Notes

MP defines a linear material property as a constant or in terms of a fourth order polynomial as a function of temperature. (See the TB command for nonlinear material property input.) Linear material properties typically require a single substep for solution, whereas nonlinear material properties require multiple substeps.

If the constants C1 - C4 are input, the polynomial

is evaluated at discrete temperature points with linear interpolation between points (that is, a piecewise linear representation) and a constant-valued extrapolation beyond the extreme points. First-order properties use two discrete points (±9999°). The MPTEMP or MPTGEN commands must be used for second and higher order properties to define appropriate temperature steps. To ensure that the number of temperatures defined via the MPTEMP and MPTGEN commands is minimally sufficient for a reasonable representation of the curve, Mechanical APDL generates an error message if the number is less than N, and a warning message if the number is less than 2N. The value N represents the highest coefficient used; for example, if C3 is nonzero and C4 is zero, a cubic curve is being used which is defined using 4 coefficients so that N = 4.

Some elements (for example, FLUID116) support tabular input for material properties. Use the *DIM command to create the table of property values as a function of the independent variables. Then input this table name (C0 = %tabname%) when defining the property via the MP command. Tabular material properties are calculated before the first iteration (that is, using initial values (IC)). For a list of elements that support tabular material properties and associated primary variables, see Defining Linear Material Properties Using Tabular Input in the Material Reference.

When defining a reference temperature (MP,REFT), you can convert temperature-dependent secant coefficients of thermal expansion (SCTE) data from the definition temperature to the reference temperature. To do so, issue the MPAMOD command.

This command is also valid in SOLUTION.

Considerations for Enthalpy (Lab = ENTH)

Default behavior for Emissivity (Lab = EMIS)

There is no command default value for emissivity, and you must specify it by issuing MP,EMIS. Otherwise, an error message appears. If you issue MP,EMIS without specifying C0, C1, C2, C3, C4 values, emissivity defaults to 0.

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