Discussion Forum

Hi

I'm not fmiliar with quartz AT cut material, but for most crystals (such as Si that I do use) COMSOL have a normalised material tensor (if you engage the anisotropic material option) along x,y,z, you must then define your local coordinate(s) to align the tensor with the domain orientation of interest.

I assume therefore that you must define the AT cut direction w.r.t the tensor default coordinates, and then define a local coordinate system that takes the first material AT correction and the domain orientation into account

There is now in V4 a way to show the material orientation in the plot/postprocessing menus once solved, or at least initial conditions loaded (unfortunately not yet when you define the coordinate systems ;)

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Good luck
Ivar

all what you need to create an AT or SC cut is written in a thesis of mihir patel with all sort of way to simulate quartz linear and non linear behaviour with or without viscoelastic losses. I was unable to post it because of it size so if you want it send me your e_mail at thibault.louvet-carron@temex.fr. One important trick is to put the y axis perpendicular to the quartz plane in order to respect the IEE convention.
respecting this first point, you have two way to introduce the AT material :
written the elastic coefficient rotated (see at the annex )
or written the non rotated coefficient and used a coordinate system with a rotation of -35° on the X axis
It works well in eigenfrequency,thermal static analysis and has been validated within my current job

So good luck and don't hesitate to ask me other question....
best regard

PS : all what is described is related to the 3.5 a version and below....
for V4.0a and above it is currently investigated

Hi

Yes Thibault is right, there are two ways for the tensor convention in COMSOL !!:
1) PZT applies IEEE convention, for tensor order, it's remined on the screen by the full names written out, check the subscripts

2) classical structural and elsewhere a more natural ordering of the tensor items,
I'm not sure how to check this in the material database though, if you use one convention in the materials, and expect another in the physics, you will get a mess. Hope COMSOL has set a flag for this in their DB, could be worth a question to support, such to be warned before you stand up in front of your clients trying to explain strange results ;).

This is the only place I know that COMSOl does not have an unique definition, and the historical heritage is rather
important and difficult to avoid.

Everywere else COSMOL has unified physics and "traditional" notations, that by itself is a great job.

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Good luck

Ivar

What are AC-Cut, SC-Cut, Y-Cut? Is there any diagrams to show me how quartz are cut?

Hi,

I am in great need of the material constants of STcut x quartz, like elastic constants, piezoelectric constants and dielectric constants. Do you know how to calculate them? Thanks. MY email is zhanggazi2008@gmail.com

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zhanggazi

hi zhang gazi,
i read ur post regarding the properties of st cut quartz did u get them .if yes then can u send them to my email id rohankumar03@gmail.com..waiting for ur reply


Regards

rohan