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Maximum Combined Stress CBAR/CBEAM elements

HenLopes

Hi everyone,

Could you please tell me how to get the maximum combined stress ( Axial +Bending) on nodes for bars in ALTAIR?

What kind of control card (Global Output Request) I need to define on my pre processor to have this data.

Something like this ( attached file from PATRAN)

<?xml version="1.0" encoding="UTF-8"?>

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Simon Križnik

Hi,

use Global Output Request>STRESS.

HenLopes

Hi Ivan,

Thank you for your kind reply.

I think this control card returns you a .strs output file with stresses in the elements of your 1D (CBAR) structure.

What I'm looking for is the Stress on the nodes.

Thanks

Simon Križnik

To output bending stress for the beam elements, we need to specify the Stress Recovery points C1, C2, D1, D2, E1, E2, F1, F2 which are 4 points on the cross-section at end A and B on the beam property card.

C1, C2 (or D1, D2 ...) are the y and z coordinates in the BEAM element coordinate system of a point at which stresses are calculated. For e.g if you need to calculate the stresses on the surface for the tubular x-section you could use the following values based on the outer diameter of the tube you are using:

C1, C2 = 0.025, 0.000
D1, D2 = 0.000, 0.025
E1, E2 = -0.025, 0.000
F1, F2 = 0.000, -0.025

This is just an example, you can use any other coordinates.

Now moving to HyperView post-processing the stresses you can contour are the following:

CBAR/CBEAM Long. Stress SAC - The longitudnal (extensional) stress at end A for point C. positive values means tension, negative values means compression.
CBAR/CBEAM Long. Stress SAD - The longitudnal (extensional) stress at end A for point D.
CBAR/CBEAM Long. Stress SAE - The longitudnal (extensional) stress at end A for point E.
CBAR/CBEAM Long. Stress SAF - The longitudnal (extensional) stress at end A for point F.

CBAR/CBEAM Long. Stress SBC - The longitudnal (extensional) stress at end B for point C.
CBAR/CBEAM Long. Stress SBD - The longitudnal (extensional) stress at end B for point D.
CBAR/CBEAM Long. Stress SBE - The longitudnal (extensional) stress at end B for point E.
CBAR/CBEAM Long. Stress SBF - The longitudnal (extensional) stress at end B for point F.

CBAR/CBEAM Long. Stress SAMIN - Minimum value of longitudnal stress over points C, D, E and F at end A.
CBAR/CBEAM Long. Stress SAMAX - Maximum value of longitudnal stress over points C, D, E and F at end A.

CBAR/CBEAM Long. Stress SBMIN - Minimum value of longitudnal stress over points C, D, E and F at end B.
CBAR/CBEAM Long. Stress SBMAX - Maximum value of longitudnal stress over points C, D, E and F at end B.

Note that the long. stress is the longitudinal stress (stress along the beam) and is the sum of the Axial plus Bending stress at each point.

post-7616-0-22793500-1433483974_thumb.jp

https://altairuniversity.com/wp-content/uploads/2014/02/1DMeshing2.pdf

HenLopes

Hi Ivan,

Thank you so much for the very useful information.

Just one more question.

Is this possible to have the nodal stress values of my CBAR element in an output file?

Reason for that is because I wanted to automate my process instead of post process the results manually with hyperview.

Thank you.

Simon Križnik

Unfortunately, I do not know hot to do it.

You can go for GPFORCE to get grid point forces and knowing the beam area you can calculate the stress. GPSTRESS does not work for some reason.

Maybe someone else can offer a better suggestion.