block brake, internal expanding shoe brake, band brake, disc brake
7. Heat generation in brakes
Curved Beams, Cylinders, and Cylinder Heads, IC Engine Parts
1. Stresses in curved beams of standard cross sections used in crane hook, punching presses, and clamps, closed rings and links
2. Lame’s equations for cylinders
3. Compound cylinders
4. Stresses due to different types of fits, cylinder heads, flats
5. Design of piston, connecting rod, and crank shaft
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.
Version: 2016 x 64
Additional resources or files: N/A