Papers by Keyword: Adaptive Mesh

Abstract: The core of the numerical manifold method (NMM) is a two-mesh problem description. Two meshes are employed in an analysis: the mathematical mesh provides the nodes for building a finite covering of the solution domain, while the physical mesh provides the domain of integration. The NMM can deal with the continuum and discontinuous problem, and has been applied to the rock mechanics and engineering widely. This paper introduces the research progress of the NMM in the basic theory and application aspects. The adaptive mesh generation of NMM is discussed. The adaptive finite cover mesh reconstruction technology is given.

Abstract: Fatigue crack propagation in two-dimensional rail track model under constant amplitude loading was analyzed using finite element method. The stress intensity factor was predicted using the displacement correlation method that was written in FORTRAN code and exported to Post2D to run the program and utilizing the singular elements around the crack tip area with automatic remeshing model. The fatigue crack propagation is modeled through the successive linear extensions under the linear elastic assumption. To simulate the propagation a single edge angled-crack was introduced to calculate the accurate values of stress intensity factors. The fatigue crack propagation for rail track under four point bend loading model was successfully simulated. The crack was initially propagated in direction inclined to the rail head surface but changed its direction 90° to rail head surface after certain crack length. The mix mode stress intensity factors were also successfully determined through the proposed model.

Abstract: Stress distribution analysis on four types of stress corrosion cracking (SCC) specimen is presented in this paper. This work was performed using commercial finite element based software, ANSYS. Two types of mesh arrangements, fixed mesh with different mesh size and adaptive mesh, were employed in this work to study the effect of mesh size on stress distribution of SCC specimen. Four types of SCC specimen were studied in this work, i.e. C-ring specimen, tensile test specimen, pre-crack cantilever beam specimen and U-bend specimen. Simulation result shows that stress distribution on the SCC specimen much affected by mesh size and arrangement, especially for specimen with notch. By performing the stress analysis, less effort needed in order to determine the location of corrosion potential measurement on the SCC specimen. This will be very helpful for future work of SCC study.

Abstract: We demonstrate how algorithms to compute hierarchical triangular meshes. We can generate the hierarchical triangular meshes using level-of-detail for the mesh data structure. We perform hierarchical regional partitions using Ward's method with hierarchical data structure to achieve the level-of-detail. The meshes using this data structure can be hierarchically compressed and be unpacked at a faster pace. Additionally, we introduce the adaptive mesh generation algorithms for the parameters of computational mechanics by setting some kind of metrics in the level-of-detail.

Abstract: The purpose of this work is the modeling and simulation of the material behavior of aluminum alloys during extrusion processes. In particular, attention is focused here on aluminum alloys of the 6000 series (Al-Mg-Si) and 7000 series (Al-Zn-Mg). The material behavior of these alloys during extrusion is governed mainly by dynamic recovery and static recrystallization during cooling. The current material model is based on the role of energy stored in the material during deformation, as it acts as the driving force for microstructural development. The concept of internal variables is used to describe state quantities such as dislocation density, average grain size and average grain orientation. The focus of the current paper is on some of the numerical aspects of the extrusion process simulation such as contact problems and adaptive mesh refinement which should be considered in order to obtain more accurate and robust results.

Abstract: An adaptive finite element method for analyzing two-dimensional and axisymmetric nonlinear elastic fracture mechanics problems with cracks is presented. The J-integral is used as a parameter to characterize the severity of stresses and deformation near a crack tip. The domain integral technique is utilized as the J-integral solution scheme with the 9-node degenerated crack tip elements. The solution accuracy is further improved by incorporating an error estimation procedure to a remeshing algorithm with a solution mapping scheme to resume the analysis at a particular load level after the adaptive remeshing technique has been applied. Two benchmark problems are analyzed to evaluate the efficiency of the combined procedure.

Abstract: This paper describes the numerical modeling based on combination of finite element method (FEM) and discrete element method (DEM) has been employed to simulate crack propagation under mixed mode loading. The work demonstrates the ability of combination finitediscrete element method to simulate the crack propagation that is usually performed through, what is termed, transition from continua to discontinua process. Crack propagation trajectory under selected loading angles (30o & 60o) are presented. The result obtained using the proposed model compare well with experimental result.

Abstract: The implementation of inter-element model to simulate crack propagation by using finite element analysis with adaptive mesh is presented. An adaptive finite element mesh is applied to analyze two-dimension elastoplastic fracture during crack propagation. Displacement control approach and updated Lagrangean strategy are used to solve the non-linearity in geometry, material and boundary for plane stress crack problem. In the finite element analysis, remeshing process is based on stress error norm coupled with h-version mesh refinement to find an optimal mesh. The crack is modeled by splitting crack tip node and automatic remeshing calculated for each step of crack growth. Crack has been modeled to propagate through the inter-element in the mesh. The crack is free to propagates without predetermine path direction. Maximum principal normal stress criterion is used as the direction criteria. Several examples are presented to show the results of the implementation.