Systematic Engineering Design Process

• The lecture discusses the engineering design process by using a systematic design approach.
• The notes will cover the systematic design process, the requirements and specifications, the function tree, and quality function deployment (QFD).
• Additionally, the notes will cover ethics during the requirements, specifications, and QFD stages.

Outcomes

• The lecture aims to enable students to apply the design process using systematic design methods to develop engineering components.
• Learn to identify customer requirements.
• Learn to identify engineering specifications and constraints.
• Learn to create a Function Tree and a stage 1 QFD Chart.

Review of Last Lecture

• Review of Design Importance
• Discussion of why Design is difficult.
• Definition of the Design Schools of thoughts
• Discussion on the of classical Brainstorming
• A True or False quiz tests on the role of cutomers
• Conventional design has more opportunities for weakness Identification.

Systematic Design Process - Steps

• Requirements
• Specifications
• Conceptual Design
• Embodiment Design
• Detailed Design
• The systematic design process includes Requirements, Specifications, Conceptual Design, Embodiment Design, and Detailed Design, often utilizing Quality Function Deployment (QFD).
• QFD is a method to prioritize specifications based on customer requirements.

Requirements

• Requirements are a 'wish list' of what the product needs to do, or what is expected of it.
• Requirements are usually given by customers or sponsors, or a list of requirements in the designer's mind.
• Requirements are not usually technical.
• For example A requirement for a coffee cup would be to hold coffee.
• One needs to find the requirement for a kettle.
• The need of a society for a vessel to transfer heat from an energy source to water, keep the temperature close to the boiling point, and safely transfer the boiled water into a coffee mug or tea cup.
• Resources of Requirements come from Market Segments, Economical/Political considerations and Research & Development activities.
• Market segments might include gas fire kettles and electric kettles for travel
• It also includes, small users, large and small numbers of cups with energy efficiency and electric kettles with aesthetically pleasing appearance for the affluent users.
• Requirements could include, heat varied amounts of water
• Other kettle requirements could be, energy efficient
• It could also address easy to move around or Safe handling during pouring.
• Kettle requirements should address aesthetically pleasing surface
• Kettles should be able to boil water fast, it also needs an automatic switching off from the energy source or alert user when water is boiling

Problems of requirements analysis

• Stakeholders don't know what they really want.
• Stakeholders express requirements in their own terms.
• Different stakeholders may have conflicting requirements.
• Organizational and political factors may influence the system requirements.
• The requirements change during the analysis process and new stakeholders may emerge.

Requirements elicitation

• There are four parts Requirement Elicitation
• The parts are, Requirements discovery
• Next comes, Requirements classification and organization
• Followed by, Requirements prioritization, and negotiation
• Finally, there is Requirements specification
• Requirements discovery relates to interaction with stakeholders to discover their requirements, including domain requirements.
• Requirements classification and organization involves grouping related requirements into coherent clusters.
• Prioritisation and negotiation involves prioritizing requirements and resolving conflicts.
• Requirements specification involves documenting requirements for the next round of the spiral.

Specifications

• Specifications, refer to a description of the product, generated beforehand, to guide the development of the product.
• Specifications lay down the requirements in technical terms for the product to be designed.
• They conver the 'requirements' into Engineering terms.
• Specifications are what the product SHOULD DO.
• Constraints are the opposite of specifications, describing what the product CANNOT OR SHOULD NOT DO.
• Most Definitions are usually defined in terms of functions.
• Efforts go into determining, the most important specifications, How to determine the most important one? Quality Function Deployment (QFD)

Coffee Cup Example

• A reasonable size for sufficient quantity of hot coffee with minimum possibility of accidental spilling.
• It is Carried by hand without burning the hand.
• Aesthetically pleasing.
• Examples of specifications of a Coffee Cup (without measure)Storage for hot coffee
• Stability when placed on the tray or table, Minimum heat loss
• Allow for Easy holding and tipping and protects hands from burning by providing easily washable surfaces (smooth, non-sticky) and an aesthetically pleasing appearance.
• There are specifications for the Khalifa Tower, as an example.
• Wish list for the product EXPECT to do come from stakeholders
• Requirements dont follow technical terms
• Specifications usually conform to technical terms

Function Tree

• Specifications describe the functions performed by the product to meet customer requirements, usually with a measure attached, e.g., a power source lasting more than 36 hours.
• Functions often have an underlying law of physics or engineering
• Systematizing Functions means drawing relationships between individual functions performed by the object of analysis and showing these relationships on a chart (Function Tree).
• The reason for Function Tree is, to help the designer.
• Its usedto Identify high order functions (Level One).
• To identify the links among functions of the product, and to it helps create alternatives to be designed or improved.
• Components of Function Description
• Involves asking the question What is its action?
• Glue A and B should be an example
• Separate C and D is another example of a function
• This method makes it possible to identify each function clearly
• Makes functions understandable to anyone
• It also makes it easier to come up with ideas.
• Light Bulb Example of a Function Tree

Quality Function Deployment (QFD)

• Systematic Design often makes use of QFD
• QFD (Quality Function Deployment) is known as a house of quality to measure requirements against specifications.
• QFD allows each stage of the design process to be measured quantitatively on achieving the previous stage.
• It helps determines how good the design is.
• QFD has been around for Nearly 50 Years.
• Professors Yoji Akao and Shigeru Mizuno initially developed them during the late 1960s.
• Mitsubishi Heavy Industries, Kobe Shipyard implemented during the 1972 timeframe.
• By 1983, QFD introduced into the Americas and Europe
• The 1977 timeframe, Toyota, had a major effort in North America
• It resulted in virtual elimination of rust related warranty problems, and led to reduction in development costs
• American automotive manufacturers adopted QFD
• Examples, Ford and GMC, plus General Electric, IBM and AT&T.
• Chart 1 (House of Quality) shows various relationships
• A relationship can be seen between Customer and Requirements
• There is relationship to Customer and importance Rating
• Absolute and relative ratings also exists
• These influence decisions about Benchmarking
• In Stage 1 Chart there is information on how Requirements & Specifications interact.
• Each requirement gets a rating from 1-9 (9 being the most important).
• If safety is very important rate at 9
• The NO relationship, leaves the grid space blank
• Slight or weak correlation, rate at 1
• If there is medium correlation, rate as 3
• If there is high/strong correlation, rate as 9
• One also needs to Multiply each specification rating by requirement importance rating and add it up to get the absolute importance rating.

Ethics & the early stages of design

• Identify ethical issues arising during the requirements and specifications stage of the design process.
• Discuss ethical issues related to the QFD.
• In groups, identify and list these ethical considerations.