Engineering Design Systems Engineering
Lecture 02 Engineering Design and Systems Engineering Through the Lens of Decision Making
Jitesh H. Panchal
ME 597: Decision Making for Engineering Systems Design
Design Engineering Lab @ Purdue (DELP) School of Mechanical Engineering Purdue University, West Lafayette, IN http://engineering.purdue.edu/delp
August 27, 2019
ME 597: Fall 2019 Lecture 02 1 / 46 Engineering Design Systems Engineering Objectives for Today
1 To provide an overview of the engineering design and systems engineering processes. 2 To identify the decisions made within systematic engineering design processes. 3 To understand the nature of design decisions.
ME 597: Fall 2019 Lecture 02 2 / 46 Engineering Design Systems Engineering Recall: Basic Elements of a Decision
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Decision A2 O22 U(O22) Select Ai
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An On2 U(On2)
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Alternatives Outcomes Preferences Choice
ME 597: Fall 2019 Lecture 02 3 / 46 Engineering Design Systems Engineering Example: A Lottery
Cost: $2 Odds of winning the jackpot: 1 in 259 Million!
What are the alternatives? outcomes? preferences? information? choice?
ME 597: Fall 2019 Lecture 02 4 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Design as Decision Making
Let us start with a simple decision-based view of design.
??? Design = Choosing the best alternative (solution) ???
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A1 O12 U(O12)
p1k O1k U(O1k)
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Decision A2 O22 U(O22) Select Ai
p1k O2k U(O2k)
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An On2 U(On2)
pnk Onk U(Onk)
Alternatives Outcomes Preferences Choice
Is this an accurate (complete) view of design? Why / Why Not? ......
ME 597: Fall 2019 Lecture 02 5 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Design as a Decision-making Process
Is this an accurate (complete) view of design? Why / Why Not?
Design is typically not a single decision. It is a network of decisions. Outcomes are only clear at the end of the process. Not all alternatives are available. Need to generate alternatives. Not all information is available. Need to generate information. Not all information about preferences is directly available. Need to understand preferences (gradually). Resources are always limited. There may be multiple decision makers involved in the design process. ...
Design methods provide guidance in navigating these decisions.
ME 597: Fall 2019 Lecture 02 6 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach The Process of Design Thinking
Design thinking is a process by which designers approach problem solving.
Image Source: https://i.pinimg.com/originals/bb/19/c2bb19c2522081dad7f682c10d99a07903.jpg ME 597: Fall 2019 Lecture 02 7 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach (Some) Principles of Design Thinking
Empathize and understand what users need; Find the latent needs Prototype early, and prototype often Work quickly: do not wait for the final design Test ASAP; Launch Beta Iterate, Iterate, Iterate
“Fail fast to succeed sooner” - David Kelley
ME 597: Fall 2019 Lecture 02 8 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach A systematic engineering design process
Consider an example of a systematic design process.
ME 597: Fall 2019 Lecture 02 9 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach The Pahl and Beitz Systematic Design Method
Phase 0 - Start Customer Clarification of Task Specification Conceptual Design Concept
Embodiment Design Preliminary Layout Upgrade and Improve
Definitive Layout Detail Design Documentation Solution
ME 597: Fall 2019 Lecture 02 10 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Phase 1: Clarifying the Task
An engineer’s first problem in any design situation is to discover what the problem really is. What objectives must the intended solution satisfy? What properties must it have? What properties must it not have?
Task
Analyze market / company Find and select product ideas Formulate a product proposal Phase 1 Phase Product Planning Product Clarifying the Task Proposal
Clarify the task Elaborate a requirements list
Specification
ME 597: Fall 2019 Lecture 02 11 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Need for Planning and Clarification of Task
what the what marketing what engineering customer said understood designed
what manufacturing how customer service what the customer realized solved the problem really wanted
ME 597: Fall 2019 Lecture 02 12 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Clarification of Task
What is the problem really about? What implicit wishes and expectations are involved? Do the specified constraints actually exist? Avoid fixed solution ideas / solution-specific considerations fictional constraints and concrete implications
The outcome is a requirements list.
ME 597: Fall 2019 Lecture 02 13 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Example Requirements List
Requirements List for Water-Dispensing Device Page: 1 Problem Statement: Schematic:
Develop a device that, upon demand, conveniently provides cool, clean water for human consumption. The device must fit in a particular building space (see schematic) and function appropriately in an office environment.
D Changes Responsibility W Requirements 1. Water Characteristics Design Team Members D Flow rate should be < 35 mL/s D Flow velocity should be 20 - 40 cm/s * Modified D Water temperature (dispensed) should be 5 - 8 ºC 8/2/00 D Water quality (dispensed) must meet EPA guidelines, e.g., Contaminant Threshold Arsenic < 0.05 mg/L Fluoride < 4.0 mg/L Lead < 0.015 mg/L Copper < 1.3 mg/L Mercury < 0.002 mg/L as specified in Safe Drinking Water Act (1996)
ME 597: Fall 2019 Lecture 02 14 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Example Requirements List (cont.)
Requirements List for Water-Dispensing Device Page: 2 D Changes Responsibility W Requirements * Adjusted 2. Ergonomics Design Team 8/2/00 Members D Must be easy to use D Must be accessible to all (esp. those in wheelchairs) D Must be attractive W Should be free of splattering D Must be safe D Must be quiet W Must remain sanitary
3. Cost
D Total cost (installed) < $450 US * Added D Operating cost < $200 per year 8/2/00 4. Production, Installation, & Maintenance
D Must be manufactured from standard parts/assemblies W Should be installed < 35 minutes by 2 skilled laborers D Must be easily maintained over 12 week service intervals
ME 597: Fall 2019 Lecture 02 15 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Outcome of the Clarification of Task Phase
A decision to proceed to Phase 2 is predicated on answers in the affirmative to the following questions: Has the task been clarified sufficiently to allow development of a solution in the form of a design? Must further information about the task be acquired?
ME 597: Fall 2019 Lecture 02 16 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach What is the nature of these decisions?
O U(O ) p11 11 11
A1 O12 U(O12)
p1k O1k U(O1k)
O U(O ) p21 21 21
Decision A2 O22 U(O22) Select Ai
p1k O2k U(O2k)
pn1 On1 U(On1)
An On2 U(On2)
pnk Onk U(Onk)
Alternatives Outcomes Preferences Choice
ME 597: Fall 2019 Lecture 02 17 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Phase 2: Conceptual Design
Specification
Abstract to identify essential problems In conceptual design the basic Establish function structures solution path is laid down in the form of a solution principle, through the Search for working principles following steps:
1 identification of the essential Combine working principles into problems through abstraction, working structures 2 establishment of function structures, and Select suitable combinations 3 search for appropriate working Firm up into principle solution variants principles and their combination.
Evaluate against technical and economic criteria
Concept
ME 597: Fall 2019 Lecture 02 18 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Abstraction of Requirements
Abstraction is ignoring what is particular or incidental and emphasizing what is general, and identifying fictitious constraints and eliminating all but genuine restrictions.
Steps in abstraction:
1 Eliminate personal preferences from the requirements list. 2 Consider only requirements that affect function and essential constraints. 3 Transform quantitative into qualitative data, reducing them to essential ideas. 4 Broaden essential ideas systematically (generalize). 5 Formulate the design problem in solution-neutral terms.
ME 597: Fall 2019 Lecture 02 19 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Abstraction: Example of Motor Vehicle Fuel Gauge
Eliminate personal preferences.
Consider only requirements that affect function and essential constraints
Transform quantitative into qualitative data
Broaden essential ideas systematically
Formulate in solution- neutral terms as an overall function
ME 597: Fall 2019 Lecture 02 20 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Phase 2: Function Structures
A function specifies the relationship between inputs and outputs in terms of energy, material (matter), signal (information).
ME 597: Fall 2019 Lecture 02 21 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Function Structure – Example
Develop a device that, upon demand, conveniently provides cool, clean water for human consumption.
Deliver Dispose Purify Cool Water Water Water Water
Deliver Control Hold Dispense Water Delivery Liquid Liquid
Function structures allow clear definition of existing or necessary subsystems so that they can be dealt with separately (reducing complexity!).
ME 597: Fall 2019 Lecture 02 22 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Search for Solution Principles
Solution (working) principles represent a physical effect and preliminary embodiment (e.g., “cartoon” sketch). Use ideation techniques, searches, and analysis of known or existing systems to determine solution principles. For each subfunction, identify as many working principles as possible.
Morphological matrix:
Principal Solution Alternatives
Sub-Functions
Store Energy
Force Cycle Oscillating crystal
Change Signal Meter Electrical motor Stroke magnet
Display Time
ME 597: Fall 2019 Lecture 02 23 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Combine Solution Principles into Working Structures
Select a working structure.
ME 597: Fall 2019 Lecture 02 24 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach What is the nature of concept selection decisions?
O U(O ) p11 11 11
A1 O12 U(O12)
p1k O1k U(O1k)
O U(O ) p21 21 21
Decision A2 O22 U(O22) Select Ai
p1k O2k U(O2k)
pn1 On1 U(On1)
An On2 U(On2)
pnk Onk U(Onk)
Alternatives Outcomes Preferences Choice
ME 597: Fall 2019 Lecture 02 25 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Phase 3: Embodiment Design
Concept
Develop preliminary layouts and form Complexity!! Many simultaneous, designs interdependent activities! Select best preliminary layouts Analysis and synthesis alternate
Refine and evaluate against technical and complement each other! and economic criteria Optimization and error ID +
Preliminary Layout solution search and evaluation. Proceed from qualitative to Eliminate weak spots quantitative, from abstract to Check for errors & cost effectiveness concrete, from rough to detailed, with provisions for checks and Prepare preliminary parts list and production documents corrections (i.e., iterations!).
Definitive Layout
Outcome of Phase 3 A definitive layout for which production documents can be prepared with minimal detail design.
ME 597: Fall 2019 Lecture 02 26 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Examples of Preliminary and Definitive Layout
Principal Preliminary Definite Solution layout layout
8 working elements 50 working elements 280 working elements 20 form elements (0.04%) 2000 form elements (4%) 50000 form elements (100%) Adapted from Prof. H. Birkhofer’s lecture “Produktentwicklung”, TU-Darmstadt, 2004.
ME 597: Fall 2019 Lecture 02 27 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach What is the nature of these decisions?
O U(O ) p11 11 11
A1 O12 U(O12)
p1k O1k U(O1k)
O U(O ) p21 21 21
Decision A2 O22 U(O22) Select Ai
p1k O2k U(O2k)
pn1 On1 U(On1)
An On2 U(On2)
pnk Onk U(Onk)
Alternatives Outcomes Preferences Choice
ME 597: Fall 2019 Lecture 02 28 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach Phase 4: Detail Design
Finalize detailed drawings of Definitive Layout components, detailed optimization of shapes, materials, Finalize details surfaces, tolerances and fits. Complete all documents Integrate individual components into assemblies and assemblies Check all documents into overall product. Include assembly drawings, part lists. Documentation Complete production documents
Solution (manufacturing, assembly, transport, operating instructions).
Outcome of Phase 4 Final production documents (tolerances, assembly processes, materials, tooling, etc.)
ME 597: Fall 2019 Lecture 02 29 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach What is the nature of these decisions?
O U(O ) p11 11 11
A1 O12 U(O12)
p1k O1k U(O1k)
O U(O ) p21 21 21
Decision A2 O22 U(O22) Select Ai
p1k O2k U(O2k)
pn1 On1 U(On1)
An On2 U(On2)
pnk Onk U(Onk)
Alternatives Outcomes Preferences Choice
ME 597: Fall 2019 Lecture 02 30 / 46 Engineering Design a. Pahl and Beitz Systematic Design Method Systems Engineering b. Four Phases of Pahl and Beitz Approach In Summary: Nature of Engineering Design Decisions
ME 597: Fall 2019 Lecture 02 31 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Systems and Systems Engineering
System a collection of hardware, software, people, facilities, and procedures organized to accomplish some common objectives. a collection of components organized to accomplish a specific function or set of functions. (IEEE STD 610.12)
Systems Engineering An interdisciplinary approach and means to enable the realization of successful systems. (INCOSE, 1999) The application of the system analysis and design process and the integration and verification process to the logical sequence of the technical aspect of the product life cycle. (Forsberg and Mooz, 1992)
ME 597: Fall 2019 Lecture 02 32 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Example of a Human Designed System
Subject of Command, Control Study and Communications Orbit and Constellation
Mission Operations Payload
Spacecraft Ground Element Bus Launch Element
(Adapted from Wertz and Larson, 1999)
ME 597: Fall 2019 Lecture 02 33 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Systems Engineering goes Beyond the Product
System Organization
Cabling Loft Production
Service Electronics MANUFACTURE CONTROL Armament GROUP GROUP Hydraulics
PAYLOAD PROPULSION GROUP GROUP Engine Fuselage STRUCTURE AERO GROUP GROUP Streamline Equipment Empennage Weight Stress Wings
Hierarchy is an effective way of managing complexity! The driving principle is near-decomposability (Simon, 1961).
ME 597: Fall 2019 Lecture 02 34 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes The VEE model of Systems Engineering
Understand User Demonstrate and Requirements, Develop Validate System to System Concept and User Validation Plan Validation Plan
Develop System Integrate System and Perform Performance Specification System Verification to and System Validation Plan Performance Specifications
Expand Performance Assemble CIs and Specifications into CI Perform CI Verification “Design-to” Specs and CI to CI “Design-to” Decomposition Verification Plan Specifications and Definition Systems Engineers Domain Engineers
Evolve “Design-to” IntegrationQualification and Specifications into “Build- Inspect to to” Documentation and “Build-to” Inspection Plan Documentation
Fab, Assemble and Code to Time “Build-to” Documentation
ME 597: Fall 2019 Lecture 02 35 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Examples of Decisions in Systems Engineering (1)
Development Examples of Decisions in Systems Engineering Phase 1. Conceptual * Should a conceptual design effort be undertaken? Design * Which system concept (usually a mixture of technolo- gies) should be the basis of the design? * Which technology for a given subsystem should be cho- sen? * What existing hardware and software can be used? * Is the envisioned concept technically feasible, based on cost, schedule and performance requirements? * Should additional research be conducted before a deci- sion is made?
Buede, D.M, 2009, The Engineering Design of Systems: Models and Methods, Wiley. ME 597: Fall 2019 Lecture 02 36 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Examples of Decisions in Systems Engineering (2)
Development Examples of Decisions in Systems Engineering Phase 2. Preliminary * Should a preliminary design effort be undertaken? design * Which specific physical architecture should be chosen from several alternatives? * To which physical resource should a particular function be allocated? * Should a prototype be developed? If so, to what level of reality? * How should validation and acceptance testing be struc- tured?
Buede, D.M, 2009, The Engineering Design of Systems: Models and Methods, Wiley. ME 597: Fall 2019 Lecture 02 37 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Examples of Decisions in Systems Engineering (3)
Development Examples of Decisions in Systems Engineering Phase 3. Full-scale * Should a full-scale design effort be undertaken? design * Which configuration items should be bought instead of manufactured? * Which detailed design should be chosen for a specific component given that one or more performance require- ments are critical?
Buede, D.M, 2009, The Engineering Design of Systems: Models and Methods, Wiley. ME 597: Fall 2019 Lecture 02 38 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Examples of Decisions in Systems Engineering (4)
Development Examples of Decisions in Systems Engineering Phase 4. Integration * What is the most cost-effective schedule for implemen- and qualifica- tation activities? tion * What issues should be tested? * What equipment, people, facilities should be used to test each issue? * What models of the system should be developed or adapted to enhance the effectiveness of integration? * How much testing should be devoted to each issue? * What adaptive (fallback testing in case of a failure) test- ing should be planned for each issue?
Buede, D.M, 2009, The Engineering Design of Systems: Models and Methods, Wiley. ME 597: Fall 2019 Lecture 02 39 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Examples of Decisions in Systems Engineering (5)
Development Examples of Decisions in Systems Engineering Phase 5. Product * Should a product improvement be introduced at this Refinement time? * Which technology or technologies should be the basis of the product improvement? * What redesign is best to meet some clearly defined de- ficiency in the system? * How should the refinement of existing systems be imple- mented given safety, performance and cost criteria?
Buede, D.M, 2009, The Engineering Design of Systems: Models and Methods, Wiley. ME 597: Fall 2019 Lecture 02 40 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Hierarchy of Objectives
Start with the fundamental objective (e.g., maximize safety) . . . objectives that are important to the system’s stakeholders in a value sense, i.e., the stakeholders would be willing to pay for improved performance.
The fundamental objective can be subdivided into value objectives that more meaningfully define the fundamental objective, thereby forming a fundamental objectives hierarchy or value structure.
Maximize Safety
Minimize Minimize Minimize Loss of Life Serious Injuries Minor Injuries
Adults Children Adults Children
ME 597: Fall 2019 Lecture 02 41 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Example of Objectives Hierarchy with Value Curves
ME 597: Fall 2019 Lecture 02 42 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Issues in Systems Engineering
Multi-disciplinary teams: Different disciplines must work together in an integrated manner. Distributed enterprises: need to understand interdependencies in the process. Processes, methods, and tools in the process are highly integrated. Over-the-wall method is no longer efficient. Engineering decisions must be based on an evaluation of the behavior of product when it is used in the holistic environment (hardware, software, people, production, installation, transportation, maintenance, recycling, etc.)
P. Wiese and P. John, 2003, Engineering Design in the Multi-Discipline Era. A Systems Approach, Professional Engineering Publishers. ME 597: Fall 2019 Lecture 02 43 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Interactions Among Design Teams
V-8 Engine Design
ME 597: Fall 2019 Lecture 02 44 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes Summary
Objectives for Today: 1 To provide an overview of the engineering design and systems engineering processes. 2 To identify the decisions made within systematic engineering design processes. 3 To understand the nature of design decisions.
ME 597: Fall 2019 Lecture 02 45 / 46 Engineering Design a. What is Systems Engineering? Systems Engineering b. Systems Engineering Processes References
G. Pahl, W. Beitz, J. Feldhusen, K.H. Grote, 2007, Engineering Design: A Systematic Approach, 3rd Edition, Springer London. P. Wiese and P. John, 2003, Engineering Design in the Multi-Discipline Era. A Systems Approach, Professional Engineering Publishers, 2003. D.M. Buede, 2000, The Engineering Design of Systems: Models and Methods, John Wiley & Sons. C. Paredis, “Systems Engineering”, ME8813: Modeling and Simulation in Designs, Lecture 2 Notes, Spring 2004, Georgia Tech, Atlanta F. Mistree, W. F. Smith, et al., 1990, “Decision-Based Design: A Contemporary Paradigm for Ship Design.” Transactions, Society of Naval Architects and Marine Engineers 98: 565-597.
ME 597: Fall 2019 Lecture 02 46 / 46