Negative Volume In Abaqus

[pgpada]

Dear Abaqus users,

I have a model that i wanted to solve with abaqus. After meshing it through a preprocessor and trying to run it, An error about negative volume exists.

I have seen from other users that i have to change the normals or remesh the volume or refine the area.

What i want to know is how abaqus calculates the negative volume elements in order to avoid this problem in the future because i will be using it a lot. My preprocessor doesn't find any negative volume.

Could you give me an example how abaqus finds this kind of problems? Do you have any kind of formula for that?

Thank you for your answers,



PGP

 

[lanavi017]

Hi

Ok. the negative volume element are generated due to the sequence of creation of the element, for example if we have an quadratic element call element 1, so the definition of the element is 1, 1,2,3,4 the first number is the name of the node, then node number 1 is in the corner up left, node 2 is corner down left, node 3 is the corner down right and node 4 is the node up right...so this element should be a positive volume, because their nodes are mentioned from left to right in a anti-clockwise way...now if you number the element like 1, 1,4,3,2 this element will be negative because is numbered is a wrong way..

maybe if you use a preprocessor different to abaqus, that is the problem...I use Hypermesh and then i check the normal in the tool menu..

i hope you understand me..and sorry about my English, this is no very good..

regards...Luis

 

[pgpada]

Dear Luis,

Thank you very much for your answer.

This is not always the problem. After some tests i have done it is not regarding to the normals. I use Ansa and the normals are ok but again i take negative volume elements.

I think it has something to do with the jacobian.


PGP