HSE Teachers’ Workshop Jean Kampe Summer 2011 Delivered by Jonathan Riehl. Design I. Engineering design the process the language . Today’s Focus. What engineers do …. Problem Solution. Design. is a process is modeled in many different ways involves the use of tools
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HSE Teachers’ WorkshopJean KampeSummer 2011Delivered by Jonathan Riehl
Design I
Engineering design
the process
the language
Problem Solution
Design
is a process
is modeled in many different ways
involves the use of tools
has its own language/vocabulary
A Linear Model
(Not very realistic)
Client’s
Need
Problem
Definition
Conceptual
Design
Preliminary
Design
Documentation
of Fabrication
Specifications
Detailed
Design
Ref: Dym, C.L. and Patrick Little, Engineering Design, a Project-Based Introduction, 3rd Ed., John Wiley & Sons, Inc., 2009, Chapt.2.
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Revise
No
A Cyclic Model – a much better view
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Test and evaluate
Documentation of Fabrication Specifications
Problem Definition
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Revise
No
A Cyclic Model
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Test and evaluate
Documentation of Fabrication Specifications
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Conceptual
Design
Revise
No
A Cyclic Model
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Test and evaluate
Documentation of Fabrication Specifications
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Revise
No
A Cyclic Model
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Preliminary
Design
Test and evaluate
Documentation of Fabrication Specifications
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Revise
No
A Cyclic Model
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Test and evaluate
Documentation of Fabrication Specifications
Detailed Design
Engineering Design
Is a cyclic process
real-life design does not happen in a linear sequential way
Uses tools and procedures
we need to know how to use those tools
Has its own language
we need to understand that language
Realm of our design focus
Define Criteria
Gather Information
Choose a Strategy
Start
(Define the Problem)
Engineering Design Process
Develop Alternate Solutions
Revise
No
A Cyclic Model
Does solution meet requirements?
Build a Prototype
Model and Analyze
Yes
Test and evaluate
Documentation of Fabrication Specifications
Staple Remover Exercise
Attributes the solution should have
(Think in terms of “The design should be ______.”)
Confusing Terms
These two items are very different things in design.
design criterion (a.k.a. “Objective”) n: Designer chosen characteristic of the solution that is related to the problem, such as durability, size, or weight, and used as an evaluation factor.
Plural: design criteria
design constraintn: An imposedlimit or boundary placed on the design solution by an external source, such as nature, your boss (i.e., company management), a government agency, or other vested stakeholder.
The “right” constraints, criteria, weights, and metrics are the bases of a good Decision Matrix.
Engineering is diminished and impoverished by a lack of diversity. At a fundamental level, we all experience the world differently, and those differences in experience are the “gene pool” for creativity. We will never be able to engineer as well as we could until all stakeholders are adequately represented on engineering design teams.
Paraphrasing William A Wulf (NAE):
(Former president of the National Academy of Engineering, 1996-2007)
On the lack of diversity in engineering ...
“There is a real ... cost to that ... it is an opportunity cost ... measured in design options not considered, in needs unsatisfied and hence unfulfilled.* It is measured in ‘might have beens,’ and those kinds of costs are very hard to measure. That doesn’t change the fact that they are very real and very important.”
Quoting Wm. Wulf:
* He’s talking about criteria and constraints that are either
not anticipated or not correctly interpreted because the
design team does not adequately represent all the
stakeholders.
The “right” constraints, criteria, weights, and metrics are the bases of a good Decision Matrix.
Score = Rate x weight Design with highest sum wins!!
To a Decision Matrix that is generated according to real engineering design procedures instead of guesswork
Ref: Dym, C.L. and Patrick Little, Engineering Design, a Project-Based Introduction, 3rd Ed., John Wiley & Sons, Inc., 2009, Chapt.3.
Used to help us weight our objectives
Results give an approximate subjective judgment of relative value and importance (i.e., weight) rather than a strong meaningful measurement
Ref: Dym, C.L. and Patrick Little, Engineering Design, a Project-Based Introduction, 3rd Ed., John Wiley & Sons, Inc., 2009, Chapt.3.
Example pair-wise Comparison Chart for marketability of the ladder.
Ref: Dym, C.L. and Patrick Little, Engineering Design, a Project-Based Introduction, 3rd Ed., John Wiley & Sons, Inc., 2009, Chapt.3.
Use metrics to measure how well a design alternative achieves the objective, then rate the designs using those measurements (e.g., use a scale of 1-5 with higher ratings being better).
Good metrics are essential to rate the design alternatives.
To develop metrics
Identify units and scale of something appropriate to measure about the objective (e.g., $$, kg, or a defendable subjective scale)
Identify the way to measure the designs in those units (tests, surveys)
Determine if the measurement is feasible (remember, the designs are only conceptual at this point)
Measures something directly related to the criterion in a way that gives you a number or value
Is capable of appropriate level of precision or tolerance
Is repeatable
Is expressed in understandable units of measure
Promotes clear interpretation
e.g., criterion = ease of assembly
Possible metrics
Number of parts
Estmated time to assemble
Score = Rate x weight Design with highest sum wins!!
Engineering design: