Fuzzy Knowledge Processing Research Articles

Development of an Automated System for Three-Dimensional J-Integral Analysis

By integrating the 3D solid modeler with the universal FEM code, an automatic nonlinear analysis system for 3D crack problems has been developed. A geometry model, that is, a solid containing one or several 3D cracks is defined. Multiple distributions of local node density are selected and automatically overlapped with each other over the geometry model using fuzzy knowledge processing. Nodes are created by the bucketing method, and tetrahedral square tetrahedral solid elements are generated by the Delaunay triangulation technique. A complete finite element (FE) model is created and stress analysis is performed. In this system, analysts can significantly reduce the burden of introducing 3D cracks into FE models and estimating fracture mechanics parameters. This paper describes a methodology for realizing such a function and demonstrates the validity of this system.

Automated Finite Element Analysis for Molding Behavior of PET Bottle

This paper describes an automated analysis methodology of 3D structures using optimal design system. An automatic finite element mesh generation technique, which is based on fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code, and a commercial solid modeler. Also, with the aid of multilayer neural networks, the present system allows us to obtain automatically a design window in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space. The developed automated FE analysis system is successfully applied to evaluate the molding behavior of PET bottles.

Finite Element Analysis Using Free Mesh Method

Recently, consumers are often dissatisfied with the battery life from even the most advanced lithium-ion rechargeable batteries in mobile phone. A mobile battery was chosen in this study because it is the flat plate of small thin wall which is expected to have some flexing. It is required to be evaluated and designed considering the coupled phenomena. Especially, this paper describes a meshless of element-free method based on fuzzy knowledge processing for battery of smart phone. Practical performance of the present method is demonstrated through heat conduction analysis.

Finite Element Analysis for Ladle Apparatus of Casting Using Free-Mesh Method

This paper describes a meshless of element-free method based on fuzzy knowledge processing. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. Practical performance of the present system is demonstrated through ladle apparatus of casting solutions.

An automated CAE system for multidisciplinary structural design: its application to micro accelerometer

This paper describes a new computer-aided engineering system for multidisciplinary structural design. An automatic finite element mesh generation technique, based on fuzzy knowledge processing and computational geometry, is incorporated into the system, together with one of the commercial finite element analysis codes. A bubble is generated if its distance from existing bubble points is similar to the bubble-spacing function at the point. The bubble-spacing function is well controlled by fuzzy knowledge processing. The Delaunay method is employed as a basic tool for element generation. Automatic finite element generation for three-dimensional MEMS holds great benefits for analyses. An optimum design solution or satisfactory solutions will be automatically searched using the genetic algorithms modified for real search space, together with the automated finite element analysis system. A novel CAE system was developed, and successfully applied to the shape design of a micro accelerometer based on a tunneling current concept.

A Fuzzy Knowledge Matching Method Based on Variable Weight IDM

Fuzzy knowledge representation and processing is a very important topic in artificial intelligence research, the key of the fuzzy knowledge inference is the knowledge matching. Via our investigation on kinds of conventional methods in fuzzy knowledge matching, we propose a knowledge matching method based on variable weights IDM (Inscribed Diameter Matching). Through our comparative analysis, Variable weights IDM is able to overcome some drawbacks exist in the traditional methods. We also give a fusion model which can improve efficiency and accuracy of knowledge inference. The experimental results verify the practicability and availability of our method.

피지이론과 버블기법을 이용한 3차원 구조물의 유한요소해석을 위한 요소생성기법

본 논문은 3차원구조물의 유한요소해석을 위한 자동 유한요소 생성에 관한 것으로 퍼지이론과 버블요소 생성기법, 상용 솔리드모델러로 구성되어진다. 새로운 요소생성과정은 (a) 해석모델인 형상모델링 정의, (b) 버블생성, 그리고 (c) 요소생성으로 이루어진다. 형상모델링에는 상용 솔리드모델러를 이용하였으며 버블은 각 지점에서의 버블간격함수에 의해 생성되어진다. 버블간격 함수는 지식처리수법에 의해 조절되어 진다. 요소생성을 위해서는 기본적으로 데로우니방법을 도입하였다. 이러한 3차원 구조물에 대한 유한요소의 자동생성은 해석을 위해 큰 잇점이 있다. 실제적인 현 시스템의 효용성을 검증하기위해 3차원 형상에 대한 예를 제시하였다. This paper describes an automatic finite element mesh generation for finite element analysis of three-dimensional structures. It is consisting of fuzzy knowledge processing, bubble meshing and solid geometry modeler. This novel mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of bubbles, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid structures. Bubble is generated if its distance from existing bubble points is similar to the bubble spacing function at the point. The bubble spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of finite element for three-dimensional solid structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for 3D geometry.

퍼지메쉬를 이용한 3차원 균열에 대한 응력확대계수 해석 시스템

Integrating a 3D solid modeler with a general purpose FEM code, an automatic stress intensity factor analysis system of the 3D crack problems has been developed. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated and quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. Finally, the complete finite element(FE) model generated, and a stress analysis is performed. This paper describes the methodologies to realize such functions, and demonstrates the validity of the present system.

Parametric Design on Bellows of Piping System Using Fuzzy Knowledge Processing

This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.

Parametric Study on Bellows of Piping System Using Fuzzy Theory

This paper describes a novel automated analysis system for bellows of piping system. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy theory and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes and one of commercial solid modelers. In this system, a geometric model, i.e. an analysis model, is first defined using a commercial solid modelers for 3-D shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation technique is introduced as a basic tool for element generation. The triangular elements are converted to quadrilateral elements. Practical performances of the present system are demonstrated through several analysis for bellows of piping system.

퍼지이론을 이용한 FEM 모델링을 위한 자동 요소분할 시스템

This paper describes an automatic finite element (FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

Development of High-Performance FEM Modeling System Based on Fuzzy Knowledge Processing

This paper describes an automatic finite element (FE) mesh generation for three-dimensional structures consisting of tree-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Voronoi diagram method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

인공지능을 이용한 3차원 구조물의 최적화 설계 : 마이크로 가속도계에 적용

본 논문은 실질적인 최적화 구조물의 설계를 위한 시스템에 대한 것으로 퍼지이론에 바탕을 둔 자동 유한요소 생성 망 기술과 계산 기하학적 기술, 해석코드 및 솔리드모델러를 시스템에 통합시켰다. 최적해 또는 만족해는 자동해석 시스템과 함께 탐색공간을 위한 유전자 알고리즘을 이용하여 자동적으로 탐색되어 진다. 또한, 유전자 알고리즘을 이용함으로써 본 설계 시스템은 다차원 해를 얻을 수 있다. 개발된 시스템은 터널전류에 바탕을 둔 마이크로 가속도계의 형상설계에 적용하였다. This paper describes an optimal design system for multi-disciplinary structural design. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry technique, is incorporated into the system, together with a commercial FE analysis code and a commercial solid modelers. An optimum design solution or satisfactory solutions are then automatically searched using the genetic algorithms modified for real search space, together with the automated FE analysis system. With an aid of genetic algorithms, the present design system allows us to effectively obtain a multi-dimensional solutions. The developed system is successfully applied to the shape design of a micro accelerometer based on a tunnel current concept.

Development of the Fuzzy-Based System for Stress Intensity Factor Analysis

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

Development of Automated Analysis System for Model Plane Engine Using Fuzzy Knowledge Processing

This paper describes a new automated analysis system for model plane engine. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes, ANSYS, and one of commercial solid modelers, Designbase, The system allows a geometry model of concern to be automatically converted to different FE models, depending on physical phenomena of plane engine to be analyzed, i.e. deformation analysis, thermal analysis and so on. The FE models are then automatically analyzed by the FE analysis code. Among a whole process of analysis, the definition of a geometry model, the designation of local node patterns, the assignment of material properties and boundary conditions onto the geometry model are only the interactive processes to be done by a user. The interactive operations can be processed in a few minutes. The other processes which are time consuming and labour-intensive in conventional CAE systems are fully automatically performed in a personal computer environment. The proposed analysis system is successfully applied to evaluate a model plane entwine.

Hexahedral mesh generation of nuclear structures using intelligent local approach

This paper describes an automated mesh generation method named Intelligent Local Approach (ILA), which can control size and shape of hexahedral elements. A solid model created by a commercial solid modeler is first converted to quadrilateral surface patches. Second, considering local information on geometrical constraints, local connectivity of one to few hexahedral elements is determined step by step through some pattern matching tests with an element pattern database. Finally appropriate locations of new nodes are determined through a fuzzy knowledge processing technique. Fundamental performances of the present method are demonstrated through generating hexahedral meshes of some nuclear structures.

Automatic Mesh Generation Method Using Intelligent Local Approach. 2nd Report. Its Extension to Hexahedral Mesh Generation.

This paper describes an automated generation method of a hexahedral mesh named Intelligent Local Approach (ILA). Here elements are generated sequentially, by taking account of both local information on geometrical constraints and user's demand on quality of elements. Topological connectivity is first determined based on a heuristic category-based method. Then a fuzzy knowledge processing technique is utilized to determine optimum positions of nodes, considering various complicated geometrical constraints for high quality hexahedral elements. The determination of hexahedral connectivity and nodes positions is important technique to overcome difficulty in generating a hexahedral mesh of an arbitrary shape. Fundamental performances of the ILA are demonstrated in detail through generating several hexahedral meshes.

Automatic mesh generation of quadrilateral elements using intelligent local approach

This paper describes a new automated mesh generation method named Intelligent Local Approach (ILA), which well controls both size and aspect ratio of quadrilateral element in a two-dimensional plane. The ILA can be straightforwardly extended to hexahedral elements in a three-dimensional solid. Here elements are created sequentially, considering local information on geometrical constraints and user's demand on quality of elements. A user can specify the following two numerical fields, (a) a field of element size and (b) that of element aspect ratio. A field of priority of element creation is also specified within the ILA. To efficiently deal with various complicated geometrical constraints for high quality quadrilateral elements, a fuzzy knowledge processing technique is effectively utilized. The ILA is implemented using an object-oriented technique. Fundamental performances of the ILA are demonstrated in detail through generating several quadrilateral meshes.

Development of New Automatic Mesh Generation Method, Intelligent Local Approach. 1st Report; Proposal of the Algorithm and Quadrilateral Mesh Generation.

This paper describes a new mesh generation algorithm, namely Intelligent Local Approach, which controls well size and aspect ratio of quadrilateral and hexahedral element simultaneously. Here we define the following three fields, i. e. a distribution of element size, that of aspect ratio and that of priority of element creation. The ILA also ensures mesh quality. In ILA, elements are created sequentially considering local information on geometrical constraints and user's demand on quality of the element to be created. To efficiently deal with various complicated geometrical constraints in a local region, a fuzzy knowledge processing technique is effectively utilized. Fundamental performances of the ILA are examined in detail through generating several quadrilateral meshes.

Automated System for Analyzing Stress Intensity Factors of Three-Dimensional Cracks: Its Application to Analyses of Two Dissimilar Semi-Elliptical Surface Cracks in Plate

This paper describes a new automated system for analyzing the stress intensity factors (SIFs) of three-dimensional cracks. A geometry model containing one or several three-dimensional cracks is defined using a commercial CAD system, DESIGNBASE. Several local distributions of node density are chosen from the database of the present system, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delaunay method. A user imposes material properties and boundary conditions onto parts of the geometry model such as loops and edges by clicking them with a mouse and by inputting values. For accurate analyses of the stress intensity factors, finer elements are generated in the vicinity of crack tips, thanks to the fuzzy knowledge processing. The singular elements such that the midpoint nodes near crack front are shifted at the quarter-points are automatically placed along the three-dimensional crack front. The complete finite element model generated is given to a commercial finite element code, MARC, and a stress analysis is performed. The stress intensity factors are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, two dissimilar semi-elliptical surface cracks in a plate subjected to uniform tension are solved, and their interaction effects are discussed in detail. It is shown from the results that ASME Boiler and Pressure Vessel Code, Section XI, Appendix A gives a conservative stress intensity factor for two identical adjacent surface cracks and for two dissimilar adjacent surface cracks.