Tetrahedral Coupled-Field Solid
|Although this legacy element is available for use in your analysis, ANSYS, Inc. recommends using a current-technology element such as SOLID227.|
SOLID98 is a 10-node tetrahedral version of the 8-node SOLID5 element. The element has a quadratic displacement behavior and is well suited to model irregular meshes (such as produced from various CAD/CAM systems). When used in structural and piezoelectric analyses, SOLID98 has large deflection and stress stiffening capabilities.
The element is defined by ten nodes with up to six degrees of freedom at each node (see KEYOPT(1)). See SOLID98 in the Mechanical APDL Theory Reference for more details about this element. The 3-D magnetic, thermal, electric, piezoelectric, and structural field capability is similar to that described for SOLID5.
The geometry, node locations, and the coordinate system for this element are shown in Figure 98.1: SOLID98 Geometry. The element input data is essentially the same as for SOLID5 except that there are 10 nodes instead of 8.
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. With the D command, the Lab variable corresponds to the degree of freedom (UX, UY, UZ, TEMP, VOLT, MAG) and VALUE corresponds to the value (displacements, temperature, voltage, scalar magnetic potential). With the F command, the Lab variable corresponds to the force (FX, FY, FZ, HEAT, AMPS, FLUX) and VALUE corresponds to the value (force, heat flow, current or charge, magnetic flux). 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 can be specified per material.
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 98.1: SOLID98 Geometry using the SF and SFE commands. Positive pressures act into the element. 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. 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.
The body loads temperature, heat generation rate, and magnetic virtual displacement may be input based on their value at the element's nodes or as a single element value [BF and BFE]. When the temperature degree of freedom is active (KEYOPT(1) = 0, 1 or 8), applied body force temperatures [BF, BFE] are ignored. In general, unspecified nodal values of temperatures and heat generation rate default to the uniform value specified with the BFUNIF or TUNIF commands. Calculated Joule heating (JHEAT) is applied in subsequent iterations as heat generation rate loading.
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.
I, J, K, L, M, N, O, P, Q, R
|UX, UY, UZ, TEMP, VOLT, MAG if KEYOPT(1) = 0|
|TEMP, VOLT, MAG if KEYOPT(1) = 1|
|UX, UY, UZ if KEYOPT(1) = 2|
|UX, UY, UZ, VOLT if KEYOPT(1) = 3|
|TEMP if KEYOPT(1) = 8|
|VOLT if KEYOPT(1) = 9|
|MAG if KEYOPT(1) = 10|
|TB command: See Element Support for Material Models for this element.|
|MP command: EX, EY, EZ, (PRXY, PRYZ, PRXZ or NUXY, NUYZ, NUXZ), ALPX, ALPY, ALPZ (or CTEX, CTEY, CTEZ or THSX, THSY, THSZ), DENS, GXY, GYZ, GXZ, ALPD, BETD, KXX, KYY, KZZ, C, NTH, MUZERO, MURX, MURY, MURZ, RSVX, RSVY, RSVZ, E, MGXX, MGYY, MGZZ, PERX, PERY, PERZ, DMPR|
face 1 (J-I-K), face 2 (I-J-L), face 3 (J-K-L), face 4 (K-I-L)
T(I), T(J), T(K), T(L), T(M), T(N), T(O), T(P), T(Q), T(R)
HG(I), HG(J), HG(K), HG(L), HG(M), HG(N), HG(O), HG(P), HG(Q), HG(R)
VD(I), VD(J), VD(K), VD(L), VD(M), VD(N), VD(O), VD(P), VD(Q), VD(R)
EFX, EFY, EFZ. See "SOLID98 Assumptions and Restrictions".
|Birth and death|
Degree of freedom selection:
UX, UY, UZ, TEMP, VOLT, MAG
TEMP, VOLT, MAG
UX, UY, UZ
UX, UY, UZ, VOLT
Specific heat matrix:
Consistent specific heat matrix
Diagonalized specific heat matrix
Extra element output:
Basic element printout
Nodal stress or magnetic field printout
The solution output associated with the element is in two forms:
Nodal degree of freedom results included in the overall nodal solution
Additional element output as shown in Table 98.1: SOLID98 Element Output Definitions
Several items are illustrated in Figure 98.2: SOLID98 Element Output. The component output directions are parallel to the element coordinate system. The reaction forces, heat flow, current, and magnetic flux at the nodes can be printed with the OUTPR command. 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 98.1: SOLID98 Element Output Definitions
|NODES||Corner nodes - I, J, K, L||Y||Y|
|XC, YC, ZC||Location where results are reported||Y||3|
|PRES||Pressures P1 at nodes J, I, K; P2 at I, J, L; P3 at J, K, L; P4 at K, I, L||Y||Y|
|TEMP(INPUT)||Temperatures T(I), T(J), T(K), T(L), T(M), T(N), T(O), T(P), T(Q), T(R)||Y||Y|
|HGEN(INPUT)||Heat generations HG(I), HG(J), HG(K), HG(L), HG(M), HG(N), HG(O), HG(P), HG(Q), HG(R)||Y||-|
|S:X, Y, Z, XY, YZ, XZ||Stresses||1||1|
|S:1, 2, 3||Principal stresses||1||1|
|EPEL:X, Y, Z, XY, YZ, XZ||Elastic strains||1||1|
|EPEL:1, 2, 3||Principal elastic strains||1||-|
|EPEL:EQV||Equivalent elastic strains ||1||1|
|EPTH:X, Y, Z, XY, YZ, XZ||Thermal strains||1||1|
|EPTH:EQV||Equivalent thermal strain ||1||1|
|LOC||Output location (X, Y, Z)||1||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|
|FJB||Lorentz magnetic force components (X, Y, Z)||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 (FJB or FMX) force components||-||1|
|EF:X, Y, Z||Electric field components||1||1|
|EF:SUM||Vector magnitude of EF||1||1|
|JS:X, Y, Z||Source current density components||1||1|
|JSSUM||Vector magnitude of JS||1||1|
|JHEAT:||Joule heat generation per unit volume||1||1|
|D:X, Y, Z||Electric flux density components||1||1|
|D:SUM||Vector magnitude of D||1||1|
|U(E, D, M)||Elastic (UE), dielectric (UD), and electromechanical coupled (UM) energies||1||1|
|TG:X, Y, Z||Thermal gradient components||1||1|
|TG:SUM||Vector magnitude of TG||1||1|
|TF:X, Y, Z||Thermal flux components||1||1|
|TF:SUM||Vector magnitude of TF (Heat flow rate/unit cross-section area)||1||1|
|HFILM||Film coefficient at each node of face||2||-|
|TBULK||Bulk temperature at each node of face||2||-|
|TAVG||Average face temperature||2||2|
|HEAT RATE||Heat flow rate across face by convection||2||2|
|HEAT RATE/AREA||Heat flow rate per unit area across face by convection||2||-|
|HFLUX||Heat flux at each node of face||2||-|
|HFAVG||Average film coefficient of the face||2||2|
|TBAVG||Average face bulk temperature||-||2|
|HFLXAVG||Heat flow rate per unit area across face caused by input heat flux||-||2|
Available only at centroid as a *GET item.
The equivalent strains use an effective Poisson's ratio: for elastic and thermal this value is set by the user (MP,PRXY).
Table 98.2: SOLID98 Miscellaneous Element Output
Table 98.3: SOLID98 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 98.3: SOLID98 Item and Sequence Numbers:
Table 98.3: SOLID98 Item and Sequence Numbers
The element requires an iterative solution for field coupling (displacement, temperature, electric, magnetic, but not piezoelectric)
When using SOLID98 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. Elements may be numbered either as shown in Figure 98.1: SOLID98 Geometry or may have node L below the IJK plane.
An edge with a removed midside node implies that the displacement varies linearly, rather than parabolically, along that edge. See Quadratic Elements (Midside Nodes) for more information about the use of midside nodes.
The difference scalar magnetic 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.
Temperatures and heat generation rates, if internally calculated, include any user defined heat generation rates.
Large-deflection capabilities available for KEYOPT(1) = 2 and 3 are not available for KEYOPT(1) = 0. Stress stiffening is available for KEYOPT(1) = 0, 2, and 3.
This element may not be compatible with other elements with the VOLT degree of freedom. To be compatible, the elements must have the same reaction solution for the VOLT DOF. Elements that have an electric charge reaction solution must all have the same electric charge reaction sign. For more information, see Element Compatibility in the Low-Frequency Electromagnetic Analysis Guide.
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.