A great deal of progress has been made in recent years in the field of global digital
image correlation (DIC), where higher-order, element-based approaches were proposed
to improve the interpolation performance and to better capture the displacement
fields. In this research, another higher-order, element-based DIC procedure is introduced.
Instead of the displacements, the elements’ global nodal positions and nodal
position-vector gradients, defined according to the absolute nodal coordinate formulation,
are used as the searched parameters of the Newton–Raphson iterative procedure.
For the finite elements, the planar isoparametric plates with 24 nodal degrees of freedom
are employed to ensure the gradients’ continuity among the elements. As such,
the presented procedure imposes no linearization on the strain measure, and therefore
indicates a natural consistency with the nonlinear continuum theory. To verify the new
procedure and to show its advantages, a real large deformation experiment and several
numerical tests on the computer-generated images are studied for the standard,
low-order, element-based digital image correlation and the presented procedure. The
results show that the proposed procedure proves to be accurate and reliable for describing
the rigid-body movement and simple deformations, as well as for determining the
continuous finite strain field of a real specimen.
Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
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