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Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Basics of CAD
Ahto KALJA
Department of Computer Engineering
Masinprojekteerimise alused * A. Kalja * Arvutitehnika instituut
CAD referencies:
1. A.Kalja, T.Tiidemann, E.Tõugu. Masin- projekteerimine. Tallinn, Valgus, 1991, 105 lk.2. A. Saxena, B. Sahay. Computer Aided Engineering Design. Springer, 2005, 394 p.3. Dean L. Taylor. Computer-Aided Design. Addison-Wesley, 1992, 492 p. 4. http://cs.ioc.ee/~nut/5. Eds. J. Gero and F. Sudweeks. Artificial Intelligence in Design ‘96. Kluwer Academic Publishers, 1996, Dordrecht, 782 p.6. Sixth International Conference on Design Computing and Cognition (DCC'14 or DCC14)7. Electronic magazine Computer-Aided Design
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
CAD
1. Definitions
CAD, in broadest sense, is the use of computersfor the design workCAD, in the narrower sense, is any object or process project automated preparation using a computer
CADCAD Computer Aided DesignCAMCAM Computer Aided ManufacturingCAD/CAMCAD/CAM
CAECAE Computer Aided Engineering
CATCAT C A Testing
CAPCAP C A Planning
CAIIPCAIIP
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Domains of CAD
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Dialog
Data base
Software
Main program
Basic software
Hardware
Computer graphics
General structure of a CAD system
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
A) Public CAD system
B) One user sytem
C) Local area network of a CAD system
Classification of CAD systems
. . .
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Optimization
Spreadsheets Simulation
Finite ElementMethod
Geometry
Graphics
AlgebraicManipulation
calculation
recordkeeping
visualization
Relationship among CAD applicationsand aspects of computation
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Learn about the unique features of NEi Nastran with this 90-second overview. [Watch video]
NEi Nastran Demo VideoLearn about the unique features
of NEi Nastran with this 90-second overview. [Watch video]
http://www.nenastran.com/newnoran/neiNastranDemo
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
2. Methods
2.1 Designing
Technical proposal
Rough plan
Technical project
Documentation
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
How Vasa was built
The work on Vasa was led by a Dutchman, Henrik Hybertsson, an
experienced shipwright. In this period, Dutch ships were not built
from drawings, instead the shipwright was given the overall dimensions and used proportions and rules of thumb based on his
own experience to produce a ship with good sailing qualities.
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Steps of design
Designproblem
Functionaldesign
Functional schema
Schema design
Principle schema
Detailschema
Project-documentation
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Design problem setting
Start
Assessment andproblem
adjustment
Modeling
Synthesis Analysis
End
Design cycle
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
2.2 ModelingWe take a look the concept „modeling“ in broader sence, which also includes the preparation of models
Modeling problems
static dynamic
problemsof continuousprocesses
problemsof discreteprocesses
Problems of statistical processesProblems of statistical processesAccording to the equations:- Models with functional dependencies- Models with ordinary differential equations- Models with partial derrivatives differ. equations
ExampleExample:: shaftneckneck:
d:numl:nummass:nummass=pi*7.83*d*d*l/4*106
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
shaft:mass:numlength:numall.mass->mass(sum)all.length->length(sum)
v: A1:neck d=28, l=30 A2:neck d=40 A3:neck d=30, l=40 copy shaft
Possible calculations:- ?A1.mass- ?A3.mass- length:=125 ?A2.L- A2.L:=55 ?A2.mass- A2.L:=55 ? length- A2.L:=55 ?mass- length:=125 ? mass
Descript. of a shaft:
Description of a shaft with 3 necks:
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
neck
l
shaft
A1 A2 A3
30 ? 40
?
28
40
30
d
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
2.3 Optimization
Let x be the set of projected object parameters.To maximize f (x), varying x-i in the domain S, where f (x) is the objective function, expresses kindness, productivity, ...To minimize g (x), varying x-i in the domain S, where g (x) is the objective function, expresses the cost of mass, consumed capacity or other.
g(x)=-f(x)restrict. inequalities hi(x)>0; i=1,2,…,n
S equalities vj(x)=0; j=1,2,…,m
ExampleExample:: rectangular cross-section of the pipeFind the maximum surface, x1 and x2 are the sides,
Restrictions x1>=c ja x2>=c i.e. none of the side should not be too short
2(x1+ x2)<=c1 i.e.circumference of the pipe should not be too big
,where c ja c1 are constances
Maximize the value of x1*x2, varying vector (x1, x2) in the domain, which has been given byx1-c>=0, x2-c>=0 ja c1-2(x1+x2)>=0
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
SolutionSolution:: Hyperbole, which touch to the area S, due to the symmetry of the solution is x1 = x2, so 2 (x1 + x2) = c1
x1=x2=c1/4
Finding min. material cost 2 (x1 + x2)restricting surface value x1x2>=(c1/4)2
Minimizing the x1 + x2 value, varying a vector(x1, x2) in the domain, which is given byx1-c>=0, x2-c>=0 ja x1x2-c1
2/16>=0
SolutionSolution: : is is here too : x1=x2=c1/4
x1x1
x2x2
PipePipe
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut
Examples of the optimizations
Masinprojekteerimine * A.Kalja * Arvutitehnika instituut