© T. W. SIMPSON

Eduardo González Mendívil Professor

Mechanical Engineering ITESM campus Monterrey

email: egm@itesm.mx

Design Methodologies

© T. W. SIMPSON

Product Architecture

© T. W. SIMPSON

Product Architecture

• Product architecture is: “the scheme by which the function of a product is allocated to

physical components”

• Purpose of product architecture is: “to define the basic physical building blocks of the product in

terms of what they do and what their interfaces are to the restof the device”

• More formally, a product architecture is: the arrangement of functional elements the mapping of functional elements to physical components the specification of the interfaces among physical components

Sources:• Ulrich, K., 1995, "The Role of Product Architecture in the Manufacturing Firm," Research Policy, Vol. 24(3), pp.

419-440.• Ulrich, K. T. and Eppinger, S. D., 2000, Product Design and Development (2nd Ed.), McGraw-Hill, NY, NY.

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Functional Elements

• What is a functional element (functions)? “The functional elements of a product are the individual

operations and transformations that contribute to the overallfunction of a product”

requirements or functions, what the product does usually expressed as a (verb, noun) pair

• Function ≠ form

• The form of a product is embodied by physical elementswhich comprise the parts, components, and sub-assemblies that ultimately implement each function.

• Functional elements combine to form a functionstructure which dictates what the product does at anabstract level.

© T. W. SIMPSON

Example: Coffee Maker

Mix Coffeeand Water

HeatCoffee

HeatWater

StoreWater

Electricity

Water

GroundCoffee Coffee

BrewCoffee

OverallFunction

SupportingSub-Functions

AuxiliaryFunctions

Shut-offHeater

CoffeeBeans

GrindBeans

StoreGrounds

StoreCoffee

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How to Create a Function Structure

Source: Pahl, G. and Beitz, W., 1996, Engineering Design: A Systematic Approach (2nd Rev. Ed.), Springer-Verlag,New York.

1. Formulate the overall product function2. Split up overall function into sub-functions3. Determine simplified functions structure4. Identify material, energy, and information/signal flows5. Add secondary/auxiliary functions and flows

Black Box Design

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Morphological Matrix

• Search for solution principlesto fulfill sub-functions Identify as many solutions for

each sub-function and auxiliaryfunctions as possible

• Combine solutions to embodyphysical concepts Use morphological matrix to

identify combinations of solutions Each combination of solutions will

fulfill overall function

• Use expertise and heuristics toeliminate infeasible solutioncombinations

Morphological Matrix

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Morphological Matrix for Coffee Maker

Hea

tC

offe

eH

eat

Wat

erS

tore

Wat

erS

tore

Gro

unds

Mix

Cof

fee

and

Wat

erS

tore

Cof

fee

Bre

wC

offe

e

S11 S12 • • • S1j S1m• • • • • •

Si1 Si2 • • • Sij Sim• • • • • •

Sn1 Sn2 • • • Snj Snm• • • • • •

•••

• •

•

•••

• •

•

•••

Filter Osmosis Dissolve Ionize • • • • • • Stir

© T. W. SIMPSON

Modularity Defined

• After we brainstorm solutions for each sub-function, wecombine them to create the product architecture.

• As part of this process, we seek to identify modules.

• Modularity is defined as (Ulrich and Tung, 1991):1. there is a one-to-one correspondence between functional

elements and physical structures ...AND...

2. unintended interactions between modules are minimized (i.e.,component interfaces are de-coupled).

• The opposite of modularity is referred to as integral.

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Product Architecture Definition

• Recall that a product architecture is: the arrangement of functional elements the mapping of functional elements to physical components the specification of the interfaces among physical components

• A modular architecture is: One physical component per function; de-coupled interfaces

• An integral architecture is: Coupled interfaces; multiple functions per physical component

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Types of Modularity: Slot

• In a slot architecture, each modulehas a different interface with theoverall system.

• Why different interfaces? So that various components cannot be interchanged

• Examples: Ethernet, and parallel ports on laptop

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Types of Modularity: Bus

• In a bus architecture, there is acommon bus to which modulesconnect via the same interface.

• What are the advantages of this type of modularity?

• Examples: Modem and Internet cards on laptop; CD and disk drive

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Types of Modularity: Sectional

• In a sectional architecture, allinterfaces are the same typebut there is no single elementto which modules attach.

• What are advantages anddisadvantages of a sectionalapproach?

• Examples: Legos

Using a sectional architecture,the assembly is built up by

connecting the modules to eachother via identical interfaces.

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Sectional Modularity at Nippondenso

• Nippondenso can make 288 different panel metersfrom variations of 8 modules (17 different parts)

© T. W. SIMPSON, 2001

© T. W. SIMPSON

Products, Modules, and Attributes

Product 1

Product 2

Products ModulesModule

Attributes

Different products

A1

B1

C1

D1

A1

B2

C2

Types ofModules:

CommonA1

VariantC1,C2

UniqueB1, B2, D1

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Example: B&D Versapack® Toolkit

Unique

Common

Variant Variant

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Creating a Module-Based Product Family

1.Decompose products into their representative functions2.Develop modules with one-to-one (or many-to-one)

correspondence with functions3.Group common functional modules into a common

product platformCommonFunctions

SpecificFunction 1

SpecificFunction 2

SpecificFunction k

DerivativeProduct 1

DerivativeProduct 2

DerivativeProduct k

4.Standardize interfaces tofacilitate addition, removal,and substitution ofmodules

ProductFamily {

ProductPlatform}

© T. W. SIMPSON

Example: Braun Family of Coffee Makers

KF130

BasicModel

KF180

Auto Shut-off, Clock

KF185

AdjustableHeater

KF190

FrothingAttachment

KF170

ThermosKarafe

KF145

WaterFilter

CommonFunction

BrewCoffee

Electricity

Water

GroundCoffee CoffeeMix Coffee

and Water

HeatCoffee

StoreWater

StoreGrounds

StoreCoffee

HeatWater

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Developing Modular Architectures

• What are some rules of thumb you, as an engineer,might follow to develop a modular product architecture?

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Some Heuristics for Module Development

• Stone, et al. (1998) developed a set of three heuristicsto identify product modules from a function structure: Dominant Flow:

– examines flows through a function structure, following flowsuntil they either exit from the system or are transformed

– the sub-functions through which these flows are traceddefine a module

Branching Flows:– examines flows that branch into or converge from parallel

function chains– each branch of a flow can become a module; modules

interface at point where flow branches or converges Conversion-Transmission:

– examines flows that are converted from one type to another– develop a module which converts an energy or material flow

into another form and then transmits it

© T. W. SIMPSON

Some Heuristics for Module Development

• Zamirowski and Otto (1999) define two heuristics to aidin module identification within a product family:

Shared Functions:– functional groups which share similar flows and functions

and appear multiple times within a product family shouldbe grouped into a single module

– this module can then be reused across the product family

Unique Functions:– identify functions that are unique to a single product or

subset of products– group functions into modules to facilitate product variety

© T. W. SIMPSON

Advantages of Modular Architectures

• Facilitates product change and product variety modules can easily be upgraded, degraded, and added-on modules can easily be reused or replaced

• Modular products can be quickly reconfigured to meetchanging market requirements

• Improves economies of scale through component andmodule sharing across products (economies of scope)

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•

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Disadvantages of Modular Architectures

• Easier to reverse engineer

• Modular products tend to sub-optimal

• Assembly costs are slightly higher

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•

•

•

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Advantages of Integral Architectures

• Facilitates the optimization of “holistic performancecharacteristics and those that are driven by the size,shape, and mass of a product” [UE00]

• Minimizes redundancy through function sharing

• Minimizes number of parts which much be assembled

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Disadvantages of Integral Architectures

• Difficult to upgrade and reconfigure

• Adjusting or “fine-tuning” a single function can be morecomplex and difficult

• Components and modules cannot be easily replaced ifworn or broken

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© T. W. SIMPSON

In-Class Activity: Modular Design

• Working with your group (count off 1-5), develop a: function structure, morphological matrix, and product architecture

for a family of Hospital Clothes.

• Process:1. Identify the overall function, major sub-functions, and

auxiliary functions for Hospital Cloth

2. Identify the material, energy, and signal flows for each sub-function and auxiliary function

3. Sketch the corresponding function structure

4. Brainstorm 2-3 solution principles for each sub-function

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Hospital Cloth: Brainstorming Session

5. Create a morphological matrix listing all sub-functions andcorresponding solution principles

6. Identify 3 possible combinations of solution principles torealize Hospital Cloth

7. Sketch the morphological matrix and show the combinations8. Pick one of the combinations and identify potential modules

for the Hospital Cloth9. Sketch the corresponding product architecture (modules and

interfaces) for the Hospital Cloth10. Finally, imagine that you are designing a family of Hospital

Clothes based on 3 different auxiliary (unique) functions.What are those functions and what are the correspondingmodules you would develop to embody those functions?