Axiomatic Design Theory

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# Axiomatic Design Theory - PowerPoint PPT Presentation

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.

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## Axiomatic Design Theory

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Presentation Transcript
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.

Axiomatic Design Theory
• Axiom 1: Independence Axiom
• Axiom 2: Information Content

### Axiomatic Design Theory(Axiom 1)

Axiom 1 – Design example

Requirement:

hold hot (~100oC) water with hand

Hold hot water

Grasp the holder

Hold water without consideration of temperature

Resist heat conduction

Isolating material

DP

DP

DP

Resist heat conduction

Grasp the holder

Hold water without consideration of temperature

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

### Axiom 1

Uncoupled

(Diagonal matrix)

To satisfy the independence axiom, the design matrix must be either diagonal or triangular

Coupled

(Full matrix)

Decoupled

(Triangular matrix)

Example – Axiom 1

Hinge

FR2=Minimize energy loss

S1’=Horizontally hung door

Hinge

FR2=Minimize energy loss

S1=Vertically hung door

S2=Thermal insulation material in the door

Hinge

Decoupled

Uncoupled

The cold air stays inside when the door is opened

12 FRs:

Contain axial pressure,

Withstand a moderate impact when the can is dropped,

Physical pieces: Just 3

(the body, the lid, the opener tab)

DPs: 12

The thickness of the can body

The curvature at the bottom of the can etc.

Axiom 1 is focusing upon Functional independence but not physical independence

Physical integration

FR and DP in ADT refer to the logical level

FR1/DP1

One

FR2/DP2

Notion: logical and physical

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
Decoupled Design

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

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

### Axiom 1 revision

Remark: In the recent development, decoupled situation of FR will also be considered in Axiom 1, i.e., acceptable as a better design.

Summary

Axiom 1 of ADT concerns coupling, decoupling, and uncoupling among functional requirements both in direct and indirect (through DP) manners.

Axiom 1 suggests the better design to be uncoupled or decoupled.

Logical design versus physical design.

Physical design refers to embodiment design.

Axiom 1 of ADT is only applicable to the conceptual design.

Summary
• Redundant design concept: more DP than FR.
• It is a relative concept about coupling, decoupling and uncoupling.