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A Finite Element Framework for Geotechnical Applications based on Object-Oriented Programming

Abstract:

Geotechnical engineering covers one small field only in the whole spectrum of cicil engineering. Numerical analyses in Geotechnis just provide a limited contribution to the design process. However the fundamentals of modeling in numerics and satisfying requirements of the users are quite demanding. For these reasons private industry is commercially not interested to develop FE programs for solving special problems in geotechnical engineering or research work. However, they agree that they do need novel numerical tools. Therefore, special-purpose FE codes have to be developed by research groups.

FE programs in the field of Geotechnics involve a large number of topics, including modeling, mechanics, mathematics and visualization. The software itself should satisfy extreme efficiency requirements. It should enable the casual user to define his or her model in an easy and foolproof way, and the programmer to extend an application program to include a specific feature with a minimum amount of work and even more important, with no side effects.

The objectives of the FE framework IMAGINE (Integrated Modeling and Analysis in Geotechnics by finite Elements) are twofold:

  • provide scientists and practicing engineers in the field of geotechnical engineering with the means to develop applications tailored to their requirements,
  • development of an example application for geomechanics for a de facto proof of the applicability of the framework. Furthermore, this application might be used by students, scientists and practicing engineers.

IMAGINE is less a new application program, but a numerical infrastructure, on which developers can build to integrate required extensions with a minimum expenditure of development time.

A technical summary of the work may be found below under the heading "Remarks".

Authors:

Fritz, Pit and Zheng, Xiong

Index Terms:

FEM; Framework; finite elements; C++; geotechnics; rock; Object Oriented Programming; OOP; mechanics; Informatics; TunnelingGroup; Fritz, Pit; Zheng, Xiong

Remarks:

Technical Summary

This publication describes an alternative methodology for finite element programming based on object-oriented techniques. The basic concepts of object-oriented programming are outlined and it is explained, how this new concept facilitates design, implementation and support of large programming systems. Because the knowledge of object-oriented programs is not dispersed in the actual code, but rather localized in structures, the causal knowledge, meta knowledge and constraints may be integrated in a uniform manner. Control structures separate the external level ('what') from the internal ('how') by encapsulating the actual implementation. As programming language C++ is used.

Up till now several object-oriented finite element frameworks have been presented which are partially extendable. However, the extendibility is limited to a few specific directions, e.g. the introduction of new element types or solving strategies. Much less support is available for task control, creation of new material models, configurable field variable types or extensions of the analysis model. No framework is available which is especially designed to cover the problems encountered when dealing with geotechnical engineering. IMAGINE tries to close these gaps.

The nucleus of the Finite Element framework presented relies on abstractions, which include common concepts accepted in mathematics, mechanics, engineering and interactive visualization techniques, and serve as the fundamental object-oriented framework of classes for finite element applications and task management. The aim of the framework was not to include as many features as possible (e.g. a variety of types of finite elements or material laws), but to provide a sophisticated and robust foundation which may be used in the future due to ist inherent capabilities of simple maintenance, adaptability to new resources and extendibility, especially directed towards applications in geotechnical engineering.

Based on this framework an experimental finite element application for geomechanics is presented. Here everything is regarded as an object: loads, load groups, computational tasks etc. Thanks to the graphical user interface under MS-Windows and the rule of non-anticipation on which the objects rely, the handling of the program is straightforward. Some test examples illustrate ist usage

Additional Information

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Further Information:

Date published: 2002