Hi,zhuxiaorui

Sorry to reply late because i just finished my finals.As for you problem,
i think your model doesnot have enough constraints. I donot know how you
built your model in detail, the following is my guess based on my
experiences:

Eventhough you chosen shell63 and defined beam thickness through material
property, you still need to build 3D model and fixed all of one end
surface Otherwise if you just build 2D model and fixed one end, you just
fixed one line not all of the end surface because of shell element. Thsi
is reason why you have instable or unconstrait problem. There are
two methods to solve your problem.

1. 3D model and shell element or solid element

2 2D model and solid element.

if you have problem, feel free to contact me.

Best

shifeng

>From: "zhuxiaorui" >To: [email protected] >Subject: about ansys
>Date: Fri, 14 Dec 2001 14:52:23 +0800 > >Dear Li > >Thanks for your
information in MEMS-talk. However I still have some detail problems to
query. > >I take advantage of the element "Shell63". I constrain all the
DOF of one side of it. I use polysilicon as the material. When I add a
pressure on its bottom surface, the kind of error I mentioned appears.
But I think the constraint and the material property are both correct. >
>I will appreciate if you give me any advice. > >Best regards, > >Zhu
Xiaorui > > zhuxiaorui > [email protected] >

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