Incremental Global DVC

Perform incremental DVC analysis for a series of deformed image, using either small strain or large strain approaches (note: to run correctly the Green Lagrange strain script needs to be installed).

iterative_global_DVC

Description

This module takes a reference image alongside a series of deformed image, and a reference mesh where the strains will be computed.

Ports

Approach

If Small strain is selected, the selected reference mesh is used for each DVC computation (0-1,0-2,0-3,etc...). In this mode, each successive DVC computation can be initialized by the previous one (0-2 computation initialized by the result of 0-1, etc...). The Cauchy strain tensor is used to derive the strains from the displacement field.

If Large strain is selected, the reference mesh is successively deformed by the measured displacement field at each step. The Green-Lagrange strain tensor is used to derive the strains from the cumulated displacement field.

Large strain e.g.:

  • 0-1 is computed with the reference mesh.
  • Reference mesh is deformed by 0-1 displacement field
  • 1-2 is computed with the resulting mesh
  • 0-2 displacement field is calculated as 0-1Disp+1-2Disp
  • 0-2 strain is measured from 0-2 displacement field
  • Repeat steps ii until v for each additional step

Max iterations

The number of iterations can be set for all computations.
Default is set to 200 to ensure a higher likelihood of reaching convergence at each step.

Initialisation between steps

Allow or not to initialize the DVC analysis at time ti with displacement from previous analysis ti+1.
Option only shown in small strain approach.

Output

ln Lagrange mode, the output data are stored on the reference mesh.
In Lagrange+Incremental mode, the results of the intermediary deformed meshes are also stored for visualisation of the deformation.
Option shown only in Large strain approach.