APPLICATION OF THE LINEARLY INDEPENDENT HIGH-ORDER NUMERICAL MANIFOLD METHOD IN FRACTURE MECHANICS
XU Dongdong1,YANG Yongtao2,ZHENG Hong2,WU Aiqing1
(1. Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources,Yangtze River Scientific Research Institute,Hubei,Wuhan 430010,China;2. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Hubei,Wuhan 430071,China)
Abstract:The numerical manifold method(NMM) has succeeded in providing a unified solution to continuum and discontinuum problems and therefore it is highly suitable for solving fracture mechanics problems. However,the conventional high-order NMM using the first order polynomial as the local displacement function has the problem of linear dependence,which restricts to a certain degree its further development and application. A new NMM framework was established in this research by introducing a new localized displacement function,as well as a special displacement function for modeling the stress singularity around crack tips. A new paradigm that eliminates the problem of linear dependence is then derived to solve linear elastic fracture mechanics problems. The numerical examples show that:(1) The proposed method successfully eliminates the problem of linear dependence;(2) For classic linear elastic fracture problems,the stress intensity factors at the crack tip can be calculated accurately even if the mesh is relatively sparse;(3) The stress function at interpolation points inside the physical domain is continuous;(4) All the degrees of freedom defined on non-singular physical patches are physically meaningful,with the third to the fifth being the strain components at the interpolation point of the patch. As a result,the stress components at the interpolation point can be directly obtained. Finally,the proposed approach can be easily extended to other methods based on the theory of the partition of unity.
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