Aerospace Systems Engineering A Modern Approach

1
Aerospace Systems EngineeringA Modern Approach

• Dr. Daniel P. Schrage
• Professor and Director,
• Center of Excellence in Rotorcraft
  Technology(CERT)
• Center for Aerospace Systems Analysis (CASA)

2
Course Materials

• Primary Text, Dieter, Engineering Design A
  Materials and Processing Approach, 3rd Edition,
  McGraw Hill, 2000
• Secondary Text,Systems Engineering Fundamentals
  Defense Systems Management College, 1998

3
The Product Design Process(Chapter 1, Dieter)

• Introduction and Importance of Product Design
• The Design Process A Simplified Approach
• Considerations of a Good Design
• Detailed Description of Design Process
• Marketing
• Organization for Design
• Computer-Aided Engineering
• Designing to Codes and Standards
• Design Review
• Technological Innovation and the Design Process

4
Some Important Concepts

• Design to fashion after a plan (Webster
  Dictionary)
• leaves out the essential fact that to design is
  to create something that has never been
• Synthesis pulling together
• Ability to design is both a science and an art
• The science can be learned through techniques
  methods
• The art is best learned by doing design
• Discovery getting the first sight of, or the
  first knowledge of something, as when Columbus
  discovered America
• Invention requires the design be a step beyond
  the limits of existing knowledge (beyond the
  state of the art). Some designs are truly
  inventive, but most are not

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Integrated Synthesis and AnalysisVarying
Fidelity of Synthesis, Sizing Analysis
Safety
Safety
Economics
Aerodynamics
Aerodynamics
Economics
S
ynthesis Sizing
SC
Manufacturing
Manufacturing
SC
Integrated Routines
Increasing

Table Lookup
Sophistication and

Structures
Complexity
Performance

Conceptual Design Tools
(
First-Order Methods)
Approximating Functions
Direct Coupling of Analyses
Propulsion
Structures
Performance

Preliminary Design Tools
(
Higher-Order Methods)
Propulsion
6
Definition of Design(per Dieter)

• Design establishes and defines solutions to and
  pertinent structures for problems not solved
  before, or new solutions to problems which have
  previously been solved in a different way

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Good Design requires both Synthesis Analysis

• Typically, we approach complex problems like
  design by decomposing the problem into manageable
  parts or components
• Because we need to understand how the part will
  perform in service we must be able to calculate
  as much about the parts behavior as possible by
  using the appropriate disciplines of science and
  engineering science and the necessary
  computational tools
• This is called Analysis and usually involves the
  simplification of the real world through models
• Synthesis involves the identification of the
  design elements that will comprise the product,
  its decomposition into parts, and the combination
  of the part solutions into a total workable
  system
• In the typical design you rarely have a way of
  knowing the correct answer. Hopefully, your
  design works, but is it the best, most efficient
  design that could have been achieved under the
  conditions? Only time will tell

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The Four Challenges (Cs) of the Design
Environment

• Creativity
• Requires creation of something that has not
  existed before or not existed in the designers
  mind before
• Complexity
• Requires decisions on many variables and
  parameters
• Choice
• Requires making choices between many possible
  solutions at all levels, from basic concepts to
  smallest detail of shape
• Compromise
• Requires balancing multiple and sometimes
  conflicting requirements

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Product Design Process

• Engineering design process can be applied to
  several different ends
• Design of Products, whether they be consumer
  goods and appliances or highly complex products
  such as missile systems or jet planes
• Another is a complex engineered system such as an
  electric power generating station or a
  petrochemical plant
• Yet another is the design of a building or bridge
• The principles and methodology of design can be
  usefully applied in each of these situations.
  However, the emphasis in Dieters book is on
  product design and in this course is complex
  product design, specifically Aerospace Systems

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Dieters Book Goal

• Provide insight into the current best practices
  for doing product design
• The design process should be conducted so as to
  develop quality cost-competitive products in the
  shortest time possible
• Is necessary, but insufficient for Aerospace
  Systems Design

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Japanese Auto Industry and The U.S. Auto Industry
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The Quality Engineering Process provides
Recomposition Methods Tools
Knowledge Feedback
Quality Function Deployment Off-Line
Seven Management and Planing Tools Off-Line
Statistical Process Control On-Line
Robust Design Methods (Taguchi, Six - Sigma,
DOE) Off-Line
Customer

• Identify Important Items

• Variation Experiments
• Make Improvements

• Hold Gains
• Continuous Improvement

• Needs

Having heard the voice of the customer, QFD
prioritizes where improvements are needed
Taguchi provides the mechanism for identifying
these improvements
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Traditional Design Development Using only a Top
Down Decomposition Systems Engineering Process
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IPPD Environment for System Level Design Trades
and Cycle Time Reduction
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Typical System Life Cycle Cost
100 75 50 25 0

Cumulative Percent of LCC

Life Cycle Cost Actually Expended

Production, Deployment, Operations and Support
EMD
PD RR
Con Exp
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Ramifications of the Quality Revolution

• Decisions made in the design process cost very
  little in terms of the overall product cost but
  have a major effect on the cost of the product
• Quality cannot be built into a product unless it
  is designed into it
• The design process should be conducted so as to
  develop quality cost-competitive products in the
  shortest time possible

17
Design Process Paradigm Shift(Research
Opportunities in Engineering Design, NSF
Strategic Planning Workshop Final Report, April
1996)

• A paradigm shift is underway that attempts to
  change the way complex systems are being designed
• Emphasis has shifted from design for performance
  to design for affordability, where affordability
  is defined as the ratio of system effectiveness
  to system cost profit
• System Cost - Performance Tradeoffs must be
  accommodated early
• Downstream knowledge must be brought back to the
  early phases of design for system level tradeoffs
• The design Freedom curve must be kept open until
  knowledgeable tradeoffs can be made

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Static vs Dynamic Products

• Some products are static, in that the changes in
  their design concept take place over a long time
  period rather, incremental changes occur at the
  subsystem and component levels (most air vehicles
  are static)
• Other products are dynamic, like
  telecommunications systems and software, that
  change the basic design concept fairly frequently
  as the underlying technology changes (avionics
  and mission equipment software are dynamic)

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Simplified Design Process

• Definition of the Problem
• Gathering Information
• Generation of Alternative Solutions
• Evaluation of Alternatives
• Communication of the Results

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Georgia Tech Generic IPPD Methodology
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Detailed Description of Design Problems(Morris
Asimows Morphology of design)

• Phase I. Conceptual Design
• Phase II. Embodiment Design (Preliminary Design)
• Phase III. Detail Design
• Phase IV. Planning for Manufacture
• Phase V. Planning for Distribution
• Phase VI. Planning for Use
• Phase VII. Planning for Retirement of the Product

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Discrete Steps in Engineering Design Process
23
Design Depends on Individual Who Defines Problem
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Classification of Products Based on Market

• Platform Product
• Is built around a preexisting technological
  subsystems, e.g. Apple Macintosh operating
  systems
• Is similar to a technology-push product
• Process-Intensive Products
• Manufacturing process places strict constraints
  on the properties of the product
• Examples are automotive sheet, steel, food
  products, semiconductors chemicals and paper
• Customized Products
• Variations in configuration and content created
  in response to a s

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The Total Materials Cycle
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The Systems Engineering Process

• Process Input
• Customer Needs/Objectives/ Requirements
• - Missions
• - Measures of Effectiveness
• - Environments
• - Constraints
• Technology Base
• Output Requirements from Prior Development
  Effort
• Program Decision Requirements
• Requirements Applied Through
• Specifications and Standards

System Analysis Control (Balance)

• Requirements Analysis
• Analyze Missions Environments
• Identify Functional Requirements
• Define/Refine Performance Design
• Constraint Requirement

• Trade-Off Studies
• Effectiveness Analysis
• Risk Management
• Configuration Management
• Interface Management
• Performance Measurement
• - SEMS
• - TPM
• - Technical Reviews

Requirement Loop

• Functional Analysis/Allocation
• Decompose to Lower-Level Functions
• Allocate Performance Other Limiting
  Requirements to
• All Functional Levels
• Define/Refine Functional Interfaces
  (Internal/External)
• Define/Refine/Integrate Functional Architecture

Design Loop

• Synthesis
• Transform Architectures (Functional to Physical)
• Define Alternative System Concepts,
  Configuration
• Items System Elements
• Select Preferred Product Process Solutions
• Define/Refine Physical Interfaces
  (Internal/External)

Verification
Related Terms Customer
Organization responsible for Primary Functions
Primary Functions Development,
Production/Construction, Verification,
Deployment, Operations,
Support Training, Disposal Systems Elements
Hardware, Software, Personnel, Facilities, Data,
Material,
Services, Techniques

• Process Output
• Development Level Dependant
• - Decision Data Base
• - System/Configuration Item
• Architecture
• - Specification Baseline

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Systems Engineering, Its Purpose

• To satisfy a mission need with a system
• that is cost effective, operationally
• suitable, and operationally effective.

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Systems Engineering Objectives

• Translate customer needs into balanced
  system/subsystem design requirements and product
• Integrate technical inputs of the entire
  development community and all technical
  disciplines into a coordinated program effort
• Transition new technologies into product and
  abatement program
• Ensure the compatibility of all functional and
  physical interfaces
• Verify that the product meets the established
  requirements
• Conduct a formal risk management and

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What Is a System?

• A system is a collection of components
  (subsystems) that
• Interact with one another
• Have emergent capabilities - capabilities above
  and beyond what the same collection of
  components would if they did not interact
• Interacting components implies architecture

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Elements of a System

• Elements
• Equipment Hardware
• Software
• Facilities
• Personnel
• Data
• All elements are interrelated

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System Element Constituents

• Equipment Hardware
• Mission hardware
• Ground equipment
• Maintenance equipment
• Training equipment
• Test equipment
• Special equipment
• Real Property
• Spares

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System Element Constituents (cont.)

• Software
• Instructions
• Commands
• Data
• Facilities
• Industrial
• Operational
• Training
• Depot

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Systems Engineering Principles Apply to All
Acquisition Phases at All Levels of the
Engineering Hierarchy
Levels in the System Hierarchy
System analysis/ control/evaluation
Requirements analysis
Configurationsynthesis
Functional analysis

• System ofsystems
• System
• Segment
• Subsegment
• Item

P/D
EMD
PDRR
AcquisitionPhases
CED
CED - Concept Exploration/Definition PDRR -
Program Definition Risk Reduction
EMD - Engineering/Manufacturing Definition P/D -
Production/Deployment
Pre-CED
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Systems Engineering In IPD
IPD
Product Teams
Concurrent Development
Systems Engineering Process
Systems Engineering Process
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Ability to Influence Cost
High
CED
PDRR
EMD
Production.
Deployment
Low
Time
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System Element Constituents (cont.)

• Personnel
• Training
• Tasks
• Number
• Types and skills
• Data
• Parts Manuals
• Maintenance Manuals
• Operating Manuals

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Systems Thinking
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Roles of Systems Engineers

• Requirements Owner
• System Designer
• System Analyst
• Validation/Verification Engr
• Logistics/Ops Engineer
• Glue Among Subsystems

• Customer Interface
• Technical Manager
• Information Manager
• Process Engineer
• Coordinator
• Classified Ads SE

Source Twelve Roles of Systems Engineers, Sarah
Sheard URL www.software.org/pub/externalpapers/
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What Is a System?

• A system is a collection of components
  (subsystems) that
• Interact with one another
• Have emergent capabilities - capabilities above
  and beyond what the same collection of
  components would if they did not interact
• Interacting components implies architecture

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Examples of Systems

• Aircraft engine vs a collection of parts
• Aircraft with engines and avionics
• Air traffic control with aircraft, airfields,
  radars, controllers, CCS
• Air transportation with air traffic control,
  airlines, passengers, cargo, maintenance,
  pickup and delivery

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More Complex SystemsSystems of Systems

• Individual systems can operate on their own
• Systems of systems not owned and controlled as a
  whole by single entity
• Mark Maier, Architecting Principles for
  Systems-of-Systems, Journal of the International
  Council on Systems Engineering, Vol I, 1998

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Examples of Systems of Systems

• Internet
• Auto and truck transportation
• Air Defense System maybe
• National Airspace System (NAS)
• Future Combat Systems (FCS) for the Objective
  Force Brigade (Unit of Action)

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Technical Director Is the Systems Thinker

• If not, objectives, approaches, and decisions
  will not reflect systems thinking
• Technical Directors who dont think systems
  inhibit systems thinking on their project

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Why Is Systems Thinking Good?

• Intractable problems often have solutions in the
  design space of the larger system
• Solutions in the larger systems space are often
  less costly or less risky
• Integration with external systems are addressed
  early in the development

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A Community Example

• The Problem (or so they thought)
• Trees, fuels and other natural resources are
  being used up, so we need to recycle them
• The Solution (or so they thought)
• Collect selected trash separately and sell it to
  recycling facilities

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A Dose of Reality

• Separate trash collections for recycleable would
  double the cost
• Market for recycled newspaper and aluminum cans
  was saturated
• Unsold recycleables would have to be stored --
  at additional cost

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Starting to Think Systems

• Who currently collects trash?
• From whom?
• What is done with the trash?

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Answers and More Questions

• Two trash collectors
• One collects from homes
• One collects from businesses
• Does the collector from businesses separate the
  recycleables?
• Both put trash in land fills
• Both pay to put trash in land fills
• How much does it cost to put trash in a land
  fill?

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The Land Fills as Part of the System

• 17 per ton to dump trash in the land fill
• Expected to reach 30 per ton in 15 years
• Land fills charge 150 per ton in New York
• Gee, maybe we should think about conserving the
  land fills?

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A Systems Solution

• Two collections per week
• One for recycleables
• One for non-cycleable trash
• Slight increase in fees for storing recycleables
• Market demand of recycled paper and aluminum
  increase soared in 5 years

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Consequences of Systems Thinking

• The original objective (saving resources) was
  satisfied
• Current costs were contained
• Future cost containment made the slight increase
  saleable to the public

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Dieter Chapter 2Need Identification and Problem
Definition

• Of all the steps in the engineering design
  process, problem definition is the most important
• Before the Problem-Definition Step Design
  projects commonly fall into one of five types
• Variation of an existing product
• Improvement of an existing product
• Development of a new product for low-volume
  production run
• Development of a new product for mass production
• One-of-a-kind- design
• Identifying Customer Needs
• Gathering Information from Customers

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Dieter Chapter 2Need Identification and Problem
Definition

• Constructing a Survey Instrument
• Benchmarking
• Customer Requirements
• Quality Function Deployment
• Product Design Specification
• The basic control and reference document for the
  design and manufacture of the product
• In-Use Purposes and Market
• Functional Requirments
• Corporate Constraints
• Social, Political and Legal Requirements

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Presentation Outline

• Synthesis and Sizing of Aerospace Vehicles
• Maneuverability and Agility Considerations for
  Aerial Vehicles
• Autonomous Vehicle Considerations
• Summary and Conclusions

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Synthesis and Sizing of Aerial Vehicles

• For Aerial Vehicles Synthesis and Sizing provides
  the Closure between Mission Requirements and
  Geometric Configuration Solutions
• A Fuel and Thrust/Power Balance Approach is used
  which allows for analytical design optimization
  (min. GW, etc.) through the coupling of a few
  critical design parameters (FWaspect ratio, wing
  loading RWdisk loading)
• Maneuverability and Agility can be related to
  Energy Principles (differences between
  Thrust/Power Available and Thrust/Power
  Required), Handling Qualities and the design of
  the Flight Control System

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Maneuverability and Agility Considerations for
Aerial Vehicles

• Fixed Wing Fighter Aircraft normally have a good
  high speed capability, good maneuverability at
  normal combat speeds (medium to high subsonic and
  transonic speeds), high specific excess power,
  good to excellent avionics, and the ability to
  employ guns and a wide range of air-to-air
  missiles. To achieve these capabilities, their
  optimum maneuvering speeds are usually rather
  high, impacting on low speed maneuverability
• Rotary Wing Aircraft have excellent low speed
  capability due to the rotor hub control moments
  which provides excellent control power in any
  axix. This allows rotary wing aircraft to fly
  Nap-of-the-Earth and stress aggressive concealed
  movement to take full advantage of masking
  provided by trees and terrain and attacking from
  a position of advantage at maximum standoff range

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Summary and Conclusions

• Aerial Vehicle Design and Performance is highly
  dependent on the Mission identified and use of a
  Fuel and Thrust/Power Synthesis Approach
• For high speed, high altitude, high maneuvering
  attack missions, such as Suppression of Enemy Air
  Defense (SEAD), Fixed Wing Aerial Vehicle are the
  Choice
• For low speed, low altitude, high agility(along
  with vertical takeoff and landing
  (VTOL)capability) reconnaissance and attack
  missions, such as Urban Warfare, Rotary Wing
  Aerial Vehicles are the Choice

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Technological Innovation and The Design Process

• The advancement of technology has three phases
• Invention The creative act whereby an idea is
  conceived
• Innovation The process by which an invention or
  idea is brought into successful practice and is
  utilized by the economy
• Diffusion The successive and widespread
  initiation of successful innovation
• The technological innovation activity can
  considered to be

Commerc Exploitation
Develop ment
Ident. Of Mkt Need
Product idea
Pilot lot
Trial sales
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Successful products delineate four factors that
lead to success

1. Product planning and research Products where
   adequate time was spent in problem definition
   concept development
2. Product superiority Having a superior
   high-quality product that delivers real value to
   the customer makes all the differences between
   winning and losing
3. Quality marketing High in importance is how well
   the marketing activities were executed from
   concept of the idea to the launch of the product
   in the marketplace
4. Proper organizational design Successful products
   are most often developed by a cross-functional
   team, led by a product champion, supported by top
   management, and accountable for the entire
   project from beginning to end

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Product and Process Cycles

• Product Life Cycle and Cash Flow Analysis
• Technology Development Cycle and S- Curves
• Process Development Cycle
• Uncoordinated development
• Segmental development
• Systematic development
• Producition and Consumption Cycle

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Societal Considerations in Engineering

• Characteristics of an Environmentally Responsible
  Design
• Five roles of government in interacting with
  technology
• Technology Identification, Evaluation and
  Selection (TIES)

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Dieter Chapter 3 Team Behavior and Tools

• A team is a small number of people with
  complementary skills who are committed to a
  common purpose, performance goals, and approach
  for which they hold themselves mutually
  accountable
• Differences between a working group and a team
• Working Group Team
• -Strong, clearly focused leader -Individual
  mutual accountability
• -The group,s purpose is the - Specific team
  purpose that the team
• Same as the broader org.msn. Itself develops
• Individual work products - Collective work
  products
• Runs efficient meetings - Encourages open-ended
  discussion
• and active problem-solving meetings
• Measures its effectiveness - Measures performance
  directly by
• indirectly by its influence assessing collective
  work products
• -Discusses,decides and delegates - Discusses,
  decides and does real work
• together

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Dieter Chapter 3 Team Behavior and Tools

• What It Means to be an Effective Team Member
• Take responsibility for the success of the team
• Be a person who delivers on commitments
• Be a contributor to discussions
• Give your full attention to whomever is speaking
  and demonstrate this by asking helpful questions
• Develop techniques for getting your message
  across to the team
• Learn to give and receive useful feedback
• The following are characteristics of an effective
  team
• Team goals are as important as individual goals
• The team understands the goals and is committed
  to achieving them
• Trust replaces fear and people feel comfortable
  taking risks
• Respect, collaboration and open-mindedness are
  prevalent
• Team members communicate readily diversity of
  opinions are encouraged
• Decisions are made by consensus and have the
  acceptance and support of the members of the team

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Dieter Chapter 3 Team Behavior and Tools

• TEAM ROLES Within a team members assume
  different roles in addition to being an active
  team member
• TEAM DYNAMICSStudents of team behavior have
  observed that most teams go through five stages
  of development
• EFFECTIVE TEAM MEETINGS Students who complain
  about design projects taking too much time often
  are really expressing their inability to organize
  their meetings and manage their time effectively
• PROBLEMS WITH TEAMS A well-functioning team
  achieves its objectives quickly and efficiently
  in an environment that induces energy and
  enthusiam

65
Dieter Chapter 3 Team Behavior and Tools

• PROBLEM SOLVING TOOLS
• TIME MANAGEMENT
• PLANNING AND SCHEDULING

66
Dieter Chapter 5 Concept Generation and
Evaluation

• With a clear product design specification
  developed in Chap. 2 we have arrived at the point
  where we are ready to generate design concepts,
  evaluate them, and decide which one will be
  carried forward to a final product
• The principle that grades this work is that put
  forth by the American architect-engineer Louis
  Henri Sullivan, form follows function
• By this we mean, if the functions of the design
  are clearly understood, then its appropriate form
  or structure will be easier to determine

67
Dieter Chapter 5 Concept Generation and
Evaluation

• A design concept is an idea that is sufficiently
  developed that it can be evaluated in terms of
  physical realizability, i.e., the means of
  performing each major function has been
  determined
• The process that is applied in this chapter will
  result in the generation of multiple design
  concepts
• Then, with a set of design concepts we will
  subject them to an evaluation scheme to determine
  the best concept or small subset of best concepts
• Finally, a decision process will be used to
  decide on the best concept to develop into the
  final design

68
Dieter Chapter 5.2
-Creativity and Problem Solving

• Creative thinkers are distinguished by their
  ability to synthesize new combinations of ideas
  and concepts into meaningful and useful forms
• A characteristic of the creative process is that
  initially the idea is only imperfectly understood
• Usually the creative individual senses the total
  structure of the idea but initially perceives
  only a limited number of the details
• The creative process be viewed as moving from an
  amorphous idea to a well-structured idea, from
  the chaotic to the organized, from the implicit
  to the explicit
• Engineers, by nature and training, usually value
  order and explicit detail and abhor chaos and
  vague generality
• To achieve a truly creative solution to a problem
  a person must utilize two thinking styles
  vertical or convergent thinking and lateral or
  divergent thinking
• Vertical thinking is the type of analytical
  though process reinforced by most engineering
  courses where one moves forward in sequential
  steps after a positive decision has been made
  about the idea
• In lateral thinking your mind moves in may
  different directions, combining different pieces
  of information into new patterns (synthesis)
  until several solution concepts appear

69
Dieter Chapter 5.3 -Creativity Methods5.4
Creative Idea Evaluation

• Mental Blocks Perceptual blocks, Emotional
  blocks, Cultural blocks, Environmental blocks,
  Intellectual blocks
• Brainstorming Carefully define the problem at
  the start Allow 5 minutes for each individual to
  think the problem on their own before starting
  the group process SCAMPER checklist to aid in
  brainstorming
• Synectics technique for creative thinking which
  draws on analogical thinking Direct analogies,
  Personal analogies, Symbolic analogies, Fantasy
  analogies
• Force-Fitting Methods SCAMPER is one of most
  widely used methods
• Mind Map Concept map

70
Dieter Chapter 5.5 Theory of Inventive Problem
Solving (TRIZ)

• Developed in Russia, starting around 1946,
  Genrich Altshuller,etc. Studied over 1.5 million
  patents
• They organized the problem solutions from the
  patent literature into five levels
• Level 1 Routine design solutions (30)
• Level 2 Minor corrections to an existing system
  (45)
• Level 3 Fundamental improvements which resolve
  contradiction (20) This is where creative
  design solutions would appear
• Level 4 Solutions based on appln of new
  scientific principle to perform the primary
  functions of the design (4)
• Level 5 Pioneering inventions based on rare
  scientific discovery (lt1)

71
Dieter Chapter 5.6 Conceptual Decomposition

• Two chief approaches to conceptual decomposition
• Decomposition in the physical domain
• Decomposition in the functional domain the
  great advantage of functional decompostion is
  that the method facilitates the examination of
  options that most likely would not have been
  considered
• Decomposition in the Physical Domain an
  important emerging design consideration is
  product architecture scheme by which the
  functional elements of the product are arranged
  into physical building blocks
• Functional Decomposition systems functions are
  described as a transformation between an initial
  state and a desired final state originated with
  the German school of design methodology

72
Dieter Chapter 5.7 Generating Design Concepts

• Concept Development
• Morphological Chart
• Combining Concepts

73
Dieter Chapter 5.8 Axiomatic Design

• Axiom 1 The independence axiom
• Maintain the independence of functional
  requirements (FRs)
• Axiom 2 The information axiom
• Minimize the information content

74
Dieter Chapter 6Embodiment (Preliminary) Design

• Many U.S. writers divide the design process into
  3 phases
• Conceptual Design
• Preliminary (Embodiment) Design
• Detail Design
• Others call embodiment design analytical design
  because it is the design phase where most of the
  detailed analysis and calculation occurs
• Dieter adopts the terminology conceptual design,
  embodiment design, and detail design because they
  seem to be more descriptive of what takes place
  in each of these design phases
• Moving the setting of dimensions and tolerances
  into embodiment design (from detail design) is in
  keeping with the current trend for utilizing CAE
  so as to move the decision making as early as
  possible in the desing process to compress the
  product development cycle

75
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Dieter Chapter 6

• Three different forms of design
• Routine design the attributes that define the
  design and the strategies and methods for
  attaining them are well known
• Innovative design not all attributes of the
  design may be known beforehand, but the knowledge
  base for creating the design is known
• Creative design neither the attributes of the
  design nor the strategies for achieving them are
  known ahead of time
• The Conceptual design phase is most central to
  innovative design
• At the opposite pole is selection design or
  catalog design, which is more central to routine
  design

77
Dieter Chapter 6Product Architecture

• Product architecture is the arrangement of the
  physical elements of a product to carry out its
  required functions
• It is in the Embodiment design phase that the
  layout and architecture of the product must be
  established by defining what the basic building
  blocks of the product should be in terms of what
  they do and what their interfaces will be between
  each other. Some organizations refer to this as
  system-level design
• There are two entirely opposite styles of product
  architecture, modular and integral
• Modular components (chunks) implement only one
  or a few functions and the interactions are well
  defined
• Integral implementation of functions uses only
  one or a few components (chunks) leading to
  poorly defined interactions between components
  (chunks)
• In integral product achitectures components
  perform multiple functions
• Products designed with high performance as a
  paramount attribute often have an integral
  architecture

78
Dieter Chapter 6Product Architecture

• A modular design makes it easier to evolve the
  design over time, to adapt it to the needs of
  different customers, to replenish components as
  they wear out or are used up, and to reuse the
  product at the end of its useful life by
  remanufacture
• Modular design may even be carried to the point
  of using the same component in multiple products,
  a product family
• Integral desing is often adopted when constraints
  of weight,k space, or cost require that
  performance be maximized
• There is a natural tension between component
  integration to minimize costs and product
  architecture
• The best approach is to consider integration of
  components only within a single chunk (set of
  components) of the product architecture
• Thus, the product architecture has strong
  implications for manufacturing costs
• A modular architecture tends to shorten the
  product development cycle becasuse module can be
  deveolped independently provided there is not
  coupling of functon betgween modules, and
  provided that interfaces are well laid out and
  understood

79
Dieter Chapter 6Product Architecture

• Four step process for establishing the product
  architecture
• Create a schematic diagram of the product (FFBD,
  Schematic Block Diagram)
• Cluster the elements of the schematic (DSM,
  DeMAID)
• Create a rough geometric layout (3-view drawing)
• Identify the fundamental and incidental
  interactions (Interrelationship Diagraph,
  Compatibility Matrix)
• SEE EXAMPLES FROM TEXT

80
Dieter Chapter 6Configuration Design

• In configuration design we establish the shape
  and general dimensions of components. Exact
  dimensions and tolerances are established in
  parametric design
• The term component is used in the generic sense
  to include special-purpose parts, standard parts,
  and standard assemblies or modules
• A part is a designed object that has no assembly
  operations in its manufacture
• A standard part is one that has a generic
  function and is manufactured routinely w/o regard
  to a particular product (bolts, washers, etc.)
• A special-purpose part is designed and
  manufactured for a specific purpose in a specific
  product line
• An assembly is a collection of two or more parts
• A subassembly is an assembly that is included
  within another assembly or subassembly
• A standard assembly or standard module is an
  assembly or subassembly which has a generic
  function and is manufactured routinely (electric
  motors, pumps, etc.)

81
Dieter Chapter 6Configuration Design

• Steps in starting Configuration design
• Review the PDS
• Establish the spatial constraints that pertain to
  th product or the subassembly being designed.
  Most have been set by the product architecture
• Create and refine the interfaces or connections
  between components
• Maintain functional independence in the design of
  an assembly or component
• Answer the following questions
• Can the part be eliminated or combine with
  another part?
• Can a standard part or module be used
• Generally, the best way to get started with
  configuration design is to just start sketching
  alternative configurations of a part

82
Dieter Chapter 6Parametric Design

• In configuration design the emphasis was on
  starting with the product architecture and then
  working out the best form for each component
• In parametric design the attributes of parts
  identified in configuration design become the
  design variables for parametric design
• A design variable is an attribute of a part whose
  value is under the control of the designer
• Robustness means achieving excellent performance
  under the wide range of conditions that will be
  found in service

83
Dieter Chapter 6Parametric Design

• Read Table 6.2 Questions for revealing part
  configuration design risks
• Failure Modes and Effects Analysis (FMEA)
• Design for Reliability
• Robust Design
• Tolerances
• Design Guidelines for Best Practices

84
Dieter Chapter 7Modeling and Simulation

• The Role of Models in Engineering Design
• Descriptive model
• Predictive model
• Static or dynamic
• Deterministic or probabilistic
• Iconic-analog-symbolic
• Simulation
• The Prototype

85
Dieter Chapter 7Modeling and Simulation

• Mathematical Modeling
• The components of a system are represented by
  idealized elements that have the essential
  characteristics of the real components and whose
  behavior can be described by mathematical
  equations
• Techniques for treating large and complex systems
  by isolating the critical components and modeling
  them are at the heart of the growing discipline
  called systems engineering
• Important simplification results when the
  distributed properties of physical quantities are
  replaced by their lumped equivalents.
• A system is said to have lumped parameters if it
  can be analyzed in terms of the behavior of the
  endpoints of a finite number of discrete elements
• Once the chief components of the system have been
  identified, the next step is to list the
  important physical and chemical quantities that
  describe and determine the behavior of the system

86
Dieter Chapter 7Modeling and Simulation

• Dimensional Analysis
• Buckingham Pi Theorem
• Similitude and Scale Models
• Scale models
• Geometric similarity
• Model dimension scale factor x prototype
  dimension
• Static similarity-same portion as geometric dim
  under cons. stress
• Kinematic similarity- ratio of time
  proportionality
• Dynamic similarity- fixed ratio of forces

87
Dieter Chapter 7Modeling and Simulation

• Simulation
• Finite-Difference Method
• A method of approximate solution of partial
  differential equations
• Monte Carlo Method
• A way of generating information for a simulation
  when events occur in a random way
• Geometric Modeling on the Computer
• From it initiation,CAD has promised 5 important
  benefits to the engineering design process
• Automation of routine design tasks
• Ability to design in 3D
• Design by Solid Modeling
• Electronic transfer of the design db to manuf
  (CAD/CAM)
• A paperless design process

88
Dieter Chapter 7Modeling and Simulation

• Surface Modeling
• Methods of Generating Solids
• Constraint-Based Modeler and Features
• Finite-Element Analysis
• Types of Elements
• Steps in the FEA Process
• Preprocessing Geometry, Matl constit reln, FE
  mesh, Bndy Conds
• Postprocessing Data interpret., Error estim.,
  Design optim

89
Dieter Chapter 7Modeling and Simulation

• Computer Visualization
• Dynamic Analysis
• Interactive Product Simulation
• Rapid Prototyping

90
Dieter Chapter 8Materials Selection and
Materials in Design

• The selection of the correct materials for a
  design is a key step in the process because it is
  the crucial decision that links computer
  calculations and lines on an engineering drawing
  with a working design
• Materials, and the manufacturing processes which
  convert the material into a useful part, underpin
  all engineering design
• The adoption of concurrent engineering methods
  has brought materials engineers into the design
  process at an earlier stage, and the importance
  given to manufacturing in present day product
  design has reinforced the fact that materials and
  manufacturing are closely linked in determining
  final product performance
• The extensive activity in materials science
  worldwide has created a variety of new materials
  and focused our attention on the competition
  between six broad classes of materials metals,
  polymers, elastomers, ceramics, glasses, and
  composites

91
Dieter Chapter 8Materials Selection and
Materials in Design

• Relation of Materials Selection to Design
• An incorrectly chosen material can lead not only
  to failure of the part but also to unnecessary
  life-cycle cost
• Selecting the best material for a part involves
  more than selecting a material that has the
  properties to provide the necessary performance
  in service it is also intimately connected with
  the processing of the material into the finished
  part (Fig. 8.1)
• As design proceeds from concept design, the
  material and process selection becomes more
  detailed
• Figure 8.2 compares the design methods and tools
  used at each design stage with the materials and
  processes selection
• Thus, material and process selection is a
  progressive process of narrowing from a large
  universe of possibilities to a specific material
  and process selection

92
Dieter Chapter 8Materials Selection and
Materials in Design

• General Criteria for Selection Materials are
  selected on the basis of four general criteria
• Performance characteristics (properties)
• Processing characteristics
• Environmental profile
• Business considerations
• The chief business consideration that affects
  materials selection is the cost of the part that
  is made from the material
• This considers both the purchase cost of the
  material and the cost to process it into a part.
  A more rational basis for selection is life cycle
  cost (LCC), which includes the cost of replacing
  failed parts and the cost of disposing of the
  material at the end of its useful life

93
Dieter Chapter 8Materials Selection and
Materials in Design

• Performance Characteristics of Materials
• The performance or functional requirements of
  material usually is expressed in terms of
  physical, mechanical, thermal, electrical, or
  chemical properties
• Material properties are the link between the
  basic structure and composition of the material
  and the service performance of the part (Figure
  8.3)
• We can divide structural engineering materials
  into metals, ceramics, and polymers Further
  division leads to the categories of elastomers,
  glasses, and composites Finally, there is the
  technology driving class of electronic, magnetic,
  and semiconductor materials
• The chief characteristics of metals, ceramics,
  and polymers are given in Table 8.1

94
Dieter Chapter 8Materials Selection and
Materials in Design

• Performance Characteristics of Materials
• The ultimate goal of materials science is to
  predict how to improve the properties of
  engineering materials by understanding how to
  control the various aspects of structure
• Figure 8.4 relates various dimensions of
  structure with typical structural elements
• The first task in materials selection is to
  determine which material properties are relevant
  to the situation
• Figure 8.5 shows the relations between some
  common failure modes and the mechanical
  properties most closely related to the failures
• The material properties usually are formalized
  through specifications Performance and Product
  specifications
• Table 8.2 provides a fairly complete listing of
  material performance characteristics
• Figure 8.6 illustrates the generic tree that is
  developed by expanding the category of fatigue
  properties

95
Dieter Chapter 8Materials Selection and
Materials in Design

• The Materials Selection Process
• The problem is not only often made difficult by
  insufficient or inaccurate property data but is
  typically one of decision making in the face of
  multiple constraints without a clear-cut
  objective function
• A problem of materials selection usually involves
  one of two different situations
• Selection of the materials for a new product or
  design
• Reevaluation of an existing product or design to
  reduce cost, increase reliability, improve
  performance, etc.
• It generally is not possible to realize the full
  potential of a new material unless the product is
  redesigned to exploit both the properties and the
  manufacturing characteristics of the material
• In other words, a simple substitution of a new
  material without changing the design rarely
  provides optimum utilization of the material

96
Dieter Chapter 8Materials Selection and
Materials in Design

• Materials selection for a new product or new
  design The steps that must be followed are
• Define the functions that the design must perform
• Define the manufacturing parameters
• Compare the needed properties and parameters with
  large database
• Investigate the candidate materials in more
  detail
• Develop design data and/or a design specification
• Materials substitution in an existing design
• Characterize the currently used material in terms
  of performance, manufacturing requirements, and
  cost
• Determine which characteristics must be improved
  for enhanced product function
• Search for alternative matls processing routes
• Compile a short list of matls processing routes
  and use these to estimate the costs of
  manufactured parts
• Evaluate the results of Step 4 make a
  recommendation for a replacement material

97
Dieter Chapter 8Materials Selection and
Materials in Design

• Design Process and Materials Selection
• There are two approaches to determing the
  material-process combination for a part
• Material first approach the designer begins by
  selecting a material class and narrowing it down
• Process first approach the designer begins by
  selecting the manufacturing process
• While materials selection issues arise at every
  stage in the design process, the opportunity for
  greatest innovation in materials selection occurs
  at the conceptual design stage
• Ashby Charts Figure 8.7a Youngs modulus vs
  density Figure 8.7b Strength vs density

98
Dieter Chapter 8Materials Selection and
Materials in Design

• Materials Selection in Embodiment (Preliminary)
  Design
• Detailed materials selection is typically carried
  out in the embodiment design phase using the
  process illustrated in Fig. 8.8
• When the material process selection is deemed
  adequate for the requirements, the process passes
  to a detailed specification of the material and
  the design
• Once the component goes into production, the
  early runs will be used to fine tune the
  manufacturing process and to gauge the market
  receptivity to the product

99
Dieter Chapter 8Materials Selection and
Materials in Design

• Sources of Information on Materials Properties
• The purpose of this section is to provide a guide
  to material property data that are readily
  available in the published technical literature
• Scatter or variability of material property
  results is considerable, however, it is rare to
  find a property data presented in a proper
  statistical manner by a mean value and the
  standard deviation (See Chap. 10)
• Obviously, for critical applications in which
  reliability is of great importance, it is
  necessary to determine the frequency distribution
  of both the material property and the parameter
  that describes the service behavior
• Figure 8.9 shows that when the two frequency
  distributions overlap, there will be a
  statistically predictable number of failures

100
Dieter Chapter 8Materials Selection and
Materials in Design

• Sources of Information on Materials Properties
• Conceptual Design
• Typical material selection references, such as
  Ashby scheme
• Embodiment (Preliminary) Design
• Design decisions are being made on the layout and
  size of parts and components
• Design calculations require materials properties
  for a narrower class of materials but specific to
  a particular heat treatment or manufacturing
  process
• These data are typically found in handbooks and
  computer dbs.
• Detail Design
• Very precise data is required
• This goes beyond just material properties to
  include information on manufacturability, cost,
  the experience in other applns, avail in the
  sizes and forms needed, and issues of repeat. of
  properties QA
• Two often overlooked factors are whether the
  manufacturing process will produce different
  properties in different directions in the part,
  and whether the part will contain a detrimental
  state of residual stress after manufacture

101
Dieter Chapter 8Materials Selection and
Materials in Design

• Economics of Materials
• Ultimately the decision on a particular design
  will come down to a trade-off between performance
  and cost
• Where performance doesnt dominate the
  manufacturer must provide a value to cost ratio
  that is no worse, and preferably better,
• than the competition
• By value we mean the extent to which the
  performance criteria appropriate to the
  application are satisfied. Cost is what must be
  paid to achieve that level of value
• Because cost is such an overpowering
  consideration in material selection we need to
  give this factor additional attention
• Scarcity - Cost amount of energy required to
  process
• Basic supply demand for the material
• Increases in properties, like yield strength,
  beyond those of the basic material are produced
  by changes in structure brought about by
  compositional changes and additional processing
  steps

102
Dieter Chapter 8Materials Selection and
Materials in Design

• Methods of Materials Selection
• There is no method or small number of methods of
  materials selection that has evolved to a
  position of prominence
• Since the final choice is a trade-off between
  cost and performance (properties), it is logical
  to attempt to express that relation as carefully
  as possible
• Figure 8.10 shows the costs of substituting
  lightweight magterials to achieve weight saving
  (fuel economy) in automobiles
• It is important to realize that the cost of a
  material expressed in dollars per pound may not
  always be the most valid criterion
• Total LLC is the most appropriate cost to
  consider
• Consideration of factors beyond just the initial
  materials cost leads to relations like the
  relation shown in Figure 8.11
• A classic situation regarding cost is the choice
  between two or more materials with different
  initial costs and different expected lives. This
  is a standard problem in the field of engineering
  economy (See Chap. 13)

103
Dieter Chapter 8Materials Selection and
Materials in Design

• Selection with Computer-Aided Databases
• Use of a Merit Factor approach similar to an OEC
• Material Performance Indices
• A materials performance index is a group of
  material properties which governs some aspect of
  the performance of a component
• Decision Matrices
• Pugh Selection Method
• Weighted Property Index
• Materials Selection by Expert Systems
• Value Analysis

104
Dieter Chapter 8Materials Selection and
Materials in Design

• Design for Brittle Fracture An important advance
  in engineering knowledge has been the ability to
  predict the influence of cracks and crack-like
  defects on the brittle fracture of materials
  through the science of fracture mechanics
• Design for Fatigue Failure Materials subjected
  to a repetitive or fluctuating stress will fail
  at a stress much lower than required to cause
  fracture on a single application of load
• Infinite-life design
• Safe-life design
• Fail-safe design
• Damage-tolerance design
• Design for Corrosion Resistance
• Designing with Plastics
• Designing with Brittle Materials

105
Dieter Chapter 9Materials Processing and Design

• Role of Processing in Design
• Producing the design is a critical link in the
  chain of events that starts with a creative idea
  and ends with a successful product in the
  marketplace
• A serious problem has been the tendency