Mechanical APDL Basic Analysis Guide - Ansys

Chapter 1: Getting Started with ANSYS
Figure 1.1 Sample MPPLOT Display
Following are some notes about temperature-dependent material properties:
• To modify a property data point on an existing curve, simply redefine the desired data point by issuing
MPDATA with the appropriate location number. For example, to change the ENTH value in location 6
of the above enthalpy-temperature curve from 82.31 to 83.09, the command would be MP-
DATA,ENTH,4,6,83.09
• To modify a temperature data point on an existing curve, you need two commands: MPTEMP with the
appropriate location number to specify the new temperature value, and MPDRES to associate the new
temperature table with the material property. For example, to change the temperature in location 7 of
the above enthalpy-temperature curve from 2345 to 2340, the commands would be:
MPTEMP,7,2340 ! Modifies location 7, retains other locations
MPDRES,ENTH,4 ! Associates ENTH for material 4 with new temps
You need to use the MPDRES command to modify stored properties. Whenever you define a temperaturedependent
property, the temperature-property data pairs are immediately stored in the database. Modifying
the temperature data points affects only material properties that are subsequently defined, not what is
already stored. The MPDRES command forces modification of what is already stored in the database. Two
additional fields on MPDRES allow you to modify a stored property and store it under a new label or a new
material reference number.
The MPTRES command allows you to replace the current temperature table with that of a previously defined
material property in the database. You can then use the previous temperature data points for another
property.
For temperature-dependent secant coefficients of thermal expansion (ALPX, ALPY, ALPZ), if the base temperature
for which they are defined (the definition temperature) differs from the reference temperature (the
temperature at which zero thermal strains exist, defined by MP,REFT or TREF), then use the MPAMOD
command to convert the data to the reference temperature. This conversion is not necessary when you input
the thermal strains (THSX, THSY, THSZ) or the instantaneous coefficients of thermal expansion (CTEX, CTEY,
CTEZ).
ANSYS accounts for temperature-dependent material properties during solution when element matrices are
formulated. The materials are evaluated at once (at or near the centroid of the element) or at each of the
integration points. For more information about how ANSYS evaluates temperature-dependent material
properties, see Linear Material Properties.
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