ENGINEERING DESIGNENGINEERING DESIGN

ENGINEERING DESIGNENGINEERING DESIGNUnderstanding the Client’s Problem

The client’s understanding of the problem usually requires clarification by the designer

“ Objectives are the desired attributes of a design”

“ Constraints are limits that a design must meet to be acceptable”

“Functions are actions that a successful design must perform”

ENGINEERING DESIGNENGINEERING DESIGNObjectives Tree

• Is a ordered list of desired attributes of a design• The highest level is the top-level design goal• It describes dimensions of quality of a proposed

design:1. Performance (operating characteristics)2. Features (functions)3. Reliability (product failing)4. Durability (product life)5. Serviceability (during breakdown)6. Conformance (rules & regulations)7. Aesthetics (ergonomics)8. Perceived quality (reputation/branding)

ENGINEERING DESIGNENGINEERING DESIGNObjectives tree

ENGINEERING DESIGNENGINEERING DESIGNConstraints: setting limits on what the user can have

• a sort of checklist for design to be in a manageable size

• is a strategy of “satisficing” • Example: ladder should be cheap and manufacturing cost

should not exceed RM30.

ENGINEERING DESIGNENGINEERING DESIGNSETTING PRIORITIES: Rank Ordering

• It is almost certain that some objectives will be moreimportant than others.

• It ought to be recognized and measure it. HOW? • Pairwise comparison chart (PCC): help to understand

relative importance of the objectives1. Based on the binary choices ( 1 or 0 or ½). 1 = preferred

0=not preferred, ½= equally valued2. Based on team’s consensus. Indicates preferences. A>B>C etc3. Based on relationship. 1=strong, ½= moderate, 0= weak

ENGINEERING DESIGNENGINEERING DESIGNIDENTIFYING FUNCTIONS

• Tells us what the designed object must do.• Highlighting relationship between input and output• Avoid tying a function to a particular solution.• Approaches towards identifying and specifying functions:

1. Enumeration or list of all functions2. Black boxes & transparent boxes3. Function-means trees4. Reverse engineering/dissection

ENGINEERING DESIGNENGINEERING DESIGNEnumerationBeverage container design• contain liquid• fill the container• empty the container• close the container after opening• resist forces induced by temperature• resist forces induced by handling in transit

ENGINEERING DESIGNENGINEERING DESIGNBlack boxes & transparent boxesWashing machine

ENGINEERING DESIGNENGINEERING DESIGNFunction-means treeCigarette lighter

ENGINEERING DESIGNENGINEERING DESIGNReverse engineering/ dissection

• taking artifacts to dissecting or deconstructing or disassembling it to find out , in great details, just how it functions/works• Several cautions about using reverse eng/dissection:

a) the designer should focus on the current needsb) do not become captive to the design being usedc) always define functions in the broadest possible

terms

ENGINEERING DESIGNENGINEERING DESIGN

QUESTIONS AND DISCUSSIONS