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- 2015 (3) (entfernen)
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- Clay fill (1)
- Evolutionary computing (1)
- Inverse problem (1)
- Multimodal solution (1)
- Physical model testing (1)
- Pile monitoring (1)
- Railway embankment (1)
- System identification (1)
This paper deals with the system identification of a mechanical structure supported by nonlinear springs subjected to an external load. If all mechanical parameters of the system were known, the displacement of the system subjected to this load could be easily calculated. However, the monitoring applications often deal with the inverse problem. The loads and displacements of the system are known and certain mechanical Parameters of the system are sought. The solution of such inverse problems can be difficult, especially when they have a nonlinear and multimodal character, which often makes them appear intractable at first sight. However, evolutionary computing can be applied to solve this inverse, nonlinear and multimodal problem. Sometimes a prior knowledge exists on certain system properties, which is difficult to implement into analytical or numerical solvers. This knowledge can play a decisive role in identifying the System properties and it can be easily included as a boundary condition when applying evolutionary algorithms.
This article discusses how and under what conditions the unknown spring resistances can be identified. The practical application of this procedure is exemplified here with the mechanical system of a pile foundation.
Most railway embankments in the UK were built in the Victorian era and are of end-tipped construction using materials (usually cohesive) excavated from adjacent cuttings, resulting in a clod-and-matrix structure. Historically, there has been a lack in understanding of the mechanical behaviour of such railway embankments. In the next decade railway traffic in the UK, particularly freight, is forecast to grow considerably. Consequently, there is a need to improve the understanding of how increases in rail traffic loading may influence the mechanical behaviour of railway embankments and thus track performance. The Rail Safety and Standards Board in conjunction with Network Rail is currently undertaking a programme of applied research into this topic. As part of these studies a programme of physical model tests has been carried out. Physical model tests can provide high quality data on system performance under a large range of loading conditions and geometrical configurations. The data can be generated rapidly, with test periods of weeks or months rather than years or decades. Additionally, boundary conditions are well-defined and controlled, compared with the complex situations encountered in full scale embankments in the field. This paper summarises the physical model test programme, the development of the test set-up, the tests themselves and the conclusions drawn.
In diesem Artikel wird ein 3D FE-Modell für den Brückenübergangsbereich vorgestellt, das eine Bewertung hinsichtlich des Langzeitverhaltens ermöglicht und an dem Optimierungsmaßnahmen diskutiert werden können. Bestandteile des numerischen Modells sind das Fahrzeug-Fahrwegmodell mit Brückenstruktur und eine Randformulierung mit der SBFEM. Die hier diskutierten Optimierungsmaßnahmen fokussieren sich auf eine reine Anpassung der Fahrwegsteifigkeit durch elastische Elemente auf der Brückenstruktur.