PLANE35
2D 6-Node
Triangular Thermal Solid
PLANE35 Element Description
PLANE35 is a 6-node triangular element compatible with the 8-node PLANE77 element. The triangular shape makes it well suited to model irregular meshes (such as produced from various CAD/CAM systems). The element has one degree of freedom, temperature, at each node.
The 6-node thermal element is applicable to a 2D, steady-state or transient thermal analysis. If the model containing this element is also to be analyzed structurally, the element should be replaced by an equivalent structural element (such as PLANE183). The element may be used as a plane element or as an axisymmetric ring element. See PLANE35 in the Mechanical APDL Theory Reference for more details about this element.
PLANE35 Input Data
The geometry, node locations, and the coordinate system for this element are shown in Figure 35.1: PLANE35 Geometry.
Orthotropic material directions correspond to the element coordinate directions. The element coordinate system orientation is as described in Coordinate Systems. Specific heat and density are ignored for steady-state solutions. Properties not input default as described in the Material Reference.
Element loads are described in Element Loading. Convection or heat flux (but not both) and radiation may be input as surface loads at the element faces as shown by the circled numbers on Figure 35.1: PLANE35 Geometry. Heat generation rates may be input as element body loads at the nodes. If the node I heat generation rate HG(I) is input, and all others are unspecified, they default to HG(I). If all corner node heat generation rates are specified, each midside node heat generation rate defaults to the average heat generation rate of its adjacent corner nodes. An edge with a removed midside node implies that the temperature varies linearly, rather than parabolically, along that edge. See Quadratic Elements (Midside Nodes) in the Modeling and Meshing Guide for more information about the use of midside nodes.
A summary of the element input is given in "PLANE35 Input Summary". A general description of element input is given in Element Input. For axisymmetric applications see Harmonic Axisymmetric Elements.
PLANE35 Input Summary
- Nodes
I, J, K, L, M, N
- Degrees of Freedom
TEMP
- Real Constants
None
- Material Properties
MP command: KXX, KYY, DENS, C, ENTH
- Surface Loads
- Convection or Heat Flux (but not both) and Radiation (using Lab = RDSF) --
face 1 (J-I), face 2 (K-J), face 3 (I-K)
- Body Loads
- Heat Generations --
HG(I), HG(J), HG(K), HG(L), HG(M), HG(N)
- Special Features
- KEYOPT(1)
Specific heat matrix:
- 0 --
Consistent specific heat matrix
- 1 --
Diagonalized specific heat matrix
- KEYOPT(3)
Element behavior:
- 0 --
Plane
- 1 --
Axisymmetric
PLANE35 Output Data
The solution output associated with the element is in two forms:
Nodal temperatures included in the overall nodal solution
Additional element output as shown in Table 35.1: PLANE35 Element Output Definitions
For an axisymmetric analysis the face area and the heat flow rate are on a full 360° basis. Convection heat flux is positive out of the element; applied heat flux is positive into the element. 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 letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.
Table 35.1: PLANE35 Element Output Definitions
| Name | Definition | O | R |
|---|---|---|---|
| EL | Element Number | Y | Y |
| NODES | Nodes - I, J, K, L, M, N | Y | Y |
| MAT | Material number | Y | Y |
| VOLU: | Volume | Y | Y |
| XC, YC | Location where results are reported | Y | 2 |
| HGEN | Heat generations HG(I), HG(J), HG(K), HG(L), HG(M), HG(N) | Y | - |
| TG:X, Y, SUM | Thermal gradient components and vector sum at centroid | Y | Y |
| TF:X, Y, SUM | Thermal flux (heat flow rate/cross-sectional area) components and vector sum at centroid | Y | Y |
| FACE | Face label | 1 | 1 |
| AREA | Face area | 1 | 1 |
| NODES | Face nodes | 1 | 1 |
| HFILM | Film coefficient | 1 | 1 |
| TAVG | Average face temperature | 1 | 1 |
| TBULK | Fluid bulk temperature | 1 | - |
| HEAT RATE | Heat flow rate across face by convection | 1 | 1 |
| HEAT RATE/AREA | Heat flow rate per unit area across face by convection | 1 | - |
| HFLUX | Heat flux at each node of face | 1 | - |
| HFAVG | Average film coefficient of the face | - | 1 |
| TBAVG | Average face bulk temperature | - | 1 |
| HFLXAVG | Heat flow rate per unit area across face caused by input heat flux | - | 1 |
Available only at centroid as a *GET item.
Table 35.2: PLANE35 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 35.2: PLANE35 Item and Sequence Numbers:
- Name
output quantity as defined in the Table 35.1: PLANE35 Element Output Definitions
- Item
predetermined Item label for ETABLE command
- FC
N sequence number for solution items for element Face
N
PLANE35 Assumptions and Restrictions
The area of the element must be positive.
The element must lie in an X-Y plane as shown in Figure 35.1: PLANE35 Geometry and the Y-axis must be the axis of symmetry for axisymmetric analyses.
An axisymmetric structure should be modeled in the +X quadrants.
A face with a removed midside node implies that the temperature varies linearly, rather than parabolically, along that face.
The specific heat and enthalpy are evaluated at each integration point to allow for abrupt changes (such as melting) within a coarse grid of elements.
A free surface of the element (that is, not adjacent to another element and not subjected to a boundary constraint) is assumed to be adiabatic.
Thermal transients having a fine integration time step and a severe thermal gradient at the surface will require a fine mesh at the surface.