Print Email Facebook Twitter Modelling Delaminations in Composite Panels Title Modelling Delaminations in Composite Panels: Including Novel Theories for Post-Buckling and Delamination Growth Author Dykstra, D.M.J. Contributor Kassapoglou, C. (mentor) Esrail, F. (mentor) Faculty Aerospace Engineering Department Aerospace Structures & Materials Programme Aerospace Structures & Computational Mechanics Date 2016-06-28 Abstract Even though composite materials are being applied more and more often, these materials are often not used to their full potential. In particular, composite materials are very sensitive to Compression-After-Impact (CAI), typically leading to knockdown factors in the order of 0.65. Many researchers have tried to predict the effects of Compression-After-Impact, either using finite element or analytical methods. While non-linear finite element methods can capture most of the damage mechanisms accurately, large computational power is required rendering such methods unpractical for optimisations. On the other hand, many analytical methods are limited in accuracy, especially at higher impact energies, which are often critical for design. In particular, no analytical model has ever been developed which can capture the progressive post-buckling behaviour of a panel with elliptical delaminations, let alone in a variable stiffness laminate. In order to solve this problem, a novel general theory for post-buckling was proposed. With this theory, the non-linear effects of post-buckling phenomena can be captured using a quasi-linear system of equations. This theory was used, in combination with the Rayleigh-Ritz method, to model the progressive post-buckling behaviour of variable stiffness composite laminates with single and multiple delaminations under compression. In general, very good agreement was found in comparison with non-linear finite element methods. A novel theory was also proposed to predict growth of post-buckling elliptical delaminations by analysing the delaminating resin layer as elastic foundation. The methods developed in this thesis shows promising results for applications in models which determine the compressive strength of composite panels after impact or the compressive strength of composite panels with delaminations in general. In particular, models using these theories will be able to capture the combined effect of various damage phenomena for panels with larger delaminations, which is typically a limitation of existing models. Moreover, the developed theory for post-buckling is not only applicable to the Rayleigh-Ritz method but can be used for general post-buckling calculations of panels and beams. In particular, this theory could also be interesting for finite element calculations. Subject bucklingpost-bucklingcompositescomposite panelscompressiondelamination growthimpact To reference this document use: http://resolver.tudelft.nl/uuid:21486e29-e491-4e0b-b170-a30af9a24f7b Part of collection Student theses Document type master thesis Rights (c) 2016 Dykstra, D.M.J. Files PDF Thesis_final.pdf 21.39 MB Close viewer /islandora/object/uuid:21486e29-e491-4e0b-b170-a30af9a24f7b/datastream/OBJ/view