Modelling of crack propagation of gravity dams by scaled boundary polygons and cohesive crack model
- Authors: Shi, Mingguang , Zhong, Hong , Ooi, Ean Tat , Zhang, Chuhan , Song, Chongmin
- Date: 2013
- Type: Text , Journal article
- Relation: International Journal of Fracture Vol. 183, no. 1 (2013), p. 29-48
- Full Text: false
- Reviewed:
- Description: Crack propagation in concrete gravity dams is investigated using scaled boundary polygons coupled with interface elements. The concrete bulk is assumed to be linear elastic and is modelled by the scaled boundary polygons. The interface elements model the fracture process zone between the crack faces. The cohesive tractions are modelled as side-face tractions in the scaled boundary polygons. The solution of the stress field around the crack tip is expressed semi-analytically as a power series. It reproduces the singular and higher-order terms in an asymptotic solution, such as the William's eigenfunction expansion when the cohesive tractions vanish. Accurate results can be obtained without asymptotic enrichment or local mesh refinement. The stress intensity factors are obtained directly from their definition and provide a convenient and accurate means to assess the zero-K condition, which determines the stability of a cohesive crack. The direction of crack propagation is determined from the maximum circumferential stress criterion. To accommodate crack propagation, a local remeshing algorithm that is applicable to any polygon mesh is augmented by inserting cohesive interface elements between the crack surfaces as the cracks propagate. Three numerical benchmarks involving crack propagation in concrete gravity dams are modelled. The results are compared to the experimental and other numerical simulations reported in the literature. © 2013 Springer Science+Business Media Dordrecht.
Efficient prediction of deterministic size effects using the scaled boundary finite element method
- Authors: Ooi, Ean Tat , Yang, Zhenjun
- Date: 2010
- Type: Text , Journal article
- Relation: Engineering Fracture Mechanics Vol. 77, no. 6 (2010), p. 985-1000
- Full Text: false
- Reviewed:
- Description: This paper develops an efficient numerical approach to predict deterministic size effects in structures made of quasi-brittle materials using the scaled boundary finite element method (SBFEM). Depending on the structure's size, two different SBFEM-based crack propagation modelling methodologies are used for fracture analyses. When the length of the fracture process zone (FPZ) in a structure is of the order of its characteristic dimension, nonlinear fracture analyses are carried out using the finite element-SBFEM coupled method. In large-sized structures, a linear elastic fracture mechanics (LEFM)-based SBFEM is used to reduce computing time due to small crack propagation length required to represent the FPZ in an equivalent nonlinear analysis. Remeshing is used in both methods to model crack propagation with crack paths unknown a priori. The resulting peak loads are used to establish the size effect laws. Three concrete structures were modelled to validate the approach. The predicted size effect is in good agreement with experimental data. The developed approach was found more efficient than the finite element method, at least in modelling LEFM problems and is thus an attractive tool for predicting size effect. © 2010 Elsevier Ltd.