Basics of CAD

1. Basics of CAD Ahto KALJA Department of Computer Engineering Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

2. 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 magazineComputer-Aided Design Masinprojekteerimise alused * A. Kalja * Arvutitehnika instituut

3. CAD 1. Definitions CAD, in broadest sense,is the use of computersfor the design work CAD, in the narrower sense, is any object or process project automated preparation using a computer CAD Computer Aided Design CAM Computer Aided Manufacturing CAD/CAM CAE Computer Aided Engineering CAT C A Testing CAP C A Planning CAIIP Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

4. Domains of CAD Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

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6. Dialog Computer graphics Data base Main program Basic software Hardware Software General structure of a CAD system Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

7. 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

8. Optimization calculation Spreadsheets Simulation Finite Element Method record keeping visualization Geometry Algebraic Manipulation Graphics Relationship among CAD applications and aspects of computation Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

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

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13. 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

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

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

16. 2.2 Modeling We take a look the concept „modeling“in broader sence, which also includesthe preparation of models Modeling problems staticdynamic 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:shaftneck neck: d:num l:num mass:num mass=pi*7.83*d*d*l/4*106 Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

17. Descript. of a shaft: shaft: mass:num length:num all.mass->mass(sum) all.length->length(sum) Description of a shaft with 3 necks: v: A1:neck d=28, l=30 A2:neck d=40 A3:neck d=30, l=40 copyshaft 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 Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

18. neck l d shaft 40 28 30 30 ? 40 ? A1 A2 A3 Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

19. 2.3 Optimization Let x be the set of projected object parameters. To maximize f (x), varying x-iin 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, consumedcapacity or other. g(x)=-f(x) restrict.inequalities hi(x)>0; i=1,2,…,n S equalities vj(x)=0; j=1,2,…,m Example:rectangular cross-section of the pipe Find 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 c1are constances Maximize the value of x1*x2, varying vector(x1, x2) in the domain, which has been given by x1-c>=0, x2-c>=0 ja c1-2(x1+x2)>=0 Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

20. Solution: 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 valuex1x2>=(c1/4)2 Minimizing the x1 + x2 value, varying a vector(x1, x2) in the domain, which is given by x1-c>=0, x2-c>=0 ja x1x2-c12/16>=0 Solution: is here too : x1=x2=c1/4 Masinprojekteerimine * A.Kalja * Arvutitehnika instituut

21. x1 x2 Pipe

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

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