Delamination analysis by using cohesive interface elements in laminated composites

Download

index.pdf

Date

2009

Author

Gözlüklü, Burak

Metadata

Show full item record

Item Usage Stats

139
views

92
downloads

Finite element analysis using Cohesive Zone Method (CZM) is a commonly used method to investigate delamination in laminated composites. In this study, two plane strain, zero-thickness six-node quadratic (6-NQ) and four-node linear (4-NL) interface elements are developed to implement CZM. Two main approaches for CZM formulation are categorized as Unified Mode Approach (UMA) and Separated Mode Approach (SMA), and implemented into 6-NQ interface elements to model a double cantilever beam (DCB) test of a unidirectional laminated composite. The results of the approaches are nearly identical. However, it is theoretically shown that SMA spawns non-symmetric tangent stiffness matrices, which may lower convergence and/or overall performance, for mixed-mode loading cases. Next, a UMA constitutive relationship is rederived. The artificial modifications for improving convergence rates such as lowering penalty stiffness, weakening interfacial strength and using 6-NQ instead of 4-NL interface elements are investigated by using the derived UMA and the DCB test model. The modifications in interfacial strength and penalty stiffness indicate that the convergence may be improved by lowering either parameter. However, over-softening is found to occur if lowering is performed excessively. The morphological differences between the meshes of the models using 6-NQ and 4-NL interface elements are shown. As a consequence, it is highlighted that the impact to convergence performance and overall performance might be in opposite. Additionally, benefits of selecting CZM over other methods are discussed, in particular by theoretical comparisons with the popular Virtual Crack Closure Technique. Finally, the numerical solution scheme and the Arc-Length Method are discussed.

Subject Keywords

Mechanical engineering., Composite materials

URI

http://etd.lib.metu.edu.tr/upload/12611005/index.pdf
https://hdl.handle.net/11511/19022

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Forced vibration analysis of generally laminated composite beams using domain boundary element method Ahmed, Zubair; Dağ, Serkan; Department of Mechanical Engineering (2018) Forced dynamic response of generally laminated composite beam is analyzed by boundary element method. Static fundamental solutions are used as weight functions in the weighted residual statements. The use of static fundamental solutions gives rise to a new formulation named as Domain Boundary Element Method. Displacement field of the generally laminated composite beam is written in accordance with first order shear deformation theory and equations of motion are derived using Hamilton’s principle. Developed ...
Failure analysis of tapered composite structures under tensile loading Çelik, Ozan; Parnas, Kemal Levend; Department of Mechanical Engineering (2016) A three dimensional finite element modeling approach is used to evaluate the effects of preliminary design variables on the performance of tapered composite laminates under tensile loading. Hashin failure criteria combined with a progressive failure algorithm is used for in-plane failure mechanisms and cohesive zone method is used for out-of-plane failures. The modeling approach is validated by a comparison with experimental results from literature. The validated model is used to examine various design vari...
Analysis of thin walled open section tapered beams using hybrid stress finite element method Akman, Mehmet Nazım; Oral, Süha; Department of Mechanical Engineering (2008) In this thesis, hybrid stress finite element is formulated for the analysis of the isotropic, thin walled, open section beams with variable cross sections. The beam element has two nodes each having seven degrees of freedom. Assumption of stress field is sufficient to determine the element stiffness matrix. Axial, flexural and torsional effects are taken into account in the analysis. The methodology can be applied both to the tapered and the uniform beams. Throughout this study, firstly element cross-sectio...
Fully Coupled Smoothed Particle Hydrodynamics-Finite Element Method Approach for Fluid-Structure Interaction Problems With Large Deflections Dincer, A. Ersin; Demir, Abdullah; Bozkuş, Zafer; Tijsseling, Arris S. (ASME International, 2019-08-01) In this study, a combination of the smoothed particle hydrodynamics (SPH) and finite element method (FEM) solving the complex problem of interaction between fluid with free surface and an elastic structure is studied. A brief description of SPH and FEM is presented. Contact mechanics is used for the coupling between fluid and structure, which are simulated with SPH and FEM, respectively. In the proposed method, to couple meshfree and mesh-based methods, fluid and structure are solved together by a complete ...
Snap-through buckling analyses of composite shallow spherical shells Akkas, N; Toroslu, R (1999-10-01) The purpose of this work is to present some numerical results on nonlinear, snap-through buckling of shallow spherical shells made of laminated composite materials under general static loading. Isotropic shells are covered as a special case of the general problem. A special-purpose finite-difference computer program has been developed. Moreover, the general-purpose computer program ANSYS has also been used. Effects of various material properties on the nonlinear behavior of the shells are investigated. One ...

Citation Formats

B. Gözlüklü, “Delamination analysis by using cohesive interface elements in laminated composites,” M.S. - Master of Science, Middle East Technical University, 2009.