Overview

Machine Design is defined as the use of engineering principles, technical information and imagination in the description of a machine or a mechanical system to perform specific functions with maximum economy and efficiency. On its own Design is an innovative and highly iterative process, which include market survey, product specification, slection of mechanisim, layout of configuration and selection of joining methods, design of individual components, preparation of prototype and manufacturing.

The aim of the moduleis to familiarise students with the various steps involved in the Design Process, understand the principles involved in evaluating the shape and dimensions of a component, to satisfy functional and strength requirements, learn to use standard practices and standard data, and learn to use catalogues and standard machine components.

T1. Introduction to Mechanical Design – Course Overview, Design Process; Materials – Material Properties, Materials Selection, Combined Loading. T2. Load and Stress Analysis – Equilibrium and Free Body Diagrams, Shear Force and Bending Moments, Stress, Strain, Torsion, Mohr’s Circle. T3. Deflection and Stiffness – Deflection Due to Bending, Deflection Analysis, Compression, Elastic Stability. T4. Failures Resulting from Static Loading – Static Strength, Stress Concentration, Failure Theories for Ductile and Brittle Materials, Cyclic Stress, Fatigue Regimes. T5. Fatigue Failure Resulting from Variable Loading, Fatigue Strength and Endurance Limits, Fluctuating Stresses and Influence of Non-Zero Mean Stress, Combination of Loading Modes. T6. Shafts and Shaft Components – Shaft Materials, Shaft Layout, Shaft design for Stress, Deflection Considerations, Critical Speeds for Shafts. T7. Gears – Types of Gears, Gear Trains. T8. Gears - Force Analysis, Spur and Helical Gears, Bevel and Worm Gears, Selection of Gears. T9. Mechanical Springs – Stresses and Deflection in Helical Springs, Compression Springs, Stability, Spring Materials. T10. Screws, Fasteners and the Design of Nonpermanent Joints – Thread Standards and Definitions, Threaded Fasteners, Joints, Bolt Strength. T11. Rolling Contact Bearings and Lubrication – Bearing Types, Bearing Life, Bearing Life, Rating Life, Selection of Bearings. T12. Clutches, Brakes, and Flywheels, Flexible Mechanical Elements.

Assessment Strategy

Three lab reports 10% of total grade each. One coursework assignment 30%. Final exam 40%.

-threshold -Equivalent to 40%.Uses key areas of theory or knowledge to meet the Learning Outcomes of the module. Is able to formulate an appropriate solution to accurately solve tasks and questions. Can identify individual aspects, but lacks an awareness of links between them and the wider contexts. Outputs can be understood, but lack structure and/or coherence.

-good -Equivalent to the range 60%-69%.Is able to analyse a task or problem to decide which aspects of theory and knowledge to apply. Solutions are of a workable quality, demonstrating understanding of underlying principles. Major themes can be linked appropriately but may not be able to extend this to individual aspects. Outputs are readily understood, with an appropriate structure but may lack sophistication.

-excellent -Equivalent to the range 70%+.Assemble critically evaluated, relevant areas of knowledge and theory to constuct professional-level solutions to tasks and questions presented. Is able to cross-link themes and aspects to draw considered conclusions. Presents outputs in a cohesive, accurate, and efficient manner.

Learning Outcomes

• Apply machine design principles to selected mechnical parts

• Choose system components for various applications based on machine design principles.

• Demonstrate experimentally the location of shear centre and torsion or various shapes

• Explain operational principles of a robotic system

• Explain the influence of steady and variable stresses in machine component design

• Show the link between rotational velocities in a differential and examine the static equilibrium of moments

• Use machine design principles to construct energy absorbing components for mechanical systems