Design Process Models

Question 1

Why is process an important part of design?

Answer 1

It allows us to coordinate many teams in the efficient creation of complex products.

Question 2

What three modes of design do Pahl and Beitz recognize in their book on Engineering Design?

Answer 2

(1) Incremental design - minor improvements to an existing product.
(2) Adaptive design - improving entire subsystems/modules of a design.
(3) Original design - making major changes to entire sub-systems or systems.

Question 3

Draw the product lifecycle as it is listed in BS 7000-2.

Answer 3

See page 21 of notes.

Question 4

What mode of design are most products designed by?

Answer 4

Iterative/incremental design.

Question 5

Describe/draw the Pahl and Beitz model of design.

Answer 5

See page 22 of notes.

Question 6

What are the four main phases of the Pahl and Beitz design model?

Answer 6

1. Task clarification.
2. Conceptual design.
3. Embodiment design.
4. Detail design.

Question 7

What does establishing function structures involve?

Answer 7

Breaking down an overall function into sub-functions that receive/emit energy, material, and information signals.

Question 8

What is concurrent engineering?

Answer 8

Executing multiple design stages at the same time in a design process (i.e. non-sequentially).

Question 9

Draw the double-diamond process model.

Answer 9

See page 23 of notes.

Question 10

List two benefits of the double-diamond design process model.

Answer 10

1. It emphasises the importance of creating a detailed and appropriate product brief based on extensive user/market research.
2. It breaks the tasks into stages with outputs (feasibility review, brief, concept review, product).

Question 11

Draw the V-model.

Answer 11

See page 24 of notes.

Question 12

In the V-model, what is the key advantage of bottom-up testing?

Answer 12

It allows component-level faults to be identified.

Question 13

In the V-model, what is the benefit of top-down design?

Answer 13

It allows the overall layout to be envisioned before the details. This makes it clearer what each component must do and how the components must interact.

Question 14

Draw the stage-gate model.

Answer 14

See page 25 of the notes.

Question 15

What are the advantages of the stage-gate model?

Answer 15

> Emphasises deliverables that are essential to progress.
A design’s performance can be defined and recorded at set milestones.
Senior managers can sign-off on progress.

Question 16

List four different design process models.

Answer 16

• Pahl + Beitz model
• V-model
• Stage-gate model
• Double-diamond model

Question 17

Why should a product always be physically tested before it is released?

Answer 17

Computer models of a product’s behaviour are not created with the product’s unknowns unknowns in mind; it is also necessary to understand the known unknowns.

Question 18

What four stages of prototyping might take place during the development of a high-cost product?

Answer 18

Breadboard model (technology feasibility)
Engineering model (main performance of design)
Qualification model (all performance aspects of a design)
Delivered model (checking the performance of the product that will be delivered)

Question 19

Why are design reviews an important part of the design process?

Answer 19

They force designers to update their managers, and they force managers to give feedback to their designers. They allow everyone to understand the current benefits/weaknesses of a product.

Question 20

What four design reviews might take place in a product’s development process?

Answer 20

Preliminary design review - concept + breadboard model
Engineering design review - detailed design and engineering models
Qualification design review - qualification model performance
Final design review - review of delivered model performance

Question 21

What pieces of terminology are essential when specifying a design?

Answer 21

Problem statement, objectives, metrics, constraints, hard requirements, soft requirements, man-machine interface

Question 22

Why is a solution-neutral problem statement necessary?

Answer 22

To avoid design fixation - choosing a solution before rationally evaluating/exploring the alternatives.

Question 23

What areas do requirements typically fall under?

Answer 23

Technical performance
Environment
Ergonomics
Luxury
Aesthetics
Safety
Cost
Regulations
Maintenance
Materials
Reliability

Question 24

List several design authorities (i.e. organisations that produce design regulations)

Answer 24

Federal Aviation Administration, Euro NCAP, Eurocodes, Medicines and Healthcare Products Regulatory Agency

Question 25

Explain what is meant by ‘functional decomposition’ and what a ‘function-means tree’ is

Answer 25

Abstract functions -> increasingly specific sub-functions -> concrete features

Draw a table, write the objective in the first row, then write a ‘how’ in the row beneath it. Keep going down the rows, writing increasingly specific sub-functions. In the bottom row, right the means by which the ‘how’ above can be achieved.

Question 26

Worst-case loading/getting details from a client

Answer 26

I should do these things

Question 27

Why are conceptual design methods helpful?

Answer 27

Because they can foster creativity

Question 28

List seven drivers of innovation.

Answer 28

(1) Legislation
(2) Customer desires
(3) Technology breakthroughs
(4) Innovators/entrepreneurs
(5) Elite activities
(6) Affluence
(7) Market pressures

Question 29

List six conceptual design methods

Answer 29

[1] Study the competition
[2] Understand the physics of the problem
[3] Bio-inspiration
[4] Technology transfer
[5] Functional decomposition/morphological chart
[6] Backwards design (work backwards from an ideal design)

Question 30

List another six conceptual design methods

Answer 30

[1] Prototyping
[2] Brainstorming
[3] Structured questioning - create a set of questions that considers what can/can’t be done to solve a problem
[4] Inversion - ‘invert’ part of an existing design and see how it affects the product’s attributes
[5] Technology opportunities - how can new technologies be exploited?
[6] Sketching

Question 31

Suggest two methods for comparing concepts.

Answer 31

Pugh matrix (comparisons of baseline design), weighted matrix (scoring concepts).