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© T. W. SIMPSON
Eduardo González Mendívil Professor
Mechanical Engineering ITESM campus Monterrey
email: [email protected]
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.
© T. W. SIMPSON
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
© T. W. SIMPSON
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
© T. W. SIMPSON
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
© T. W. SIMPSON
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.
© T. W. SIMPSON
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
© T. W. SIMPSON
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
© T. W. SIMPSON
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
© T. W. SIMPSON
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.
© T. W. SIMPSON
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
© T. W. SIMPSON
Example: B&D Versapack® Toolkit
Unique
Common
Variant Variant
© T. W. SIMPSON
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
© T. W. SIMPSON
Developing Modular Architectures
• What are some rules of thumb you, as an engineer,might follow to develop a modular product architecture?
© T. W. SIMPSON
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)
•
•
•
© T. W. SIMPSON
Disadvantages of Modular Architectures
• Easier to reverse engineer
• Modular products tend to sub-optimal
• Assembly costs are slightly higher
•
•
•
•
© T. W. SIMPSON
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
•
•
•
© T. W. SIMPSON
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
•
•
•
© 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
© T. W. SIMPSON
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?