The use of computers in various design activities, such as designing the interconnections on printed circuit boards and optimizing the aerodynamic shapes of aeroplanes. CAD makes great use of computer graphics, and generally requires relatively fast computers.
Computer-aided design (CAD) is the use of a wide range of computer-based tools that assist engineers, architects and other design professionals in their design activities. Current packages range from 2D vector based drafting systems to 3D solid and surface modellers.
CAD is sometimes translated as "computer-assisted", "computer-aided drafting", or a similar phrase. Related acronyms are CADD, which stands for "computer-aided design and drafting", CAID for Computer-aided Industrial Design and CAAD, for "computer-aided architectural design".
Introduction
CAD is used to design and develop products, which can be goods used by end consumers or intermediate goods used in other products. CAD is also extensively used in the design of tools and machinery used in the manufacture of components. CAD is also used in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial types (hospitals and factories).
CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components.
History
Designers have long used computers for their calculations.
It is argued that a turning point was the development of SKETCHPAD system in MIT in 1963 by Ivan Sutherland (who later created a graphics technology company with Dr. David Evans). The distinctive feature of SKETCHPAD was that it allowed the designer to interact with computer graphically: the design can be fed into the computer by drawing on a CRT monitor with a light pen.
First commercial applications of CAD were in large companies in the automotive and aerospace industries, as well as in electronics. Notable company projects were at GM (Dr. Patrick J.Hanratty) with DAC-1 (Design Augmented by Computer) 1964;
The most influential event in the development of CAD was the founding of MCS (Manufacturing and Consulting Services Inc.) in 1971 by Dr. P.
Other key points in the 1960s and 1970s would be the foundation of CAD systems United Computing, Intergraph, IBM, Intergraph IGDS in 1974 (which led to Bentley MicroStation in 1984)
CAD implementations have evolved dramatically since then. Advances in programming and computer hardware, notably solid modelling in the 1980s, have allowed more versatile applications of computers in design activities. Key product for 1981 were the solid modelling packages - Romulus (ShapeData) and Uni-Solid (Unigraphics) based on PADL-2 and the release of the surface modeler CATIA (Dassault Systemes). Also of importance to the development of CAD was the development of the B-rep solid modeling kernels (engines for manipulating geometrically and topologically consistent 3D objects) Parasolid (ShapeData) and ACIS (Spatial Technology Inc.) at the end of the 1980s beginning of the 1990s, both inspired by the work of Ian Braid.
Starting the late 1980's, the development of readily affordable CAD programs that could be run on personal computers began a trend of massive downsizing in drafting departments in many small to mid-size companies.
Today CAD is not limited to drafting and rendering, and it ventures into many more "intellectual" areas of a designer's expertise. Computer aided design is used in many businesses and organizations around the world.
Software providers today
This is an ever changing industry with many well known products and companies being taken over and merged with others.
Packages can be classified into three types: 2D drafting systems (e.g. However these classifications cannot be applied too strictly as many 2D systems have 3D modules, the mid-range systems are increasing their surface functionality, and the high-end systems have developed their user interface in the direction of interactive Windows systems.
Capabilities
The capabilities of modern CAD systems include:
Wireframe geometry creation 3D parametric feature based modelling, Solid modelling Freeform surface modelling Automated design of assemblies, which are collections of parts and/or other assemblies create Engineering drawings from the solid models Reuse of design components Ease of modification of design of model and the production of multiple versions Automatic generation of standard components of the design Validation/verification of designs against specifications and design rules Simulation of designs without building a physical prototype Output of engineering documentation, such as manufacturing drawings, and Bills of Materials to reflect the BOM required to build the product Import/Export routines to exchange data with other software packages Output of design data directly to manufacturing facilities Output directly to a Rapid Prototyping or Rapid Manufacture Machine for industrial prototypes maintain libraries of parts and assemblies calculate mass properties of parts and assemblies aid visualization with shading, rotating, hidden line removal, etc... and counter wise) kinematics, interference and clearance checking of assemblies sheet metal hose/cable routing electrical component packaging inclusion of programming code in a model to control and relate desired attributes of the model Programmable design studies and optimization Sophisticated visual analysis routines, for draft, curvature, curvature continuity...Software technologies
Originally software for CAD systems were developed with computer language such as Fortran, but with the advancement of object-oriented programming methods this has radically changed. The development of a typical modern parametric feature based modeler and freeform surface systems are built around a number of key, C programming language, modules with their own APIs. A CAD system can be seen as built up from the interaction a graphical user NURBS geometry via a geometric modeling kernel.
Hardware and OS technologies
Today most CAD computer workstations are Windows based PCs; some CAD systems also run on hardware running with one of the Unix operating systems and a few with Linux. however for complex product design, machines with high speed (and possibly multiple) CPUs and large amounts of RAM are recommended.
The CAD operator
Each of the different types of CAD systems requires the operator to think differently about how he will use them and he must design his 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.
3D wireframe is basically an extension of 2D drafting. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow you to use the wireframe model to make the final engineering drawing views.
3D "dumb" solids (programs incorporating this technology include AutoCAD and Cadkey 19) are created in a very similar fashion to the way you would create the real world object.
3D parametric solids (programs incorporating this technology include IronCAD, Alibre Design, SolidWorks, and Solid Edge) require the operator to use what is referred to as "design intent". The tool kits available for these systems are ever increasing, including 3D piping and injection mold designing packages.
Mid range software was integrating parametric solids more easily to the end user: integrating more intuitive functions (SketchUp), going to the best of both worlds with 3D dumb solids with parametric characteristics (VectorWorks) or making very real-view scenes in relative few steps (Cinema4D).
Top end systems offer the capabilities to incorporate more organic and ergonomic features into your designs.
The CAD operator's ultimate goal should be to make future work on the current project as simple as possible.
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