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Keywords: heterogeneous cohesive model, random heterogeneous materials, quasi-brittle failure, stochastic fracture.

Summary

Failure mechanisms of materials are intrinsically intertwined with nonhomogeneity and randomness at fine scales. By using mean field data for heterogeneous materials, homogeneous materials-based fracture models might result in the prediction of unrealistic smooth crack trajectories and consequently unreliable load-carrying capacity. This study aims to develop a heterogeneous cohesive (HC) crack model to predict macroscopic strength of materials based on meso-scale random fields of fracture properties. By characterizing spatially varying fracture properties as random fields, heterogeneous cohesive crack propagation is simulated to predict more realistic crack paths and to more reliably assess macroscopic load-carrying capacity. A new stress-based criterion to determine the crack growth direction is developed by taking into account both the crack-tip stress state and heterogeneity of the tensile strength. A concrete beam subjected to mixed-mode fracture is modelled as a benchmark example to demonstrate the HC crack model. The numerical simulation reveals that crucial fracture phenomena, such as the tortuousness in crack trajectories, can be effectively captured by the HC model. Effects of various important parameters on the crack paths, peak loads, macroscopic ductility and overall reliability, including the variance of random fields and the shear fracture resistance, are investigated and discussed.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 245 A Heterogeneous Cohesive Crack Model for Quasi-brittle Materials Considering Spatially Varying Random Fracture Properties Z.J. Yang¹ and X.F. Xu² ¹Department of Engineering, University of Liverpool, United Kingdom ²Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken NJ, United States of America doi:10.4203/ccp.88.245 purchase the full-text of this paper Full Bibliographic Reference for this paper Z.J. Yang, X.F. Xu, "A Heterogeneous Cohesive Crack Model for Quasi-brittle Materials Considering Spatially Varying Random Fracture Properties", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 245, 2008. doi:10.4203/ccp.88.245 Keywords: heterogeneous cohesive model, random heterogeneous materials, quasi-brittle failure, stochastic fracture. Summary Failure mechanisms of materials are intrinsically intertwined with nonhomogeneity and randomness at fine scales. By using mean field data for heterogeneous materials, homogeneous materials-based fracture models might result in the prediction of unrealistic smooth crack trajectories and consequently unreliable load-carrying capacity. This study aims to develop a heterogeneous cohesive (HC) crack model to predict macroscopic strength of materials based on meso-scale random fields of fracture properties. By characterizing spatially varying fracture properties as random fields, heterogeneous cohesive crack propagation is simulated to predict more realistic crack paths and to more reliably assess macroscopic load-carrying capacity. A new stress-based criterion to determine the crack growth direction is developed by taking into account both the crack-tip stress state and heterogeneity of the tensile strength. A concrete beam subjected to mixed-mode fracture is modelled as a benchmark example to demonstrate the HC crack model. The numerical simulation reveals that crucial fracture phenomena, such as the tortuousness in crack trajectories, can be effectively captured by the HC model. Effects of various important parameters on the crack paths, peak loads, macroscopic ductility and overall reliability, including the variance of random fields and the shear fracture resistance, are investigated and discussed. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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