美国麻省理工大学：《Engineering Design and Rapid Prototyping》Lecture 3 Computer Aided Design

16810(16682) Engineering Design and Rapid prototyping Lecture 3 IGa10 Computer Aided Design(CAD) Instructor(s) Prof, olivier de Weck Dr. Il Yong Kim January 9,2004 Massachusetts Institute of Technology

16.810 (16.682) 16.810 (16.682) Engineering Design and Rapid Prototyping Engineering Design and Rapid Prototyping Instructor(s) Lecture 3 Computer Aided Design (CAD) January 9, 2004 Prof. Olivier de Weck Dr. Il Yong Kim

IG a1n Plan for Today CAD Lecture(ca 50 min) CAD History, Background Some theory of geometrical representation SolidWorks Introduction(ca. 40 min) Follow along step-by-step Create CAD model of your part(ca. 90 min) Work in teams of two Use hand sketch as starting point 16.810(16682) Massachusetts Institute of techn

16.810 (16.682) 2 Plan for Today „ CAD Lecture (ca. 50 min) „ CAD History, Background „ Some theory of geometrical representation „ SolidWorks Introduction (ca. 40 min) „ Follow along step-by-step „ Create CAD model of your part (ca. 90 min) „ Work in teams of two „ Use hand sketch as starting point

A10 Course Concept today Phase 1 Problem cetch by hand CAD CAE apid Prototyping/ statement Validation Manufacturing Test Phase 2 Design Optimization Optimum solution Rapid Prototyping/ Manufacturing Test 16.810(16682) Massachusetts Institute of techn

16.810 (16.682) 3 Course Concept today

1G.810 Course Flow Diagram Learning/ Review Problem statement Deliverables due today Design Intro Hand sketching Design Sketch v1 CAD/CAM/CAE Intro CAD design Drawing v gu today Monday FEM/Solid mechanics FEM analysis Overview Analysis output v1 Manufacturing Produce Part 1 Part v1 Training Structural Test Test Experiment data v1 Training Design Optimization Optimization Design/Analysis output v2 Produce part 2 Part v2 Test Experiment data v2 Final review 16.810(16682)

16.810 (16.682) 4 Course Flow Diagram CAD/CAM/CAE Intro FEM/Solid Mechanics Overview Manufacturing Training Structural Test “Training” Design Optimization Hand sketching CAD design FEM analysis Produce Part 1 Test Produce Part 2 Optimization Problem statement Final Review 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 due today today Monday Design Intro

lG a1n What is CAD? Computer Aided Design(CAD) A set of methods and tools to assist product designers in Creating a geometrical representation of the artifacts they are designing Dimensioning, Tolerancing Configuration Management( Changes) Archiving Exchanging part and assembly information between teams organizations Feeding subsequent design steps Analysis(CAe Manufacturing(CAM) a. by means of a computer system. 16.810(16682) Massachusetts Institute of techn

16.810 (16.682) 5 What is CAD? „ Computer Aided Design (CAD) „ A set of methods and tools to assist product designers in „ Creating a geometrical representation of the artifacts they are designing „ Dimensioning, Tolerancing „ Configuration Management (Changes) „ Archiving „ Exchanging part and assembly information between teams, organizations „ Feeding subsequent design steps „ Analysis (CAE) „ Manufacturing (CAM) „ …by means of a computer system

IG Aln Brief History of CAD 1957 PRONTO (Dr Hanratty )-first commercial numerical- control programming system 1960 SKETCHPAD(MIT LincoIn Labs) Early 1960s industrial developments General Motors -DAC Design automated by computer) McDonnell Douglas-CADD Early technological developments Vector-display technology Light-pens for input Patterns of lines rendering first 2D only) 1967 Dr Jason r lemon founds sdrc in cincinnati 1979 Boeing general Electric and nist develop iges Initial Graphic Exchange Standards), e. g. for transfer of NURBS curves Since 1981: numerous commercial programs Sourcehttp://mbinfo.mbdesign.net/cad-hIstOrY.htm 16.810(16682) Massachusetts Institute of Technology

16.810 (16.682) 7 Brief History of CAD „ 1957 PRONTO (Dr. Hanratty) – first commercial numerical￾control programming system „ 1960 SKETCHPAD (MIT Lincoln Labs) „ Early 1960’s industrial developments „ General Motors – DAC (Design Automated by Computer) „ McDonnell Douglas – CADD „ Early technological developments „ Vector-display technology „ Light-pens for input „ Patterns of lines rendering (first 2D only) „ 1967 Dr. Jason R Lemon founds SDRC in Cincinnati „ 1979 Boeing, General Electric and NIST develop IGES (Initial Graphic Exchange Standards), e.g. for transfer of NURBS curves „ Since 1981: numerous commercial programs „ Source: http://mbinfo.mbdesign.net/CAD-History.htm

GG.Aln Major Benefits of CAD Productivity(=speed) Increase Automation of repeated tasks Doesnt necessarily increase creativity! Insert standard parts(e.g. fasteners)from database Supports Changeability Don't have to redo entire drawing with each change E0-"Engineering Orders Keep track of previous design iterations Communication With other teams/engineers, e.g. manufacturing, suppliers With other applications(CAE/FEM, CAM) Marketing realistic product rendering Accurate high quality drawings Caution CAD Systems produce errors with hidden lines etc Some limited analysis Mass Properties(Mass, Inertia) Collisions between parts clearances 16.810(16682) Massachusetts institute of technol ology it

16.810 (16.682) 8 Major Benefits of CAD „ Productivity (=Speed) Increase „ Automation of repeated tasks „ Doesn’t necessarily increase creativity! „ Insert standard parts (e.g. fasteners) from database „ Supports Changeability „ Don’t have to redo entire drawing with each change „ EO – “Engineering Orders” „ Keep track of previous design iterations „ Communication „ With other teams/engineers, e.g. manufacturing, suppliers „ With other applications (CAE/FEM, CAM) „ Marketing, realistic product rendering „ Accurate, high quality drawings „ Caution: CAD Systems produce errors with hidden lines etc… „ Some limited Analysis „ Mass Properties (Mass, Inertia) „ Collisions between parts, clearances

IGA10 Generic CAD Process Engineering Sketch Start Settings Units, Grid(snap), 3D 2D dim Construct basic Create lines radii, part Solids contours, chamfers Boolean Operations h extrude, rotate (add, subtract,… Add cutouts holes o Annotations Dimensioning CAD file Verification Output → Drawing(dxf) X.x IGES file 16.810(16682) Massachusetts Institute of techno ology it

16.810 (16.682) 9 Generic CAD Process Start Settings Engineering Sketch Units, Grid (snap), … Construct Basic Solids dim 3D 2D Boolean Operations (add, subtract, …) Annotations Dimensioning Verification Create lines, radii, part contours, chamfers - Add cutouts & holes extrude, rotate = CAD file Output Drawing (dxf) x.x IGES file

1G.:10 EXample CAD A/C Assembly Boeing(sample) parts A/C structural assembly 2 decks 3 frames Loft included to show interface/stayout zone to AC All Boeing parts in Catia file format Files imported into SolidWorks by converting to IGES format 16.810(16682) Massachusetts Institute of techn 10

16.810 (16.682) 10 Example CAD A/C Assembly „ 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

IG Aln Vector versus Raster Graphics Raster Graphics bmp-raw data format 424DBC020000000300200020053001 oo10000000000002B0000120B0000000 oooo00001Doo5c0000000000000F80000F800000000 0000c00000000000000000000 7000007000000003800000000c0000 00c0000000000080000c000000000070000000700 00000000000E00000003 BB BBBB8ooo0001c00000003 FFFFFFO000 aooo1aoo00000300c000400000010000003004000400000030 0o0o020060004000000070000000030050004000000060000000 020070004000000000010000000000030 grid of pixels 00400000000010000000018004000 0000400000000300100040000000c00000000200180040000000c0 o0003001800400000000020000000 a No relationships between o3 00 1800400000080 0003 00 1800 C000000030010 a4000008000000030018004000000400000010004000 eIs 0000 C000000002001800400004000100400a 0ooo00020038004000000040000000030010004000000060000000 Resolution, e. g. 72 dpi 03003000000000000 0o400000100070770700001000Fc00 (dots per inch 00001C0000000001C000000000000E000000000380000000000007 0000 000007000000000000030000000E00000000000001000000 Each pixel has color, e. g 0014000000000000003800000000000700000700 8-bit image has 256 00000oF80000F8000o0oo00000001 DO00 5C00000000000000 OFF BBF80000o00o00000017r9000000000 colors 16.810(16682) Massachusetts Institute of techn

16.810 (16.682) 12 Vector versus Raster Graphics Raster Graphics .bmp - raw data format „ Grid of pixels „ No relationships between pixels „ Resolution, e.g. 72 dpi (dots per inch) „ Each pixel has color, e.g. 8-bit image has 256 colors