4.117 SOLID117 3-D Magnetic Solid

4.117 SOLID117 3-D Magnetic Solid (UP19980821 ) SOLID117 models three-dimensional magnetic fields. The element is defined by 20 nodes. It has 12 edge-flux DOFs (AZ), one at each midside node. In a dynamic analysis, eight time-integrated electric scalar potential DOFs (VOLT) are added at the corner nodes. SOLID117 is based on the edge-flux formulation, and applies to the low-frequency magnetic field analyses: magnetostatics, eddy currents (AC time harmonic and transient analyses). The element has nonlinear magnetic capability for modeling B-H curves or permanent magnet demagnetization curves for static and transient analyses. See Sections 5.1 and 5.2, 12.9 and 14.117 of the ANSYS Theory Reference, as well as Chapters 6, 7, and 8 of the ANSYS Electromagnetic Field Analysis Guide, for details about this element.

Figure 4.117-1 SOLID117 3-D Magnetic Solid



4.117.1 Input Data

4.117.1.1 Geometry

Figure 4.117-1 shows the geometry, node locations, and the coordinate system for this element. The element is defined by 20 nodes and the material properties. A tetrahedral-shaped element and a pyramid-shaped element may also be formed as shown in Figure 4.117-1. The positive orientation of an edge points from lower to higher corner nodes of the edge.

4.117.1.2 Real Constants

The following real constants apply when considering velocity effects of a conducting body (KEYOPT(2)):

VELOX, VELOY, VELOZ

Velocity components in the global Cartesian coordinate system X, Y, and Z direction respectively.

OMEGAX, OMEGAY, OMEGAZ

Angular (rotational) velocity (Hz) about the global Cartesian coordinate system X, Y, and Z axes respectively, located at the pivot point location (XLOC, YLOC, ZLOC).

XLOC, YLOC, ZLOC

Global Cartesian coordinate point locations of the rotating body in the X, Y, and Z directions respectively.

The above real constants start in real constant location nine.

4.117.1.3 Units

Specify the type of units (MKS or user defined) using the EMUNIT command. EMUNIT also determines the value of MUZERO (free-space permeability). The EMUNIT defaults are MKS units and MUZERO = 4x 10-7 Henries/meters.

4.117.1.4 Material Properties

In addition to MUZERO, orthotropic relative permeability is available; specify it via the MURX, MURY, and MURZ material options.

Specify nonlinear magnetic B-H properties with the TB command. You can specify nonlinear orthotropic magnetic properties with a combination of a B-H curve and linear relative permeability. The B-H curve will be used in each element coordinate direction where a zero value of relative permeability is specified. For isotropic nonlinear behavior, you do not need to specify any relative permeability. You can specify only one B-H curve per material.

You can specify orthotropic resistivity through RSVX, RSVY, and RSVZ material property labels. 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 vector components MGXX, MGYY, and MGZZ determine the direction of polarization. Permanent magnet polarization directions correspond to the element coordinate directions. The element coordinate system orientation is as described in Section 2.3.

4.117.1.5 Loads

You define nodal loads using the D and the F commands. With the D command, the Lab variable corresponds to the degree of freedom (AZ and VOLT) and VALUE corresponds to the value. (Before applying a non-zero constraint on the edge-flux DOF (AZ), study the ANSYS Theory Reference carefully.) With the F command, the Lab variable corresponds to the force (Amps) and VALUE corresponds to the value (current) applied with respect to the VOLT DOF.

Use the BFE command to prescribe source current density body loads based on their value at the element's centroid location. The vector components of the current density are with respect to the element coordinate system (see Section 4.117.3 for solenoidal restriction).

4.117.1.6 Flags

Section 2.7 describes element loads. You can specify Maxwell force flags on the element faces indicated by the circled numbers in Figure 4.117-1 using the SF and SFE commands. To identify surfaces at which magnetic forces are to be calculated, use 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. You should apply the surface flag to "air" elements adjacent to the body for which forces are required. Deleting the MXWF specification removes the flag. Use the FMAGBC command to automatically apply Maxwell surface flags to a named element component.

Via the BF command, you can identify air elements in which Local Jacobian forces are to be calculated by using nodal values of 1 and 0 for the MVDI label. See the ANSYS Electromagnetic Field Analysis Guide for details. You can prescribe magnetic virtual displacements as body loads via the BF and BFE commands. Use the FMAGBC command to automatically apply virtual displacements to a named element component.

4.117.1.7 Field-Coupling

You can use the LDREAD command to make Lorentz and Maxwell forces and Joule heating (JHEAT) available for a subsequent structural analysis with companion structural elements or heat transfer with companion thermal elements. You can read element current densities using the LDREAD command from an electric current conduction analysis. In addition, you can specify the temperature (for material property evaluation only).

Note-Force coupling is supported only for first order brick elements such as SOLID45.

In general, unspecified nodal values of temperatures default to the uniform value specified with the BFUNIF or TUNIF commands.

4.117.1.8 Gauging

The ANSYS program gauges the problem domain automatically at solution time, using a Tree gauging technique. (See the description of the GAUGE command.) This produces additional constraints on nodes in the model by setting AZ to zero. The additional constraints are removed after solution. Thus, gauging is transparent to users.

The table below summarizes the element input. Section 2.1 provides a general description of element input.

Table 4.117-1 SOLID117 Input Summary

Element Name

SOLID117

Nodes

I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A, B

Degrees of Freedom

AZ if KEYOPT(1)=0 (static region)
AZ, VOLT if KEYOPT(1)=1 (dynamic region)

Real Constants

(Blank), (Blank), (Blank), (Blank), (Blank), (Blank),
(Blank), (Blank), VELOX, VELOY, VELOZ, OMEGAX,
OMEGAY, OMEGAZ, XLOC, YLOC, ZLOC

Material Properties

MUZERO, MURX, MURY, MURZ, RSVX, RSVY, RSVZ, MGXX, MGYY, MGZZ plus BH data table (see Section 2.5)

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 (Z), T (A), T (B)
Magnetic Virtual Displacements: VD (I), VD (J), VD (K),
VD (L), VD (M),VD (N), VD (O), VD (P), --VD(A), VD(B)
Source Current Density, if KEYOPT(1)=0:
(See Section 4.117.3 for solenoidal restriction)
JSX(I), JSY(I), JSZ(I), PHASE(I), JSX(J), JSY(J), JSZ(J),
PHASE(J), JSX(K), JSY(K), JSZ(K), PHASE(K), JSX(L), JSY(L), JSZ(L), PHASE(L), JSX(M), JSY(M), JSZ(M), PHASE(M), JSX(N), JSY(N), JSZ(N), PHASE(N), JSX(O), JSY(O), JSZ(O),
PHASE(O), JSX(P), JSY(P), JSZ(P), PHASE(P)

Special Features

Requires an iterative solution if nonlinear material properties
are defined

KEYOPT(1)

Used for degree of freedom selection
0 - AZ degrees of freedom
1 - AZ, VOLT degrees of freedom

KEYOPT(2)

0 - Velocity effects ignored
1 - Conventional velocity formulation (not available
if KEYOPT(1) = 0, 2, 3, or 4)

KEYOPT(5)

0 - Basic element printout
1 - Integration point printout
2 - Nodal magnetic field printout

4.117.1.9 Solution Considerations

You can choose the analysis type (static, transient, or harmonic) using the ANTYPE command.

In a harmonic analysis, the output field quantities are peak values. The ANSYS program performs a complex solution and computes two sets of data: real and imaginary. The measurable field quantities can be computed as the real step with a cosine time change minus the imaginary step with a sine time change. You can set the frequency of the time change via the HARFRQ command. The measurable magnetic energy, the Joule heat, and average Lorentz forces can be computed as a sum of the calculated real and imaginary data. RMS time averaging is applied to Joule heat and average forces. Energy is computed to reflect peak values. Section 5.1 of the ANSYS Theory Reference details complex formalism for harmonic analyses.

Use the GAUGE command to control automatic gauging of the problem domain. The default is Tree gauging, which removes constraints after the SOLVE or MAGSOLV command is issued.

To choose a solver, specify one on the EQSLV command. The ICCG or frontal solvers are recommended.

To define transient and nonlinear options, you can use the MAGSOLV command (which defines the options and solves the problem automatically) or you can issue the CNVTOL, NEQIT, and NSUBS commands. Use the OUTPR command to control printout and the OUTRES command to control database storage.

4.117.2 Output Data

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

The element output directions are parallel to the element coordinate system. Section 2.2 provides a general description of solution output. See the ANSYS Basic Analysis Procedures Guide for ways to view results.

Table 4.117-2 uses the following notation:

A colon (:) in the Name column indicates the item can be accessed by the Component Name method [ETABLE, ESOL] (see Section 2.2.2). The O and R columns indicate the availability of the items in the file Jobname.OUT (O) or in the results file (R), a Y indicates that the item is always available, a number refers to a table footnote which describes when the item is conditionally available, and a - indicates that the item is not available.

Table 4.117-2 SOLID117 Element Output Definitions

Name

Definition

O

R

EL

Element number

Y Y
NODES

Nodes - I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A, B

Y Y
MAT

Material number

Y Y
VOLU

Volume

Y Y
CENT: X, Y, Z

Global location XC, YC, ZC

Y Y
TEMP

Input 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 secant permeability (B/H)

1 1
H: X, Y, Z, SUM

Magnetic field intensity components and vector magnitude

1 1
B: X, Y, Z, SUM

Magnetic flux density components and vector magnitude

1 1
JS: X, Y, Z

Source current density, valid for static analysis only

1 1
JT(X, Y, Z)

Total current density components

1 1
JHEAT

Joule heat generation per unit volume

1 1
FJB(X, Y, Z)

Lorentz magnetic force components

1 -
FMX(X, Y, Z)

Maxwell magnetic force components

1 -
FVW(X, Y, Z)

Virtual work force components

1 1
FMAG: X, Y, Z, SUM

Combined (FJB or FMX) force components and vector magnitude

- 1
1. The solution is output if its value is not zero. The element solution is at the centroid.

Note-JT represents the total measurable current density that is induced in a conductor, including eddy current effects, and velocity effects if calculated.. Components are also available: JS component from VOLT, JE component from A, JT = JS + JE. In a static analysis, JS represents the source current density.

Table 4.117-2a SOLID117 Miscellaneous Element Output

Description

Names of Items Output

O

R

Integration Point Solution

LOC, MUX, MUY, MUZ, H, HSUM, B, BSUM

1 -
Nodal Magnetic Field Solution

H, HSUM, B, BSUM

2 -
1. Output at each integration point, if KEYOPT(5)=1

2. Output at each corner node, if KEYOPT(5)=2

Table 4.117-3 lists output available through the ETABLE command using the Sequence Number method. See Chapter 5 of the ANSYS Basic Analysis Procedures Guide and Section 2.2.2.2 of this manual for more information. The following notation is used in Table 4.117-3:

Table 4.117-3 SOLID117 Item and Sequence Numbers for the ETABLE and ESOL Commands

Name

Item

E

Source Current Density (static analysis), or time-varying component due to electric potential (VOLT)

JSX

SMISC

1
JSY

SMISC

2
JSZ

SMISC

3
JSSUM

SMISC

4
Secant Permeability B/H

MUX

NMISC

1
MUY

NMISC

2
MUZ

NMISC

3
Virtual Work Force

FVWX

NMISC

4
FVWY

NMISC

5
FVWZ

NMISC

6
FVWSUM

NMISC

7
Total (Measurable) Current Density

JTX

NMISC

12
JTY

NMISC

13
JTZ

NMISC

14
JTSUM

NMISC

15
Differential Permeability dB/dH

DMUX

NMISC

18
DMUY

NMISC

19
DMUZ

NMISC

20
1. NMISC slots 16 and 17 are reserved for future development.

4.117.3 Assumptions and Restrictions

The element must not have a zero volume or a zero length side. Error occurs frequently when the element is not numbered properly. Elements may be numbered either as shown in Figure 4.117-1 or may have the planes IJKL and MNOP interchanged. Midside nodes may not be removed from this element. See Section 2.4.2 of the ANSYS Modeling and Meshing Guide for more information about the use of midside nodes.

The continuity equation must be satisfied for a proper electromagnetic analysis as explained in Section 5.1 of the ANSYS Theory Reference. For this reason the source current density, JS, must be solenoidal (i.e.

JS = 0). You should verify that this condition is satisfied when prescribing the source current density load. If this condition is not satisfied SOLID117 can produce erroneous solutions without warning. Refer to Section 6.4 of the ANSYS Electromagnetic Field Analysis Guide for information on how to obtain solenoidal currents when the source current density is not constant.

For harmonic and transient (time-varying) analyses the following restrictions apply:

4.117.4 Product Restrictions

When used in the product(s) listed below, the stated product-specific restrictions apply to this element in addition to the general assumptions and restrictions given in the previous section.

ANSYS/Emag 3-D