3-D Magnetic
Scalar Solid
SOLID96 Element Description
SOLID96 has the capability of modeling 3-D magnetic fields. Scalar potential formulations (reduced (RSP), difference (DSP), or general (GSP)) are available [MAGOPT] for modeling magnetic fields in a static analysis. See SOLID96 in the Mechanical APDL Theory Reference for more details about this element.
SOLID96 Input Data
The geometry, node locations, and the coordinate system for this element are shown in Figure 96.1: SOLID96 Geometry. The element is defined by eight nodes and the material properties. A tetrahedral-shaped element may be formed by defining the same node numbers for nodes M, N, O, and P; and nodes K and L. A wedge-shaped element and a pyramid-shaped element may also be formed as shown in Figure 96.1: SOLID96 Geometry. The type of units (MKS or user defined) is specified through the EMUNIT command. EMUNIT also determines the value of MUZRO. The EMUNIT defaults are MKS units and MUZRO = 4π x 10-7 henries/meter. In addition to MUZRO, orthotropic relative permeability is available and is specified through the MURX, MURY, and MURZ material options.
MGXX, MGYY, and MGZZ 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, MGYY, and MGZZ. Permanent magnet polarization directions correspond to the element coordinate directions. The element coordinate system orientation is as described in Coordinate Systems. Nonlinear magnetic B-H 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 can be specified per material.
Nodal loads are defined with the D and the F commands. With the D command, the Lab variable corresponds to the degree of freedom (MAG) and VALUE corresponds to the value (magnetic scalar potential). With the F command, the Lab variable corresponds to the force (FLUX) and VALUE corresponds to the value (magnetic flux).
Element loads are described in Nodal Loading. Maxwell force flags may be input on the element faces indicated by the circled numbers in Figure 96.1: SOLID96 Geometry using the SF and SFE commands. Surfaces at which magnetic forces are to be calculated may be 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. 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. Maxwell forces may be made available for a subsequent structural analysis with companion elements (LDREAD command).
The temperature (for material property evaluation only) and magnetic virtual displacement body loads may be input based on their value at the element's nodes or as a single element value [BF and BFE]. In general, unspecified nodal values of temperature default to the uniform value specified with the BFUNIF or TUNIF commands.
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.
Current for the magnetic scalar potential options are defined with the SOURC36 element, the command macro RACE, or through electromagnetic coupling. The various types of magnetic scalar potential solution options are defined with the MAGOPT command.
A summary of the element input is given in "SOLID96 Input Summary". A general description of element input is given in Element Input.
SOLID96 Input Summary
- Nodes
I, J, K, L, M, N, O, P
- Degrees of Freedom
MAG
- Real Constants
None
- Material Properties
TB command: See Element Support for Material Models for this element.
MP command: MUZERO, MURX, MURY, MURZ, MGXX, MGYY, MGZZ
- Surface Loads
- Maxwell Force Flags --
face 1 (J-I-L-K), face 2 (I-J-N-M), face 3 (J-K-O-N), face 4 (K-L-P-O), face 5 (L-I-M-P), face 6 (M-N-O-P)
- Body Loads
- Temperatures --
T(I), T(J), T(K), T(L), T (M), T(N), T(O), T(P)
- MVDI --
VD(I), VD(J), VD(K), VD(L), VD(M), VD(N), VD(O), VD(P)
- EF --
EFX, EFY, EFZ. See "SOLID96 Assumptions and Restrictions".
- Special Features
Adaptive descent Birth and death - KEYOPT(5)
Extra element output:
- 0 --
Basic element printout
- 1 --
Integration point printout
- 2 --
Nodal magnetic field printout
SOLID96 Output Data
The solution output associated with the element is in two forms:
Nodal potentials included in the overall nodal solution
Additional element output as shown in Table 96.1: SOLID96 Element Output Definitions
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.
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 96.1: SOLID96 Element Output Definitions
| Name | Definition | O | R |
|---|---|---|---|
| EL | Element Number | Y | Y |
| NODES | Nodes - I, J, K, L, M, N, O, P | Y | Y |
| MAT | Material number | Y | Y |
| VOLU: | Volume | Y | Y |
| XC, YC, ZC | Location where results are reported | Y | 2 |
| TEMP | Temperatures T(I), T(J), T(K), T(L), T(M), T(N), T(O), T(P) | Y | Y |
| LOC | Output location (X, Y, Z) | 1 | - |
| MUX, MUY, MUZ | Magnetic permeability | 1 | 1 |
| H:X, Y, Z | Magnetic field intensity components | 1 | 1 |
| H:SUM | Vector magnitude of H | 1 | 1 |
| B:X, Y, Z | Magnetic flux density components | 1 | 1 |
| B:SUM | Vector magnitude of B | 1 | 1 |
| FMX | Maxwell magnetic force components (X, Y, Z) | 1 | - |
| FVW | Virtual work force components (X, Y, Z) | 1 | 1 |
| Combined (FJB or FMX) force components | Combined force components | - | 1 |
The solution value is printed only if calculated (based upon input data). The element solution is at the centroid.
Available only at centroid as a *GET item.
Table 96.3: SOLID96 Item and Sequence Numbers lists output available through the ETABLE command using the Sequence Number method. See The General Postprocessor (POST1) in the Basic Analysis Guide and The Item and Sequence Number Table in this reference for more information. The following notation is used in Table 96.3: SOLID96 Item and Sequence Numbers:
- Name
output quantity as defined in Table 96.1: SOLID96 Element Output Definitions
- Item
predetermined Item label for ETABLE command
- E
sequence number for single-valued or constant element data
SOLID96 Assumptions and Restrictions
The element requires an iterative solution if nonlinear material properties are defined.
When using SOLID96 with SOURC36 elements, the source elements must be placed so that the resulting Hs field fulfills boundary conditions for the total field.
The element must not have a zero volume or a zero length side. This occurs most frequently when the element is not numbered properly. Elements may be numbered either as shown in Figure 96.1: SOLID96 Geometry or may have the planes IJKL and MNOP interchanged.
The difference magnetic scalar potential option is restricted to singly-connected permeable regions, so that as μ →
in these regions, the resulting
field H → 0. The reduced scalar, and general scalar potential
options do not have this restriction.Degeneration to the form of pyramid should be used with caution. The element sizes, when degenerated, should be small in order to minimize the field gradients. Pyramid elements are best used as filler elements or in meshing transition zones.
The solenoidal current density is required for a solution, or for any postprocessing operations.
The electric field body load is not used during solution and is applicable only to POST1 charged particle tracing.
In an MSP analysis, avoid using a closed domain and use an open domain, closed with natural flux parallel boundary conditions on the MAG degree of freedom, or infinite elements. If you use a closed domain, you may see incorrect results when the formulation is applied using SOLID5, SOLID96, or SOLID98 elements and the boundary conditions are not satisfied by the Hs field load calculated by the Biot-Savart procedure based on SOURC36 current source primitive input.