Untersuchung des Einflusses großer Deformationen in Kontinuumsschädigungsmodellen auf die Abbildung des Phänomens der Lagenaufspaltung an Lochrändern in Faserverbundstrukturen

Kurzfassung

This master’s thesis deals with the investigation of the influence of large deformations in continuum damage models on the representation of the ply splitting phenomenon at laminate hole edges in fiber composite structures. To achieve this a material model, which is based on the Cuntze failure criterion and the assumption of small strains, is adapted. The existing model exhibits weaknesses in predicting laminate delamination, leading to erroneous predictions of material behavior and maximum load capacity in certain applications, especially in the case of laminate open-hole tension specimen. A comprehensive literature review reveals that the model’s inadequacy is attributed to the assumption of small strains. Based on this insight, the hypothesis is proposed that considering large deformations using Green-Lagrange strains and Second Piola-Kirchhoff stresses can accurately simulate and predict the phenomenon of ply splitting at laminate hole edges. This is expected to result in improved predictions of the maximum load capacity. The implementation of additional element deletion criteria is also carried out. In 1-element models, it is demonstrated that the modified model exhibits the same material responses as the original model under one-dimensional loading, especially under shear loading. Subsequently, using single-laminar specimen, it is shown that the phenomenon of ply splitting can be effectively simulated with the consideration of large deformations, yielding nearly exact predictions of theoretical strength.