The following element overview topics are available:
An element type is identified by a name (eight characters maximum), such as PIPE288, consisting of a group label (PIPE) and a unique identifying number (288).
The element descriptions in Element Library are arranged in order of these identification numbers. The element is selected from the library for use in the analysis by inputting its name on the element type command (ET).
Models may be either 2-D or 3-D depending upon the element types used.
A 2-D model must be defined in an X-Y plane. They are easier to set up, and run faster than equivalent 3-D models. Axisymmetric models are also considered to be 2-D.
If any 3-D element type is included in the element type (ET ) set, the model becomes 3-D. Some element types (such as COMBIN14) may be 2-D or 3-D, depending upon the KEYOPT value selected. Other element types (such as COMBIN40) have no influence in determining the model dimensions. A 2-D element type may be used (with caution) in 3-D models.
In general, four shapes are possible: point, line, area, or volume.
A point element is typically defined by one node, such as a mass element.
A line element is typically represented by a line or arc connecting two or three nodes. Examples are beams, spars, pipes, and axisymmetric shells.
An area element has a triangular or quadrilateral shape and may be a 2-D solid element or a shell element.
A volume element has a tetrahedral or brick shape and is usually a 3-D solid element.
The degrees of freedom of the element determine the discipline for which the element is applicable: structural, thermal, fluid, electric, magnetic, or coupled-field.
Select an element type with the necessary degrees of freedom characterize the model's response.
Including unnecessary degrees of freedom increases the solution memory requirements and running time. Similarly, selecting element types with unnecessary features--for example, using an element type with plastic capability in an elastic solution--also increases the analysis run time.
You can create your own element type and use it in an analysis as a user-defined element.
User-defined elements are described in Creating a New Element in the Programmer's Reference.