Release 11.0 Documentation for ANSYS
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SOLID226 has the following capabilities:
Structural-Thermal
Piezoresistive
Electroelastic
Piezoelectric
Thermal-Electric
Structural-Thermoelectric
Thermal-Piezoelectric
The element has twenty nodes with up to five degrees of freedom per node. Structural capabilities are elastic only and include large deflection and stress stiffening. Thermoelectric capabilities include Seebeck, Peltier, and Thomson effects, as well as Joule heating. In addition to thermal expansion, structural-thermal capabilities include the piezocaloric effect in dynamic analyses. The Coriolis effect is available for analyses with structural degrees of freedom. See SOLID226 in the Theory Reference for ANSYS and ANSYS Workbench for more details about this element.
The geometry, node locations, and the coordinate system for this element are shown in Figure 226.1: "SOLID226 Geometry". The element input data includes twenty nodes and structural, thermal, and electrical material properties. The type of units (MKS or user defined) is specified through the EMUNIT command. EMUNIT also determines the value of free-space permittivity EPZRO. The EMUNIT defaults are MKS units and EPZRO = 8.85e-12 Farads/meter.
KEYOPT(1) determines the element DOF set and the corresponding force labels and reaction solution. KEYOPT(1) is set equal to the sum of the field keys shown in Table 226.1: "SOLID226 Field Keys". For example, KEYOPT(1) is set to 11 for a structural-thermal analysis (structural field key + thermal field key = 1 + 10). For a structural-thermal analysis, UX, UY, and TEMP are the DOF labels and force and heat flow are the reaction solution.
Table 226.1 SOLID226 Field Keys
| Field | Field Key | DOF Label | Force Label | Reaction Solution |
|---|---|---|---|---|
| Structural | 1 | UX, UY, UZ | FX, FY, FZ | Force |
| Thermal | 10 | TEMP | HEAT | Heat Flow |
| Electric Conduction | 100 | VOLT | AMPS | Electric Current |
| Electrostatic | 1000 | VOLT | CHRG | Electric Charge |
The coupled-field analysis KEYOPT(1) settings, DOF labels, force labels, reaction solutions, and analysis types are shown in the following table.
Table 226.2 SOLID226 Coupled-Field Analyses
| Coupled-Field Analysis | KEYOPT(1) | DOF Label | Force Label | Reaction Solution | Analysis Type | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Structural-Thermal [1], [2] | 11 |
|
|
| Static Full Harmonic Full Transient | |||||||||
| Piezoresistive | 101 |
|
|
| Static Full Transient | |||||||||
| Electroelastic | 1001 [3] |
|
|
| Static Full Transient | |||||||||
| Piezoelectric | 1001 [3] |
|
|
| Static Modal Full Harmonic Full Transient | |||||||||
| Thermal-Electric | 110 | TEMP, VOLT | HEAT, AMPS | Heat Flow, Electric Current | Static Full Transient | |||||||||
| Structural-Thermoelectric [1] | 111 |
|
|
| Static Full Transient | |||||||||
| Thermal-Piezoelectric [1], [2] | 1011 |
|
|
| Static Full Harmonic Full Transient |
For static and full transient analyses, KEYOPT(2) can specify a strong (matrix) or weak (load vector) structural-thermal coupling.
For full harmonic analyses, strong structural-thermal coupling only applies.
The electrostatic-structural analysis available with KEYOPT(1) = 1001 defaults to an electroelastic analysis (electrostatic force coupling) unless a piezoelectric matrix is specified on TB,PIEZ.
As shown in the following table, material property requirements consist of those required for the individual fields (structural, thermal, electric conduction, or electrostatic) and those required for field coupling. Material properties are defined with the MP, MPDATA and TB commands.
Table 226.3 SOLID226 Material Properties
| Coupled-Field Analysis | KEYOPT(1) | Material Properties | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Structural-Thermal | 11 |
| ||||||||
| Piezoresistive | 101 |
| ||||||||
| Electroelastic | 1001 |
| ||||||||
| Piezoelectric | 1001 |
| ||||||||
| Thermal-Electric | 110 |
| ||||||||
| Structural-Thermoelectric | 111 |
| ||||||||
| Thermal-Piezoelectric | 1011 |
|
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.
Element loads are described in Node and Element Loads. Loads may be input on the element faces indicated by the circled numbers in Figure 226.1: "SOLID226 Geometry" using the SF and SFE commands. Positive pressures act into the element. Body loads may be input at the element's nodes or as a single element value using the BF and BFE commands.
SOLID226 surface and body loads are given in the following table. CHRGS and CHRGD are interpreted as negative surface charge density and negative volume charge density, respectively.
Table 226.4 SOLID226 Surface and Body Loads
| Coupled-Field Analysis | KEYOPT(1) | Load Type | Load | Command Label | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Structural-Thermal | 11 | Surface |
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| Body |
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| Piezoresistive | 101 | Surface |
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| ||||||
| Body |
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| Electroelastic and Piezoelectric | 1001 | Surface |
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| ||||||
| Body |
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| ||||||||
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| |||||||||
| Thermal-Electric | 110 | Surface |
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| ||||||
| Body |
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| ||||||||
| Structural-Thermoelectric | 111 | Surface |
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| ||||||
|
| |||||||||
| Body |
|
| ||||||||
| Thermal-Piezoelectric | 1011 | Surface |
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| ||||||
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| |||||||||
| Body |
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| ||||||||
|
|
A summary of the element input is given in "SOLID226 Input Summary". A general description of element input is given in Element Input.
I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A, B
Set by KEYOPT(1). See Table 226.2: "SOLID226 Coupled-Field Analyses".
None
| Large deflection |
| Stress stiffening |
Element degrees of freedom. See Table 226.2: "SOLID226 Coupled-Field Analyses".
Structural-thermal coupling method (KEYOPT(1) = 11, 111, or 1011):
Strong (matrix) coupling – produces an unsymmetric matrix. In a linear analysis, a strong coupled response is achieved after one iteration.
Weak (load vector) coupling – produces a symmetric matrix and requires at least two iterations to achieve a coupled response.
Electrostatic force in electroelastic analysis (KEYOPT(1) = 1001):
Applied to every element node.
Applied to the air-structure interface or to element nodes that have constrained structural degrees of freedom.
Not applied.
For more information, see Electroelastic Analysis in the Coupled-Field Analysis Guide.
The solution output associated with the element is in two forms:
Nodal degrees of freedom included in the overall nodal solution
Additional element output as shown in Table 226.5: "SOLID226 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 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 a - indicates that the item is not available.
Table 226.5 SOLID226 Element Output Definitions
| Name | Definition | O | R |
|---|---|---|---|
| EL | Element Number | - | Y |
| NODES | Nodes - I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A, B | - | Y |
| MAT | Material number | - | Y |
| VOLU: | Volume | - | Y |
| XC, YC, ZC | Location where results are reported | - | 2 |
| STRUCTURAL-THERMAL (KEYOPT(1) = 11) | |||
| S:X, Y, Z, XY, YZ, XZ | Stresses (SZ = 0.0 for plane stress elements) | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| TG:X, Y, Z, SUM | Thermal gradient components and vector magnitude | - | 1 |
| TF:X, Y, Z, SUM | Thermal flux components and vector magnitude | - | 1 |
| UT | Total strain energy [7] | - | 1 |
| PIEZORESISTIVE (KEYOPT(1) = 101) | |||
| TEMP | Input temperatures | - | Y |
| S:X, Y, Z, XY, YZ, XZ | Stresses | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPEL:EQV | Equivalent elastic strains [3] | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| EF:X, Y, Z, SUM | Electric field components (X, Y, Z) and vector magnitude | - | 1 |
| JC:X, Y, Z, SUM | Conduction current density components (X, Y, Z) and vector magnitude | - | 1 |
| JS:X, Y, Z, SUM | Current density components and vector magnitude [4] | 1 | 1 |
| JHEAT | Joule heat generation per unit volume [5] | - | 1 |
| ELECTROELASTIC (KEYOPT(1) = 1001) | |||
| TEMP | Input temperatures | - | Y |
| S:X, Y, Z, XY, YZ, XZ | Stresses | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| EF:X, Y, Z, SUM | Electric field components (X, Y, Z) and vector magnitude | - | 1 |
| D:X, Y, Z, SUM | Electric flux density components (X, Y, Z) and vector magnitude | - | 1 |
| FMAG:X, Y, Z, SUM | Electrostatic force components (X, Y, Z) and vector magnitude | - | 1 |
| PIEZOELECTRIC (KEYOPT(1) = 1001) | |||
| TEMP | Input temperatures | - | Y |
| S:X, Y, Z, XY, YZ, XZ | Stresses | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPEL:EQV | Equivalent elastic strains [3] | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| EF:X, Y, Z, SUM | Electric field components (X, Y, Z) and vector magnitude | - | 1 |
| D:X, Y, Z, SUM | Electric flux density components (X, Y, Z) and vector magnitude | - | 1 |
| JHEAT | Joule heat generation per unit volume [5], [6] | - | 1 |
| UE, UD, UM | Stored elastic, dielectric, and mutual energies | - | 1 |
| THERMAL-ELECTRIC (KEYOPT(1) = 110) | |||
| TG:X, Y, Z, SUM | Thermal gradient components and vector magnitude | - | 1 |
| TF:X, Y, Z, SUM | Thermal flux components and vector magnitude | - | 1 |
| EF:X, Y, Z, SUM | Electric field components and vector magnitude | - | 1 |
| JC:X, Y, Z, SUM | Conduction current density components and vector magnitude | - | 1 |
| JS:X, Y, Z, SUM | Current density components and vector magnitude [4] | 1 | 1 |
| JHEAT | Joule heat generation per unit volume [5], [6] | - | 1 |
| STRUCTURAL-THERMOELECTRIC (KEYOPT(1) = 111) | |||
| S:X, Y, Z, XY, YZ, XZ | Stresses (SZ = 0.0 for plane stress elements) | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| TG:X, Y, Z, SUM | Thermal gradient components and vector magnitude | - | 1 |
| TF:X, Y, Z, SUM | Thermal flux components and vector magnitude | - | 1 |
| EF:X, Y, Z, SUM | Electric field components and vector magnitude | - | 1 |
| JC:X, Y, Z, SUM | Conduction current density components and vector magnitude | - | 1 |
| JS:X, Y, Z, SUM | Current density components and vector magnitude [4] | 1 | 1 |
| JHEAT | Joule heat generation per unit volume [5], [6] | - | 1 |
| UT | Total strain energy [7] | - | 1 |
| THERMAL-PIEZOELECTRIC (KEYOPT(1) = 1011) | |||
| S:X, Y, Z, XY, YZ, XZ | Stresses (SZ = 0.0 for plane stress elements) | - | 1 |
| S:1, 2, 3 | Principal stresses | - | 1 |
| S:EQV | Equivalent stress | - | 1 |
| EPEL:X, Y, Z, XY, YZ, XZ | Elastic strains | - | 1 |
| EPEL:1, 2, 3 | Principal elastic strains | - | 1 |
| EPTH:X, Y, Z, XY, YZ, XZ | Thermal strains | - | 1 |
| EPTH:EQV | Equivalent thermal strain [3] | - | 1 |
| TG:X, Y, Z, SUM | Thermal gradient components and vector magnitude | - | 1 |
| TF:X, Y, Z, SUM | Thermal flux components and vector magnitude | - | 1 |
| EF:X, Y, Z, SUM | Electric field components and vector magnitude | - | 1 |
| D:X, Y, Z, SUM | Electric flux density components and vector magnitude | - | 1 |
| JHEAT | Joule heat generation per unit volume [5], [6] | - | 1 |
| UE, UD, UM | Stored elastic, dielectric, and mutual energies | - | 1 |
| UT | Total strain energy [7] | - | 1 |
Solution values are output only if calculated (based on input values).
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).
JS represents the sum of element conduction and displacement current densities.
Calculated Joule heat generation rate per unit volume (JHEAT) may be made available for a subsequent thermal analysis with companion thermal elements.
For a time-harmonic analysis, Joule losses (JHEAT) are time-averaged. These values are stored in both the real and imaginary data sets. For more information, see Quasistatic Electric Analysis in the Theory Reference for ANSYS and ANSYS Workbench.
For a time-harmonic analysis, total strain energy (UT) is time-averaged. These values are stored in both the real and imaginary data sets. For more information, see Thermoelasticity in the Theory Reference for ANSYS and ANSYS Workbench.
Table 226.5: "SOLID226 Element Output Definitions" 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 of this manual for more information. The following notation is used in Table 226.6: "SOLID226 Item and Sequence Numbers":
output quantity as defined in the Table 226.5: "SOLID226 Element Output Definitions"
predetermined Item label for ETABLE command
sequence number for single-valued or constant element data
Table 226.6 SOLID226 Item and Sequence Numbers
| Output Quantity Name | ETABLE Command Input | |
|---|---|---|
| Item | E | |
| UE | NMISC | 1 |
| UD | NMISC | 2 |
| UM | NMISC | 3 |
| UT | NMISC | 4 |
When NLGEOM is ON, SSTIF defaults to OFF.
In a piezoelectric analysis, electric charge loading is interpreted as negative electric charge or negative charge density.
A face with a removed midside node implies that the displacement varies linearly, rather than parabolically, along that face. See Quadratic Elements (Midside Nodes) in the Modeling and Meshing Guide for more information about the use of midside nodes.
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.
