Download GTU B.Tech 2020 Winter 6th Sem 2161903 Computer Aided Design Question Paper

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Subject Code: 2161903

GUJARAT TECHNOLOGICAL UNIVERSITY

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Instructions:

1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1

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1. Clearly distinguish between conventional design and CAD. (03)
2. Explain different coordinate systems available in a CAD software. (04)
3. Write Breshnham's algorithm for line having slope less than 45°. (07)

Q.2

1. What is homogenous coordinate system? Explain its importance in CAD. (03)

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2. Write the differences between (04)
   (1) Raster scan and Vector scan displays
   (2) Analytic curves and Synthetic curves
3. Reflect the diamond shaped polygon whose vertices are A(-1,0), B(0,-2), C(1,0) and D(0,2) about (07)
   1) Horizontal line y =2
   

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   2) Vertical line x =2

Q.3

1. Explain plane surface and revolution surface in detail. (03)
2. The endpoints of a line are P1(2, 7, 12) and P2(5, 6, 4). Determine (04)
   (1) The parametric equation of line
   

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   (2) Tangent vector of the line
   (3) Length of the line
   (4) Unit vector in the direction of the line
3. Compare wireframe, surface and solid modeling techniques. (07)

Q.4

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1. Discuss the structure of an IGES file. (03)
2. What are different representation schemes for solid models? Differentiate between CSG and B-rep. (04)
3. The coordinates of four control points relative to a current WCS are given by B0[3 3 0]T, B1[3 4 0] T, B2[4 4 0]T, B3[4 3 0] T. Find the equation of the resulting Bezier curve. Also find points on the curve for U =0, 1/4, 1/2, 3/4, 1. (07)

Q.5

1. List the fields of applications of FEA. (03)

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2. Explain Penalty approach to solve FEA problem. (04)
3. Discuss the steps involved in finite element analysis of a problem. (07)

Q.6

1. Explain curved shell elements in FEA. (03)
2. Discuss the properties of global stiffness matrix. (04)

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3. Consider a two stepped bar as shown in Figure 1 below. Determine the nodal displacements if the temperature raises by 50°C. Consider E1 =200 X 103 N/mm2, E2 = 70 X 103 N/mm2, A1 =1000 mm2, A2= (07)

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100 KN.

Figure 1

Q.7

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1. With suitable examples explain plane stress condition. Which type of element will you use to solve a plane stress problem with FEA? (03)
2. Derive the element stiffness matrix of a truss element. (04)
3. For the loading system shown in Figure 2 below, determine the displacements and stresses. Assume modulus of elasticity E =80 X 103 N/mm2, cross sectional area A = 225mm2 and F = 90 KN. (07)

Figure 2

Q.8

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1. Draw the following elements showing nodes (03)
   (1) 4 noded quadrilateral (2) 3-noded triangle (3) 8 noded hexahedron
2. A 1D spar element having a linear shape function is as shown Figure 3 below. If the temperature at node 1 is 50° C and at node 2 is -20° C, find the temperature at point P. (04)

Figure 3

3. Explain in detail the discretization process with respect to (07)
   

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   (1) Types of elements (2) Size of elements
   (3) Location of nodes (4) Number of elements

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