Stress value display on nodes

Hi all,

I want to display stress values of shell "cross section" structure on nodes. Because the only color display cannot be accepted to somebody who wants to know exact values.

Unfortunately, I coudn't find the component to show stress values of all nodes. So, I think about alternative solution! I extract RGB color from the mesh, and remap it to the stress value of legend from Karamba. I used blue, black, white and red color legend, and deleted first and last items from the "Legend C" and "Legend T" outputs.

Yes, the remapped values match the minimum & maximun values of "Legend T". I thought that I can use it for principal stress value. But, I want to check it again, so I compared it with the result of "Utilization" component.

As you can see on the attached image, two results are different; the result of "Utilization" component is bigger. I really need a help from someone to explain why this happened. Was my process wrong? or Is there an another method to get the stress values of all nodes?

I'll wait for your reply. Thanks.

p.s. The "Mesh Breps" component of Karamba said that mesh resolution should be larger than 0.05(m). But I need more detailed mesh modeling with 1cm cells(0.01m), so I input 0.01. Although that component turns to red, it still works! Is it okay to input 0.01 for mesh resolution?

Attachments:

gh_map.png, 201 KB

Replies to This Discussion

Permalink Reply by Jaeman PARK on September 18, 2015 at 6:24am

I'll add one more explanation for my modeling. There're three meshes(surfaces) and that's why the results have three paths.

Permalink Reply by Jaeman PARK on September 18, 2015 at 6:39am

I read the Karamba manual again. It says that Utilization(of beam) component includes buckling. So it might be same to Utilization(of shell) component. And then, is my approach right?

Permalink Reply by Karamba3D on September 19, 2015 at 3:04am

Hi Jamparc, my explanation for the difference between the values from the 'Utilization'-component and the remapped Van Mises Stresses is that the former consider the maximum of all layers in a cross section. Do you get better results by combining the results from the upper und lower shell layers?

The Utilization of beams includes 2nd order effects through the EC3 formulas which take account of the buckling lengths of the members. In case of shells the utilization is the ratio between the maximum Van Mises Stress in a shell cross section and the yield stress of the material there.

Best,

Clemens

Permalink Reply by Jaeman PARK on September 20, 2015 at 7:26pm

Hi Clemens,

Thanks for your reply. I understood your explanation, but it seemed there's still difference on my GH file. In fact, all the stress shows same max. & min. values on both "-1" & "1" layer.

I attaced my GH file and screen-captured image. My question is, what is correct maximum stress?

Attachments:

capture.jpg, 256 KB
stress_display_test.gh, 32 KB

Permalink Reply by Jaeman PARK on September 23, 2015 at 5:33am

Hi clemens,

Sorry that I didn't read the manual carefully and didn't search same questions as mine in this forum.

Now I knew that "Result Vectors on Shells" component show the stress value by the length of vectors.

By the way, the explanation on output says that the unit is kn/cm^2 , but I think that the result seems much smaller...

Permalink Reply by abdullah y. ibrahim on November 7, 2017 at 12:35am

what do the numbers mean on the displacement and utilization. i know they are for deformation and compression/tension values but how do you read these values? sometimes you get crazy numbers so im wondering if there is a realistic range or doesnt matter as long as you get the idea? if you can clarify please.

Thank you.

Permalink Reply by Karamba3D on November 7, 2017 at 12:30pm

for the usability limit state one usually limits the deflection of a structure to roughly L/300. Here L is the free span. In case of cantilevering structures it is double the value.

A utilization of one means that the material is at its strength limit.

For more details please see the manual.

Best,

Clemens

RSS