Design Process And Conceptual Design

Question 1

What are TRLs? How many are there?

What TRL does new product with new/old technology start at?

Where may each level be developed/progressed?

Answer 1

Technology Readiness Levels. 10 levels from 0-9.

A new product with new technology will start from TRL0, while a new product with old/reused technology may start at TRL4. Not necessarily sequential!3

TRL 0-4: Universities
TRL 2-9: Industry

Question 2

Name and briefly describe three complexities of product design.

Answer 2

Product Complexities:
Products often require a vast number of decisions to be made during the design process. They may also contain 10,000s parts (e.g. cars), which may involve precise design information. Known unknowns (e.g. true safety margins) and unknown unknowns (e.g. load cases that cannot be predicted) must too be considered.

Organisational Complexities:
The design of a product may involve multiple companies with a number of multi-disciplinary teams with thousands of people, thus require effective methods of passing around information and data.

Documentation Complexities:
Commercial products require verification and documentation, with each part having a paper trail to detail where the original materials came from, who manufactured them and to what standards.

Question 3

Name eight objectives of car design.

Answer 3

Spider diagram!

• Cost
• Environmental Performance
• Technical Performance
• Aesthetics
• Safety
• Luxury
• Reliability
• Ergonomics

Question 4

Name seven challenges associated with product design.

Answer 4

• Progressing through TRL stages when developing new products.
• Products can be complicated.
• Products have multiple objectives.
• Products are expected to have high reliability.
• Retaining knowledge through product iterations can be difficult.
• There are a number of conflicts between form and function.
• Fast changing environmental conditions.

Question 5

Why is there need for a design process?

Answer 5

To systematically co-ordinate the efforts of large, multi-disciplinary teams.

E.g. consider Airbus, with approximately 4million parts produced by 1,500 companies from 30 countries!

Question 6

Name the three modes/types of design, as described by Pahl & Beitz.

Answer 6

Incremental Design:

• Minor changes/improvements to an existing product.
• Low risk, common for high-volume production.
• Enabled by new elements of technology becoming available.

Adaptive Design:

• Significant changes/improvements to whole sub-systems.
• Common when new technologies arrive (e.g. airbags in cars).

Original Design:

• Major changes/improvements to whole sub-systems or systems.s
• High risk, often occurring with an acute need (e.g. IC engine to hybrid to tackle pollution).

Question 7

Describe the Pahl & Beitz process design model.

Answer 7

• Design process broken down into distinct stages, falling under 4 main phases.
• Top-down process starting with abstract ideas and finishing with complete details.
• Stages can be overlapped to reduced time.

Question 8

Describe the double-diamond process model.

Answer 8

Discover:
Divergent - Market research to understand task.

Define:
Convergent - Market and user information is aligned with business objectives.

Develop:
Divergent - Establish wide range of design solutions and iterate through.

Deliver:
Convergent - Complete product definition.

Question 9

Describe the V-model process model.

Answer 9

Top-Down Design:
- System must be planned before deciding on details.

Bottom-Up Verification:
- Best to test individual components before full systems.

Question 10

Describe the stage-gate model.

Answer 10

E.g. that typically used by Rolls-Royce and Airbus.

• Emphasises certain achievements are required before progress can be made.
• Regular design reviews can be performed at set dates.
• Performance of the design can be reviewed at set milestones.
• Senior managers must sign-off to approve progress.

Question 11

Why is prototyping used? Name four models.

Answer 11

Computer models have limitations. If a designer is unaware of a weakness, they may not model it in software to avoid unknown unknowns.

• Breadboard model (check feasibility).
• Engineering model (verify main performance of a solution).
• Qualification model (verify entire performance against requirements).
• Delivered model (check actual performance before delivery).

Question 12

Why are design reviews used? Name four review types.

Answer 12

To force designers to declare the design status at milestones and allow senior managers to confirm if they approve of the progress or corrective action is required.

• Preliminary design review (review concept design & breadboard model).
• Engineering design review (review detailed design & engineering model).
• Qualification design review (review of qualification model performance).
• Final design review (review of delivered model performance).

Question 13

Give an example of the importance of test verification.

Answer 13

Hubble space telescope:

• Serious problem due to wobble of the solar array.
• Caused by inadequate thermal blankets during orbital sunrise.
• Problem was not modelled because designers did not realise it was an issue.
• Physical testing/verification would have identified it.

Question 14

What are hard and soft requirements?

Answer 14

Hard requirements:
- Non-negotiable.

Soft requirements:
- Desirable.

Question 15

What is the ‘man-machine’ interface?

Answer 15

The interface between a human operator and a machine. This is a critical part of the system and must be design with great care.

Question 16

Why is a ‘solution-neutral’ problem statement important?

Answer 16

A solution neutral problem statement is important because when a particular solution is stated or implied, it may discourage innovative solutions that may turn out to be best solutions.

Question 17

List some key design authorities for the following:

• Medicines and healthcare products.
• Aircraft design.
• European car safety.
• Structural design.

Answer 17

1. Medicines and Healthcare products Regulatory Agency (MHRA)
2. FAA, CAA, ICAO
3. Euro NCAP.
4. Eurocodes 1-9

Question 18

Describe functional mean trees.

Answer 18

Functional mean trees convert abstract functions (objectives) into more specific sub-functions and eventually into concrete features. Also known as functional decomposition. Good for requirement identification and conceptual design.

• Upwards = “how” to fulfil the function.
• Downward = “why” the function needs to be fulfilled.

Question 19

How should worst-case loading be calculated?

Answer 19

From ‘worst case possible’, not the worst case normally expected.

Question 20

Give an example of poor clarification of customer information.

Answer 20

Bristol Rovers main stand.

• A ‘covered stand’ was not inferred as ‘customers to be kept dry’.
• A ‘raised stand’ was not inferred as ‘customers to be able to see pitch’.

Question 21

List some (six) challenges of conceptual design.

Answer 21

• Creating something is inherently difficult.
• Not many people are naturally inventive.
• Engineers are trained to be cautious and follow design rules.
• 2D inhibits creativity.
• One cannot force inspiration.
• Inspiration depends on mood.

Question 22

List seven drivers of innovation.

Answer 22

1. Legislation
2. Customer Wishes
3. Technology Breakthroughs
4. Innovators/Entrepreneurs
5. Elite Activities
6. Affluence
7. Competition

Question 23

List 12 conceptual design methods.

Answer 23

1. Study the competition
2. Insight
3. Bio-Inspiration
4. Technology Transfer
5. Functional Decomposition
6. Backwards Design
7. Prototyping
8. Brainstorming
9. Structured Questioning
10. Inversion
11. Technology Opportunities
12. Sketching

Question 24

Briefly describe the conceptual design method ‘insight’. Give an example.

Answer 24

Understanding the physics of the problem to help produce effective ideas.

E.g. Isambard Brunel pioneering large iron-hulled ships by realising the relation between drag and frontal area, as well as fuel capacity and volume.

Question 25

Briefly describe the conceptual design method ‘Bio-Inspiration’. List the advantages and disadvantages.

Answer 25

The approach of studying the designs found in nature to approach a given problem.

Advantages:

• Concepts that are proven to work efficiently in often harsh environments.
• Very large range of concepts.

Disadvantages:

• Often extremely complex at a micro-level.
• Not necessarily designed for long life.
• Some strategies in nature are brutal.

Question 26

Briefly describe the conceptual design method ‘backwards design’. Give an example.

Answer 26

This involves identifying an idealistic solution and then working backwards to make it work.

E.g. Double-action worm gear-set for spacecraft.

Question 27

Briefly list some of the advantages of the conceptual design method ‘Prototyping’.

Answer 27

• Gives feedback on form and function very quickly.
• Good for 3D visualisations.
• Can be cheaper than computer modelling.
• You learn things that computer models may not tell you.
• There may be no off-the-shelf computer models for novel products.
• Aids team work.
• Aids selling to investors.

Question 28

Briefly describe the conceptual design method ‘Brainstorming’.

Answer 28

• The uninhibited idea creation by a team of people bouncing ideas off of each other.
• Multi-disciplinary teams.
• Criticism is not allowed.

Question 29

Briefly describe the conceptual design method ‘Structured Questioning’.

Answer 29

The creation of a set of questions to consider what can and cannot be done.

E.g. Is it OK to join several lorries on a motorway? This has been achieved in Australia.

Question 30

Briefly describe the conceptual design method ‘Inversion’.

Answer 30

This involves investigating whether an existing design can be done another way around, i.e. by investing some part of an existing design.

Question 31

Describe TRIZ.

Answer 31

TRIZ uses the concept of an ideal system to improve an existing system.

• Contradiction checklist of 39 features that can be improved.
• Contradictions are then improved used a list of 40 design principles.