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Modelling delamination of a DCB test by using non-linear truss interface elements and plate elements with assumed shear strain

In this work we are investigating mode I delamination of plate-like specimens, where the width is comparable to the length. In such cases anticlastic bending of the plates takes place on the debonded part and the crack front is a curve, rather than a straight line. We model the interface by means of discrete non-linear truss elements with embedded exponential traction-separation law. Such choice is justified because in this test, only pure mode I (opening) displacements occur at the interface, which in our case will cause axial elongation of the truss elements. The plates are modelled using 4-node plate finite elements derived by the assumed shear strain approach that pass the general constant-bending patch test. Cohesive-zone interface parameter identification is performed by a direct method (J-integral) and by virtual experiments regression. Numerical tests have been performed and the exponential cohesive-zone interface model compared against the bi-linear in terms of precision, robustness and computational time. The results confirm the experimentally observed behavior with anticlastic bending of the arms and the curved crack front.

Fracture Mechanics, Delamination, Cohesive Zone Model, Finite Element Analysis

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