Shell offset in Nastran and Abaqus

[Alex22]

When ZOFFS is positive, the shell is above the grid plane and
when ZOFFS is negative, the shell is below the grid plane?

When Abaqus offset is negative, the shell is above the grid plane and when it is positive, the shell is below the grid plane?

Is this correct or is it the other way around?
Please help I'm confused.

 

[gwolf2]

From memory this is correct, they are different. In general you must check each new FE package which you come across - they are all different when it comes to beam and shell element data similar to this. Check all offsets visually where possible.

 

[Alex22]

thanks

 

[BlasMolero]

Dear Alex22,
In NX Nastran you can offset the CQUAD4, CQUAD8, CTRIA3, CTRIA6, CQUADR and CTRIAR elements relative to the mean plane of their connected grid points.

The orientation of the element coordinate system is determined by the order of the connectivity for the grid points. The element z-axis, often referred to as the positive normal, is determined using the right-hand rule. Therefore, if you change the order of the grid points connectivity, the direction of this positive normal also reverses.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

 

[rb1957]

"above" and "below" are probably not the best terms to use. with x- and y- axes in-plane z- is out-of-plane, and your trusty RH rule shows you the way. if what you say about abaqus is right, i suspect they define x- and z- as the in-plane axes.