Cbar results and transverse shear for composites

Rahul_P1

1. Do CBar Elements consider bending and output results for bending during analysis and optimization?
2. How do you account for transverse shear when using PCOMPP properties in HyperLaminate?

Rahul_P1

: For 1 - Yes , to request for cbeam results you need to use the stress option in control cards > global output request (and sya you choose h3d in the format field) your h3d will contain these results.
And also you need to specify the points C,D,E,F which are the stress recovery coefficients and are defined by C1,C2 D1,D2 E1,E2 and F1,F2 in the PBAR card.

In the result type of hyperview you will see the below result types in the left and each result type is explained to you below

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.
So, below you will see SAD is the sum of the bending plus axial stress at end A at point D.

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.

You should see interlaminar stresses and transverse shear stresses when you request for cstress in the control cards > global output request

You will need to of course input the G1,Z - Transverse shear modulus for shear in 1-Z plane and G2,Z - Transverse shear modulus for shear in 2-Z plane. in the Material input - MAT8

that is how they are accounted for.

Altair Forum User

GoodMorning Sir

I have a question;

I'm working on a transient modal analysis on a frame exiced by a impulsive pressure.

I have modelled the frame with CBEAM elements assigning a beamsection in property card for beams.

I have assigned the stress recovery points on the iurface of the beam section, the four points C D E F.

When i read the results on .h3d the beams bend under the load; on point C and E i have not difference in longitudianal stress.

On points D and F i have positive stresses and negative respectively.

 

Are these values the sum of positive/negative stresses due to normalstress/bendingmoments ?

 

Can i output the shear stress on these points? how?

 

It's a simple beam.

Altair Forum User

Hi,

 

The longitudinal stresses which you see is the sum of axial and bending stress. In this case the stress values are at recovery points is a sum of axial and bending stress.

 

 

You can also look at min and max stress at point A and point B.

 

I will check and update to you about shear stress on beam elements.

Altair Forum User

Thank you Prakash!! 

 

So, the Longitudinal Stress is the sum of stresses due to bending moments and normal forces.

 

And the voice 'CBAR/CBEAM Axial stress' is the stress just due to Axial Sollecitation on the beam cross section?

 

Please let me know about shear stress, if is there a way to output it.

 

Have a nice weekend

Altair Forum User

Hi Damir,

 

You can use PBARL/PBEAML instead to PBAR where shear properties are calculated at recovery points.

 

Refer to PBARL/PBEAML card in OptiStruct reference guide for more information.