For Resampling you can choose between three options: Automatic, Maintain Volume or Maintain Mass. Deformation in ElastoDict is computed and stored as a displacement field. For each voxel, this displacement field contains the information on how far it is displaced in the current deformation step.

Internally, the new material positions are calculated based on this displacement information. Since the new positions do not necessarily lie on the voxel grid, a gray value image with material Volume Fractions is computed for each material ID. These volume fractions contain the information “how much” of a given material is contained in a voxel after the deformation. These volume fractions must be resampled to the voxel geometry. In the figures below, this resampling is shown in a simplified example for one material ID. The deformed geometry is generated by thresholding the resulting gray value image containing the volume fractions.

With Automatic, the resampling of the deformed geometry is based on the volumetric strains of the materials. The resampling threshold is chosen in each step such that the calculated volume change is reached. This is the recommended resampling method as it results in most realistic deformations. Especially for applications where the volume of the material changes significantly during the computations, e.g., thermal expansion or expansion due to a negative Poisson’s’ ratio, Automatic should be used.

With Maintain Volume, the resampling threshold is chosen in such a way that the volume of each solid material in the structure stays roughly the same.

With Maintain Mass, the resampling threshold is set to 0.5.

All methods do not apply to the most soft material in the structure (e.g. pores or matrix material in a composite).