Cyclic test concrete cubes

[[Is...]]

Hello, I am trying to correlate cyclic tests for concrete cubes using GOM correlate. This allows me to plot STRESS(Shenk Machine) vs STRAIN(GOM correlate). The procedure I use is;

1; Import deformation images from a camera in black and white to GOM correlate
2; Define scale, Create a surface component and create 321 alignment
3; Define extensometer(s) at the middle of the specimen
4; Plot graphs of extensometer(s) using a change in length option.
5; Later export the extensometer(s) data in excel.csv file to match with Stress data

With all this process, I cannot have coherent strain curves from extensometer(s) using GOM.

I have tried the same method for several other specimens, but unfortunately, I cannot get a solution.

Attached are photos of my specimen and corresponding extensometer positions and also their various plots.

 

Please any suggestion(s) on how better I can analyse my data will be appreciated.

[[Iv...]]

Hi Ismail,

your workflow seems right. I would recommend to check the Length Change in the same direction like your extensometer is constructed.

Can you explain what kind of result you expect? Are you testing in the tensile and compressive force area or just in one of the forces? 

Nevertheless, it's quiet interesting that some of extensometers show the opposite behavior of other ones. Maybe the Facet Finding could lead to this results. 
Maybe if you increase the facet size in the construction dialog the finding will be more stable. 

Can you check the whole surface in epsilon direction and send it as an attachment? Just to have a global view of the strain. 

Greetings, Ivan

[[Is...]]

Hello Ivan, 

Thanks for your reply, This is still a problem for me over a year now.

The diagrams  i presented above corresponds to length change in Y axis which is actually my direction of interest

I am testing the specimen in compressive loading unloading condition(Compressive cyclic loading). So i expect to have incremental displacement in the Y axis.

 

The attached files corresponds to epsilon Y(Direction of loading)

Is it possible to schedule a Virtual session with you because i have more question in regards to this type of test.

Thank you in advance,

ismail.bello@cyu.fr

[[Iv...]]

Hello Ismail,

it's not possible to schedule a meeting with me. If you need help, please contact your local GOM Partner. In your case this should be the GOM France department. 

I guess this would be the easiest way for both sides. 

Greetings Ivan