My PLANE42 thermal strain analysis with temperature-dependent coefficient of
thermal expansion properties gives strange results, which are magnified as the
thermal gradient increases. Is this a known error?
You could be hitting Defect 32678, which was fixed in the UP20050412 build of
ANSYS 10.0. A Class 3 Error report is pending. This error exists because the
temperature-dependent coefficients of thermal expansion at an integration point
are evaluated at a temperature elsewhere within the element. Hence, the effect
of the error reduces with decreasing element size. No other material properties
or element types are affected.
Prior to ANSYS 5.3, PLANE42 material properties were simply evaluated at the element
centroid. Between ANSYS 5.3 and ANSYS 5.6, PLANE42 allowed the undocumented
KEYOPT(7) to be set to 1 which evaluated the temperature-dependent material
properties at the integration points. After ANSYS 5.6, PLANE42 had KEYOPT(7)
removed and the material properties were automatically evaluated at the integration
points if the properties were temperature dependent. Therefore, the first incorrect
version is ANSYS 5.3 and the first corrected version is ANSYS 10.0 (production build).
Consider using another element type to avoid the error. Also, as indicated above,
a finer mesh will reduce the effect of the error.