C1 Cohesive Element Models for 3D Delamination
Towards overcoming the mesh density constraint in FE delamination analyses
G. Tosti Balducci (TU Delft - Aerospace Engineering)
Bo Yang Chen – Mentor (TU Delft - Aerospace Structures & Computational Mechanics)
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Abstract
The wide adoption of composite structures in the aerospace industry asks for reliable numerical methods to account for the effects of damage, among which delamination. Cohesive elements (CEs) are a versatile and physically representative way of reproducing delamination, but, using their standard form, at least 3 elements are required in the narrow cohesive zone, hindering the applicability in practical scenarios. This limitation is due to the inability of
current models to capture the deformation of the delaminating substrates. The present work focuses on the implementation and testing of triangular thin plate substrate elements and compatible cohesive elements, which satisfy C1-continuity at their boundary. The improved regularity meets the continuity requirement coming from the Kirchhoff Plate Theory and the triangular shape allows for conformity to complex geometries. After verification of plate and
cohesive element singularly, the overall model is validated for mode I delamination. Very accurate predictions of the limit load and crack propagation phase are found, using CEs as large as 11 times the cohesive zone.