ME 2331 Design Md

Design exists between ____ and _______

Abstract and Concrete

What does it mean to design the right thing?

Fulfilling the customer's mission

What does it mean to design the thing right?

How well we do our design job

What is cost committed?

Money set aside for future in the project

What is cost incurred?

Money already spent

Product Life Cycle

Idea -> Product Design -> Manufacture -> Operation & Maintenance -> Disposal

V-Diagram for Development

Planning -> Inputs -> Outputs -> Portotyping -> Verification -> Validation -> Changes

Kickoff

-Start of project
-Design brought in
-Budget shared
-Schedule shared

SRR (Systems Requirements Review)

Every requirement is presented

PDR (Preliminary Design Review)

Presenting the Design
CAD Models
Meeting the requirements

CDR (Critical Design Review)

Presenting finished design

How to pass PDR (preliminary design review)

-design meets requirements
-design supports cost and schedule
-all risks are identified
-all interfaces are defined
-verification methods

How to pass CDR (critical design review)

-design shows all details defined
-plans for procurements and fabrication
-cost and staffing is defined
-all component drawings exist
-all hardware and analyses are done

Design

A process to bring a solution from an abstract to concrete state

What percent of a project's budget is committed by the conclusion of conceptual design

70% - 80%

What are the 4 Product Characteristics

Purpose
Function
Operation
Form

1) Purpose

What is it for?

2) Function

What does it do?

3) Operation

How does it work?

4) Form

Geometry, Material, Construction

Behavior

Describes what the device actually does

Performance

The comparison of behavior and function

What is considered "Good Performance"

Function and behavior match

What is considered "bad performance"

Behavior falls short of function

What is a machine?

A device the does work

What is a simple machine?

A machine that does work with only one movement

Examples of Simple Machines

Level, Wheel & Axle, Screw, Pulley, Wedge, Inclined Plane, Gears?, Hydraulics?

IMA (Ideal Mechanical Advantage)

Geometry-based

Effort distance / Resistance distance
Input distance / Output distance

AMA (Actual Mechanical Advantage)

Output force / Input force

Resistive force / Effort force

Mechanical Percent Efficiency

(AMA / IMA ) x 100%

1st Class MA of Level

>1 , = 1, < 1

2nd Class MA of Level

MA > 1

3rd Class MA of Level

MA < 1

Examples of Design and Development Outputs

CAD models, Engineering Reports, Drawings, BOMs

Examples of Controlled Documents

Memos/Reports
Company Procedures
CAD Models
Drawings / BOMs

Minimal Requirements for "Control"

1) Document Number (with Unique ID)
2) Title - Description
3) Version Number
4) Change Management

Configuration Break

A period of time if the product does NOT represent the model/drawing

What are the two ways to document a change on a Controlled Document

1) Roll the Revision
2) Create a new document

When do you "Roll the Revision"?

For a minor change

When do you "get a new part number"?

For a major change

The 3 F's of Changes

1) Form
2) Fit
3) Function

If all 3 are unchanged, roll the rev

Benefit of New Part Number

You preserve the old design

Disadvantage of New Part Number

Cost is higher than rev changes (new parts, new BOMs)

Identification

A collection of qualities that establish uniqueness for each part

Definition

A collection of details that describes each part

Product Structure (Order)

1) End Item (Product)
2) Assembly
3) Part
4) Hardware/COTS
5) Material

End Item

Finished Product
May have children

Assembly

Collections of Parts
Have BOMs

May have children

Part(s)

-The simplest designed thing with a drawing

-Includes Materials (only material children)

Hardware/COTs

A component that was NOT designed, but purchased elsewhere

Material

Material, part number, description, revision #

What 2 characteristics should part numbers have?

Unique and Consistent

T/F A Bill of Materials (BOM) for a given drawing is a single-level section of the overall product structure pertaining to what is contained in the drawing.

True

What is a requirement?

A brief, complete statement that describes the "necessary functions and features" of the product

How are requirements grouped?

By type and hierarchy

What part of the development path are "requirements"?

Inputs

What is proper requirement structure?

[Device Name] + [Keyword] + [Capability Description]

Requirement Keywords

Shall, Will, Should, May, (Must)

Shall

Req is a "must-have"

Will

Req is a lower priority "must have" than shall

Should

Communicates a goal the customer is interested in (not binding)

May

Req is optional or a suggestion

Must

Equivalent to "Shall"

Important Requirement Attributes

-Specific / Unambiguous
-Current (time-based)
-Verifiable
-Singular
-Consistent/Correct
-Feasible

T/F Every requirement must have a way to be checked to confirm it was met by design

True

Method of Verifying Requirements

-Examination/Observation/Inspection
-Testing
-Demonstration
-Analysis

T/F Following kickoff, the design staff typically begins design tasks while the requirements are being firmed up.

False, we need requirements

Which requirement keyword is used the least

Will

Which requirement type usually needs to be very specific/longer?

Performance Requirements

Which verification methods draws the most scrutiny from customers and reviewers?

Analysis

Where do requirements, codes, and standard belong on the V-Diagram for Development?

Inputs

Codes (Regulations)

A level of adequacy for structures, machines, and testing. Often related to safety.
(Legally based / carries the law.)

Standards

Established Norms for uniform engineering processes
(No legal basis)

T/F You should utilize standards in design whenever possible.

True

Who governs "National Standards"?

ANSI - American National Standards Institute

Who governs "International Standards"?

ISO - International Organization for Standardization

5 Types of Standards

1) Specification
2) Tests/Verification Methods
3) Practices & Procedures
4) Definition of a term
5) Units of Measurement

What is the best practice for a designer if there are overlapping standard material specifications?

Choose one material and list that

What is a "Design Concept"?

A preliminary design intended to address system/product requirements

T/F Lots of concepts and variety is preferred

True

T/F Ideas = Concepts

False

What do "Design Concepts" look like?

Sketches (pencil or digital)
Basic CAD Models

What are the four product characteristics?

1) Purpose (what is it for?)
2) Function (what does it do?)
3) Operation (how does it do it?)
4) Form (what it made of?)

Popular Ways to generate ideas

1) Analogies (previous experience / designs)
2) Brainstorming
3) Reverse Engineering
4) Extremes (ask to change reqs)
5) Permutations (changes to function sequence)

Analogous Design

Use previous designs / concepts

"Extreme" Design Strategies

Propose changes to requirements to generate ideas

"Permutations" Design Strategies

Suggest changes to the sequence of a product's function

Morphology Matrix

A way to brainstorm design concepts by combining ways to meet product requirements

Where does "Conceptual Design" occur in the development process?

Right after SRR

What are the 2 Stages of Concept Evaluation?

1) With a designer
2) With a formal group

What are the 3 categories a designer evaluates concepts with?

Feasible, Conditionally Feasible, Unfeasible

Feasible

-Meets requirements

-No unacceptable risks

Conditionally Feasible

-Meets reqs except for a small obstacle

Unfeasible

-Doesn't meet requirements
-Unacceptable risk (low TLR - tech-readiness-level)
-No sponsorship

What is considered "The Heart of a Design Matrix"

The Criteria

T/F Criteria should be based on requirements where possible

True

Datum

A chosen design to act as a benchmark for comparing designs

According to Pugh's Method/ Decision Matrix, how many criteria is a good range?

10-15 criteria

What are the 6 boxes of a Decision Matrix?

1) The Issue (Product)
2) The Concepts/Alternatives
3) Criteria
4) Weighting / Importance
5) Evaluation / Scoring
6) Results

T/F Standards can overlap.

True
EX- Pipe has ANSI and ASTM