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Gasket Stauts

Creator
Creator

I am performing an analysis, the model contains one layer of Gasket element. 

I am using Sol601, the calculation itself works well. 

but i have a question about the post-processing

 

Gasket status

 

in Help documentation (ADINA and Nastran), i saw:

Each gasket can have one of the following 5 states:

1. Open ...

2. Close ...

3 Sealed ...

4 Leaked: After plastic deformation, the gasket pressure has dropped below gasket leakage pressure 

5. Crushed: Gasket closure strain has exceeded the rupture value.

 

Now the result shows that are some gasket elements are Leaked (4). But i checked the elements, there are plastic deformation, and the gasket pressure are also higher than leakage pressure. 

Whats wrong? Great thanks to anyone who can give me an idea

4 REPLIES

Re: Gasket Stauts

Siemens Phenom Siemens Phenom
Siemens Phenom

Can you provide the model? It would really help to figure out what the issue might be.

Re: Gasket Stauts

Creator
Creator

Thanks! But i am not sure if i can send you the model. I must ask my boss.

 

Re: Gasket Stauts

Creator
Creator

hallo, dear fembrackin,

 i got the permit from my boss, i can send you the model, but i am not sure it is safe to directly upload here, can you let me know your email. the file is around 8 MPa by zip.

 

Thanks!

Re: Gasket Stauts

Siemens Phenom Siemens Phenom
Siemens Phenom

solver development responded with the following explanation:

 

We did some investigation into the code to see why the status is 4 (leaked) for some of the gasket elements when the gasket pressure indicated is above the leakage pressure.

 

First, a gasket is considered "leaked" if at any time, the gasket went plastic, then unloaded to less than the gasket leakage pressure.  Once a gasket enters the leaked status, it never leaves the leaked status. So, for instance, element 193112, it leaked at load step 3, the status remains leaked in the later steps also.

 

Second, in the program, the stresses (gasket pressure) are computed at the integration points but the output to the op2 data block is only at the centroid of the gasket element. So, a gasket element could have leaked at some integration point locations but not at the centroid location. However, to be conservative, we report the highest status number for the element. Hence, for element 193134, at load step 4, the status is leaked indicates that gasket pressure is below the leakage pressure at certain integration point of the element.

 

Note that the gasket status is just an output value and does not affect the calculations of the model.