Going from Abaqus model to 3D space

[Clas]

Hi,

we are modeling stresses on a bone, and want to compare our results to a medical image of the same bone. We have been able to go from the dicom medical image (MRI) to a model in Abacus, and forces seems to be as we expect. What I would like to do now is to compare the forces of the model directly to what we observe in another medical image (PET), in order to correlate the estimated values with the measure values on a voxel-by-voxel basis. So basically, I would like Abaqus to export the model, with the corresponding loads, as a file that I can read using medical imaging software. So a format that has 4 dimensions (x, y, z, and modeled force at that point, such as DICOM or .nii. I can export as 3DXLM, but I can not convert that into a matrix or other medical image format.

 

[FEA way]

I think that you will have to use external postprocessing software such as MatLab for this purpose (there is a plug-in for data exchange between MatLab and Abaqus). The problem is that results exported from Abaqus will be saved only at selected points (nodes). To obtain values at more points you have to interpolate it (linear interpolation in case of first order elements).

 

[Mustaine3]

>So a format that has 4 dimensions (x, y, z, and modeled force at that point, such as DICOM or .nii.

With the 3 coordinates you could only store a point cloud. It is not clear then how they are connected with elements.
And the 4. value could only represent the value of a force, not a direction. Force is a vector.

 

[Clas]

Thanks. Sorry about the non-engineering language. I am only interested in a representation of the value of a force at each position of a 3d volume, as my other medical image modality does not have a direction, just an x,y,z and a level. Is there a way to access the image rendering process in Abaqus to get simple data output?

 

[Mustaine3]

There are options to export a txt or csv file with the coordinates of the nodes. Request COORD as field output for the model and run it again. In postprocessing you can use Report->Field Output to write COORD1, CORRD2 and COORD3 of each node (Unique Nodal) into a file.

You can also add forces into that file. What forces are you looking for? The forces that are applied (CF)? Or the forces that are needed to enforce a specific movement (RF)? Or something else?

 

[Clas]

The forces that are applied at each location in the bone, thanks, will try the Field Output option

 

[adiaela]

Hi all, Ideally we would want to export a volumetric section with 1/2 associated outputs of the analysis (e.g. von mises stress, strain) and keeping it in the same coordinate system. I know you can extract the unique node coordinates with whichever output value for individual nodes but is there a way of doing it for all nodes in the structure?

 

[FEA way]

Yes, you can write text file with coordinates and output data values for all nodes of the model using approach suggested by Mustaine. Due to large number of data lines you may want to use some additional post-processing software such as MatLab or SciLab to work on this data.