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?

Dieter/Schmidt, Engineering Design 5e. ©2013. The McGraw-Hill Companies

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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.”


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.


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.


Product Cost Commitment during Phases of the Design Process

8Dieter/Schmidt, Engineering Design 5e.

©2013. The McGraw-Hill Companies

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


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



Adapted from M. Asimow, Introduction to Design, Prentice-Hall, Englewood Cliffs, NJ, 1962.

Design Method Versus Scientific Method



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


How The Design Depends On How The Problem Is Defined



Design Paradox Between Design Knowledge and Design Freedom



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


Phase I. Conceptual Design



Phase II. Embodiment Design



Phase III. Detail Design



Engineering Design Process



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


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.


Total Materials Life Cycle



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


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)


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


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


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


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.


An Examples of Design Update



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.


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


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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