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.”

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

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.

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

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.

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

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

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

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

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

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

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

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

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

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.

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

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

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

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)

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

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

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

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

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

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

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

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.

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

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.

©2013. The McGraw-Hill Companies

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

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

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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