Application Of XFEM In The Multiple Crack Propagation Analysis Of Asphalt Pavement

The dominated numerical method for analyzing the crack propagation is the finiteelement method (FEM), in which the remeshing procedure cannot be avoided during everypropagate step. Besides the increase of computational cost, the accuracy by using FEM isterribly depend on the relationship between crack and finite element mesh, since crackcould only propagate along the boundaries of element. Thus, the FEM is not capable fordealing with the complexity in multiple crack analysis in asphalt pavement. The eXtendedFinite Element Method (XFEM) can solve all the above problems. In XFEM, crack istotally independent of the mesh and can propagate inside the element, so an accuratelysimulation of crack propagation can be achieved by using XFEM. Researches in this thesisare based on Linear Elastic Fracture Mechanics (LEFM) and XFEM.Firstly, the recent developments of some relevant areas are presented. Since1999,XFEM has been applied in various fields successfully, such as, fracture mechanics,composites, contact, large deformation, shell, multi-scale analysis and et al.Secondly, the XFEM formulation for LEFM is thoroughly presented. In thisapplication, two types of the local enrichment are introduced in order to reproduce thediscontinuity along crack surface and the singular field near crack tip in the approximation.In this application, the crack can be modeled independently from the finite element meshand the complex remeshing procedure according to crack propagation can be avoided. Inaddition, the fracture mechanics parameters can be accurately evaluated without meshrefinement. Thus, the XFEM has a potential ability to solve the problem of the numericalsimulation of the crack problem. In the XFEM, the enrichment is usually localized tosub-domains thorough the introduction of enrichment functions defined at the respectivenodes. It leads the inevitable presence of the partially enriched elements called blending elements. The blending elements have the unwanted parasitic terms in the approximationand cause the problems in the numerical accuracy. The numerical results show that theaccuracy will be terribly influenced when the integral domain of J-integral is fullyoverlapped with the domain of blending element. So, during the analysis, we should choosethese parameters carefully.Finally, numerical analysis on the multiple crack propagation in asphalt pavement isconducted. The influences of location of loads and cracks, horizontal loads, modulus andthickness of asphalt pavement on the crack propagation are studied. The numerical resultshave a good agreement with the experimental results.