16.810 (16.682)
16.810 (16.682)
Engineering Design and Rapid Prototyping
Lecture 1
Course Introduction
Instructor(s)
Prof. Olivier de Weck Dr. Il Yong Kim
January 5, 2004
Happy New Year 2004
Mars Rovers MER-A “Spirit”
Body Structure (Warm Electronics
landed Sat 1/3 11:35pm ET
Box WEB). Ref: http://marsrovers.jpl.nasa.gov
We won’t be designing a Mars Rover this IAP, but ...
You will learn about the design process and fundamental
building blocks of any complex (aerospace) system
16.810 (16.682) 2
(Image is taken from NASA's Web site: http://www.nasa.gov.)
Outline
? Organization of 16.810
? Motivation, Learning Objectives, Activities
? (Re-) Introduction to Design
? Examples, Requirements, Design Processes
(Waterfall vs. Spiral), Basic Steps
? “Design Challenge” - Team Assignment
? Int’l Bicycle Corp., Requirement Sheets,
Product Team Assignments
? Facilities Tour
16.810 (16.682) 3
Organization of 16.810
(16.682)
16.810 (16.682) 4
Expectations
? 6 unit course (3-3-0) – 11 sessions
? MWF1-4, must attend all sessions
or get permission of instructors to be absent
? This is for-credit, no formal “problem sets”,
but expect a set of deliverables
? Have fun, but also take it seriously
? The course is a “prototype” itself and we are
hoping for your feedback & contributions
? Officially register under 16.682 (Jan 2004) on
WEBSIS
16.810 (16.682) 5
History of this Course
December 2002 Undergraduate Survey in Aero/Astro Department.
Students expressed wish for CAD/CAE/CAM experience.
March 2003 Preliminary discussion among faculty and staff –
O. de Weck, I.Y. Kim, D. Wallace, P. Young
April 4, 2003 Submission of proposal to Teaching and Education
Enhancement Program (“MIT Class Funds")
April 22, 2003 Submission of the proposal to CMI (pending)
May 6, 2003 Award Letter received from Dean for Undergraduate
Education ($17.5k)
June 5, 2003 Kickoff Meeting
Sept 18, 2003 Approved by the AA undergraduate committee (6 units)
Fall 2003 Preparation
Jan 5, 2004 First Class
16.810 (16.682) 6
Needs – from students
A 2001 survey of undergraduate students
(Aero/Astro) – in conjunction with new Dept. head
search
- There is a perceived lack of understanding and training in
modern design methods using state-of-the-art CAD/CAE/CAM
technology and design optimization.
- Individual students have suggested the addition of a short and
intense course of rapid prototyping, combined with design
optimization.
16.810 (16.682) 7
Needs – from industry
Industry wants/needs (dWo interpretation)
Engineers who
- are trained in integrated design methods and tools
- have personally carried out the design process from
conception to implementation at least once.
Engineers who have an initial understanding of:
- importance of requirements
- complementary roles of humans and computers in design
- difficulties at the CAD/CAE/CAM domain interfaces
- value of optimization
- importance of trading off competing objectives
- difference between predicted vs actual behavior of the artifacts
they design
16.810 (16.682) 8
the SCIENTIST / MATHEMATICIANCIAN
vs
the ENGINEER
CONFOUNDING FACTS
? Engineering requires thorough mathematical & scientific knowledge
? Engineers study science and math extensively
? Engineers may conduct scientific experiments while doing Engineering
? Scientists use engineering methods
? Some great engineers trained as scientists & mathematicians
? Some great scientists trained as engineers
? All require intensity, passion, creativity & intellectual effort
BUT, THEY ARE DISTINCT
“The scientist seeks to understand what is; the engineer seeks to
create what never was” -Von Karman
Courtesy of Prof. Chris Magee. Used with permission.
16.810 (16.682) 9
An engineer should be able to ...
? Determine quickly how things work
? Determine what customers want
? Create a concept
? Use abstractions/math models to improve a concept
? Build or create a prototypeprototy version
? Quantitatively and robustly test a prototype to improve
concept and to predict
? Determine whether customer value and enterprise
value are aligned (business sense)
? Communicate all of the above to various audiences
? Much of this requires “domain-specific knowledge” and experience
? Several require systems thinking and statistical thinking
? All require teamwork, leadership, and societal awareness
Courtesy of Prof. Chris Magee. Used with permission.
16.810 (16.682) 10
Boeing List of “Desired Attributes of an Engineer”
? A good understanding of
? Good communication skills
engineering science
? Written
fundamentals
? Oral
? Graphic
? Mathematics (including statistics)
? Listening
? Physical and life sciences
? Information technology (far more than
? High ethical standards
“computer literacy”)
? An ability to think both critically
? A good understanding of design and creatively - independently
and manufacturing processes (i.e. and cooperatively
understands engineering)
? Flexibility. The ability and self-
? A multi-disciplinary, systems
confidence to adapt to rapid or
perspective
major change
? A basic understanding of the
? Curiosity and a desire to learn for
context in which engineering is
life
practiced
? A profound understanding of the
? Economics (including business
importance of teamwork.
practice)
? History
? The environment
? Customer and societal needs
16.810 (16.682)
? This is a list, begun in 1994, of basic durable attributes
into which can be mapped specific skills reflecting the
diversity of the overall engineering environment in which
we in professional practice operate.
? This current version of the list can be viewed on the Boeing
web site as a basic message to those seeking advice from
the company on the topic. Its contents are also included
for the most part in ABET EC 2000.
11
Leads to Course Objective
Develop a holistic view and initial
competency in engineering design by
applying a combination of human creativity
and modern computational tools to the
synthesis of a single structural component
16.810 (16.682) 12
Mind Map
“
16.810
design, manufacturing,
Holistic View” - of the
“Competency” - can not
whole. Think about:
only talk about it or
- requirements,
do calculations, but
actually carry out the
testing, cost ...
process end-to-end
“Engineering Design”
- what you will likely
do after MIT
“Rapid Prototyping” -
a hot concept in
industry today.
“Human Creativity and
“Structural Components”:
Computational Tools”:
part of all aerospace systems,
design is a constant inter-
“easy” to implement in a
play of synthesis and analysis
short time
16.810 (16.682) 13
Course Concept
16.810 (16.682) 14
Course Flow Diagram
//
“Training”
Produce Part 1
Produce Part 2
Optimization
CAD CAM CAE Intro
FEM/Solid Mechanics
Overview
Manufacturing
Training
Structural Test
Design Optimization
Hand sketching
CAD design
FEM analysis
Test
Problem statement
Test
Learning/Review Deliverables
Design Sketch v1
Analysis output v1
Part v1
Experiment data v1
Design/Analysis
output v2
Part v2
Experiment data v2
Drawing v1
Design Intro
16.810 (16.682)
Final Review
15
IAP 2004 Schedule
1
Lecture
Week
L1 – Introduction
(de Weck)
Monday
L2 – Hand Sketching
(Wallace)
Wednesday
L3 – CAD modeling
( Kim, de Weck)
Friday
Hands-on
activities
Tour - Design studio
- Machine shop
- Testing area
Sketch Initial design Make a 2-D CAD model
(Solidworks) Nadir
2
Lecture
Hands-on
L4 – Introduction to CAE
(Kim)
FEM Analysis (Cosmos)
L5 – Introduction to CAM
(Kim)
Water Jet Intro machine shop
L6 – Guest Lecture 1 (Bowkett)
Rapid Prototyping
Make part version 1
3
Lecture
activities
Hands-on
Martin Luther King Jr.
Holiday – no class
L7 – Structural Testing
(Kim, de Weck)
Omax (Weiner, Nadir)
Test part ver. 1 (Kane)
L8 – Design optimization (Kim)
Introduction to Structural
4
Lecture
activities
Hands-on
activities
Carry out design optimization Manufacture part ver. 2
Test part ver. 2
L9 – Guest Lecture 2 (Sobieski)
Multidisciplinary Optimization
Optimization Programs
Final Review (de Weck, Kim)
MWF1-4pm (always meet at 1pm)
Last Lecture of IAP: January 30, 2004
16.810 (16.682) 16
Learning Objectives
At the end of this class you should be able to …
(1) Carry out a systematic design process from conception through
design/implementation/verification of a single structural component.
(2) Quantify the predictive accuracy of CAE versus actual test results.
(3) Explain the relative improvement that computer optimization can
yield relative to an initial, manual solution.
(4) Discuss the complementary capabilities and limitations of the
human mind and the digital computer (synthesis versus analysis).
16.810 (16.682) 17
Grading
? Letter Grading A-F
? Composition
? Design Deliverables 50%
? Sketch v1, Drawing v1, FEM Analysis v1/v2, Test
Protocol v1/v2, Final Review Slides (3)
? Parts (v1/v2) 30%
? (Negotiated) Requirements Compliance
? Active Class Participation 20%
? Attendance, Ask Questions, Contribute Suggestions,
Fill in Surveys
16.810 (16.682) 18
People
Instructors:
Prof. Olivier de Weck
Dr. Il Yong Kim
Postdoctoral Associate
Prof. David Wallace - ME
Staff:
- Software/Design Studio – Fred Donovan
- Manufacturing – Don Weiner
- Structural Testing – John Kane
16.810 (16.682) 19
(Re-)Introduction to
Design
16.810 (16.682) 20
Product Development - Design
Improved time-to-climb
Performance of F/A-18 in
Air-to-Air configuration by ~ 20%
Development
of Swiss F/A-18 Low Drag
Pylon (LDP) 1994-1996
“design” –
to create, fashion, execute,
or construct according to plan
Merriam-Webster
16.810 (16.682) 21
Design and Objective Space
Design Space
Objective Space
Design Variables
Performance
Remember Unified …?
Wing Area
in
2
]
Balsa Glider
Aspect Ratio
Dihedral Angle
31.5 [
6.2
0 [deg]
Time-of-Flight
5.35 sec
Distance
Ca. 90ft
Cost
Assembly Time
Fixed Parameters
87 min
- air density
- properties of balsa wood
Material Cost
$ 4.50
16.810 (16.682) 22
23
Basic Design Steps
ing” “monoplane”
“biplane”
3. Perform Design
6. Test Prototype
5. Build Prototype
4. Analyze System
7. Accept Final Design
16.810 (16.682)
“flying w
“delta dart”
1. Define Requirements
2. Create/Choose Concept
Typical Design Phases
Requirements
Definition
Design
Preliminary
Design
Selected
Design
Production
Production
?
?
? l layout
?
?
?
?
?
?
? i
Conceptual
Conceptual
baselines
baseline
Detailed
baseline
and support
General arrangement and performance
Representative configurations
General interna
Systems specifications
Detailed subsystems
Internal arrangements
Process design
Sophisticated Analysis
Problem Decomposition
Multidisc plinary optimization
16.810 (16.682) 24
PDP
Product Development Process
“A PDP is the unique sequence
of steps or activities, which an
enterprise employs to conceive,
design, and commercialize a
product”
Ulrich and Eppinger
?
A
Marketing
lways involves at least:
core
?Design
functions
? Manufacturing
16.810 (16.682) 25
Semiconductor Development Example
1 6 H W F X V W R P H U W D U J H W ? xx ?
2 ( V W L P D W H V D O H V Y R O X P H V x ? xx ?
3 ( V W D E O L V K S U L F L Q J G L U H F W L R Q x
? x ?
4 6 F K H G X O H S U R M H F W W L P H O L Q H
? x
5 ' H Y H O R S P H Q W P H W K R G V x
? x xxx
6 0 D F U R W D U J H W V F R Q V W U D L Q W V x x ? xxxx
7 ) L Q D Q F L D O D Q D O \ V L V ?
8 ' H Y H O R S S U R J U D P P D S x ? x
9 & U H D W H L Q L W L D O 4 ) ' P D W U L [ x xxx
?
10 6 H W W H F K Q L F D O U H T X L U H P H Q W V xx
? x
11 : U L W H F X V W R P H U V S H F L I L F D W L R Q xx xxx
? OOOO O O O O
12 + L J K O H Y H O P R G H O L Q J xx xx? xxx
13 : U L W H W D U J H W V S H F L I L F D W L R Q x xxxxx? xx
14 ' H Y H O R S W H V W S O D Q xx xxx ? x
15 ' H Y H O R S Y D O L G D W L R Q S O D Q xx x x
?
16 % X L O G E D V H S U R W R W \ S H x x
?
17 ) X Q F W L R Q D O P R G H O L Q J xx x? xxxxxxxx O O O O O OOOO O
18 ' H Y H O R S S U R G X F W P R G X O H V x xxxxxx xx? O
19 / D \ R X W L Q W H J U D W L R Q x xxxxxx x x?
20 , Q W H J U D W L R Q P R G H O L Q J x x xxx x x? x
21 5 D Q G R P W H V W L Q J x x ? x
22 ' H Y H O R S W H V W S D U D P H W H U V x x xxxxx
? xxx
23 ) L Q D O L ] H V F K H P D W L F V x x xxx? xx O O OO O
24 9 D O L G D W L R Q V L P X O D W L R Q x x x xxxx? xx
25 5 H O L D E L O L W \ P R G H O L Q J x xxxx
? x
26 & R P S O H W H S U R G X F W O D \ R X W xx xxx
? xx
27 & R Q W L Q X L W \ Y H U L I L F D W L R Q xx?
28 ' H V L J Q U X O H F K H F N xx x
?
29 ' H V L J Q S D F N D J H x x x x x
? O O O OOO O
30 * H Q H U D W H P D V N V x xxx ? xO
31 9 H U L I \ P D V N V L Q I D E x x x
?
32 5 X Q Z D I H U V x ? xO
33 6 R U W Z D I H U V x ?
34 & U H D W H W H V W S U R J U D P V x ?
35 ' H E X J S U R G X F W V x x xxx
? OO O OOO O
36 3 D F N D J H S U R G X F W V xx x?
37 ) X Q F W L R Q D O L W \ W H V W L Q J xx?
38 6 H Q G V D P S O H V W R F X V W R P H U V xx x x ?
39 ) H H G E D F N I U R P F X V W R P H U V x
?
40 9 H U L I \ V D P S O H I X Q F W L R Q D O L W \ x ?
41 $ S S U R Y H S D F N D J H G S U R G X F W V x x ?
42 ( Q Y L U R Q P H Q W D O Y D O L G D W L R Q xx x x ?
43 & R P S O H W H S U R G X F W Y D O L G D W L R Q x x xxx
?
44 ' H Y H O R S W H F K S X E O L F D W L R Q V xx ? xx
45 ' H Y H O R S V H U Y L F H F R X U V H V x x ? x
46 ' H W H U P L Q H P D U N H W L Q J Q D P H x ? x
47 / L F H Q V L Q J V W U D W H J \ ?
48 & U H D W H G H P R Q V W U D W L R Q xx x x
?
49 & R Q I L U P T X D O L W \ J R D O V x x x
?
50 / L I H W H V W L Q J xx x ? xx
51 , Q I D Q W P R U W D O L W \ W H V W L Q J xx x x? x
52 0 I J S U R F H V V V W D E L O L ] D W L R Q x xx
? OO
53 ' H Y H O R S I L H O G V X S S R U W S O D Q x x ?
54 7 K H U P D O W H V W L Q J xxx
?
55 & R Q I L U P S U R F H V V V W D Q G D U G V x ? xx
56 & R Q I L U P S D F N D J H V W D Q G D U G V xx xxx? x
57 ) L Q D O F H U W L I L F D W L R Q x xxx xxxxxxx
?
58 9 R O X P H S U R G X F W L R Q x ? x
59 3 U H S D U H G L V W U L E X W L R Q Q H W Z R U N xx xxxxx x ?
60 ' H O L Y H U S U R G X F W W R F X V W R P H U V x xxxxx x x x
?
x , Q I R U P D W L R Q ) O R Z V 3 O D Q Q H G , W H U D W L R Q V O 8 Q S O D Q Q H G , W H U D W L R Q V ? * H Q H U D W L R Q D O / H D U Q L Q J
Concurrent Activity Blocks
Potential Iterations
Generational Learning
Sequential Activities
xxxxx
xx
xxx
xx xx
xx
xx
xx
xx xx
xx
xxxx
xxx
xx
xx
xx
16.810 (16.682)
26Ref: Prof. Eppinger
Courtesy of Professor Steven Eppinger.
Phased vs. Spiral PD Processes
Phased, Staged, or Waterfall PD Process
Product
Planning
Product
Launch
Product
and Test
(dominant for over 30 years)
Definition
System-
Level
Design
Detail
Design
Integrate
Spiral PD Process
Product
Planning
Product
Launch
(primarily used in software development)
Define, Design, Build, Test, Integrate
Define, Design, Build, Test, Integrate
Define, Design, Build, Test, Integrate
Process Design Questions:
? How many spirals should be planned?
? Which phases should be in each spiral?
?
16.810 (16.682)
When to conduct gate reviews?
27
Stage Gate PD Process
Release
Planning
Concept
Design
Design
Design
Test
Within-Phase
Iterations
(planned)
Iterations
Wi
rd
System-Level
Detailed
Integration &
Reviews
Cross-Phase
(unplanned)
Refs: Robert Cooper, nning at New
Products 3 ed., 2001.
16.810 (16.682) 28
Spiral PD Process
Planning
Design
& Test
Design
Concept
Design
Rapid Prototyping
Is typically associated
16.810 (16.682)
Detailed
Integration
System-Level
(Cumulative Effort)
Release
With this process
Reviews
Cost
29
Basic Trade-offs in Product Development
Performance
RiskSchedule
Cost
? Performance - ability to do primary mission
? Cost - development, operation life cycle cost
? Schedule - time to first unit, production rate
? Risk - of technical and or financial failure
Ref: Maier, Rechtin, “The Art of Systems Architecting”
16.810 (16.682) 30
Key Differences in PDP’s
? Number of phases (often a superficial difference)
? Phase exit criteria (and degree of formality)
? Requirement “enforcement”
? Reviews
? Prototyping
? Testing and Validation
? Timing for committing capital
? Degree of “customer” selling and interference
? Degree of explicit/implicit iteration (waterfall or not)
? Timing of supplier involvement
16.810 (16.682) 31
Value of a structured PDP
A structured PDP …
? increases value added, efficiency and competitiveness
(e g. time to market) of the process
? provides something that can be learned and improved
? should be customized to product/market/culture
? should be based on underlying principles
16.810 (16.682) 32
Synthesis versus Anal ysis
Synthesis
Analysis
Problem definition
Quantitative answers
Desi
Computer
Graphical Representations
Human
gner
Database
- Creativity
- Number Crunching
- Intuition – Sanity Checks
- Interfacing
- Controls the Process
- Configuration Control
16.810 (1 6.682) 33
Form versus Function
Document
Concept: Network Digital Xerography
Scanner
User
Interface
Xerographic
System
Electronic
Form
System
Input
System
Finishing
System
Paper Path
Functions
?Scanning, printing, and faxing from desktop
Xerox
?Scan to file
Lakes Document
?Network document distribution
Processing System
?Remote document and device control
16.810 (16.682) 34
Hierarchy I: Parts Level
? deck components
? Ribbed-bulkheads decks
? Approximate dimensions
? 250mm x 350mm x 30mm
? Wall thickness = 2.54mm
frames
? frame components
? Ribbed-bulkheads
? Approximate dimensions
? 430mm x 150mm x 25.4mm
? Wall thickness = 2mm
? keel
? Ribbed-bulkhead
? Approximate dimensions
? 430mm x 660mm x 25.4mm
? Wall thickness = 2.54mm
keel
16.810 (16.682) 36
? Boeing (sample) parts
? A/C structural assembly
? 2 decks
? 3 frames
? Keel
? Loft included to show
interface/stayout zone to
A/C
? All Boeing parts in Catia
file format
? Files imported into
SolidWorks by
converting to IGES
format
16.810 (16.682) 37
Product Complexity
Assume 7-tree
levels =
a
?
O R J parts o
How many levels in drawing tree?
?
O R J
?
?
~ #parts
#levels
? Screwdriver (B&D) 3 1
? Roller Blades (Bauer) 30 2
? Inkjet Printer (HP) 300 3
? Copy Machine (Xerox) 2,000 4
? Automobile (GM) 10,000 5
? Airliner (Boeing) 100,000 6
simple
16.810 (16.682)
complex
39
“Design Challenge” and
Team Assignments
16.810 (16.682) 40
Design of a Structural Part
Forbidden
Given holes
zone
Design domain
Displacement measure (δ)
Loading
Fixed Boundary Condition
Problem
P L Q L P L ] H P D V V
statement:
6 X E M H F W W R δδ ≤
C
16.810 (16.682) 41
Setting: “Int’l Bicycle Corp.”
We, the class, are collectively the staff of the “International
Bicycle Corporation”.
In the past we produced a
“one-size fits all” product
(Mass Production)
Recently there has been increased
Market competition.
We need to start offering
tailored products for
different market segments
(Mass Customization)
Y. M. Huang and J. C. Pan, “Topology Optimization and Dynamic Performance of a Bike Frame with Dampers,” Proceedings of DETC’03, ASME
2003 Design Engineering Technical Conferences, Chicago, Illinois, USA, September 2-6, 2003.
16.810 (16.682) 42
Organization Chart
ivision
i
CEO – de Weck
Consumer Division
Specialty D
Motor Division
1 – Family Economy 2 – Family Deluxe 3 - Crossover 4 – C ty Bike
5 - Racing 6 - Mountain 7 – BMX Sports 8 - Acrobatics
9 – Motor Bike
Chief Engineer – Il Yong Kim
Design – Bill Nadir IT – Fred Donovan Mfg – Don Weiner Test – John Kane
16.810 (16.682) 43
Requirements (I): Geometry
44
δ
δ
1
F
F
F
Applied loads
Material: Al 6061-T6
Thickness ?”
Scale ca. 1:5
16.810 (16.682)
Fixed
Fixed
Laser displacement sensors
Mass
Manufacturing cost
Measured
displacements
Forbidden
zone
Configuration
Requirements (II): “Family Economy”
1. Market Description
This bicycle is to be designed for the mass consumer market. The expected sales volume
is 100,000 per year. Affordability, excellent performance/cost ratio and light weight are
most important to be successful in this market.
2. Requirements
Manufacturing Cost (C): C ≤ $3.50/part
Performance (δ1, δ2, f1, m): Displacement δ1 ≤ 0.060 mm
Displacement δ2 ≤ 0.009 mm
First natural frequency f1 ≥ 200 Hz
Mass: ≤ 0.110 lbs
Surface Quality: 2
Load Case: F1 = 50 lbs / F2 = 50 lbs / F3 = 100 lbs
3. Priorities
“Ishii-Matrix”
pp
Mass
pp
pp
16.810 (16.682)
Modifications to these
requirements have to
be negotiated with
Management.
Cost
Performance
Accept OptimizeConstrain Attribute
45
Spiral Development (DSM)
1 – Requirements Analysis
2 – Concept/Sketching
3 – CAD Modeling (.prt)
4 – FEM Analysis
5 – Design Optimization
6 – Make Drawing (.dxf)
7 – CAM Layout (.ord)
8 – Manufacture (Omax)
9 – Structural Testing
10 – Accept Part
12345678910
1
1X X
2
X2 X X
3
X3X X
4
X4X X
5
X 5
6
X6
7
X7
8
X8
9
X9
10
XX X
10
16.810 (16.682) 46
Facilities Tour
16.810 (16.682) 47
Facilities Tour
* Design Studio
* Machine Shop
-Water Jet cutter
- 14 networked CAD/CAE workstations
that are used for complex systems design
and optimization.
* Testing Lab
-Static and Dynamic Testing
Will carry out
testing with a
customized setup.
* Software to be used:
- MATLAB - Omax
- Solidworks - web-based topology
- Cosmos optimizer:
16.810 (16.682) 48
Next Steps
? Study 2 Page Requirements Sheets
? Think about your team’s concept
? Product Name?
? Look at CAD/CAE/CAM manual
? Register on WEBSIS if not already done
? Complete Attendance Sheet
? Next Lecture
? Wed 1/7/2004 at 1pm – “Hand Sketching”
16.810 (16.682) 49
| 课件名称： | 美国麻省理工大学：Engineering Design and Rapid Prototyping |
| 课件分类： | 航空航天 |
| 课件类型： | 教学课件 |
| 文件大小： | 6.61MB |
| 下载次数： | 0 |
| 评论次数： | 0 |
| 用户评分： | 0 |
- 1. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l11_biography
- 2. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l1_intro
- 3. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l3_cad
- 4. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l4_cae
- 5. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l5_mfg
- 6. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l6_nucast_slides
- 7. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l7_str_test
- 8. 美国麻省理工大学：Engineering Design and Rapid Prototyping：l8_optimize