Chapter 1
Transcript of Chapter 1
DEPARTMENT OF
MANUFACTURING AND
MATERIALS ENGINEERING
MME 4116
PRODUCT DESIGN AND
DEVELOPMENTBY:
DR MOHD RADZI BIN HAJI CHE DAUD
CHAPTER 1
ENGINEERING DESIGN
1.1 Introduction
What is design?
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What is design?
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• “To fashion after a plan!”• To design is:
To synthesize new or to arrange existing things in a new way to satisfy a recognized need of society.
“Design establishes and defines solutions to and pertinent structures for problems not solved before, or new solutions to
problems which have previously been solved in a different way.”
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The Four C’s of Design
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• Creativity
Requires creation of something that has not existed before or
has not existed in the designer’s mind before.
• Complexity
Requires decisions on many variables and parameters.
• Choice
Requires making choices between many possible solutions at all levels, from basic concepts to the smallest detail of shape.
• Compromise
Requires balancing multiple and sometimes conflicting requirements.
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1.2 Engineering Design Process
Why is engineering design process needed?
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Importance of the Engineering Design Process
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• Decisions made in the design process cost very little in terms of the overall product cost but have a major effect on the cost of the product.
• You cannot compensate in manufacturing for defects introduced in the design phase.
• The design process should be conducted so as to develop quality, cost-competitive products in the shortest time possible.
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Product Cost Commitment during Phases of the Design Process
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Adapted from D. Ullman, The Mechanical Design Process, 4th ed., McGraw-Hill, New York,2010.
Types of Designs
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• Original Design: Innovative design
• Adaptive Design
• Redesign: Variant design
• Selection design
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1.3 Ways To Think About The Engineering Design Process
What do we mean by “designing a system”?
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Simplified Iteration Model
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Adapted from M. Asimow, Introduction to Design, Prentice-Hall, Englewood Cliffs, NJ, 1962.
Design Method Versus Scientific Method
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Adapted from P. H. Hill, The Science of Engineering Design, Holt, Rinehart and Winston, New York 1970.
A Problem-Solving Methodology
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• Definition of the problem
• Gathering of information
• Generation of alternative solutions
• Evaluation of alternatives and decision making
• Communication of the results
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How The Design Depends On How The Problem Is Defined
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Design Paradox Between Design Knowledge and Design Freedom
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1.4 Description of Design Process
What are the steps of Design Process?
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Design Process Phases
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• Phase I:
Conceptual Design
• Phase III:
Detail Design
• Phase II:
Embodiment Design
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Phase I. Conceptual Design
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Phase II. Embodiment Design
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Phase III. Detail Design
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Engineering Design Process
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1.5 Consideration Of A Good Design
What are the various considerations of a good design?
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Considerations of Good Design
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1) Achievement of Performance Requirements
2) Life-Cycle Issues
3) Social and Regulatory Issues
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Achievement of Performance Requirements
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• A major characteristic of a design is its function.• Performance Requirements:
Primary Performance RequirementsComplementary Performance Requirements
Part (Component): A single piece requiring no assembly
Assembly: When two or more parts are joined.
Subassemblies: Smaller assemblies which compose larger assemblies.
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Total Materials Life Cycle
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Reproduced from “Materials and Man’s Needs,” National Academy of Sciences, Washington, D.C., 1974.
Regulatory and Social Issues
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The code of ethics of all professional engineering societies require the engineer to protect public health and safety.
Example of Standards and Codes:
ASME: American Society of Mechanical EngineersASTM: American Society for Testing and Materials
OSHA: Occupational Safety and Health AdministrationCPSC: Consumer Product Safety Commission
EPA: Environmental Protection AgencyDHS: Department of Homeland Security
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1.6 Computer-Aided Engineering
What are the changes that plentiful computing has produced?
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Computer-Aided Engineering (CAE)
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The advent of plentiful computing has produced a major change in the way engineering design is practiced.
Advantages of Computer-Aided Engineering:
Automated engineering drawing in two dimensionsThree dimensional modelingFinite Element Modeling (FEM)Rapid prototypingDesign optimizationComputer-Aided Design (CAD) Computer-Aided Manufacturing (CAM)
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1.7 Designing To Codes And Standards
What are the codes and standards?
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Designing To Codes And Standards
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• A code is a collection of laws and rules that assists a government agency in meeting its obligation to protect the general welfare by preventing damage to property or injury or loss of life to persons.
• A standard is a generally agreed-upon set of procedures, criteria, dimensions, materials, or parts.
• Efficiency• Safety• Interchangeability • Compatibility
Chief Aspects of Designing To Codes and Standards:
Increase
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Two Broad Forms of Codes
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• Performance Codes are stated in terms of the specific requirement that is expected to be achieved.
• Prescriptive(specification) Codes state the requirements in terms of specific details and leave no discretion to the designer.
Performance Codes Prescriptive Codes
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1.8 Design Review
What is design review?
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Design Review
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• A design review is a retrospective study of the design up to that point in time.
• The essence of the technical review of the design is to compare the findings against the detailed Product Design Specification (PDS).
• The PDS is a detailed document that describes what the design must be in terms of:– Performance requirements– Environment in which it must operate– Product life– Quality – Reliability – Cost– Host of other design requirements
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Redesign
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• Two categories of redesigns:
– Fixes
– Updates
• A fix is a design modification that is required due to less than acceptable performance once the product has been introduced into the marketplace.
• Updates are usually planned as part of the product’s life cycle before the product is introduced to the market.
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An Examples of Design Update
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1.8 Societal Considerations in Engineering Design
What are the effects of engineering design on society?
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Societal Considerations in Engineering Design
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• ABET Code of Ethics:
“Engineers shall hold paramount the safety, health, and welfare of the public in the
performance of their profession.”
• Some influences on the practice of engineering design due to increased societal awareness of technology:
– Greater influence of lawyers on engineering decisions
– More time spent in planning and predicting
– Emphasis on “defensive research and development”
– More effort expended in research, development, and engineering in environmental control and safety. Dieter/Schmidt, Engineering Design 5e.
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Characteristics of an Environmentally Responsible Design
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• Easy to disassemble
• Able to be recycled
• Contains recycled materials
• Uses identifiable and recyclable plastics
• Reduces use of energy and natural materials in its manufacture
• Manufactured without producing hazardous waste
• Avoids use of hazardous materials
• Reduces product chemical emissions
• Reduces product energy consumption
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Keys Roles of Government in Interacting with Technology
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• As a stimulus to free enterprise through changes in the tax system
• By influencing interest rates and the supply of venture capital through changes in fiscal policy to control the growth of the economy
• As a major customer for high technology, chiefly in military, space, andS energy systems
• As a funding source (patron) for research and development
• As a regulator of technologyDieter/Schmidt, Engineering Design 5e. ©2013. The McGraw-Hill Companies
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