Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
22 juin 2012, 08:01 UTC−4
Hi
a few comments to get htere quicker:
1) do add a new "Definitions View", and therein under CAMERA sub node remove the "Preserve aspect ratio" this makes life so much easier in MEMS, you can then switch between the two views easily
2) for such geometries, make a global 3D block and add the layers as "Advanced Layer" (check the doc, give several layers each with its own incremental thickness
3) your mesh density is far to low, you need at least 3-5 mesh elements in the thickness, else you can consider "just" a "thin layer physics BC" i.e. Pt layer ... I would also consider brick or sweep elements
4) add a Domain node "Linear elastic material model" and select all linear elastic materials, at least our Pt, and SiO2, you need a second one for your Si that is normally anisotropic, but not PZT, for your other layers I do not know exactly which structure they have for your case. Then do not forget the order of the tensors, PZT and anisotropic material tensor index orders are different be aware (check the doc)
5) and what about adding some electrodes, a GND perhaps a terminal or voltage distribution layer
--
Good luck
Ivar
Hi
a few comments to get htere quicker:
1) do add a new "Definitions View", and therein under CAMERA sub node remove the "Preserve aspect ratio" this makes life so much easier in MEMS, you can then switch between the two views easily
2) for such geometries, make a global 3D block and add the layers as "Advanced Layer" (check the doc, give several layers each with its own incremental thickness
3) your mesh density is far to low, you need at least 3-5 mesh elements in the thickness, else you can consider "just" a "thin layer physics BC" i.e. Pt layer ... I would also consider brick or sweep elements
4) add a Domain node "Linear elastic material model" and select all linear elastic materials, at least our Pt, and SiO2, you need a second one for your Si that is normally anisotropic, but not PZT, for your other layers I do not know exactly which structure they have for your case. Then do not forget the order of the tensors, PZT and anisotropic material tensor index orders are different be aware (check the doc)
5) and what about adding some electrodes, a GND perhaps a terminal or voltage distribution layer
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
22 juin 2012, 10:53 UTC−4
4) add a Domain node "Linear elastic material model" and select all linear elastic materials, at least our Pt, and SiO2, you need a second one for your Si that is normally anisotropic, but not PZT, for your other layers I do not know exactly which structure they have for your case. Then do not forget the order of the tensors, PZT and anisotropic material tensor index orders are different be aware (check the doc)
Is there a specific document you are referring to that may help me with finding the differences between the two?
5) and what about adding some electrodes, a GND perhaps a terminal or voltage distribution layer
I want to find the area of the greatest stress and strain first and that will be the area where I will add the electrode.
[QUOTE]
4) add a Domain node "Linear elastic material model" and select all linear elastic materials, at least our Pt, and SiO2, you need a second one for your Si that is normally anisotropic, but not PZT, for your other layers I do not know exactly which structure they have for your case. Then do not forget the order of the tensors, PZT and anisotropic material tensor index orders are different be aware (check the doc)
[/QUOTE]
Is there a specific document you are referring to that may help me with finding the differences between the two?
[QUOTE]
5) and what about adding some electrodes, a GND perhaps a terminal or voltage distribution layer
[/QUOTE]
I want to find the area of the greatest stress and strain first and that will be the area where I will add the electrode.
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
22 juin 2012, 14:32 UTC−4
Hi
there are 3 sources for the index order, the material node explanations, the help doc for the PZT and material node, and then the main pdf doc for PZT (and structural). The conventions used by COMSOL on tensor index order are the most used ones, but one should notice these index orders are different for PZT and solid
Then for the electrodes, at least ensure you have a GND somewhere or some BC that ensure a fixed point also for the voltage, else there might be no single solution to the PDE and the solver will have issues to converge
Do not forget that in multi-physics, you still need that all dependent variables have enough BCs to ensure a single solution (per physics)
--
Good luck
Ivar
Hi
there are 3 sources for the index order, the material node explanations, the help doc for the PZT and material node, and then the main pdf doc for PZT (and structural). The conventions used by COMSOL on tensor index order are the most used ones, but one should notice these index orders are different for PZT and solid
Then for the electrodes, at least ensure you have a GND somewhere or some BC that ensure a fixed point also for the voltage, else there might be no single solution to the PDE and the solver will have issues to converge
Do not forget that in multi-physics, you still need that all dependent variables have enough BCs to ensure a single solution (per physics)
--
Good luck
Ivar