Deformation Gradient from clouds of points
I have some difficulties to build up my deformation gradient from the results of Abaqus in Matlab.
I want to do a sensitivity analysis in matlab and I want to import the results (stress-strain abaqus) of another hyper-elastic simulation to matlab.
What I have in matlab is the Coordinates in reference and deformed configurations, strains and stresses in local coordinates.
What I have to do is to reconstruct the deformation gradient for each element.
I have read some stuff on the internet, but all of the examples are when you have a function that you can derivative easily based on initial configuration. But in my case I have just the coordinates while the strains and stresses in abaqus are calculated in integration points(8Node elements).
I have also seen some information of spectral decomposition of strain tensor (to get eigenvalues and eigenvectors) and THEN recompute the gradient of deformation but I dont get how to do the THEN part.
Any help, hints or keywords that can guide me somewhere is very appreciated.