Engineering Design

MOHD NAZIM ABDUL RAHMANSEMESTER 2 / 2013/2014

BMCD 25731

BMCD 2573|Engineering Design

Introduction to Engineering Design

Learning outcomes Characterize analysis problems and design

problems Explain how the form follows function are

interrelated Characterize five phases of design – design

process Describe product realization process Explain the economic life cycle of a product

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BMCD 2573|Engineering Design

What is Design, really?

Which of the following is design and which is analysis?

A. Given that the customer wishes to fasten together two steel plates, select appropriate sizes for the bolt, nut and washer.

B. Given the cross-section geometry of a new airplane wing we determine the lift it produces by conducting wind tunnel experiments.

Design Analysis

 Form is the solution to a design problem.

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BMCD 2573|Engineering Design

How are Function and Form related

Design

controlholdmoveprotectstore 

decision making processes

shapeconfigurationsizematerialsmanufacturing processes

Function

Form

Form Ever Follows FunctionLuis Sullivan

 

 

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BMCD 2573|Engineering Design

What is Design?

“to fashion after a plan” - Webster's dictionary

to design is to create something that has never been

although engineers are not the only people who design things

To design is to pull together / synthesis something new or to arrange existing things in a new way to satisfy a recognized need of society

Design – definition

Set of decision making processes and activities

to determine the form of an object,

given the customer’s desired function.

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BMCD 2573|Engineering Design

Design

Good design requires both analysis and synthesis

Understand how the part will perform in service Able to calculate expected behavior before it

exists in physical form by using the appropriate disciplines of science and engineering and the necessary computational tools – ANALYSIS

Identification of the design elements that will comprise the product into workable system - SYNTHESIS

Engineering Design Process

Starts with recognition of the need for the product.

Both design and redesign require knowledge of the intended use of the product, plus information on the Market Technical data Materials and production

For any product design you are part of a team!!!

Engineering Design Process contn’

Determine the need Starts with recognition of a need Sketching of the solution (product) is very

useful during this step. Establish known information

Includes gathering information on aspects of the products such as possible materials, market analysis, ability to manufacture, cost to manufacture, etc.

Engineering Design Process contn’ Stimulate Design Concepts

Consider the various aspects in the manufacture of the product such as material, shape, etc.

Investigate Design Concepts with Analytical Tools Use modern methods and tools to analyze

design alternatives.

Engineering Design Process contn’ Gather all information and review

Gather together all information and design alternatives and review so that decisions can be made.

Test the design that appears best. Accept, Modify, or Reject Optimize the design by iteration

Making Decisions? Use the design process

Establish functional requirementsDetermine constraintsSet performance targets

GeneratingAlternatives

FormulatingProblem

AnalyzingAlternatives

EvaluatingAlternatives

Create alternative forms(shape, configuration, size, materials, manufacturing processes)

all alternatives

feasible alternatives

Red

esig

nit

erat

ionDesign specifications

best alternative design candidateManufacturing specifications

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Example design problem - Stop a spinning shaft

(8 inch diameter, 1000 lbs, steel, 3000 rpm)

•Decide upon a satisfactory rate of deceleration •Determine the length of the shaft•Determine where it is supported•Determine what actuating energy is available•Decide to reverse engineer an existing product•Choose to research brakes in the library

“Formulation” Phase

Early in the design process, we decide upon the specifics of the function to be performed:

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BMCD 2573|Engineering Design

Decisions relating to concept?

•1. surface friction (e.g. drum brake, disk/caliper)

•2. opposing magnetic fields (e.g. inverse motor)

•3. air friction (e.g. fan blades)

Assume we decide on surface friction

Decide physical principles that will perform the function

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“Coneptual Design” Phase

Decisions on configuring products and new components?

Product configuration: disk/caliper, or drum, or band brake

location on shaft (right. left, middle) (Assume we decide on a disk/caliper brake) Part configuration:

relative size of hub to diskrelative size of rotor thickness to diameter

“Configuration Design” Phase

Decide upon product components & how they are arrangedDecide upon part features & how they are arranged

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1. rotor diameter (outer)2. rotor thickness3. brake pad width4. pad material5. hydraulic pressure on piston

Values for Parameters?

Decide upon specific values for design variables

“Parametric Design” Phase

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•machined rotor tolerances•pad bonding resin•assembly/testing procedure

Completing the details

“Detail Design” Phase

Decide upon the remaining manufacturing specifications

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Function ---- stop a spinning shaft

Final “Form” is the solution to a design problem

Form• rotor: 10 inch diameter, steel, 3/8-inch thick, cooling passages• forged steel caliper/housing • brake pads, 2 opposing, 4 sq. in., metal particles/epoxy matrix• steel piston,1-inch diameter, with elastomeric seals• 100 psi hydraulic piston pressure

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Design Phases

Formulation

Detail

Parametric

Configuration

Concept

Embodiment Design

Preliminary Design

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Design versus the Product Realization Process?

Industrial Design

Engineering Design

Production Design

Manufacturing(Production)

Distribution

Service Disposal

CustomerNeed

RealizedProduct

Sales / Marketing

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BMCD 2573|Engineering Design

Phases in the life of a product

Manufacture

Retire

Design

Use

establish functiondetermine form

fabricateassembledistribute

set upoperatemaintainrepair take down disassemble recycledispose

To satisfy the consumer…We must consider all the phases in the life of a product

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Inco

me

Inve

stm

ent

Introduction Growth Maturity Saturation Decline

Sales

Time

Product Development

Product realization begins the Product Life Cycle

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Types of Design

Original design - innovative design, It employs an original, innovative concept to achieve a need

Adaptive design - adapts a known ' solution to satisfy a different need to produce a novel application

Redesign - improve an existing design

Types of Design

Selection design - design task consists of selecting the components with the needed performance, quality, and cost from the catalogs of potential vendors

Industrial design - improving the appeal of a product to the human senses, especially its visual appeal, more artistic than engineering

Summary

• Design is “decision” making• Product realization process includes

engineering design• Design process requires formulating,

generating, analyzing, evaluating, refining• Every product have their own Product Life

Cycle

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BMCD 2573|Engineering Design