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Ch#1 MET 304 Mechanical design

By Dr.S.G.A

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Ch#1 MET 304 Mechanical design

  1. 1. MET 304Mechanical Design 1 4 5 0 1 2 3 Dr. Salah Gasim Ahmed ACX F92
  2. 2. Objectives To integrate knowledge learned in the mechanics, structures, materials, and manufacturing courses. Systematically analyze an engineering problem and obtain a suitable solution Understand the concepts of factor of safety and stress concentration To obtain a working knowledge in the use of the proper failure theories under steady and variable loadings. Design shafts and keys under various types of loading. Select standard V-belts. Select standard anti friction bearings Design mechanical joints, mainly; welded, riveted and screw fastened joints.
  3. 3. Student Learning Outcome1. Students will demonstrate ability to analyse engineering problems and obtain possible solutions [1,]2. Students will demonstrate ability to write design specifications for engineering systems. [1]3. Student will demonstrate ability to design shafts and keys under various types of loading [2,3,4,5]4. Students will demonstrate ability to select standard components: belts and bearings for various applications. [3,6,7]5. Students will demonstrate ability to design different types of mechanical joints. [ 3, 8]
  4. 4. Mechanical design 1: Design Process Stress and factor of safety Design of shafts Selection of belts Bearings Welded joints Riveted joints Screw fasteners
  5. 5. Textbook and References Mechanical Engineering Design, , Joseph E. Shigley, Charles R. Mischke and Richard G. Budyans McGraw Hill , International editions, Seventh edition, 2004 Fundamentals of machine Component Design, Robert C. Juvinall, Kurt M. Marshek, John Wilely & Sons, Forth edition, 2005 Machinery’s Handbook, , Eric Oberg, Franklin D. Jones and Holbrook L. Horton. Industrial Press Inc., 27th edition, 2004
  6. 6. Engineers Provide:Engineering Products:Washing machines, foodprocessors, trucks, weapons, toothbrush, etcEngineering services:operation, maintenance, etc
  7. 7. Life of engineering product:  Design  Manufacture  Test  Develop
  8. 8. A product design must be: Functional :The product must perform to fill its intended need Safe :The product is not hazardous to users Reliable :The product will perform its intended function satisfactory at a given age. Manufacturable:The product can be manufactured with the available technology with required quantities Marketable:The product can be bought and service, repair, is available Competitive : the product is contender, challenger, in its market
  9. 9. The Design Process Recognition of need Definition of problem Presentation Synthesis Evaluation Analysis and optimisation
  10. 10. Synthesis :• It is the methods of obtaining alternative solution, Ideas• It is sometimes called the invention of the concept• In this stage as many solutions or ideas as possible are required
  11. 11. Factor which drives invention or creativity  Inherited qualities ,talent: we cannot all inherit Leonardos genes, but each of us must have some talents qualities.  Thinking Methods: you can employ proven techniques to increase your inventive powers  Attitude: you must be positive, you can invent!  Knowledge and experience: your understanding of how related problems are solved can be increased  Effort: Edison (inventor of the light bulb) put more effort to develop and improve his invention
  12. 12. Methods of obtaining alternative solution  Standard parts  Method of Inversion  Solution at stages  Black-box concept  Brain storming
  13. 13. Standard parts Copy an existing solution Change manual system into automatic one Change the system from batch to continuous production If the required system is very large and only part of it is available, use the available parts and fill the gap with new design Look for similar systems and modify to suit the required one
  14. 14. Method of Inversion Inversethe characteristics of the system to get new ideas Change shape: convex to concave etc. Change motion: rotary to linear, moving to stationary etc. Change position: front to rear, top to bottom, vertical to horizontal inside to outside etc
  15. 15. Solution at stages Divide the complex system into stages Find alternative solution for each stage. Combine the best and compatible solution from each stage
  16. 16. Black-box concept Consider the system as consisting of black boxes Do not investigate the details of each box at this stage
  17. 17. Brain storming  Itis a free association of ideas where each idea is recorded and actively encouraged to initiate further ideas A group of people with different backgrounds A leader  No criticism during ideation  Any idea which gives birth to other ideas cannot be wholly daft,
  18. 18. General guidelines for writing designspecification Title Role of equipment Inputs Outputs Environment and location Measures of value
  19. 19. Title The title should be very specific Doesnot mix with other or previous specifications. Wordsshould give specific meaning and can be easily translated to other languages
  20. 20. Role of equipment  It describes broadly what the system is supposed to do  It does not provide a solution to the problem  The role of equipment is very important for the designer as well as the user.  Also it helps the manufacturer in understanding the required specifications.
  21. 21. Inputs It describes the characteristics of the inputs to the system – Nature (electric current, gas pressure, mechanical movement) – Quantity, (weight volume, distance speed etc.) – The rate of change (kg/sec, m3/min..etc.) – The shape of change (sine wave, constant, arbitrary)
  22. 22. Outputs Similarly the output from the system should be described Without mentioning the relation between the inputs and outputs Unless the customer insists in a certain way of transforming the inputs to ouputs
  23. 23. Environment and location  Environment  all factors which may influence the design and has not been mentioned in previously.  location is the relative position of the system to other systems and equipment. – Human  Equipment are in direct or indirect relation with humans.  Man has a role in their design, manufacture, assembly, use, or maintenance.  Dimensions of human body  Natural abilities of human body Comfort. – Auxiliary services  services needed for the system (compressed air, water supply, electricity, hydraulic power )
  24. 24. Measures of valueMeasure of value may includes: Performance Initial cost Operation cost Maintenance cost EQUIPMENT RENT COST Total life Comfort and ease of use Appearance Safety Training Reliability
  25. 25. Thank You