Study Mech

  Q-5. Mention the design guidelines to be followed in low quantity production. Ans: In any product, manufacturing and assembly cost is a very important consideration. It affects the overall cost in a significant manner. However during the design phase, with some consideration in product design, production cost can be reduced.  In case of low quantity production. Design guidelines to be followed in low quantity production:   During the design phase, it is good to use standard components in design. Because of low quantity production, using non-standard components may significantly increase the cost. For lower quantity production, worst case tolerance can be used. Providing loose tolerance may reduce part rejection in the inspection phase, hence maximum parts can be approved. If too tight tolerance is not necessary, then try to provide more tolerance range. Hence, it also eliminates the use of a special finishing process and reduces post processing cost. In case of low qua...

  Q-4. What is redesign? What are the steps to be followed to reduce the cost in the existing part or assembly? Ans: Concept of redesign refers to changing or improving the existing product characteristic by design or material improvement. Product may be a single part of an assembly. Based on market requirements or to take advantage of new facilities, it's necessary to redesign products.  Steps to be followed to reduce the cost in the existing part or assembly:   Product development starts from design. During the design phase, the product should be designed in such a way that it can be easily manufactured with existing facilities. Hence, excess cost can be reduced. Assembly or part manufacturing cost can be reduced by choosing the right manufacturing process for the product. Also, selection of the manufacturing process is based on material, quantity of product  and other design parameters,like dimensions, tolerance etc. Using too tight tolerance leads to extra proce...

  Q-3. Briefly explain the mathematical modelling of any one of the manufacturing processes. Ans:   Mathematical model of polymer extrusion process : Polymer material consists of long chain molecules. In extrusion of thermoplastic polymers, important parameters are Material flow and type of flow Heat transfer in flow Residence time Mixing of particles in flow in multiple polymers, etc. To analyse these parameters, mathematical models are useful. Using governing equations and boundary conditions (B.C), a model is created and a solution is obtained for particular B.C. Governing equations:   To model any flow and thermal transport in the manufacturing process, conservation of mass, conservation of  energy and the force momentum balance equation is used. The equations are as follow, Where, ρ is density,  t is time, T is temperature, V is the velocity vector, μ is dynamic viscosity, F is body force, p is pressure, Cp is specific heat at constant pressure, β is coeffi...

  Q-2.Consider any one of the metal forming operations and list out the important parameters involved during the process. Ans: Rolling is a metal working process. In rolling, the metal stock or billet is passed through a pair of rolls to reduce the thickness. During the rolling process, the width of the stock remains constant. The important parameters involved during the rolling process are, Diameter of rolls. Friction generation between workpiece and roll surface & Neutral plane position. Deformation resistance of metal and temperature of billet, etc. Diameter of rolls: In the rolling process, rolling force is directly proportional to the diameter of roll. Rolling force increases as the roll diameter. As a decrease in diameter of roll, length of arc of contact  also decreases. Hence, smaller diameter roll provides uniform reduction in thickness of billet. Hence, small diameter rolls are generally used in rolling purposes.  Larger rolls are used as back up rolls, hen...

2-D Static Stress Analysis on a Flat plate with Hole Problem1 Description: Examine the stress concentrations in a flat rectangular plate of size 0.5 × 0.2 with three holes whose dimensions are as follows, Centre X Y Radius Hole 1 0.25 0.1 0.01 Hole 2 0.23 0.1 0.005 Hole 3 0.27 0.1 0.005 Given: Young’s Modulus = 70e9, Poisson ratio = 0.3, Pressure 100 N: * All dimensions are in meters. For,   Results: Discipline: Structural Analysis Type: Static Element type: Solid, Quadrilateral 4 node 182 Material model: Linear elastic isotropic   Max deflection:   After applying 100N tensile force at the free end, the plate gets a maximum deformation of 0.72E-9 m in X-direction. Element solution:   For an elemental solution, using the 1st principal stress approach we get max stress 290.34  N/m2. Maximum stress occurs at element no. 1270.   Vector plot:   Using a vector plot to visualize translations U, we get maximum translation at node 3, which is 0.72E-9 m in ...

3D Dimensional Truss Problem Description: Determine the nodal deflections, reaction forces, and stress for the truss system shown below (E = 200GPa, Pipe diameter = 30 mm, Wall thickness =2mm   Results: Discipline: Structural Analysis Type: Static No of elements: 06 No of Nodes:   05 Max Deflection (Image & Table)      PRINT REACTION SOLUTIONS PER NODE     ***** POST1 TOTAL REACTION SOLUTION LISTING *****                           LOAD STEP= 1  SUBSTEP= 1                                            TIME= 1.0000      LOAD CASE=   0                                         THE FOLLOWING X,Y,Z SOLUTIONS ARE IN THE GLOBA...

2D Dimensional Truss Problem Description: Determine the nodal deflections, reaction forces, and stress for the truss system shown below (E = 200GPa, A = 3250mm2). Results: Discipline: Structural Analysis Type: Static No of elements: 11 No of Nodes: 07   Max Deflection (Image & Table)      PRINT U NODAL SOLUTION PER NODE   ***** POST1 NODAL DEGREE OF FREEDOM LISTING *****                          LOAD STEP= 1 SUBSTEP= 1                                            TIME= 1.0000  LOAD CASE= 0         THE FOLLOWING DEGREE OF FREEDOM RESULTS ARE IN THE GLOBAL COORDINATE SYSTEM                          ...