DESIGN 1 DPT224 TOPIC 2: ENGINEERING DESIGN PROCESS

Objectives  At the end of this topic, students should be able to: Describe and explain the engineering design process Explain various tools in engineering design

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“Design of a Safe Ladder”  Questions that arise: How is the ladder to be used? How much should it cost? Should the ladder be portable? What does “safe” mean? What is the market for this ladder? How many steps are there on the ladder? Etc

Engineering Design Process  Decomposing or “break down” the questions will lead into process tasks or sequence of steps (design tasks)  This is done without using any mathematical models, engineering equations or engineering laws

Example:  Question 1: How is the ladder to be used? How much should it cost?  Clarifying the objectives set for the design

Example  Question 2: Should the ladder be portable? How much can it cost?  Establish user requirements for the design

Example  Question 3: What does “safe” means? How much that the customer willing to pay?  Identifying the constraints of the design

Example  Question 4: Can the ladder lean against a supporting surface? Must the ladder support someone carrying something?  Establish the design functions

Example  Questions 5: How much weight should a safe ladder support? What is the “allowable load” on a step? How high should someone on the ladder be able to reach? What is the material of the ladder?  Establish the design specifications

Example  Question 6: Could the ladder be made of wood, aluminium or fiberglass? Generate design alternatives

Example  Question 7: What is the maximum stress in a step supporting the “design load”? Does the ladder meet OSHA’s safety specification?  Model, analyze, test and evaluate the design

Example  Question 8: Is there a more economic design? Is there a more efficient design?  Refine and optimize the design

Example  Question 9: What information does the client need to fabricate the design? What is the justification for the design decisions that were made?  Documents the completed design and its process

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Conceptual Design  Defined the characteristics of the product  Three characteristics: Form – shape, size, materials and style Fit – comparing with the competitors’ product Function – performance, reliability, maintainability

Preliminary Design & Detailed Design  Analyzing the single design solution or several alternatives design choices  Using engineering formulations Stress analysis, flow analysis, heat transfer analysis Electrical and electronic analyses  Working drawings, detail and assembly drawings Standard components, manufacturing notes and all dimensions and tolerances  Refine and optimize the final design

Tools in engineering design  CAD – Computer Aided Design  AutoCAD, Solid Works, Pro/ Engineer, Catia, UG NX  CAGD – Computer Aided Geometrical Design  Alias, IronCAD, etc  CAM – Computer Aided Manufacturing  MasterCAM, Edge CAM, etc  CAE – Computer Aided Engineering Analysis  Ansys, Moldflow, Abacus, etc  Gantt Chart – Design Project Scheduling

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