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Computer-aided design, also known as computer-aided design and drafting, is the use of computer technology for the process of design and design-documentation. Computer aided design describes the process of drafting with a computer. CADD software, or environments, provides us with input-tools for the purpose of design processes; drafting, documentation, and manufacturing processes. CADD output is often in the form of electronic files for print or machining operations. The development of CADD-based software is in direct correlation with the processes it seeks to economize; industry-based software (construction, manufacturing, etc.) typically uses vector-based (linear) environments whereas graphic-based software utilizes raster-based (pixelated) environments.
CADD environments often involve more than just shapes. As in the manual drafting of technical and engineering drawing , the output of CAD must convey information, such as materials , processes, dimensions , and tolerances , according to application-specific conventions.
CAD may be used to design curves and figures in two-dimensional (2D) space; or curves, surfaces, and solids in three dimensional (3D) objects.
CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CAD is also widely used to produce computer animation for special effects in movies, advertising and technical manuals. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry.
The design of geometric models for object shapes, in particular, is often called computer-aided geometric design (CAGD).
A CAD Model of a cycle
Originally software for Computer-Aided Design systems was developed with computer languages such as Fortran, but with the advancement of object-oriented programming methods this has radically changed. Typical modern parametric feature based modeler and freeform surface systems are built around a number of key C modules with their own APIs. A CAD system can be seen as built up from the interaction of a graphical user interface (GUI) with NURBS geometry and/or boundary representation (B-rep) data via a geometric modeling kernel. A geometry constraint engine may also be employed to manage the associative relationships between geometry, such as wireframe geometry in a sketch or components in an assembly.
Unexpected capabilities of these associative relationships have led to a new form of prototyping called digital prototyping. In contrast to physical prototypes, which entail manufacturing time in the design.
Today, CAD systems exist for all the major platforms (Windows, Linux, UNIX and Mac OS X; some packages even support multiple platforms.
Right now, no special hardware is required for most CAD software. However, some CAD systems can do graphically and computationally expensive tasks, so good graphics card, high speed (and possibly multiple) CPUs and large amounts of RAM are recommended.
The human-machine interface is generally via a computer mouse but can also be via a pen and digitizing graphics tablet. Manipulation of the view of the model on the screen is also sometimes done with the use of a spacemouse/SpaceBall. Some systems also support stereoscopic glasses for viewing the 3D model.
There are several different types of CAD. Each of these different types of CAD systems require the operator to think differently about how he or she will use them and he or she must design their virtual components in a different manner for each.
There are many producers of the lower-end 2D systems, including a number of free and open source programs. These provide an approach to the drawing process without all the fuss over scale and placement on the drawing sheet that accompanied hand drafting, since these can be adjusted as required during the creation of the final draft.
3D wireframe is basically an extension of 2D drafting. Each line has to be manually inserted into the drawing. The final product has no mass properties associated with it and cannot have features directly added to it, such as holes. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow using the wireframe model to make the final engineering drawing views.
3D "dumb" solids (programs incorporating this technology include (AUTO_CAD) are created in a way analogous to manipulations of real world objects. Basic three-dimensional geometric forms (prisms, cylinders, spheres, and so on) have solid volumes added or subtracted from them, as if assembling or cutting real-world objects. Two-dimensional projected views can easily be generated from the models. Basic 3D solids don't usually
include tools to easily allow motion of components, set limits to their motion, or identify interference between components.
3D parametric Solid modeling requires the operator to use what is referred to as "design intent". The objects and features created are adjustable. Any future modifications will be simple, difficult, or nearly impossible, depending on how the original part was created. One must think of this as being a "perfect world" representation of the component. If a feature was intended to be located from the center of the part, the operator needs to locate it from the center of the model, not, perhaps, from a more convenient edge or an arbitrary point, as he could when using "dumb" solids. Parametric solids require the operator to consider the consequences of his actions carefully.
Some software packages provide the ability to edit parametric and non-parametric geometry without the need to understand or undo the design intent history of the geometry by use of direct modeling functionality. This ability may also include the additional ability to infer the correct relationships between selected geometry (e.g., tangency, concentricity) which makes the editing process less time and labor intensive while still freeing the engineer from the burden of understanding the modelââ‚¬â„¢s design intent history. These kind of non history based systems are called Explicit Modellers or Direct CAD Modelers. The first Explicit Modeling system was introduced to the world at the end of 80's by Hewlett-Packard under the name Solid designer.
Draft views are able to be generated easily from the models. Assemblies usually incorporate tools to represent the motions of components, set their limits, and identify interference. The tool kits available for these systems are ever increasing; including 3D piping and injection mold designing packages.
Mid range software are integrating parametric solids more easily to the end user: integrating more intuitive functions (Sketch up), using the best of both 3D dumb solids and parametric characteristics (Vector Works), making very real-view scenes in relative few steps (Cinema 4-D) or offering all-in-one (Form-Z).
Top end systems offer the capabilities to incorporate more organic, aesthetics and ergonomic features into designs (Catia, Generative Components). Free from surface modeling is often combined with solids to allow the designer to create products that fit the human form and visual requirements as well as they interface with the machine.
Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.
CAD is one part of the whole Digital Product Development (DPD) activity within the Product Llifecycle Management (PLM) process, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:
Computer Aided Engineering (CAE) and Finite Element Analysis (FEA).
Computer Aided Manufacturing (CAM) including instructions to Computer Numeric Control (CNC) machines.
Photo realistic Rendering.
Document management and Revision Control using Product Data Management (PDM).
CAD is also used for the accurate creation of photo simulations that are often required in the preparation of Environmental Impact Reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like were the proposed facilities allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.
CAD is not only made for artists specifically but has the diversity to entertain all kinds of designing enthusiasts. This software has all built in features as per users need and come with many templates and symbols, for designing and drafting purposes, which gives it a wide area of application. It is the primary geometry-authoring tool used for all 2D and 3D designing purposes. It is useful for engineers, architects, and other designing professions.
CAD is applied in mechanical, automotive, aerospace, consumer goods, machinery, and shipbuilding applications.
In this field, it is used for designing various machinery and tools that are useful for manufacturing purposes.
In the field of electronics, it is used in manufacturing process planning, digital circuit design, and other software applications.
In the field of architecture, it is used as an effective tool for designing all types of buildings and assessing the integrity of steel-framed buildings. It enables them to design buildings in 2D and 3D models to give almost a real replica of the original work.
It is useful in engineering processes in conceptual design, and laying out and analyzing components in manufacturing methods.
Computer Aided Software Applications are now available on personal computers to facilitate users to work from home.