Consists basically of:
Hardware: the computer and associated peripheral equipment.
Software: the computer program(s) running on the hardware.
Data: the data structure created and manipulated by the software.
Human knowledge and activities.

CAD systems are no more than computer programs. The software comprises a number of different elements or functions that process the data stored in the database in different ways.

Main Functions of CAD Systems
1. Model definition: for example to add geometric elements to a model of the form of a component.
2. Model manipulation: to move, copy, delete, edit or otherwise modify elements in the design model.
3. Picture generation: to generate images of the design model on a computer screen or on some hard-copy device.
4. User interaction: to handle commands input by the user and to present output to the user about the operation of the system.
5. Database management: for the management of the files that make up the database.
6. Applications: these elements of the software do not modify the design model, but use it to generate information for evaluation, analysis or manufacture.
7. Utilities: a “catch-all” term for parts of the software that do not directly affect the design model, but modify the operation of the system in some way (for example, to select the color to be used for display, or the units to be used for construction of a drawing).

These features may be provided by multiple programs operating on a common database, or by a single program encompassing all of the elements.

Sometimes, a CAD system can be considered as consisting of three major parts:
*Hardware: computer and input/output (I/O) devices
*Operating system software
*Application software: CAD package

Modeling objects
The model of an engineering object consists of geometry, topology, and auxiliary information. Geometry includes points, lines, circles, planes, cylinders and other surfaces. It defines the basic shape characteristics. Topology represents the relationships of the geometry of an object. In addition to its shape, an engineering object also possesses some other attributes. Dimensions, tolerances, and surface finish are some important attributes.

CAD is a tool not only to represent an engineering model, but also to manipulate it. To construct or display a model, geometric transformations and view transformations are needed.

Bookmark This Page: