## *TEMPERATURE

Keyword type: step

This option is used to define temperatures and, for shell and beam elements, temperature gradients within a purely mechanical *STEP definition. *TEMPERATURE should not be used within a pure thermal or combined thermomechanical analysis. In these types of analysis the *BOUNDARY card for degree of freedom 11 should be used instead.

Optional parameter are OP, AMPLITUDE, TIME DELAY, USER, SUBMODEL, STEP, DATA SET, FILE and BSTEP. OP can take the value NEW or MOD. OP=MOD is default and implies that thermal load in different nodes is accumulated over all steps starting from the last perturbation step. Specifying the temperature for a node for which a temperature was defined in a previous step replaces this last value. OP=NEW implies that the temperatures are reinitialised to the initial values. If multiple *TEMPERATURE cards are present in a step this parameter takes effect for the first *TEMPERATURE card only.

For shell elements a temperature gradient can be defined in addition to a temperature. The temperature applies to nodes in the reference surface, the gradient acts in normal direction. For beam elements two gradients can be defined: one in 1-direction and one in 2-direction. Default for the gradients is zero.

The AMPLITUDE parameter allows for the specification of an amplitude by which the temperature is scaled (mainly used for dynamic calculations). Thus, in that case the values entered on the *TEMPERATURE card are interpreted as reference values to be multiplied with the (time dependent) amplitude value to obtain the actual value. At the end of the step the reference value is replaced by the actual value at that time, for use in subsequent steps.

The TIME DELAY parameter modifies the AMPLITUDE parameter. As such, TIME DELAY must be preceded by an AMPLITUDE name. TIME DELAY is a time shift by which the AMPLITUDE definition it refers to is moved in positive time direction. For instance, a TIME DELAY of 10 means that for time t the amplitude is taken which applies to time t-10. The TIME DELAY parameter must only appear once on one and the same keyword card.

If the USER parameter is selected the temperature values are determined by calling the user subroutine utemp.f, which must be provided by the user. This applies to all nodes listed beneath the *TEMPERATURE keyword. Any temperature values specified behind the nodal numbers are not taken into account. If the USER parameter is selected, the AMPLITUDE parameter has no effect and should not be used.

The SUBMODEL parameter is used to specify that the nodes underneath the *TEMPERATURE card should get their temperature values by interpolation from a global model. Each of these nodes must be listed underneath exactly one nodal *SUBMODEL card. The SUBMODEL parameter automatically requires the use of the STEP or DATA SET parameter.

In case the global calculation was a *STATIC calculation the STEP parameter specifies the step in the global model which will be used for the interpolation. If results for more than one increment within the step are stored, the last increment is taken.

In case the global calculation was a *FREQUENCY calculation the DATA SET parameter specifies the mode in the global model which will be used for the interpolation. It is the number preceding the string MODAL in the .frd-file and it corresponds to the dataset number if viewing the .frd-file with CalculiX GraphiX. Notice that the global frequency calculation is not allowed to contain preloading nor cyclic symmetry.

If the SUBMODEL card is used no temperature values need be specified. The SUBMODEL parameter and the AMPLITUDE parameter are mutually exclusive.

Temperature gradients are not influenced by the AMPLITUDE parameter.

If more than one *TEMPERATURE card occurs in an input deck, the following rules apply: if a *TEMPERATURE is applied to the same node as in a previous application then the previous value and previous amplitude are replaced.

Finally, temperatures can also be read from an .frd file. The file name has to be specified with the FILE parameter, the step within this file from which the temperatures are to be read can be specified with the BSTEP parameter, default is 1. All temperatures for that step available in the .frd file will be read and stored. In case part of the temperatures is listed explicitly in the input deck and/or part is defined by a user routine and/or part is read from file (by using several *TEMPERATURE cards within one and the same step) it is important to know that reading from file takes precedence. This means that (no matter the order in which the *TEMPERATURE cards are defined in the input deck):

• temperatures defined explicitly in the input deck will be overwritten by file values for the same node
• nodes for which the temperature is supposed to be defined by a user routine will get the file value for this node, if any.

The format is as following:

First line:

• *TEMPERATURE
• enter any parameters, if needed.

Following line (only in the absence of the FILE parameter):

• Node number or node set label.
• Temperature value at the node.
• Temperature gradient in normal direction (shells) or in 2-direction (beams).
• Temperature gradient in 1-direction (beams).
Repeat this line if needed.

Example:

*TEMPERATURE
N1,293.
300,473.
301,473.
302,473.


assigns a temperature T=293 to all nodes in (node) set N1, and T=473 to nodes 300, 301 and 302.

*TEMPERATURE,FILE=temperatures.frd,BSTEP=4


will read the temperatures from step 4 in file “temperatures.frd”.

Example files: beam8t, beam20t, beamnlt, beamt4, beamfrdread.