Modeling of mixed-mode delamination in composite t-joints

Download
index.pdf
2014
Gülaşık, Hasan
Show full item record
201
views
153
downloads
Stiffened panel, consisting of skin and stiffeners, is the main design option for aerospace structures. When manufactured with laminated composite materials, they provide high strength/stiffness to weight ratio, resulting in high performance and less fuel consumption. T-joint is one of the typical configurations for composite stiffened panels which consist of a skin panel and stiffeners co-bonded or co-cured together with a filler material between them. T-joints are prone to delaminations between skin/stiffener plies and debonds between skin-stiffener-filler interfaces. In this study, delamination/debond behavior of a co-bonded composite T-joint is investigated with 2D finite element method. A commercial FEA software, Abaqus with zero-thickness cohesive elements with bilinear cohesive law is used to simulate delamination/debond at all ply interfaces and bonding lines in the structure. Numerical results for the T-joints show that, delamination/debond initiation and propagation scenarios are different for 0°, 45° and 90° pull loads which simulate different loading conditions in aerospace structures. Different failure initiation mechanisms of the T-joints observed in the literature are captured in a parametric study for 0° pull load with geometry and material property changes. Failure initiation and propagation behaviors, load displacement curves, initial and max failure loads and stress fields are affected by the property changes. Generally, mixed-mode behavior is observed in the failure initiation and propagation stages. Additionally, in the numerical studies of the DCB, ENF and MMB delamination tests, Abaqus CZM is validated with the analytical solutions and the numerical and experimental data from the literature.
Composite materials, Composite materials, Plates (Engineering)., Joints (Engineering).
http://etd.lib.metu.edu.tr/upload/12616767/index.pdf
https://hdl.handle.net/11511/23262
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Numerical modeling of failure in composite L-beam and T-joint structures
Temiz, Pakize; Çöker, Demirkan; Department of Aerospace Engineering (2022-12-02)
Laminated curved-shape composite structures which are used as stiffening components in aerospace, wind, automotive and marine industries are subjected to high radial and tangential stresses. For the scope of this thesis, different modelling strategies are investigated to simulate interlaminar and intralaminar failure in composite L-beam and T-joint structures using commercial finite element (FE) code ABAQUS/Standard 2020. In the first part, [030] and [03/903/03/903/03]s laminated L-beams are evaluated using...
Post-buckling behaviour of metallic skin-stringer assemblies and buckling of composite flat panels
Aydın, Enes; Kayran, Altan; Department of Aerospace Engineering (2018)
Stiffened thin panels are very common and important structural elements in aerospace structures because of the weight and stiffness advantages they provide. The stiffener section is important to determine the support condition that the stiffener provides on the unloaded edges of the panel. In the first phase of the thesis study, the effect of the boundary conditions on the buckling coefficients of stiffened metal flat panels is investigated utilizing finite element and empirical approaches. Empirical approa...
Numerical investigation of delamination in L-shaped cross-ply composite bracket
Gümüş, M.; Gözlüklü, B.; Çöker, Demirkan (null; 2014-01-01)
Interlaminar normal stresses are induced with interlaminar shear stresses leading to mixed-mode delamination (MMD) in curved cross-ply composite laminates. Dynamic mixed-mode delamination is studied using explicit finite element method and Cohesive Zone Modelling Dynamic response of the specimen is compared with the experiments.
MODELING OF DYNAMIC DELAMINATION IN L-SHAPED COMPOSITE BRACKETS
Gozluklu, Burak; Çöker, Demirkan (2012-11-15)
One of the widely used geometrically complex parts in recent civil passenger aircrafts is the L-shaped composite brackets connecting ribs to skins. Due to the sharp curved geometry, interlaminar opening stresses are induced and delamination occurs under considerable mode-mixities at the corner. Dynamic phenomena during delamination initiation and propagation of L-shaped beams are investigated using dynamic (explicit) finite element analysis in conjunction with cohesive zone methods (CZM). In ABAQUS a sequen...
Experimental investigation of dynamic delamination in curved composite laminates
Uyar, İmren; Çöker, Demirkan; Department of Aerospace Engineering (2014)
In the aerospace industry, high demand for lightweight structures is fostering the use of composite laminates in a wide variety of shapes, as primary load carrying elements. However, once a composite laminate takes a highly curved shape, such as an L-shape, high interlaminar stresses induced in the curved region causes dynamic delamination formation. This thesis discusses the experimental investigation of delamination in L-shaped CFRP composite laminates under quasi-static shear loading. An experimental set...
Citation Formats
H. Gülaşık, “Modeling of mixed-mode delamination in composite t-joints,” M.S. - Master of Science, Middle East Technical University, 2014.
METU IIS - Integrated Information Service open@metu.edu.tr