OUR-OMA employs a finite element approach to extract the J-integral from digital image correlation (DIC) and digital volume correlation (DVC) measured displacement fields. OUR-OMA has been developed in python and runs inside Abaqus via its scripting interface.

DIC/DVC measured displacement fields are imported as a set of full field boundary conditions into a finite element model of the crack. The location of the crack tip and mouth in the displacement field must be known and specified in the code. A region around the crack, chosen by the user, is then re-meshed with higher order elements for improved accuracy. The user selects another region larger than the first re-meshed area, which is free from boundary conditions, to allow for more realistic material response/deformation. The J-integral around the crack is then computed using a user defined number of contours.

More detailed information about the precise implementation can be found in the associated journal publication:

Barhli, S. M., Mostafavi, M., Cinar, A. F., Hollis, D., & Marrow, T. J. (2017). J-Integral Calculation by Finite Element Processing of Measured Full-Field Surface Displacements. Experimental Mechanics, 57(6), 997–1009. https://doi.org/10.1007/s11340-017-0275-1. https://doi.org/10.1007/s11340-017-0275-1

OUR-OMA is coded in python and runs inside the Abaqus FEA software (preferably Abaqus 6.14 or more recent) via its scripting interface. The code requires numpy, which comes pre-built with the Abaqus python scripting API.

The OUR-OMA script must be saved into the same directory as the displacement field to be evaluated. To run enter 'abaqus cae noGUI=OUROMAv2.3_CL.py' on the command line. The full path and the crack tip and mouth positions must be specified in OUROMAv2.3_CL.py.