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Computer-aided Design

"CADD" and "CAD" redirect here. For other uses, see CADD (disambiguation) and CAD (disambiguation).
“ECAD” redirects here. For other uses, see ECAD (disambiguation).
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A design drawing for an engine.


Computer-aided design (CAD) is use of a wide range of computerbased tools that assist engineers, architects and other design professions in their design activities. It is the main geometry authoring tool within the Product Lifecycle Management process and involves both software and sometimes special-purpose hardware. Current packages range from 2D vector base drafting systems to 3D solid and surface modellers.

Origins and terminology

CAD originally meant Computer Aided Drafting because of its original use as a replacement for traditional drafting. Now, CAD usually means Computer Aided Design to reflect the fact that modern CAD tools do more than just drafting.

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". All these terms are essentially synonymous, but there are a few subtle differences in meaning and application. CAM (Computer-aided manufacturing) is also often used in a similar way, or as a combination (CAD/CAM). The term CAD is generally used for graphical design, whereas non-graphical computer-aided design is usually called Knowledge-based engineering (KBE).

Introduction

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The CAD process.
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Commercial floor plan.


CAD is used to design, develop and optimize 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, and in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial structures (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.

CAD has become an especially important technology, within the scope of Computer Aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to lay out and develop work on screen, print it out and save it for future editing, saving time on their drawings.

Fields of use

History

[1] [2] [3] [4] [5] Designers have long used computers for their calculations. Initial developments were carried out in the 1960s within the aircraft and automotive industries in the area of 3D surface construction and NC programming, most of it independent of one another and often not publicly published until much later. Some of the mathematical description work on curves was developed in the early 1940s by Isaac Jacob Schoenberg, Apalatequi (Douglas Aircraft) and Roy Liming (North American Aircraft). Robert A. Heinlein in his 1957 novel The Door into Summer suggested the possibility of a robotic Drafting Dan. However, probably the most important work on polynomial curves and sculptured surface was done by Pierre Bezier (Renault), Paul de Casteljau (Citroen), Steven Anson Coons (MIT, Ford), James Ferguson (Boeing), Carl de Boor (GM), Birkhoff (GM) and Garibedian (GM) in the 1960s and W. Gordon (GM) and R. Riesenfeld in the 1970s.

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 his computer graphically: the design can be fed into the computer by drawing on a CRT monitor with a light pen. Effectively, it was a prototype of graphical user interface, an indispensable feature of modern CAD.

First commercial applications of CAD were in large companies in the automotive and aerospace industries, as well as in electronics. Only large corporations could afford the computers capable of performing the calculations. Notable company projects were at GM (Dr. Patrick J.Hanratty) with DAC-1 (Design Augmented by Computer) 1964; Lockhead projects; Bell GRAPHIC 1 and at Renault (Bezier) – UNISURF 1971 car body design and tooling.

One of the most influential events in the development of CAD was the founding of MCS (Manufacturing and Consulting Services Inc.) in 1971 by Dr. P. J. Hanratty[6], who wrote the system ADAM (Automated Drafting And Machining) but more importantly supplied code to companies such as McDonnell Douglas (Unigraphics), Computervision (CADDS), Calma, Gerber, Autotrol and Control Data.

As computers became more affordable, the application areas have gradually expanded. The development of CAD software for personal desk-top computers was the impetus for almost universal application in all areas of construction.

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. Initially, with 2D in the 1970s, it was typically limited to producing drawings similar to hand-drafted drawings. Advances in programming and computer hardware, notably solid modeling in the 1980s, have allowed more versatile applications of computers in design activities.

Key products 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). Autodesk was founded 1982 by John Walker, which led to the 2D system AutoCAD. The next milestone was the release of Pro/ENGINEER in 1988, which heralded greater usage of feature-based modeling methods and parametric linking of the parameters of features. 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 and beginning of the 1990s, both inspired by the work of Ian Braid. This led to the release of mid-range packages such as SolidWorks in 1995, SolidEdge (Intergraph) in 1996, and IronCAD in 1998. Today CAD is one of the main tools used in designing products.

Software providers today

Main articles: List of CAD companies and .

Capabilities

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An example of a CAD engineering drawing.
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Reuse of component from design library
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Simulation of airflow over an engine


The capabilities of modern CAD systems include:

Software technologies

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A CAD model of a mouse.


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. 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 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.

Advanced 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 and material costs, digital prototypes allow for design verification and testing on screen, speeding Time-to-market and decreasing costs. As technology evolves in this way, CAD has moved beyond a documentation tool (representing designs in graphical format) into a more robust designing tool that assists in the design process[7]

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. Some CAD systems such as NX provide multiplatform support including Windows, LINUX, UNIX and Mac OSX.

Generally no special hardware is required with the exception of a high end OpenGL based Graphics card; however for complex product design, machines with 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.

Using CAD

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CAD 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. Each of the different types of CAD systems requires the operator to think differently about how he will use them and he 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 AutoCAD and Cadkey 19) are created in a similar fashion to the way you would create the real world object. Each object and feature, after creation, is what it is. If the operator wants to change it, he must add "material" to it, subtract "material" from it, or delete the object or feature and start over. Due to this, it doesn't matter how the initial operator creates his components, as long as the final product is represented correctly. If future modifications are to be made, the method used to make the original part will not, in most cases, affect the procedure used to make the new modifications. Draft views can easily be generated from the models. Assemblies generally don't include tools to easily allow motion of components, set limits to their motion, or identify interference between components.

3D parametric solid modeling (programs incorporating this technology include Alibre Design, TopSolid, SolidWorks, and Solid Edge) require 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. What may be simplest today could be worst case tomorrow.

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.

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 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, aesthetics and ergonomic features into designs. Freeform surface modelling 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.

The CAD operator's ultimate goal should be to make future work on the current project as simple as possible. This requires a solid understanding of the system being used. A little extra time spent now could mean a great savings later.

Starting in the late 1980s, 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. As a general rule, one CAD operator could readily replace at least three or five drafters using traditional methods. Additionally, many engineers began to do their own drafting work, further eliminating the need for traditional drafting departments. This trend mirrored that of the elimination of many office jobs traditionally performed by a secretary as word processors, spreadsheets, databases, etc. became standard software packages that "everyone" was expected to learn.

Another consequence had been that since the latest advances were often quite expensive, small and even mid-size firms often could not compete against large firms who could use their computational edge for competitive purposes. Today, however, hardware and software costs have come down. Even high-end packages work on less expensive platforms and some even support multiple platforms. The costs associated with CAD implementation now are more heavily weighted to the costs of training in the use of these high level tools, the cost of integrating a CAD/CAM/CAE PLM using enterprise across multi-CAD and multi-platform environments and the costs of modifying design workflows to exploit the full advantage of CAD tools. CAD vendors have been effective in providing tools to lower these costs.

The adoption of CAD studio or "paper-less studio," as it is sometimes called, in architectural schools was not without resistance, however. Teachers were worried that sketching on a computer screen did not replicate the skills associated with age-old practice of sketching in a sketchbook. Furthermore, many teachers were worried that students would be hired for their computer skills rather than their design skill, as was indeed common in the 1990s. Today, however, (for better or worse, depending on the authority cited) education in CAD is now accepted across the board in schools of architecture. It should be noted, however, that not all architects have wanted to join the CAD revolution.

See also

CAD is one part of the whole Digital Product Development (DPD) activity within the Product Lifecycle Management (PLM) process, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:

Other related topics

References

1. ^ History of CAD/CAM. CADAZZ (2004).
2. ^ Pillers, Michelle (1998.03). MCAD Renaissance of the 90's. Cadence Magazine.
3. ^ Bozdoc, Martian. The History of CAD. iMB.
4. ^ Joneja, Ajay. Some Important Events in the Development of Computer-Aided Design and Manufacturing. IELM.
5. ^ Carlson, Wayne (2003). A Critical History of Computer Graphics and Animation. Ohio State University.
6. ^ MCS Founder.
7. ^ Winds of Change.

External links


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CADD may refer to:
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CAD may refer to:
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ECAD may refer to:
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computer is a machine which manipulates data according to a list of instructions.

Computers take numerous physical forms. The first devices that resemble modern computers date to the mid-20th century (around 1940 - 1941), although the computer concept and various machines
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engineer is someone who is trained or professionally engaged in a branch of engineering.[1] Engineers use technology, mathematics, and scientific knowledge to solve practical problems.
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An architect is a person who is involved in the planning, designing and oversight of a building's construction. The word "architect" (Latin: architectus) derives from the Greek arkhitekton (arkhi (chief) + tekton (builder))")[1]
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Design, usually considered in the context of the applied arts, engineering, architecture, and other such creative endeavors, is used both as a noun and a verb. As a verb, "to design" refers to the process of originating and developing a plan for a product, structure, system, or
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This is list of geometry topics, by Wikipedia page.
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Product lifecycle management (PLM) is the process of managing the entire lifecycle of a product from its conception, through design and manufacture, to service and disposal.[1] It is one of the four cornerstones of a corporation's information technology structure.
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Vector graphics (also called geometric modeling or object-oriented graphics) is the use of geometrical primitives such as points, lines, curves, and polygons, which are all based upon mathematical equations to represent images in computer graphics.
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Technical drawing, also known as drafting, is the practice of creating accurate representations of objects for technical, architectural and engineering needs. A practitioner of the craft is known as a draftsman, draftsperson
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Solid modeling (or modelling) is the unambiguous representation of the solid parts of an object, that is, models of solid objects suitable for computer processing. It is also known as volume modeling.
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Freeform surface modelling is the art of engineering Freeform Surfaces with a CAD or CAID system.

Introduction

The technology encompasses two main fields. Either creating aesthetic (Class A surfaces) that also perform a function; for example, car bodies and consumer
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Technical drawing, also known as drafting, is the practice of creating accurate representations of objects for technical, architectural and engineering needs. A practitioner of the craft is known as a draftsman, draftsperson
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Not to be confused with Qaid.


Caid may refer to:
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Computer Aided Architectural Design (CAAD) software programs are the repository of accurate and comprehensive records of buildings and is used by architects and architectural companies.
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Typical areas of concern:

Machining process


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Knowledge-based engineering (KBE) is a discipline with roots in computer-aided design (CAD) and knowledge-based systems but has several definitions and roles depending upon the context.
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Aspinwall Classification System (Leo Aspinwall, 1958) classifies and rates products based on five variables:
  1. Replacement rate (How frequently is the product repurchased?)
  2. Gross margin (How much profit is obtained from each product?)

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A good or commodity in economics is any object or service that increases utility, directly or indirectly, not to be confused with good in a moral or ethical sense (see Utilitarianism and consequentialist ethical theory).
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Technical drawing, also known as drafting, is the practice of creating accurate representations of objects for technical, architectural and engineering needs. A practitioner of the craft is known as a draftsman, draftsperson
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building may refer to one of the following:
  1. Any man-made structure used or intended for supporting or sheltering any use or continuous occupancy, or
  2. An act of construction.

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CAx is a summary term for various kinds of Computer Aided technologies.

CAx is a broad term describing the use of computer technology to aid in the design, analysis and manufacture of products.
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Architecture is the art and science of designing buildings and structures. A wider definition often includes the design of the total built environment: from the macrolevel of town planning, urban design, and landscape architecture to the microlevel of construction details and,
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Building engineering as a discipline

Building engineering is an emerging engineering discipline, better known in the US as architectural engineering, that offers a general engineering approach to the planning, design, construction, operation, renovation, and maintenance of
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Civil engineering is a professional engineering discipline that deals with the design and construction of the physical and natural built environment, including works such as bridges, roads, canals, dams and buildings.
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Public works are the construction or engineering projects carried out by the state on behalf of the community.

Overview

The notion of internal improvements or public works is a concept in economics and politics.
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construction is the building or assembly of any infrastructure on a site or sites. Although this may not be thought of as a single activity, in fact construction is a feat of multitasking.
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road is an identifiable route, way or path between two or more places.[1] Roads are typically smoothed, paved, or otherwise prepared to allow easy travel;[2]
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Highway is a term commonly used to designate major roads intended for travel by the public between important destinations, such as cities. The term highway can also be varied country-to-country, and can be referred to a road, freeway, superhighway,
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