Axiomatic Design Theory

1. 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.

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

3. Axiomatic Design Theory(Axiom 1)

4. 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

5. Isolating material DP DP DP Resist heat conduction Grasp the holder Hold water without consideration of temperature

6. 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

8. Uncoupled (Diagonal matrix) To satisfy the independence axiom, the design matrix must be either diagonal or triangular Coupled (Full matrix) Decoupled (Triangular matrix)

9. Example – Axiom 1 Hinge FR1=Provide access to items stored in the refrigerator FR2=Minimize energy loss

10. S1’=Horizontally hung door 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

11. Hinge Decoupled Uncoupled The cold air stays inside when the door is opened

12. 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 body The curvature at the bottom of the can etc. Axiom 1 is focusing upon Functional independence but not physical independence

13. Physical integration FR and DP in ADT refer to the logical level FR1/DP1 One FR2/DP2 Notion: logical and physical

14. 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

15. Decoupled Design

16. 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

17. 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.

18. Redundant design

19. Redundant design

20. 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.

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