The nonlocal integral method typically requires a very high computing cost to search neighborhood integration points for calculating the nonlocal variable, which limits its application in large-scale problems. This pa...
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The nonlocal integral method typically requires a very high computing cost to search neighborhood integration points for calculating the nonlocal variable, which limits its application in large-scale problems. This paper proposes an efficient nonlocal integral method based on the octree algorithm, in which the integration point information is stored in the tree data structure to accelerate the search task. Firstly, the fundamental principles and implementation details of using the octree algorithm to search neighborhood integration points are described in detail. Subsequently, a Mohr-Coulomb nonlocal damage plastic model is presented as the application object of the proposed method. The model is implemented further in the ABAQUS using the octree-based nonlocal method and the return mapping algorithm enhanced by a line search method. Finally, two typical boundary value problems are simulated to verify the effectiveness and to assess the computational efficiency of the proposed nonlocal method. For the given test environment, the octree algorithm can achieve up to 100 times speedup at the integration point level compared to the traversal algorithm, and the developed efficient nonlocal method can achieve up to 7.9 times speedup at the boundary value problem level compared to the original nonlocal method.
Accurate terrain data should be obtained in order to research geological structure modeling problem, and it is difficult to truly reflect the form of three-dimensional geological body by traditional three-dimensional ...
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ISBN:
(纸本)9783037859285
Accurate terrain data should be obtained in order to research geological structure modeling problem, and it is difficult to truly reflect the form of three-dimensional geological body by traditional three-dimensional spatial data model method. By taking geological structure modeling problem as research object, this paper analyzes geological modeling principles, builds the volume element model of octree subdivision algorithm, proposes to build a three-dimensional geological body by octree subdivision algorithm based on multi-scale, meets the needs of multi-scale organization of data as well as multi-scale division of geological bodies and attributes based on the geological object expression of octree subdivision algorithm, establishes the links between various geological objects through spatial volume element, lays a good foundation for spatial analysis and provides data support for the three-dimensional visualization of geology. The results of simulation experiment show that the proposed geological modeling method through octree subdivision algorithm is accurate and efficient, and it can adapt to the construction of three-dimensional complex geological model under common complex geological conditions and reflect the true form of three-dimensional geological body.
Techniques are now available to generate high-quality polyhedral elements offering a good alternative way for accurate stress analysis for solids. However, distorted polyhedral elements cannot be effectively used in s...
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Techniques are now available to generate high-quality polyhedral elements offering a good alternative way for accurate stress analysis for solids. However, distorted polyhedral elements cannot be effectively used in standard finite element methods (FEM) without extra complicated treatments, due to the hanging nodes on the element edges and complex shape of polyhedral elements. On the contrary, the hanging nodes and complex shape of the elements can be naturally dealt with in the smoothed finite element method (S-FEM). This paper, utilizes the octree method to automatically and efficiently generate unstructured polyhedral meshes, using the standard tessellation language (STL). We develop three S-FEM models for octree meshes, using all existing node-based, edge-based and face-based smoothing domains. A subdomain smoothing technique is developed to re-cut the smoothing domain (SD), which simplifies the process of smoothing domain formation. The shapes of the subdomains have some common geometries that are much easier to handle, making use of the good features offered by the S-FEM formulation. The introduction of subdomains does not affect the results of the calculations, and the properties of the three S-FEMs are still preserved. Several demonstration examples are presented to verify the efficiency of the present S-FEM models. (C) 2019 Elsevier B.V. All rights reserved.
Generating random aggregate models (RAMs) plays a key role in the mesoscopic modelling of concrete-like composite materials. The arbitrary geometry, wide gradation, and high volume ratio of aggregates pose a great cha...
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Generating random aggregate models (RAMs) plays a key role in the mesoscopic modelling of concrete-like composite materials. The arbitrary geometry, wide gradation, and high volume ratio of aggregates pose a great challenge for fast and efficient numerical construction of concrete meso-structures. This paper presents a simple strategy for generating RAMs of concrete based on Laguerre tessellation, which mainly consists of three steps: tessellation, geometric smoothing, and scaling. The computer-assisted design (CAD) file of RAMs obtained by the proposed approach can be directly adopted for the construction of random numerical concrete samples. Combined with the image-based octree meshing algorithm, the scaled boundary finite element method (SBFEM) was adopted for an automatic stress analysis of mass concrete samples, and a parametric study was conducted to investigate the meso-structural effects on concrete elasticity properties. The modelling results successfully reproduced the increasing trend of concrete elastic modulus with the grading of coarse aggregates in literature test data and demonstrate the effectiveness of the proposed strategy.
At present, most anti-collision mechanisms use graphics processing unit (GPU) for operations and object simulations are drawn using polygonal meshes. However, their costs are always very high. Therefore, we propose a ...
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ISBN:
(纸本)9781728190327
At present, most anti-collision mechanisms use graphics processing unit (GPU) for operations and object simulations are drawn using polygonal meshes. However, their costs are always very high. Therefore, we propose a novel approach to improve the anti-collision mechanism for robotic arms. We apply the octree algorithm to decompose the object model and cooperate with the Bounding Box technology to form the object into a covering box. In this manner, the computation space will be reduced and simplify the calculation of the anti-collision. Finally, the proposed work has been implemented on Rhino to construct a simulation system for industrial manufacturing production lines.
This paper presents a development of the algorithm for combination of block-merge algorithm and octree algorithm. The memory insufficiency problem, which is caused by heaps of temporary variables when researching pore...
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ISBN:
(纸本)9780819495884
This paper presents a development of the algorithm for combination of block-merge algorithm and octree algorithm. The memory insufficiency problem, which is caused by heaps of temporary variables when researching pore structure by octree algorithm, has been effectively solved. The pore structure information of cellular metallic material with large area has been extracted, which provides an important method for the study on the relationship between the structure of porous metal material and function. By applying this method to store more data with less memory, an effective and accurate result is achieved. This work would represent a significant advance for research of pore structure using improved octree algorithm.
After the analysis of collision detection process, we founded that the collision nodes have little relations among them, which makes it possible to be parallelized. Based on message passing interface (MPI), the octree...
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After the analysis of collision detection process, we founded that the collision nodes have little relations among them, which makes it possible to be parallelized. Based on message passing interface (MPI), the octree collision detection algorithm is properly modified for parallel collision detection algorithm in this work. Based on tests, the efficiency of collision detection is shown greatly increased.
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