Computer Aided Design Software - Assignment Example

COMPUTER AIDED DESIGN Author’s Name Class Name Professor’s Name School City and State Date Part 1 CAD Software There are two types of computer-aided design (CAD) software of generic type available for use by mechanical engineers namely 2D and 3D computer graphics software. 2D Computer Graphics Software The 2D computer Graphics software enables users of CAD system to develop two-dimensional geometric models that are used in generating computer-based digital images. The software is mainly applied in the development of drawn or printed applications. The 2D CAD software generates an electronic image or file that can be transmitted electronically as DFX or printed on paper. 2D CAD software defines manufacturing requirements, geometrical tolerances, and normal dimensions (Wang, Stoll & Conley, 2010, p. 64). One of the remarkable features of 2D software is that it facilitates structuring unknown compounds. Uses of 2D Computer Graphics Software in Mechanical Engineering In mechanical engineering, 2D CAD software is applied in drawing drafting and drawing designs for solid objects. The 2D drafting software enables mechanical engineers to generate two-dimensional models that help in generating images and drawings for solid objects. The 2D design software enhances the ability of mechanical engineers to develop good designs (Wang, Stoll & Conley, 2010, p. 65). 3D Computer Graphics Software The 3D CAD software is used to develop computer-generated imagery based on three-dimensional modeling for analytical, industrial or scientific purposes. The software enables designers to create or alter models to fit the desired angles or views. The software can import information from other applications that are used to create new models. A remarkable feature of the software is that it produces graphics with very accurate projections (Wang, Stoll & Conley, 2010, p. 67). Uses of 2D Computer Graphics Software in Mechanical Engineering In mechanical engineering, 3D CAD software is widely used for simulation and modeling purposes. For instance, the software enables mechanical engineers to create features and objects that are modifiable. Also, the software enables mechanical engineers to design and create objects with geometrical features that can be modified without focusing on history tree (Wang, Stoll & Conley, 2010, p. 67). Advantages of CAD methods There are two main advantages of CAD methods over the manual methods. First, the CAD methods involve the use of software that are used in many organizations and are used to update the precise utilities, service, and equipment layout. As such, the software becomes freely available to engineers for use in layout design purposes. The second advantage is that the CAD software usually exploits notions of drawing layers and drawing object libraries, which ease and speed up the layout drawing effort. Disadvantages of CAD Methods The main disadvantage of the CAD methods is that they are meant for precise drawing and sometimes, it becomes cumbersome to apply them in making designs for objects. Second, the CAD software does not understand layout design (Taylor, 2007, p. 65). Part 2 CAD Hardware The components of CAD hardware include a graphics terminal, input devices, a CPU, output devices such as printers and plotters and a secondary storage. Graphics Terminal A graphic terminal consists of display devices. The display devices resemble the screens of televisions, tablets, and phones. As engineers view the content displayed in the graphic devices, they use input devices to make designs for objects. In other words, the purpose of the graphic terminal is to generate images that are viewed by the users as they carry out CAD processes (Sarcar, Rao, & Narayan, 2008, p. 53). In a typical industrial situation, the graphics terminal is configured in a way that graphic images are displayed on a screen of a monitor. In most cases, the raster display monitor, which creates images through illuminating pixels, is used. The monitor is placed on a viewing area. Resolution on the monitor is adjusted through changing pixels per inch Sarcar, Rao, & Narayan, 2008, p. 53). Input Devices Input devices are used to input information in the form of either text or graphics into the CPU. Examples of input devices are a mouse, keyboard, and the digitizer. The mouse controls the cursor on the screen of a display device (Sarcar, Rao, & Narayan, 2008, p. 54). Through typing, the keyboard inputs information in the form of text into the CAD system. A digitizer is an electro-mechanical device that looks like an electronic tablet. In an industrial situation, the input devices are configured in a way that they are connected to the CPU and are placed on a surface from where users operate (Sarcar, Rao, & Narayan, 2008, p. 54). CPU CPU is the part of a CAD system that processes data. It comprises of arithmetic and logic unit, control unit and main memory. As such, its purpose is to process information that is received from input devices. The CPU applies mathematical computations to convert the information received from input devices into graphics (Sarcar, Rao, & Narayan, 2008, p. 56). In an industrial situation, the CPU is configured in a way that it connects the graphic devices, input devices, and output devices. The CPU is configured further through fitting the RAM in a manner that allows for one-way-slot operation. Afterward, the modules of the CPU fit themselves (Sarcar, Rao, & Narayan, 2008, p. 56). Output Devices Output devices are used to obtain hard copies. Plotters are the most common output devices used in a CAD system. They are special-purpose output devices used to produce images or drawings on cards and other hardcopy materials (Sarcar, Rao, & Narayan, 2008, p. 57). In an industrial situation, plotters are configured through selecting non-default settings. To achieve this, information about the plotting device is preserved in an AutoCAD. Storing the configuration information facilitates the use of a plotter on a shared project. Autoconfiguration can also be done on the plotters using information stored in the AutoCAD. To facilitate effective autoconfiguration, there is a need to create PC3 files and connect and configure them with the dialogue box (Sarcar, Rao, & Narayan, 2008, p. 57). Secondary Storage The secondary storage consists of disks and tapes that are used for the purpose of storage of information. The secondary storage devices are configured through accurately mounting NFS, SMB, and SAN. The different devices should be configured in a way that they have specific directories to the secondary directory location. The last step is to mount the secondary directory on the CPU (Sarcar, Rao, & Narayan, 2008, p. 58). Part 3 Finite Element Analysis (FEA) FEA is a method that is designed to obtain approximate solutions to complex engineering problems. It is a numerical technique, which is based on the premise that complex engineering problems can be solved by subdividing them into smaller problems or into more manageable elements and then solving them separately. How FEA works According to Rao (2011, p. 11), any particular variable in a complex problem has an infinite number of values since it is a function of each point or node within a structure. Therefore, a problem describing a model comprise of an infinite number of unknown values. The finite element method is used to solve such a problem in three major phases: Pre-processing phase, analysis phase and post-processing phase (Rao, 2011, p. 11). The first step in the Pre-processing phase involves subdividing a model or solution region into finite elements. This is done by taking into account any symmetry, loadings, material changes or boundary conditions. The unknown variables within each element are then expressed in terms of a less complex set of functions describing each element. These functions are then defined in terms of the unknown variables at specific points known as nodes (Rao, 2011, p. 11). Nodes or nodal points reflect the changes in geometry, material properties, applied loads and constraint conditions. These points usually lie on the boundaries between elements. The less complex functions representing finite elements are then selected to represent the differences in variables within an element. This process is known as meshing. As Rao (2011, p. 12) points out, polynomials are used as the functions for the variables since they are easier to differentiate and integrate. The degree of polynomials selected is dependent on the number of unknown variables at each nodal point, the number of nodal points that are assigned to each finite element and the continuity requirements imposed at interpolation boundaries and at the nodes. After the finite element mesh has been successfully established, matrix functions expressing the properties of each finite element are formed. The last step in the pre-processing stage involves incorporation of boundary conditions. The boundary conditions are applied at the nodal points (Desai, 2012, p.58). The second phase is the analysis or solution phase. This phase involves calculation of matrix equations for each finite element. The system equations are solved either by elimination method or wavefront method to give the unknown values at the nodal points. The post-processing phase involves calculation of displacements and strains or stresses. Simplex elements are evaluated at nodes while high-order elements are evaluated at integration points. Finally, the nodal values are averaged and the results are presented in printed or plotted format (Desai, 2012, p.58). The advantages FEA method FEA method has several advantages compared with manual methods. First, the FEA method has extensive applications than manual methods. For instance, it applies to all problems in solid mechanics. Second, FEA method allows for the use of composite materials since the adjacent elements need not be similar. Further, the numerous optimal modes associated with the FEA method help in facilitating variable approximation. Last, the FEA method enables engineers to undertake several complex functions within a short duration of time, unlike the manual method (Rao, 2013, p. 72). Disadvantages of FEA Method One of the disadvantages of FEA method is that unlike the manual method, it requires the use of computers and other facilities that sometimes costly. Second, the computers and facilities used in the FEA method cause pollution when not well disposed or handled. Further, FEA method is that it is an approximate technique and in some cases, it results into discontinuous FEA remedies (Rao, 2013, p. 72). References Desai, Y. M., 2012. Finite Element Method with applications in Engineering. New Delhi: Pearson Education Taylor, G. D. (2007). Logistics Engineering Handbook. London: CRC Press. Rao, S. S., 2011. The Finite Element Method in Engineering. New York, NY: Butterworth Heinemann. Rao, S. S., 2013. The Finite Element Method in Engineering: Pergamon International Library of Science, Technology, Engineering and Social Studies. London: Elsevier. Sarcar, M. M. M., Rao, K. M & Narayan, K. L., 2008. Computer Aided Design and Manufacturing. New Delhi: PHI Learning Pvt. Ltd. Wang, W., Stoll, H. W. &. Conley, J. G., 2010. Rapid Tooling Guidelines For Sand Casting. New York, NY: Springer Science & Business Media. Read More