arXiv subjects

Christos Kassapoglou

Publications and source records attributed to Christos Kassapoglou.

3 recordsLinked to original sources

arXiv2026

Accurate simulation of delamination with a resin-rich layer-dependent penalty stiffness based on structural cohesive elements

Shell-based cohesive elements tend to overestimate the compression ahead of the crack tip because of approximations in the penalty stiffness. In this study, the higher-order structural cohesive element previously developed by the authors is enhanced with a resin-rich layer-dependent penalty stiffness to improve both computational efficiency and predictive accuracy. The proposed formulation distinguishes between the normal and shear penalty stiffnesses. It extends the resin-rich layer-based penalty stiffness from the layer-wise to the equivalent single-layer framework. This extension is achieved using the through-thickness distributions of the out-of-plane normal and transverse shear stresses derived from beam theory. The proposed method is verified and validated against benchmark problems for Mode I, Mode II, mixed-mode, and reinforced DCB configurations. Compared with the conventional formulation, it exhibits significantly improved mesh convergence and provides more accurate predictions of the compression distribution ahead of the crack tip and the delamination propagation.

cs.CE↗

arXiv2026

A new approach for the determination of through-thickness and free-edge stresses in composite laminates based on structural elements

Thin shell elements based on the Kirchhoff-Love hypothesis account for only three stress components: the in-plane normal stresses and the in-plane shear stress. The out-of-plane stress components required by conventional three-dimensional damage criteria are unavailable. As a result, damage initiation in composite laminates cannot be accurately predicted. This paper presents a method for capturing free edge effects in multilayer structural elements with arbitrary composite layups based on the Kirchhoff-Love hypothesis.The proposed formulation employs structural cohesive elements to model composite laminates and uses an accurate penalty stiffness derived from the laminate's resin-rich layers. By accurately characterizing the interfacial mechanical response, out-of-plane stress components can be recovered.

cs.CE↗

arXiv2024

Structural cohesive element for the modelling of delamination in composite laminates without the cohesive zone limit

Delamination is a critical mode of failure that occurs between plies in a composite laminate. The cohesive element, developed based on the cohesive zone model, is widely used for modeling delamination. However, standard cohesive elements suffer from a well-known limit on the mesh density-the element size must be much smaller than the cohesive zone size. This work develops a new set of elements for modelling composite plies and their interfaces in 3D. A triangular Kirchhoff-Love shell element is developed for orthotropic materials to model the plies. A structural cohesive element, conforming to the shell elements of the plies, is developed to model the interface delamination. The proposed method is verified and validated on the classical benchmark problems of Mode I, Mode II, and mixed-mode delamination of unidirectional laminates, as well as on the single-leg bending problem of a multi-directional laminate. All the results show that the element size in the proposed models can be ten times larger than that in the standard cohesive element models, with more than 90% reduction in CPU time, while retaining prediction accuracy. This would then allow more effective and efficient modeling of delamination in composites without worrying about the cohesive zone limit on the mesh density.

cs.CE↗