Generation Of Finite Element Models Research Articles

Finite Element Analysis of Effective Thermal Conductivity of Filled Polymeric Composites

A novel method to predict the macroscopic effective thermal conductivity of filled composites, based on its microstructural characteristics is developed and validated. A finite element method which incorporates the effect of microstructural characteristics such as filler aspect ratio, interfacial thermal resistance, volume fraction, and filler and fiber dispersion to determine the effective thermal conductivity of a composite with circular and rectangular fillers is presented. Filler interactions and chain formation effects are included in the model. To overcome the laborious task of repeated finite element model generation, an algorithm which generates the positions and orientations of the fillers in the matrix is developed. The automated model development capability is used to create several microstructures for finite element analysis. The trends predicted by the finite element models are compared with existing analytical models and available experimental results. The advantage of this method over existing analytical and semi-empirical models is that it can handle interactive effects, provide a detail heat flux pattern, and also model high filler volume fractions.

Requirements for finite element model generation from CAD data—An approach using numerical conformal mapping

A critical problem facing the mechanical design community is that of bridging the gap between mechanical CAD data (typically boundary rep trimmed NURB surfaces) and finite element models. A number of papers have discussed this issue and identified it as a critical technology for developing future mechanical design methodologies [Crabb, In Implementation Road Map for Design and Manufacturing, D. H. Brown Sponsored Conference, Ann Arbor, MI (1994)]. While a variety of procedures for finite element model generation from CAD data have been proposed and commercialized, the resulting models have, in general, received much resistance from the professional analyst community. A set of criteria by which the quality of a proposed finite element model generation procedure can be evaluated analytically using elementary control theory is discussed. Additional observations of mesh behavior based on the dimensional anisotropy of general geometric components are presented. Finally a criterion for qualitatively evaluating optimal edge orientations for many of the classical element families is discussed. It is suggested that a combination of these approaches provides an opportunity to semi-quantitatively rank order proposed finite element model generation procedures. A finite element model generation procedure based on numerical conformal mapping is then proposed. It is demonstrated that this procedure ranks very highly when evaluated against the previous criteria. Further, a technical proof of concept implementation demonstrates that numerical conformal mapping appears to be suitable for application to a wide variety of boundary rep solid models.

Development of Finite Element Modeling System for Ship Structures

In dealing with structures of complex configurations such as ship structures, generation of finite element model is one of a major bottleneck. To overcome this problem, an object oriented finite element modeling system, MODIFY, has been developed by authors1)2)3)4). In ship structural design, many kind of finite element analyses are carried out for different geometric models. For example, whole ship analyses with shell elements are carried out in early design stages, and analyses of welding part with solid elements are done for detailed design stages.In this paper, several improvements of the finite element modeling system are introduced. First, a solid-object is defined as a geometry-object to deal with solid models. second, a two-manifold B-Rep model is used for a geometrical representation of all geometry-objects and analytical-condition-objects. Third, a 3 D solid mesh generator based on the front method is developed. Finally, by using an object oriented database for construction of the system, it becomes possible to deal with a large number of object oriented data in the system.Several examples of a finite element model generated by the system are shown.

Multimodeling strategy for assessment of complex mechanical systems

Engineering modeling plays an important role in the overall design process for a complex mechanical and/or structural system, yet the development and generation of a suitable finite element model for the static, dynamic, or thermal analysis of the system is one of the most tedious and time consuming tasks in engineering analysis. Enormous amounts of resources (human and computational) are dedicated and lost to the development of complex mathematical models that do not accomplish the function they are intended to fulfill, namely to produce reliable results. This paper presents a strategy for complex system modeling using the application of finite element modeling techniques. In this approach, the model reflects the objective of the analysis and its associated attributes. Said attributes indicate the type of analysis required, the type of loading and boundary conditions, the type of geometry and the environment for the analysis, including hardware, software, and time-frame resources. To illustrate this strategy, the paper concludes by presenting a model of a flexible internal combustion engine system based on the Stiller-Smith mechanism, in which a combination of solid, beam, and gap elements is used to represent an entire, three-dimensional system. The model presented is used to produce elastodynamic response needed for system design.

Parallel Mesh Generation of Ship Structure Using Object Oriented Finite Element Modeling System

In dealing with structure of complex configuration such as ship structure, generation of finite element (FE) model is a major bottleneck. To overcome this problem, object-oriented FE modeler, MODIFY, has been developed by the authors1), 2), 3) . When using MODIFY, user defines and assembles geometry objects, analytical condition objects and relation objects. Then MODIFY generates mesh for each geometry objects independently. For this reason, MODIFY can easily generate mesh for complicated configuration like ship structures.In this paper, parallelization using engineering work station (WS) on network environment is studied in order to enhance the speed of mesh generation. This concept is incorporated in MODIFY based on client-server model that is a basic idea for network application. The efficiency of parallel mesh generation is shown with several examples.

Strategies for automatic finite element modeling

In this paper strategies for the development and implementation of automatic finite element modeling systems are discussed within the context of knowledge engineering. In the light of language analysis, the finite element model generation, which involves transformation between three models: physical, analytical, and finite element models, is seen as a process of language translation. Taking into consideration the knowledge structure of finite element modeling, we have suggested both upward and downward strategies of developing finite element modeling systems. In the downward strategy a knowledge-based system CONSMOD-II is developed based on the language transformation and the newly developed data model of abstract structure of object representation. The upward strategy makes use of an existing mesh generation system MESHG and extends it to further automate the mapping element input and check the consistency of input data by means of geometric reasoning. The two systems are expected to merge together to provide a novel finite element modeling system. Further research areas are indicated.

Development of an automated fracture assessment system for nuclear structures

A program system for fracture assessment of nuclear power plant structures has been developed. The system consists of an easy-to-use program for engineering analysis and an automated finite element (FE) program system for more accurate analysis with solid three-dimensional (3D) models. The VTTSIF (SIF stress intensity factor) program for engineering fracture assessment applies either the weight function method or superposition method in calculating the stress intensity factor, and the fatigue crack growth analysis is based on the Paris equation. The structural geometry cases of the VTTSIF program are organized in an extendable subroutine database. The generation of a 3D FE model of a cracked structure is automated by the ACR program (automatic finite element model generation for part through cracks). The FE analyses are created with generally accepted commercial programs, and the virtual crack extension method (VCE) is used for fracture parameter evaluation by the VTTVIRT postprocessor program (program for J-integral evaluation using virtual crack extension method). The several test cases have demonstrated that the accuracy of the present system is satisfactory for practical applications.

Generation and decomposition of finite element models for parallel computations

The utilization of compact parallel computers with distributed memory for finite element computations requires a balanced decomposition of the discretized domain, which has to be performed automatically for geometrically complex problems. The paper summarizes the basic issues related to the parallelization of finite element algorithms and introduces a systematic mesh generation procedure which encompasses the automatic decomposition of the finite element mesh and ensures a balanced distribution of the computational load of the subsequent parallel processing. The decomposition process is performed prior to the ultimate generation of the mesh so that the latter can be carried out in parallel on the created subdomains.

An AutoCAD Finite Element Analysis Interface

Abstract: The popular CAD package AutoCAD has many features making it a useful tool for finite element model generation and output postprocessing. A true ‘WYSIWYG’ interface is developed and used in and environment familiar to many Civil Engineers. The format of the interface is presented. Specific considerations for AutoLISP programming within AutoCAD and compiled language programming are discussed. A 2-D truss structure is presented to demonstrate use of the interface.

Automated three-dimensional finite element modelling of bone: a new method

Three-dimensional finite element stress analysis of bone is a key to understanding bone remodelling, assessing fracture risk, and designing prostheses; however, the cost and complexity of predicting the stress field in bone with accuracy has precluded the routine use of this method. A new, automated method of generating patient-specific three-dimensional finite element models of bone is presented — it uses digital computed tomographic (CT) scan data to derive the geometry of the bone and to estimate its inhomogeneous material properties. Cubic elements of a user-specified size are automatically defined and then individually assigned the CT scan-derived material properties. The method is demonstrated by predicting the stress, strain, and strain energy in a human proximal femur in vivo. Three-dimensional loading conditions corresponding to the stance phase of gait were taken from the literature and applied to the model. Maximum principal compressive stresses of 8–23 MPa were computed for the medial femoral neck. Automated generation of additional finite element models with larger numbers of elements was used to verify convergence in strain energy.

Graphical representation of models and results in the finite element system COSAR

The finite element method has become one of the most-used calculation procedures in various fields of engineering in recent years. Due to progress in hardware architecture and computer graphics, the efficiency of its application could increase decisively. Notably, the solution of complex problems would be unthinkable today without the availability of powerful graphic processors. In connection with the development of the finite element system COSAR at the Technical University Magdeburg, various graphic processors were created. In this paper, these processors are introduced. Information is given about interactive techniques for the generation of finite element models, about checking procedures for complex 3D structures by graphical means, and about possibilities for result presentation with colored pictures. Requirements for hardware architecture and software tools in the field of graphical input and output are discussed.

The generation of airframe finite element models using an expert system

This paper presents an expert system-based procedure for the creation of airframe finite element models from the geometric model available in a computer-aided design system. The objectives of the approach presented is the computerization of a process that is currently carried out in a semimanual manner, include previous modeling knowledge into the system, and provide a clear path for an ever-increasing level of automation in the process of creating analysis models for this class of structure. A main feature of the system developed is the combined use of algorithmic procedures and expert knowledge operating on data provided by previously run design software to produce an entirely different form of model to be used as input to a numerical analysis.

Automatic and adaptive mesh generation

Techniques for the automatic generation and adaptive control of finite element models for both two and three-dimensional domains are presented. The algorithmic approaches to automatic mesh generation and the approaches for adaptively improving finite element meshes are discussed. The integration of these procedures with solid modeling is also considered.

Finite element modeling within an integrated geometric modeling environment: Part II?Attribute specification, domain differences, and indirect element types

This is the second of a two part paper that addresses the integration of finite element modeling and geometric modeling. Instead of considering the integration of currently available systems, this paper addresses both modeling techniques in general terms and identifies the functions that are needed to integrate them, taking full advantage of the capabilities of both. A set of geometric communication operators are identified and defined for use in carrying out this integration process. Part I [1] considered the integration of geometric modeling and finite element mesh generation. This part considers the remaining areas of the specification of finite element analysis attribute information, accounting for domain differences between the geometric and finite element models and the generation of finite element models using element types that are of a lesser dimension than the geometric entity they represent.

Digitizing for Computer-Aided Finite Element Model Generation—Part 2: Use of Digitizing in Mesh Generation

Digitizing for Computer-Aided Finite Element Model Generation—Part 2: Use of Digitizing in Mesh Generation

Digitizing for Computer-Aided Finite Element Model Generation—Part 1: The General Program

Computer-aided design is a complex process involving many disciplines. This two part paper describes an approach to computer-aided design which has evolved for the specific discipline of structural analysis. The vehicle for the implementation of the approach is a collection of programs called the GIFTS system. The first part of the paper describes the latest version of GIFTS. The second part of the paper will discuss a digitizing program aimed at facilitating the preparation of input defining complex two-dimensional models for the GIFTS mesh generator.

A general theory of finite elements. II. Applications

AbstractIn Part I of the this paper, topological properties of finite element models of functions defined on spaces of finite dimension were examined. In this part, a number of applications of the general theory are presented. These include the generation of finite element models in the time domain and certain problems in wave propagation, kinetic theory of gases, non‐linear partial differential equations, non‐linear continuum mechanics, and fluid dynamics.