PLANE13 Element Description

PLANE13 has a 2-D magnetic, thermal, electrical, piezoelectric, and structural field capability with limited coupling between the fields. PLANE13 is defined by four nodes with up to four degrees of freedom per node. The element has nonlinear magnetic capability for modeling B-H curves or permanent magnet demagnetization curves. PLANE13 has large deflection and stress stiffening capabilities. When used in purely structural analyses, PLANE13 also has large strain capabilities. See PLANE13 in the Mechanical APDL Theory Reference for more details about this element. Other coupled-field elements are SOLID5, and SOLID98.

Figure 13.1:  PLANE13 Geometry

PLANE13 Input Data

The geometry, node locations, and the coordinate system for this element are shown in Figure 13.1: PLANE13 Geometry. The element input data includes four nodes and magnetic, thermal, electrical, and structural material properties. The type of units (MKS or user defined) is specified through the EMUNIT command. EMUNIT also determines the value of MUZERO. The EMUNIT defaults are MKS units and MUZRO = 4 π x 10^-7 henries/meter. In addition to MUZERO, orthotropic relative permeability is specified through the MURX and MURY material property labels.

MGXX and MGYY represent vector components of the coercive force for permanent magnet materials. The magnitude of the coercive force is the square root of the sum of the squares of the components. The direction of polarization is determined by the components MGXX and MGYY. Permanent magnet polarization and orthotropic material directions correspond to the element coordinate directions. The element coordinate system orientation is as described in Coordinate Systems. Nonlinear magnetic B-H, piezoelectric, and anisotropic elastic properties are entered via the TB command. Nonlinear orthotropic magnetic properties can be specified with a combination of a B-H curve and linear relative permeability. The B-H curve is used in each element coordinate direction where a zero value of relative permeability is specified. Only one B-H curve may be specified per material.

Various combinations of nodal loading are available for this element (depending upon the KEYOPT(1) value). Nodal loads are defined with the D and the F commands. Nodal forces, if any, should be input per unit of depth for a plane analysis and on a full 360° basis for an axisymmetric analysis.

Element loads are described in Nodal Loading. Pressure, convection or heat flux (but not both), radiation, and Maxwell force flags may be input on the element faces indicated by the circled numbers in Figure 13.1: PLANE13 Geometry using the SF and SFE commands. Positive pressures act into the element. Surfaces at which magnetic forces are to be calculated are identified by using the MXWF label on the surface load commands (no value is required). A maxwell stress tensor calculation is performed at these surfaces to obtain the magnetic forces. These forces are applied in solution as structural loads. The surface flag should be applied to "air" elements adjacent to the body for which forces are required. Deleting the MXWF specification removes the flag.

Body loads - temperature, heat generation rate, and magnetic virtual displacement - may be input at the element's nodes or as a single element value [BF, BFE]. Source current density loads may be applied to an area [BFA] or input as an element value [BFE]. When the temperature degree of freedom is active (KEYOPT(1) = 2 or 4), applied body force temperatures [BF, BFE] are ignored. In general, unspecified nodal temperatures and heat generation rates default to the uniform value specified with the BFUNIF or TUNIF command. Heat generation from Joule heating is applied in Solution as thermal loading for static and transient analyses.

If the temperature degree of freedom is present, the calculated temperatures override any input nodal temperatures.

Air elements in which local Jacobian forces are to be calculated may be identified by using nodal values of 1 and 0 for the MVDI label [BF]. See the Low-Frequency Electromagnetic Analysis Guide for details. These forces are not applied in solution as structural loads.

A summary of the element input is given in "PLANE13 Input Summary". A general description of element input is given in Element Input. For axisymmetric applications see Harmonic Axisymmetric Elements.

PLANE13 Output Data

The solution output associated with the element is in two forms:

Several items are illustrated in Figure 13.2: PLANE13 Element Output. The element output directions are parallel to the element coordinate system. A general description of solution output is given in Solution Output. See the Basic Analysis Guide for ways to view results.

Figure 13.2:  PLANE13 Element Output

Because of different sign conventions for Cartesian and polar coordinate systems, magnetic flux density vectors point in opposite directions for planar (KEYOPT(3) = 0) and axisymmetric (KEYOPT(3) =1) analyses.

The Element Output Definitions table uses the following notation:

A colon (:) in the Name column indicates that the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file Jobname.OUT. The R column indicates the availability of the items in the results file.

In either the O or R columns, “Y” indicates that the item is always available, a number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

Table 13.3: PLANE13 Item and Sequence Numbers lists output available through the ETABLE command using the Sequence Number method. See The General Postprocessor (POST1) of the Basic Analysis Guide and The Item and Sequence Number Table in this reference for more information. The following notation is used in Table 13.3: PLANE13 Item and Sequence Numbers:

PLANE13 Assumptions and Restrictions

PLANE13 Product Restrictions

There are no product-specific restrictions for this element.