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.

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 Analysis of Dynamic Fracture Parameters in Functionally Graded Material Plates with Cracks by Graded Finite Element Method and Virtual Crack Closure Technique

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Li Ming Zhou ◽  
Guang Wei Meng ◽  
Xiao Lin Li ◽  
Feng Li
Keyword(s):  
Finite Element ◽  
Crack Closure ◽  
Dynamic Fracture ◽  
Functionally Graded Material ◽  
Functionally Graded ◽  
Interface Element ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Graded Material ◽  
Element Method

Based on the finite element software ABAQUS and graded element method, we developed a dummy node fracture element, wrote the user subroutines UMAT and UEL, and solved the energy release rate component of functionally graded material (FGM) plates with cracks. An interface element tailored for the virtual crack closure technique (VCCT) was applied. Fixed cracks and moving cracks under dynamic loads were simulated. The results were compared to other VCCT-based analyses. With the implementation of a crack speed function within the element, it can be easily expanded to the cases of varying crack velocities, without convergence difficulty for all cases. Neither singular element nor collapsed element was required. Therefore, due to its simplicity, the VCCT interface element is a potential tool for engineers to conduct dynamic fracture analysis in conjunction with commercial finite element analysis codes.

scholarly journals Cell-Based Smoothed Finite Element Method-Virtual Crack Closure Technique for a Piezoelectric Material of Crack

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Li Ming Zhou ◽  
Guang Wei Meng ◽  
Feng Li ◽  
Hui Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Closure ◽  
Piezoelectric Materials ◽  
Piezoelectric Element ◽  
Fracture Analysis ◽  
Virtual Crack Closure Technique ◽  
Closure Technique ◽  
Smoothed Finite Element Method ◽  
Element Method

In order to improve the accuracy and efficiency of solving fracture parameters of piezoelectric materials, a piezoelectric element, tailored for the virtual crack closure technique (VCCT), was used to study piezoelectric materials containing a crack. Recently, the cell-based smoothed finite element method (CSFEM) and VCCT have been used to simulate the fracture mechanics of piezoelectric materials. A center cracked piezoelectric materials with different material properties, crack length, mesh, and smoothing subcells at various strain energy release rates are discussed and compared with finite element method-virtual crack closure technique (FEM-VCCT). Numerical examples show that CSFEM-VCCT gives an improved simulation compared to FEM-VCCT, which generally simulates materials as too stiff with lower accuracy and efficiency. Due to its simplicity, the VCCT piezoelectric element demonstrated in this study could be a potential tool for engineers to practice piezoelectric fracture analysis. CSFEM-VCCT is an efficient numerical method for fracture analysis of piezoelectric materials.

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