QUESTION:
A PLANE223 piezoelectric model that ran successfully at release 10 no longer runs at release 11. I now get the following error message:
*** ERROR *** CP = 187.844 TIME= 12:20:09
There are elements with negative and positive electric charge reaction
solutions for the VOLT degree of freedom inthe model. This analysis
is not valid.
Why is this happening?
ANSWER:
Your model has two components - a pair of electrodes and the piezoelectric substrate atop which they reside. Both the electrodes and piezoelectric substrate are modeled with PLANE223, keyoption(1)=1001.
There is a new feature for PLANE223 at v11 ' electroelastic coupling (useful for the simulation of electrostatically actuated MEMS devices). This is now the default behavior for PLANE223 when keyopt(1)=1001 AND when no piezoelectric properties are defined [TB,PIEZ]. For this option, the element nodal electric reaction (or 'through variable' if you prefer) is positive charge (see table 223.2 in the V11 Elements Reference). The electrodes in your model were defined in this manner.
If you define a piezo matrix [TB,PIEZ], this option of PLANE223 becomes piezoelectric and has negative electriccharge as its nodal electric reaction. This is the option you used to define the piezoelectric substrate in your model.
The conflicting reaction variables make the results that would be obtained from this combination of element types meaningless, hence the error trap.
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QUESTION: A PLANE223 piezoelectric model that ran successfully at release 10 no longer runs at release 11. I now get the following error message: *** ERROR *** CP = 187.844 TIME= 12:20:09 There are elements with negative and positive electric charge reaction solutions for the VOLT degree of freedom inthe model. This analysis is not valid. Why is this happening? ANSWER: Your model has two components - a pair of electrodes and the piezoelectric substrate atop which they reside. Both the electrodes and piezoelectric substrate are modeled with PLANE223, keyoption(1)=1001. There is a new feature for PLANE223 at v11 ` electroelastic coupling (useful for the simulation of electrostatically actuated MEMS devices). This is now the default behavior for PLANE223 when keyopt(1)=1001 AND when no piezoelectric properties are defined [TB,PIEZ]. For this option, the element nodal electric reaction (or `through variable` if you prefer) is positive charge (see table 223.2 in the V11 Elements Reference). The electrodes in your model were defined in this manner. If you define a piezo matrix [TB,PIEZ], this option of PLANE223 becomes piezoelectric and has negative electriccharge as its nodal electric reaction. This is the option you used to define the piezoelectric substrate in your model. The conflicting reaction variables make the results that would be obtained from this combination of element types meaningless, hence the error trap. |
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