scholarly journals An Image-Based Double-Smoothing Cohesive Finite Element Framework for Particle-Reinforced Materials

Mathematics ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 543
Author(s):  
Xiaoming Bai ◽  
Xue Mi ◽  
Hai Xie ◽  
Kaikai Shi ◽  
Furui Xiong ◽  
...  
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Digital Image ◽  
Fracture Process ◽  
Element Mesh ◽  
Micro Scale ◽  
Double Smoothing ◽  
Reinforced Materials

In order to simulate the fracture process of particle-reinforced materials on the micro-scale, an image-based double-smoothing cohesive finite element framework is proposed in the present paper. Two separate smoothing processes are performed to reduce the noise in the digital image and eliminate the jagged elements in the finite element mesh. The main contribution of the present study is the proposed novel image-based cohesive finite element framework, and this method improved the quality of the meshes effectively. Meanwhile, the artificial resistance due to the jagged element is reduced with the double-smoothing cohesive finite element framework during the crack propagation. Therefore, the image-based double-smoothing cohesive finite element framework is significant for the simulation of fracture mechanics.

Automated Fracture Mechanics and Fatigue Analyses Based on Three-Dimensional Finite Element for Welding Components

2014 ◽  
Author(s):  
Hitoshi Nakamura ◽  
Seiichi Tajima ◽  
Osamu Hazama ◽  
Wenwei Gu
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Hexahedral Mesh ◽  
Element Mesh ◽  
Fem Model ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper describes the structure and application of a software system that automates the fatigue initiation and crack propagation analysis based on FEM. The system automatically performs necessary procedures to track propagation history of cracks: insertion of a crack and updating of three-dimensional finite element mesh in accordance with the crack propagation. Most of the meshing is carried out by a Delaunay tessellation method. A tubular hexahedral mesh is generated at the crack front and the fracture mechanics parameters are computed using commercial codes to ensure accuracy. The generation of this tubular hexahedral mesh is fully automatic as well. The system is equipped with a function to automatically perform fatigue analyses using the stress-strain histories at nodes of a three-dimensional FEM model. The standard low cycle fatigue analysis approach is adopted. Using the function, cumulative fatigue for a given FEM model is provided. Some analyses for several examples were carried out for validation. The important example is the surface crack propagation in steel pipes with residual stress.

A Constrained Optimization Approach to Finite Element Mesh Smoothing

1991 ◽  
Author(s):  
V. N. Parthasarathy ◽  
Srinivas Kodiyalam
Keyword(s):  
Finite Element ◽  
Constrained Optimization ◽  
Finite Element Mesh ◽  
Optimization Approach ◽  
Element Mesh ◽  
Initial Mesh ◽  
Nodal Coordinates ◽  
Automatic Mesh ◽  
Mesh Generators

Abstract The quality of a finite element solution has been shown to be affected by the quality of the underlying mesh. A poor mesh may lead to unstable and lor inaccurate finite element approximations. Mesh quality is often characterized by the “smoothness” or “shape” of the elements (triangles in 2-D or tetrahedra in 3-D). Most automatic mesh generators produce an initial mesh where the aspect ratio of the elements are unacceptably high. In this paper, a new approach to produce acceptable quality meshes from an initial mesh is presented. Given an initial mesh (nodal coordinates and element connectivity), a “smooth” final mesh is obtained by solving a constrained optimization problem. The variables for the iterative optimization procedure are the nodal coordinates (excluding, the boundary nodes) of the finite element mesh, and appropriate bounds are imposed on these to prevent an unacceptable finite element mesh. Examples are given of the application of the above method for 2/3-D triangular meshes generated using a QUADTREE | OCTREE automatic mesh generators. Results indicate that the new method not only yields better quality elements when compared with the traditional Laplacian smoothing, but also guarantees a valid mesh unlike the Laplacian method.

A Framework for Finite Element Mesh Quality Improvement and Visualization in Orthopaedic Biomechanics

2009 ◽  
Author(s):  
Kiran H. Shivanna ◽  
Srinivas C. Tadepalli ◽  
Vincent A. Magnotta ◽  
Nicole M. Grosland
Keyword(s):  
Finite Element ◽  
Quality Improvement ◽  
Biological Processes ◽  
Mesh Quality ◽  
The Finite Element Method ◽  
Element Mesh ◽  
Invaluable Tool ◽  
Finite Element Meshing ◽  
Mesh Quality Improvement

The finite element method (FEM) is an invaluable tool in the numerical simulation of biological processes. FEM entails discretization of the structure of interest into elements. This discretization process is termed finite element meshing. The validity of the solution obtained is highly dependent on the quality of the mesh used. Mesh quality can decrease with increased complexity of the structure of interest, as is often evident when meshing biologic structures. This necessitated the development/implementation of generalized mesh quality improvement algorithms.

The Implementation of Inter-Element Model for Crack Growth Simulation

2004 ◽  
Vol 261-263 ◽  
pp. 687-692 ◽  
Author(s):  
Ahmad Kamal Ariffin ◽  
Syifaul Huzni ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Problem ◽  
Adaptive Mesh ◽  
Element Model ◽  
Error Norm ◽  
Element Analysis ◽  
Element Mesh

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.

Inverse Pre-deformation of Finite Element Mesh for Large Deformation Analysis

2005 ◽  
Vol 5 (4) ◽  
pp. 338-347 ◽  
Author(s):  
Arbtip Dheeravongkit ◽  
Kenji Shimada
Keyword(s):  
Finite Element ◽  
Large Deformation ◽  
Premature Termination ◽  
Deformation Analysis ◽  
Lagrangian Analysis ◽  
Element Analysis ◽  
Element Mesh ◽  
Bilinear Mapping ◽  
Optimal Node

The process of finite element analysis that deals with large deformation often produces distorted elements in the later stages of the analysis. These distorted elements lead to analysis problems, such as inaccurate solutions, slow convergence, and premature termination of the analysis. This paper proposes a new mesh generation algorithm to mesh the input part for pure Lagrangian analysis, where our goal is to improve the shape quality of the elements along the analysis process to reduce the number of inverted elements at the later stage, and to decrease the possibility of premature termination of the analysis. One pre-analysis is required to collect geometric and stress information in the analysis. The proposed method then uses the deformed-shape boundary known from the pre-analysis, finds the optimal node locations, considers the stress information to control the mesh sizes, as well as control the mesh directionality, generates meshes on the deformed boundary, and finally, maps the elements back to the undeformed boundary using inverse bilinear mapping. The proposed method has been tested on two forging example problems. The results indicate that the method can improve the shape quality of the elements at the later stage of the analysis, and consequently extend the life of the analysis, thereby reducing the chance of premature analysis termination.

Automated Fracture Mechanics and Fatigue Analyses Based on Three-Dimensional Finite Elements

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hitoshi Nakamura ◽  
Wenwei Gu ◽  
Seiichi Tajima ◽  
Osamu Hazama
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Three Dimensional ◽  
3D Fem ◽  
Element Mesh ◽  
Fem Model ◽  
Steel Pipes ◽  
Fatigue Initiation ◽  
Propagation Analysis ◽  
History Of

This paper describes the structure and application of a software system that automates the fatigue initiation and crack propagation analysis based on finite element method (FEM). The system automatically performs necessary procedures to track propagation history of cracks: insertion of a crack and updating of three-dimensional (3D) finite element mesh in accordance with the crack propagation. The system is equipped with a function to automatically perform fatigue analyses using the stress–strain histories at nodes of a 3D FEM model. Some analyses for several examples were carried out for validation. The important example is the surface crack propagation in steel pipes with residual stress.

scholarly journals AN INVESTIGATION OF IRREGULAR CRACK PATH EFFECTS ON FRACTURE MECHANICS PARAMETERS USING A GRAIN MICROSTRUCTURE MESHING TECHNIQUE

2012 ◽  
Vol 04 (01) ◽  
pp. 1250001 ◽  
Author(s):  
A. MEHMANPARAST ◽  
F. BIGLARI ◽  
C. M. DAVIES ◽  
K. M. NIKBIN
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Analytical Solutions ◽  
Numerical Solutions ◽  
Crack Path ◽  
Crack Tip ◽  
Grain Structure ◽  
Element Mesh ◽  
Mesh Structure ◽  
Crack Paths

A sub-grain size finite element modelling approach is presented in this paper to investigate variations in fracture mechanics parameters for irregular crack paths. The results can be used when modelling intergranular and transgranular crack growth where creep and fatigue are the dominant failure mechanisms and their crack paths are irregular. A novel method for sub-grain scale finite element mesh consisting of multiple elements encased in ~50–150 μm-sized grains has been developed and implemented in a compact tension, C(T), mesh structure. The replicated shapes and dimensions were derived from an isotropic metallic grain structure using representative random sized grain shapes repeated in sequence ahead of the crack tip. In this way the effects of crack tip angle ahead of the main crack path can be considered in a more realistic manner. A comprehensive sensitivity analysis has been performed for elastic and elastic-plastic materials using ABAQUS and the stress distributions, the stress intensity factor and the J-integral have been evaluated for irregular crack paths and compared to those of obtained from analytical solutions. To examine the local and macroscopic graph path effects on fracture mechanics parameters, a few extreme cases with various crack-tip angles have been modelled by keeping the macroscopic crack path parallel to the axis of symmetry. The numerical solutions from these granular mesh structures have been found in relatively good agreement with analytical solutions.

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