Automatic dynamic crack propagation modeling using polygon scaled boundary finite elements
- Authors: Ooi, Ean Tat , Shi, Mingguang , Song, Chongmin , Tin-Loi, Francis , Yang, Zhenjun
- Date: 2013
- Type: Text , Conference proceedings
- Relation: 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012; Sydney, NSW; Australia; 11th-14th Dec 2012 published in From Materials to Structures: Advancement Through Innovation p. 411-416
- Full Text: false
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- Description: This study develops a simple and efficient methodology for automatic dynamic crack propagation modeling in structures. It uses high order, arbitrary n-sided polygon elements that are constructed within the scaled boundary finite element framework. Each polygon is treated as a scaled boundary finite element subdomain and their governing equations of equilibrium are assembled using standard finite element procedures. Polygon meshes are automatically generated from a Delaunay triangulated mesh. This method inherits all the positive characteristics of the scaled boundary finite element method. Orders of singularities of any kind can be accurately represented in a unified manner by generalized stress intensity factors to evaluate the crack propagation criterion without dense meshes around the crack tip, special purpose elements or nodal enrichment functions. Crack propagation is efficiently modeled using a simple, yet flexible automatic local remeshing algorithm that is linked to the pre-processing module of a commercial finite element package and can be applied to any polygon mesh. Remeshing involves only polygons around the crack and only minimally changes the global mesh structure. Application of the methodology to model dynamic crack propagation problems is demonstrated by two numerical examples. It is found that the predicted dynamic fracture parameters e.g. dynamic stress intensity factor histories, crack velocity histories, crack length histories and crack paths show good agreement with experiment observations and numerical simulations reported in the literature. © 2013 Taylor & Francis Group.
- Description: From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012
Evaluation of stress intensity factors on cracked functionally graded materials using polygons modelled by the scaled boundary finite element method
- Authors: Ooi, Ean Tat , Chiong, Irene , Song, Chongmin
- Date: 2013
- Type: Text , Conference proceedings
- Relation: 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012; Sydney, NSW; Australia; 11th-14th Dec, 2012 published in From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM p. 201-206
- Full Text: false
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- Description: Functionally graded materials are a relatively newclass of composite materialswhere its material properties are defined by a continuous function on the spatial coordinates. Its use in engineering practice is increasingly popular due to its superior mechanical and thermo-mechanical properties. Understanding the behaviour of cracks in functionally graded materials is important in the assessment of their structural integrity. This study develops a novel approach using polygon elements, which are modelled by the scaled boundary finite element method, to analyse the fracture behaviour in functionally graded materials. The scaled boundary finite element equations are reformulated in terms of nodal shape functions. Each polygon is then treated using standard finite element procedures. The non-uniform material properties are locally represented by a polynomial fit in the element formulation. This formulation still inherits all the advantages of the scaled boundary finite element method. Orders of singularities and hence, stress intensity factors can be computed accurately using only singular modes in the scaled boundary finite element solution without nodal enrichment functions. Mesh refinement at the crack tip is significantly less compared to that required in standard finite element method and is only necessary to model the graded material properties throughout the computational domain. The efficiency of the method in evaluating stress intensity factors are demonstrated using a few numerical examples. © 2013 Taylor & Francis Group.
- Description: From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012
Crack propagation modeling in functionally graded materials using polygon elements modeled by the scaled boundary finite element method
- Authors: Ooi, Ean Tat , Guo, ShuHong , Song, Chongmin
- Date: 2013
- Type: Text , Conference proceedings
- Relation: 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012; Sydney, NSW; Australia; 11th-14th December 2012; Published in From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM p. 133-138
- Full Text: false
- Reviewed:
- Description: Functionally graded materials (FGMs) are multi-phased composites that are specifically engineered so that their material properties vary continuously in a predetermined direction. The heterogeneity in FGMs results in superior fracture resistance, making them suitable for use as medical implants and components in nuclear, aerospace and electro-mechanical industries. The degree to which the fracture resistance of FGMs can be improved is usually not known a priori. Understanding their fracture behaviour provides insights to design better FGMs and enables quantitative assessment of the structural integrity in manufactured FGM products. A novel methodology is developed in this study to model crack propagation in FGMs. It uses high order polygon elements that are modelled by the scaled boundary finite element method. The displacement and stress fields in each polygon are expressed using scaled boundary shape functions and corresponding nodal displacements. Material heterogeneity is modelled by locally fitting a polynomial curve in terms of scaled boundary finite element coordinates over each polygon. The developed method is very efficient in modelling singular stress fields in the vicinity of cracks. Stress intensity factors are evaluated directly from the singular modes in the scaled boundary finite element solutions to determine the crack propagation direction.A simple local remeshing algorithm for polygons is developed to accommodate crack propagation. Fracture analyses of FGMs are conducted on three numerical examples to validate the methodology and demonstrate its salient features. Fracture parameters e.g. stress intensity factors, critical failure load and crack propagation paths of FGM specimens can be obtained from these analyses. © 2013 Taylor & Francis Group.
- Description: From Materials to Structures: Advancement Through Innovation - Proceedings of the 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012