Are resulting stresses in global or element coordinate system; especially Line3 element?

SandpointDave

It appears to be global. If so, how determine the stresses along the Line3 coordinate system (varies for non-linear, large deflection analysis) coordinate system especially? Is it possible to output the Line3 loads in terms axial, bending moment, torsion and shear loads?

Victor

You can use the SECTION FORCES parameter on the *EL FILE card. To do this in Mecway, under CCX in the outline tree, add a custom step contents containing:

*EL FILE,OUTPUT=2D,SECTION FORCES
S

Then the stress components in the solution have different meanings from their names according to this table from the CCX manual:
• xx: Shear force in 1-direction
• yy: Shear force in 2-direction
• zz: Normal force
• xy: Moment about the 1-direction
• xz: Moment about the 2-direction
• yz: Torque

I'm not sure if these are in a coordinate system that rotates with the beam at large displacements so you might need to test that.

SandpointDave

I tried (minus the quotes):

1. "*EL FILE,OUTPUT=2D,SECTION FORCES
   S"
   
   
2. "*EL FILE,OUTPUT=2D,SECTION FORCES"
   
   
3. "*EL FILE,OUTPUT=3D,SECTION FORCES"
   
   
4. "*EL FILE,SECTION FORCES"
   

Each crashed the solver. If I suppress the custom model definition it calculates fine except I don't get forces. Please understand that I am trying very hard to figure this out including searching the CCX manual and am not trying to have you fix all my problems except now I am stumped. I have taken the liberty of emailing you my file. It is only a validation so there are no concerns about being proprietary data.



Thanks,
Dave

SandpointDave

1. 
   

Nevermind

Victor

WARNING for anyone else using this. SandpointDave discovered that the SECTION FORCES results are wrong. This seems to be a bug in CCX 2.10-2.13 for circular tubes. It looks like you can do further calculation on the results to correct for that though. See my recent post on the Yahoo CCX forum or ask on here if you want further details.