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ME/MECA 238A - Mechanical/Mechatronic Design Project I

ME/MECA 238A - Mechanical/Mechatronic Design Project I. Course notes prepared by G.A. Kallio, based on The Mechanical Design Process, by D.G. Ullman. Project Planning (Ch. 5). Step 1: Identify the tasks Use WBS (work breakdown structure) or flowchart network

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ME/MECA 238A - Mechanical/Mechatronic Design Project I

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  1. ME/MECA 238A - Mechanical/Mechatronic Design Project I Course notes prepared by G.A. Kallio, based on The Mechanical Design Process, by D.G. Ullman ME/MECA 238A

  2. Project Planning (Ch. 5) • Step 1: Identify the tasks • Use WBS (work breakdown structure) or flowchart network • Be as specific and detailed as possible • Include course-related presentations & reports ME/MECA 238A

  3. Project Planning, cont. • Step 2: State objective of each task • What will be the result (deliverable) of each task? • May be information, a completed drawing, calculation results, test data, a report, a generated concept, manufactured component, etc. ME/MECA 238A

  4. Project Planning, cont. • Step 3: Estimate the personnel, time, and other resources needed to meet objectives • Specify who • Specify work rate (e.g., hours/week) • Specify period of time • Specify total time for each task ME/MECA 238A

  5. Project Planning, cont. • Step 4: Develop a sequence for the tasks • Identify precessors and successors for each task • Sequential (series) vs. parallel tasks • Coupled vs. uncoupled parallel tasks • Design structure matrix (DSM) • Identify critical path(s) ME/MECA 238A

  6. Project Planning, cont. • Step 5: Estimate the product development costs • Design costs de-emphasized • Material costs are real • Manufacturing costs may be real • Testing costs de-emphasized ME/MECA 238A

  7. ISO-9000 • International Standards Organization’s quality management system • Standardized documentation of the product development process • ISO-9000 certification – similar to University accreditation – indicates to the world that product quality is managed, controlled, and assured by the ISO ME/MECA 238A

  8. Concept Generation (Ch. 7) • A concept is an idea or “structure” that is sufficiently developed to • evaluate the physical principles that govern its behavior • evaluate technologies needed to realize them • allow a rough sketch • Concepts follow function • Products follow concepts ME/MECA 238A

  9. Functional Decomposition • Technique used to define and refine product functions at all levels • Function can be described in terms of • energy flow (mechanical, electrical, fluid, thermal) • material flow (through-, diverging, converging) • information flow (mechanical & electrical signals, software) ME/MECA 238A

  10. Step 1: Find Overall Function • Single, most important, statement of function based upon customer requirements • Verb-noun-modifier form • Model using control volume approach • system boundary • inflows, outflows • conservation of material, energy ME/MECA 238A

  11. Step 2: Describe Subfunctions • Decompose overall function using verb-noun-modifier description • Consider what, not how • List all alternative functions • Consider all operational sequences • Include all input and output energy, materials, and information • “Post-it” note exercise ME/MECA 238A

  12. Step 3: Order the Subfunctions • Ordering may be chronological, spatial, disciplinary, or some other logic • remove redundancy • finalize functional choices • eliminate functions not within system boundary ME/MECA 238A

  13. Step 4: Refine the Subfunctions • Examine each subfunction to see if it can be further divided • Decomposition ends when function becomes “atomic”, i.e., can be satisfied with an existing object or the invention of a new object ME/MECA 238A

  14. Generating Concepts from Functions • Recall: “concepts follow function” • Concepts can be represented by sketches, block diagrams, verbal description, or models (paper, clay, etc.) • Two-step process ME/MECA 238A

  15. Step 1: Develop Concepts for Each Function • Develop as many as possible • Should be able to generate at least three (3) concepts for each refined function; if not • Re-examine function: “what” vs. “how” • Have ridiculous options been eliminated? • Is knowledge of function limited? ME/MECA 238A

  16. Step 2: Combine Concepts • Combine each possible concept from each function into “n” overall conceptual designs • This generates (too) many possible designs • Some combinations will be mutually incompatible, obviously inefficient, or ridiculous – eliminate these ME/MECA 238A

  17. Sources for Concept Ideas • Use existing information and designs! • Patents • Reference books • Trade journals • Research journals • Group brainstorming • Faculty, industry contacts ME/MECA 238A

  18. Example: Tortilla Maker • Primary Specifications: • Tortilla diameter: 101/2 (251.3 cm) • Tortilla thickness: 1/16 – 1/4 (1.6 – 6.4 mm) • Speed: 60 sec per tortilla (1/16) • Footprint size:  2 2 (60 cm  60 cm) • Weight:  10 lbs. (4.5 kg) ME/MECA 238A

  19. Example: Tortilla Maker • Features: • Auto start/stop with cancel function • Adjustable thickness • Adjustable cooking time • Easy cleaning: food handling parts removable and dishwasher-safe ME/MECA 238A

  20. Concept Evaluation (Ch. 8) • Choose best concepts for development into a product (with limited information) • Evaluation consists of comparison, followed by decision making • Comparison can be absolute or relative • Two or more concepts may be developed in parallel until relative merits become clear ME/MECA 238A

  21. Evaluation Techniques • Text suggests a sequence of steps for evaluating concepts and two different decision-making paths (Figure 8.1) ME/MECA 238A

  22. Feasibility Judgment • Gross judgement based upon intuition or “gut feel” • Do not eliminate concepts for reasons such as “it’s too different” or “it’s already been done” ME/MECA 238A

  23. Go - No Go Screening • Customer requirements/engineering specifications – can they be satisfied with a given concept? • Readiness of technology – is the technology (engineering & manufacturing) mature? ME/MECA 238A

  24. Decision Matrix Method • Semi-quantitative method for evaluating concepts (Tables 8.2, 8.3) • Most effective when done by each team member • Often requires iteration (repetition) as more is learned about the problem and concepts ME/MECA 238A

  25. Robust Decision Making • Robust – insensitive to uncertainty, incompleteness, and evolution of design • Decisions based upon: • Satisfaction = belief that a concept meets the criteria • Belief = knowledge + confidence • Figures 8.4-8.9, Tables 8.4, 8.5 ME/MECA 238A

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