Post on 31-Dec-2015
description
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Axiomatic Design Theory
What is axiom?– is known to be true by understanding its
meaning without proof. – a starting point for deducing and inferring
other (theory dependent) truths.
Axiomatic design theory: it is a design theory that has been verified by numerous applications. In other words, it is true (starting point) and accepted by engineers without proof.
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Axiomatic Design Theory
Axiom 1: Independence Axiom
Axiom 2: Information Content
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Axiomatic Design Theory(Axiom 1)
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Axiom 1 – Design example
Hold hot water
Requirement:
hold hot (~100oC) water with hand
Grasp the holder
Hold water without consideration of
temperature
Resist heat conduction
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Isolating material
Grasp the holder
Hold water without consideration of
temperature
Resist heat conduction
DPDP
DP
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Axiom 1
The better design meets:
Design or function requirement (FR) should be independent or uncoupled on their own right
Design parameters (DP) should maintain the FR independent – i.e., not making FR coupled
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2
1
220
011
2
1
DP
DP
A
A
FR
FR
8
2
1
2221
1211
2
1
DP
DP
AA
AA
FR
FR
2
1
2221
11
2
1
DP
DP
AA
A
FR
FR
2
1
22
11
2
1
DP
DP
A
A
FR
FRUncoupled
Coupled
Decoupled
To satisfy the independence axiom, the design matrix must be either diagonal or triangular
(Diagonal matrix)
(Full matrix)
(Triangular matrix)
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Example – Axiom 1
Hinge
FR1=Provide access to items stored in the refrigerator
FR2=Minimize energy loss
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Hinge
FR1=Provide access to items stored in the refrigerator
FR2=Minimize energy loss
S1=Vertically hung door
S2=Thermal insulation material in the door
S1’=Horizontally hung door
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2
1
2221
11
2
1
DP
DP
AA
A
FR
FR
Hinge
2
1
22
11
2
1
DP
DP
A
A
FR
FR
Decoupled Uncoupled
The cold air stays inside when the door is opened
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12 FRs:Contain axial pressure,Withstand a moderate impact when the can is dropped,Provide easy access to liquid, etc.
Physical pieces: Just 3(the body, the lid, the opener tab)
DPs: 12 The thickness of the can bodyThe curvature at the bottom of the can etc.
Axiom 1 is focusing upon Functional independence but not physical independence
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Physical integrationPhysical integration
Notion: logical and physical
OneFR1/DP1
FR2/DP2
FR and DP in ADT refer to the logical level
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Solution principle 1 for opening type 1 of lid At the conceptual design phase
Solution principle 2 for opening type 2 of lid At the conceptual design phase
The geometry of each of them refers to the embodiment design phase
Their relationship (distance, material interface) refers to the embodiment design phase
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Decoupled DesignDecoupled Design
2
1
2221
1211
2
1
DP
DP
AA
AA
FR
FR
2
1
2221
11
2
1
DP
DP
AA
A
FR
FR
2221212
1111
DPADPAFR
DPAFR
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Decoupled DesignDecoupled Design
2221212
1111
DPADPAFR
DPAFR
Step 1: Change DP1 to affect FR1 and FR2
Step 2: Change DP2 to affect FR2
Step 1 has also affected FR2 but in Step 2, this effect is changed back and to further affected by DP2 only
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Axiom 1 revision
The better design meets:
Design or function requirement (FR) should be independent or uncoupled on their own right
Design parameters (DP) should maintain the FR independent – i.e., not making FR coupled
Remark: In the recent development, decoupled situation of FR will also be considered in Axiom 1, i.e., acceptable as a better design.
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3
2
1
232221
131211
2
1
DP
DP
DP
AAA
AAA
FR
FR
Redundant design
2
1
2221
1211
2
1
DP
DP
AA
AA
FR
FR
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Redundant designRedundant design
2222
3131111
DPAFR
DPADPAFR
3
2
1
232221
131211
2
1
DP
DP
DP
AAA
AAA
FR
FR
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SummarySummary
1. Axiom 1 of ADT concerns coupling, decoupling, and uncoupling among functional requirements both in direct and indirect (through DP) manners.
2. Axiom 1 suggests the better design to be uncoupled or decoupled.
3. Logical design versus physical design.
4. Physical design refers to embodiment design.
5. Axiom 1 of ADT is only applicable to the conceptual design.
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SummarySummary
6. Redundant design concept: more DP than FR.
7. It is a relative concept about coupling, decoupling and uncoupling.