Basics of CAD Ahto KALJA Department of Computer

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

CAD referencies: 1. A. Kalja, T. Tiidemann, E. Tõugu. Masinprojekteerimine. 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 DCC 14) 7. Electronic magazine Computer-Aided Design Masinprojekteerimise alused * 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 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

Domains of CAD Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

Dialog Computer graphics Data base Main program Basic software Hardware Software 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 calculation Spreadsheets record keeping Simulation Finite Element Method visualization Geometry Algebraic Manipulation Graphics Relationship among CAD applications and aspects of computation Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

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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

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

Start Design problem setting End Assessment and problem adjustment Analysis Synthesis Modeling 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 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: d: num l: num mass=pi*7. 83*d*d*l/4*106 Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

Descript. of a shaft: mass: num length: num all. mass->mass(sum) all. length->length(sum) Description of a shaft with 3 necks: v: A 1: neck d=28, l=30 A 2: neck d=40 A 3: neck d=30, l=40 copy shaft Possible calculations: - ? A 1. mass - ? A 3. mass - length: =125 ? A 2. L - A 2. L: =55 ? A 2. mass - A 2. L: =55 ? length - A 2. L: =55 ? mass - length: =125 ? mass Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

neck d l 30 ? 30 28 40 shaft 40 ? A 1 A 2 A 3 Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

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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 Example: rectangular cross-section of the pipe Find the maximum surface, x 1 and x 2 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 x 1*x 2, varying vector (x 1, x 2) 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 x 1 = x 2, so 2 (x 1 + x 2) = c 1 x 1=x 2=c 1/4 Finding min. material cost 2 (x 1 + x 2) restricting surface value x 1 x 2>=(c 1/4)2 Minimizing the x 1 + x 2 value, varying a vector (x 1, x 2) in the domain, which is given by x 1 -c>=0, x 2 -c>=0 ja x 1 x 2 -c 12/16>=0 Solution: is here too : x 1=x 2=c 1/4 Masinprojekteerimine * A. Kalja * Arvutitehnika instituut

x 1 x 2 Pipe

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

Masinprojekteerimine * A. Kalja * Arvutitehnika instituut