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 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 computers for the design work CAD, in the narrower sense, is any object or process project automated preparation using a computer CAD CAD Computer Aided Design CAM CAM Computer Aided ManufacturingCAD/CAM CAE CAE Computer Aided Engineering CAT CAT C A Testing CAP CAP C A Planning CAIIP

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut Domains of CAD

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 Element Method Geometry Graphics Algebraic Manipulation calculation record keeping visualization Relationship among CAD applications and aspects of computation

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

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Masinprojekteerimine * A.Kalja * Arvutitehnika instituut 2. Methods 2.1 Designing Technical proposal Rough plan Technical project Documentation

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.Henrik Hybertsson

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut Steps of design Design problem Functional design Functional schema Schema design Principle schema Detail schema Project- documentation

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut Design problem setting Start Assessment and problem adjustment Modeling Synthesis Analysis End Design cycle

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut 2.2 Modeling We take a look the concept „modeling“ in broader sence, which also includes the preparation of models Modeling problems static dynamic problems of continuous processes problems of discrete processes Problems of statistical processes According to the equations: - Models with functional dependencies - Models with ordinary differential equations - Models with partial derrivatives differ. equations Example: Example: shaftneck neck: d:num l:num mass:num mass=pi*7.83*d*d*l/4*10 6

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut shaft: mass: num length: num all.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 ? 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 h i (x)>0; i=1,2,…,n S equalities v j (x)=0; j=1,2,…,m Example: Example: rectangular cross-section of the pipe Find the maximum surface, x1 and x2 are the sides, Restrictions x 1 >=c ja x 2 >=c i.e. none of the side should not be too short 2(x 1 + x 2 )<=c 1 i.e. circumference of the pipe should not be too big,where c ja c 1 are constances Maximize the value of x1*x2, varying vector (x1, x2) in the domain, which has been given by x 1 -c>=0, x 2 -c>=0 ja c 1 -2(x 1 +x 2 )>=0

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut Solution: Hyperbole, which touch to the area S, due to the symmetry of the solution is x1 = x2, so 2 (x1 + x2) = c1 x 1 =x 2 =c 1 /4 Finding min. material cost 2 (x1 + x2) restricting surface value x 1 x 2 >=(c 1 /4) 2 Minimizing the x1 + x2 value, varying a vector (x1, x2) in the domain, which is given by x 1 -c>=0, x 2 -c>=0 ja x 1 x 2 -c 1 2 /16>=0 Solution: is Solution: is here too : x 1 =x 2 =c 1 /4

x1 x2 Pipe

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut Examples of the optimizations

Masinprojekteerimine * A.Kalja * Arvutitehnika instituut