Axiomatic Design Flashcards
What is axiomatic design?
- A design theory based in basic principles related to product properties and characteristics
- Evaluation od decision consequences must be based on basic axioms
—>product focus
—> prescriptive
Hierarchic functional and physical top down composition supporting synthesis
Functional coupling
descriptive method?
describing how things are done in practice
- guidlines
- not so precise of how and when?
prescriptive method?
Exactly what should to and how to do it
what is design?
An interaction process where we are going between WHAT (functional requirements) we and to a achieve and HOW (design p?) we will achieve this
Axiomatic hierarchic FR-DP decomposition?
mapping between functional domain to the physical domain
what is functional interference?
When two functions realized by the solution is coupled or functionally dependent
what is good characteristics?
Axiom 1.
The independence axiom:
- maintain independence between functional requirements and solutions
Axiom 2.
The information axiom:
—> simplicity
—> minimize the information content
definition of an axiom?
Principals always true and impossible to falsify
physical integration?
Might be good but not always
- To inegrate to uncoupled functional requirement is good according to
what is design parameters?
- Functional carrier
- Organ
—> - Means
- Design solution
- Functional feature
- Product/Systems
- sub-systems
- Component
- Design features
NOT the same thing as a component structure,
might be e.g.a hole
map between functional domain and physical domain?
E.G. FRs: -Toast bread —> heat bread —> handle bread —> carry parts
DPs: - Toaster —> heating systems —> Load/eject system —> Chassis
Each FRs can map to one DPs
Most important:
- FRs and DPs shall be functionally independent
2. Minimize the number of FRs and DPs
Functional coupling analysis?
Linear systems?
If DPs influences all FRs
—> axiom 1 is not fulfilled
—> completely coupled design
—> functional interferences
Uncoupled design?
diagonal symmetric a matrix —> each DP influences only its own FR —> axiom 1 is fulfilled
Semi-coupled design?
lower symmetric matrix(?)
Each FR can be fulfilled “independently” of each other if it is for in correct order”
- use boundary conditions e.g.
- axiom 1 is fulfilled
- rather robust
design synthesis and analysis?
- non-zero coefficient if the DP effect the FR
- zero coefficient if DP do NOT affect FR
- make lower triangular—> the most zeros in row 1
- if not lower triangular is possible? —> ?
More FR:s than DPs?
Theorem 2
- The design solution is coupled
- All FRs can not be fulfilled
Theorem 2?
More FRs than DPs but triangular sub-matrix
—> solution can be decoupled by adding DPs so that the number of FRs= the number of DPs
More DPs than FRs?
- Uncoupled solution but DP3 has no function or influence at all —> unnecessary
- redundant design
- coupled design
Theorem 3?
If the number of DPs bigger than FRs the design solution is coupled orreduntant
Theorem 4?
The ideal design solution the
- FR=DP
Theorem 5?
If FRs for an existing design solution are changed or added, the existing solution can not fulfill the new FRs
A new/ modified solution must be developed
What does Axiomatic design synthesis strive for?
Uncoupled or semi-coupled design solutions
- diagonal or triangular matrices
Axiomatic design analysis and evaluation?
- set up the design equation and determine design matrix
- Analyze the design matrices and their couplings
- Change solutions and remove seven couplings
- determine coupling degree
- Compare different solutions design matrices
Name 4 points of departure for the scientific base!
- A design decision influences all product life cycle phases and particularly the downstream steps in the product development process
- A base for design science must contain principles and methods supporting decision making
- Evaluation of decision consequences must be based on axioms
- Products and processes are hierarchic and can be decomposed in Hierarchic structures
What is functional requirements? (FRs)
The goal (WHAT) is specified in the functional domain
what is design parameters? (Dp?
Solutions (HOW) fulfilling the goal are generated and defined in the physical domain
Axiom 1? (the independence axiom?
Maintain the independence of functional requirements and solutiona
Axiom 2 (the information axiom)
Minimize the information content
When can it be GOOD to integrate two uncouple design solutions?
To integrate two uncoupled design solutions which fulfill their own FRs without influencing the fulfillment of each others FRs negatively IS GOOD according to axiom 2 (simplify)
When can it be NEGATIVE to integrate two uncouple design solutions?
To integrate and thereby functionally couple two design solutions, so they will influence the fulfillment of each others FRs negatively is BAD according to axiom 1 (independence of requirements and solutions)
Give an example with the hammer head!
FR1=Hit nails
FR2= remove nails
hammer with integrated nail remover and hitting surface
Good according to axiom 2
—> less complexity
“Bad” according to axiom
—> dependent solutions
when you have more design parameters than components?
Integration of function carriers (organs) /design parameters
when you have more components than design parameters?
A function is realized by interacting components
Is a DP structure the same thing as a component?
NO
- for example a clearance seal empty space) might be a design parameter but is NOT a component
Describe the functional structure of a toaster!
Toast bread - Heat bread —> generate heat —> connect electricity —> control heat - Handle bread —> eject bread —> hold bread - Carry parts —> hold parts —> Cover parts
Discrive physical structure of a toaster!
Toaster - Heating system —> hot wire —> connecting system —> timer - Load/Ejectc —> spring ejector —> wier box - Chassis —> frame —> cover
Concept generation strategy? with FR & DP
- Derive as many sub-solution alternatives as possible to each sub-function on current hierarchical level
- Combine sub-solution alternatives to total solution alternatives on current hierarchical level
- Choose the best total solution alternative on current hierarchical level
- Go to next lower hierarchical level and turn to 1
Name 3 important conclusions of axiomatic design!
- FR and Dp stal be functionally independent
- Minimize the number of FRs as each FR requires a solutions that adds to the complexity
- (combine FR)
- (remove redundant (FR) - FR shall not be decomposed into the next hierarchical level before a solution (DP) exists
Synthesis and analysis within Axiomatic design?
SYNTHESIS
Hierarchic functional and physical top-down decomposition supporting synthesis
ANALYSIS
Functional coupling analysis
(complexity/information analysis)
what is a theorem?
a non-evident proposition that can be deduced from one or many axioms
what is corollary?
A non-evident proposition that can be deduced from one or many axioms or down accepted basic knowledge
How is functional coupling analysis performed?
The design equation:
FR=A*DP
