scholarly journals Mesh size sensitivity analysis for interlaminar fracture of the fiber-reinforced laminated composites

2019 ◽  
Vol 14 ◽  
pp. 155892501988346 ◽  
Author(s):  
Fatih Daricik
Keyword(s):  
Crack Closure ◽  
Strain Energy ◽  
Three Dimensional ◽  
Laminated Composite ◽  
Mesh Size ◽  
Strain Energy Release ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Interlaminar Fracture ◽  
Element Size

The virtual crack closure technique is a well-known finite element–based numerical method used to simulate fractures and it suits well to both of two-dimensional and three-dimensional interlaminar fracture analysis. In particular, strain energy release rate during a three-dimensional interlaminar fracture of laminated composite materials can successfully be computed using the virtual crack closure technique. However, the element size of a numerical model is an important concern for the success of the computation. The virtual crack closure technique analysis with a finer mesh converges the numerical results to experimental ones although such a model may need excessive modeling and computing times. Since, the finer element size through a crack path causes oscillation of the stresses at the free ends of the model, the plies in the delaminated zone may overlap. To eliminate this problem, the element size for the virtual crack closure technique should be adjusted to ascertain converged yet not oscillating results with an admissible processing time. In this study, mesh size sensitivity of the virtual crack closure technique is widely investigated for mode I and mode II interlaminar fracture analyses of laminated composite material models by considering experimental force and displacement responses of the specimens. Optimum sizes of the finite elements are determined in terms of the force, the displacement, and the strain energy release rate distribution along the width of the model.

scholarly journals Implementation of Virtual Crack Closure Technique for Damaged Composite Plates Using Higher-Order Layerwise Model

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Kwang S. Woo ◽  
Jae S. Ahn
Keyword(s):  
Crack Closure ◽  
Edge Crack ◽  
Present Model ◽  
Three Dimensional ◽  
Higher Order ◽  
Virtual Crack Closure Technique ◽  
Single Edge ◽  
Displacement Fields ◽  
Closure Technique ◽  
Aluminum Plates

A higher-order layerwise model is proposed to determine stress intensity factors using virtual crack closure technique for single-edge-crack aluminum plates with patch repairs. The present method is based onp-convergent approach and adopts the concept of subparametric elements. In assumed displacement fields, strain-displacement relations and three-dimensional constitutive equations of layers are obtained by combination of two- and one-dimensional shape functions. Thus, it allows independent implementation ofp-refinement for in-plane and transversal displacements. In the proposed elements, the integrals of Legendre polynomials and Gauss-Lobatto technique are employed to interpolate displacement fields and to implement numerical quadrature, respectively. For verification of the present model, not only single-edge-crack plates but also V-notch aluminum plates are first analyzed. For patched aluminum plate with behavior of complexity, the accuracy and simplicity of the present model are shown with comparison of the results with previously published papers using the conventional three-dimensional finite elements based onh-refinement.

EFG Virtual Crack Closure Technique for the Determination of Stress Intensity Factor

2011 ◽  
Vol 250-253 ◽  
pp. 3752-3758 ◽  
Author(s):  
Xue Ping Chang ◽  
Jun Liu ◽  
Shi Rong Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Closure ◽  
Crack Opening ◽  
Crack Tip ◽  
Strain Energy Release ◽  
Virtual Crack Closure Technique ◽  
Opening Displacement ◽  
Closure Technique

The aim of this paper is to introduce a virtual crack closure technique based on EFG method for thread-shape crack. The cracked component is discretized and the displacement field is determined using a coupled FE/EFG method, by which EFG nodes are arranged in the vicinity of crack tip and FE elements in the remain part in order to improve computational efficiency. Two typical parameters, nodal force and crack opening displacement attached to crack tip are calculated by means of setting up an auxiliary FE zone around crack tip. Strain energy release rate (SERR), further stress intensity factor (SIF) are determined by the two parameters. The method to calculate SIF is named as virtual crack closure technique based on EFG method. It is showed by several numerical examples that using the method presented in this paper, SIF on the crack tip can be obtained accurately.

Corrosion Fatigue Crack Propagation of 6151-T6 Aluminum Alloy Based on Virtual Crack Closure Technique

2014 ◽  
Vol 998-999 ◽  
pp. 31-34
Author(s):  
Guang Ming Kong ◽  
Xu Dong Li ◽  
Zhi Tao Mu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Closure ◽  
Strain Energy Release ◽  
Interface Element ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Accelerated Corrosion ◽  
Stress Levels

Using the virtual crack closure technique (VCCT), an interface element that can calculate stress intensity factors (SIFs) directly and simulate the crack propagation conveniently has been developed. Based on an accelerated corrosion experiment, the fatigue crack propagation behavior of the 6151-T6 aluminum alloys under different corrosion years and stress levels were simulated, and it was proved to be convenient to calculate strain energy release rate and SIFs of AA 6151-T6 under different stress levels and corrosion years. The proposed method is characterized by higher accuracy and less calculation elements, provides a new way for engineering fracture analysis of the structure.

Virtual crack closure technique: History, approach, and applications

2004 ◽  
Vol 57 (2) ◽  
pp. 109-143 ◽  
Author(s):  
Ronald Krueger
Keyword(s):  
Crack Closure ◽  
Composite Structures ◽  
Three Dimensional ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Element Analysis ◽  
Shell Elements ◽  
Engineering Problems ◽  
History Approach ◽  
Insight Into

An overview of the virtual crack closure technique is presented. The approach used is discussed, the history summarized, and insight into its applications provided. Equations for two-dimensional quadrilateral finite elements with linear and quadratic shape functions are given. Formulas for applying the technique in conjunction with three-dimensional solid elements as well as plate/shell elements are also provided. Necessary modifications for the use of the method with geometrically nonlinear finite element analysis and corrections required for elements at the crack tip with different lengths and widths are discussed. The problems associated with cracks or delaminations propagating between different materials are mentioned briefly, as well as a strategy to minimize these problems. Due to an increased interest in using a fracture mechanics–based approach to assess the damage tolerance of composite structures in the design phase and during certification, the engineering problems selected as examples and given as references focus on the application of the technique to components made of composite materials.

scholarly journals Adhesive Boundary Element Method Using Virtual Crack Closure Technique

2021 ◽  
Vol 7 ◽  
Author(s):  
Yang Xu ◽  
Rongxin Zhou
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Crack Closure ◽  
Crack Nucleation ◽  
Mesh Size ◽  
Work Of Adhesion ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Mesh Grid ◽  
Element Method

In this study, a new adhesive contact model is built upon a boundary element method (BEM) model developed by Pohrt and Popov (2015). The strain energy release rate (SERR) on the edge of the bonding interface is evaluated using Virtual Crack Closure Technique (VCCT) which is shown to have better accuracy and weaker mesh-size dependency than the closed-form SERR formula derived by Pohrt and Popov. A composite delamination criterion is proposed for crack nucleation and propagation. Numerical results predicted by the present model are in good agreement with the analytical solutions of two classic problems, namely, the axisymmetric parabolic contact and the sinusoidal waviness contact in the plane strain condition. The model of Pohrt and Popov can achieve a similar accuracy for the axisymmetric parabolic contact where the mesh grid is non-conforming to the crack front. Once the conforming mesh grid is used, the accuracy of their model is significantly deteriorated, especially at high work of adhesion and high mesh density. In both BEM models, however, the crack nucleation is found to be mesh-dependent which may be solved by introducing an upper limit for the tensile normal traction.

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