Definition of various terms of a Shell Element

[VN1981]

Hi Folks,
I was trying to get a better understanding of definition of various shell/plate element terms (Z1, Z2, Top, Bottom, Face 1, Face 2). I did a simple case study of a cantilever plate subjected to transverse load. Basically put the plate in bending. Did the case study in two FEA packages: MSC Patran & Femap. Based on the output and verifying via the software, I was able to get some clarity on the definition of the above terms with respect to Shell Element Normal Vector. I have created an illustration of the same. Would love to hear feedback from other users on its accuracy.

Regards,
- VN

 

[nlgyro]

Remark 11 in the nastran quick reference guide under PSHELL essentially tells you the definition of Z1 & Z2. See below

 

[aerostress82]

Model a cantilever beam with shell elements and applied a vertical distributed force at the end of your beam. Constrain from the other end of your beam. Check to see what your element normal vector is, and what your Z1-Z2 stresses are for both Patran and Femap.

As you know, one of the faces will be in tension and the other in compression. This way you can compare any software packages' top/bottom/face1/face2/Z1/Z2 & etc. definitions, no matter what the software is. Should take you 5 minutes to find out..

Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer

 

[Zadrobu]

It's also good to make a distinction between Nastran-fundamental shell properties and preprocessor-specific shell properties. The element normal direction and Z1/Z2 directions are definitely Nastran-fundamental properties, but what is called top/bottom or face1/face2 might be preprocessor-specific.

 

[VN1981]

Aerostress82,
Thats how I got a better understanding of definition of various terms. Checked the stress signs on two different FEA packages.