Engineering Design GE121 The Design Process (continued – Part III) Lecture 8B

Strategies/Methods/Means in the Design Process Even formal prescriptive processes don’t tell us HOW to Generate or Create Designs Will introduce: Formal Design Methods Means of Acquiring Design Related Information Decision-support techniques and tools to explain HOW to design Describing thought processes or cognitive tasks

Strategic Thinking in the Design Process Least Commitment Unwise to commit to a concept or configuration until forced to (exhausted information search / alternate designs) ‘Never marry your first design’ Premature commitments can be dangerous and lead to sub-optimal designs Decomposition: Divide and Conquer Break down / subdivide / decompose larger problems Smaller sub-problems or ideas easier to solve / handle Be careful – sub-problems often interact ‘How do you eat an elephant?’ ……. One bite at a time!

Formal Methods for Design Process Objectives Trees Used to clarify and better understand Client Statement Tree-like structure Clustered by sub-objectives Have seen an example in the Case Study Will discuss in detail in section 3.1 Pairwise Comparison Charts Used to rank-order Design Objectives Relatively simple Compare Objectives on a pair-by-pair basis Have seen an example in Case Study Will discuss in detail in section 3.3

Formal Methods for Design Process (cont’d) Functional Analysis ‘Black Box’ is the starting point – clearly delineates boundaries between proposed device and its surroundings Decompose functions into sub-functions Track flow of material / signals through device & detail what is needed to produce desired functions Have previously seen the Function-Means tree Detailed in section 4.1

Formal Methods for Design Process (cont’d) Performance Specifications Elaboration of Design Specifications Solution independent attributes and performance specifications Hard numbers for both desired and required features Covered in section 5.2 Morphological Charts Identify the Ways or Means that can be used to make the required functions happen Provides a framework for visualizing a ‘design space’ of potential solutions Covered in sections 5.1 and 5.3

Formal Methods for Design Process (cont’d) Quality Function Deployment More advanced tool Builds on Performance Specification, with goal of higher quality product Used widely in product manufacturing Charts client and user requirements and engineering attributes in matrix form – relate and weight them, one against another Creates a ‘House of Quality’ that exposes both positive and negative interactions Described briefly in section 8.5

Means of Acquiring/Processing Design Knowledge Knowledge is a critical component of design Means for Acquiring Information Literature reviews Enhance understanding of potential users, clients and the design problem itself Prior and existing / competing solutions Physical properties during conceptual design Handbooks, codes, and part/component libraries in detailed design User surveys / questionnaires Market research Identify User understanding of problem Help Designer clarify / understand problem early on Can be used later during the selection process In electronics design, manufacturers include typical application circuits for their components to make it easier for designers to use their components. Circuit design handbooks are essentially compendia of circuits developed by others.

Means of Acquiring/Processing Design Knowledge (cont’d) Focus groups Expensive Allow design team to observe response of selected users to potential designs Also involve knowledge/sophistication in psychology – not often used by students Informal and structured interviews Informal Interviews should be focused so as not to waste the time of the interviewee – helpful to send topics or questions ahead of time Structured Interviews – combines focus of a survey with the flexibility of an informal interview to allow follow-up on areas of interest, or new areas

Means of Acquiring/Processing Design Knowledge (cont’d) Brainstorming Generate related or even unrelated ideas, without evaluation Free-wheeling Opens up new avenues, ideas Important for all members to maintain respect for the ideas of others Important to capture ALL ideas as they are offered Synectics Environment similar to brainstorming Explore relationships and similarities between relationships and ideas that initially seem unrelated Explore similar ideas/solutions (analogies) from different disciplines of engineering Brainstorming can be an iterative process. Do some evaluation and research on ideas generated in one session. Follow up with elimination of some of the less hopeful ideas. Then have another brainstorming session to generate new ideas that may come from the evaluation and research, or they may have come through further creative thinking by team members.

Means of Acquiring/Processing Design Knowledge (cont’d) Benchmarking Take competitive products and use them as a ‘benchmark’, or reference, then try to make it better Reverse engineering Sometimes referred to as dissection Literally take it apart to try to determine design intent Find better ways to perform the same or similar sub-functions

Means of Acquiring/Processing Design Knowledge (cont’d) Means for Analyzing Information / Testing Outcomes Defining metrics is important – we often need ways of determining a numeric value for metrics, or determine if a specification can be met Laboratory experiments May involve physical testing of a basic structure or component Prototyping Prototype or test unit is produced to verify functional operation May not look like final product, and may only have a subset of the key functions tested (saves money / time)

Means of Acquiring/Processing Design Knowledge (cont’d) Proof of concept testing Idea is to show that design can fulfill functions under certain prescribed conditions Tested unit may not survive, or perform stated function, but still may prove the concept Computer models Simulation software Discipline-specific CADD (Computer Aided Design and Drafting) software Means for Obtaining Feedback Regularly scheduled meetings with Users and Clients!! Formal Design Review (must learn give and take) Public Hearings Focus Groups Beta testing