Mann Kyo Cho
26 Jun 2015
— Edited @
03 Nov 2021
I had a few questions regarding VABS 4.0, specifically in regards to the piezoelectric analysis flags 3 and 32.
1) Regarding the output format, I was under the impression that for the 32 case (I believe the actuator case) with a specified voltage at each element, I would get the 6×6 stiffness array and a 6×1 array containing F1,F2,F3,M1,M2,M3 which I could then input into GEBT. However the output file labels this as “nonmechanical stresses”. Does this mean that these are actually stress outputs for the cross-section and thus need to be converted into forces?
2) Additionally there was another output labeled as thermal strains, and I was a bit concerned regarding this. The analysis flag I used was 32. However at the end of the input file, as per the manual, I specified the applied voltages at each element. However the manual seemed to indicate the same format to apply temperatures. Was there any additional flags or steps I needed to ensure these were voltages and not temperatures?
3)In the 2007 Paper, “A geometrically exact active beam theory for multibody dynamics simulation” specifically in section 5.2 regarding a three-layer composite table 4. Are the epsilon values the relative permittivity values? In which case for the dielectric constant values needed for VABS would I input these values multiplied by the relative permittivity of vacuum?
4)Secondly I noticed not all of the piezoelectric coefficients were listed, does this mean that all other piezoelectric coefficients can be assumed to be zero when running this particular set up?
5)A quick question on dimensional constancy. If I specified the dimensions in meters, pascals and the piezoelectric constants in C m-2, should I specify the voltage in just Volts ?
28 Jun 2015
1) The quantities labeled 'nonmechanical stresses' are actually the stress resultants due to nonmechanical fields. These are the 'F1 F2 F3 M1 M2 M3' in your question. BTW, I don't think the current GEBT has such nonmechanical degree-of-freedoms.
2) I think you are doing right. Again, this is semantics, the 'thermal strains' are actually the 'nonmechanical strains' which are conjugate to the 'nonmechanical stress' in your previous question.
3) , 4), and 5): For the units, please refer to the attached paper. A detailed discussion on the units has been presented on Page 3 to 5.
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