BazTech - Yadda

1

Non-line analysis of stiffness in compression conditions

Kahsin M., Stecki D.

Polish Maritime Research

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2018

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nr 2

100--107

EN

The analyzes were aimed at demonstrating the influence of parameters describing the deformation of the structure on the uncertainty of critical force, and the impact of technological imperfections on stress uncertainty in compression conditions. In a linear buckling analysis, the problem is considered only for the initial, permanent state of the stiffness matrix. In the case of demonstrating the influence of initial deformations on the behavior of the structure under load, it is necessary to visualize changes in stiffness over time. To this end, a non-linear MES analysis was carried out, which will take into account local changes in the stiffness of the model through a gradual increase in the load. Thus, the difference in stiffness is taken into account, which in the linear problem is infinite. The analysis was used to examine the local and global sensitivity of the parameters describing: plating thickness as well as deformation caused by the technological process on the stress value reduced by Huber hypothesis, and the value of normal stress. To take into account the influence of non-specified values of the magnitude of geometric deviations, and their simultaneous influence on the range of obtained results, the Experimental Planning Method and the Surface Method of Answers were used.

2

Numerical modelling of structures with uncertainties

Kahsin M.

Polish Maritime Research

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2017

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S 1

125--132

EN

The nature of environmental interactions, as well as large dimensions and complex structure of marine offshore objects, make designing, building and operation of these objects a great challenge. This is the reason why a vast majority of investment cases of this type include structural analysis, performed using scaled laboratory models and complemented by extended computer simulations. The present paper focuses on FEM modelling of the offshore wind turbine supporting structure. Then problem is studied using the modal analysis, sensitivity analysis, as well as the design of experiment (DOE) and response surface model (RSM) methods. The results of modal analysis based simulations were used for assessing the quality of the FEM model against the data measured during the experimental modal analysis of the scaled laboratory model for different support conditions. The sensitivity analysis, in turn, has provided opportunities for assessing the effect of individual FEM model parameters on the dynamic response of the examined supporting structure. The DOE and RSM methods allowed to determine the effect of model parameter changes on the supporting structure response.

3

Dynamic investigation of twist-bend coupling in a wind turbine blade

Luczak M., Manzato S., Peeters B., Branner K., Berring P., Kahsin M.

Journal of Theoretical and Applied Mechanics

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2011

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Vol. 49 nr 3

765-789

EN

This paper presents some results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study in static and dynamic domains on the bend-twist coupling in the full scale section of a wind turbine blade structure. The main goal of the conducted research is to confirm experimentally the numerical prediction of modification of the dynamic and static properties of a wind turbine blade. The bend-twist coupling was implemented by adding angled UD (UniDirectional) layers on the suction and pressure side of the blade. Static and dynamic tests were performed on a section of the full scale wind turbine blade provided by VestasWind Systems A/S. The results are presented and compared with the measurements of the original and modified blade. Comparison analysis confirmed that UD layers introduce measurable bend-twist couplings, which was not present in the original blade.

PL

W artykule przedstawiono wyniki multidyscyplinarnych prac badawczych prowadzonych na sekcji dużej łopaty turbiny wiatrowej. Prace obejmowały badania eksperymentlane oraz symulacje numeryczne sprzężenia typu zginanie-skręcanie w statyce i dynamice badanej łopaty. Podstawowym celem badawczym było potwierdzenie w drodze eksperymentu wyników symulacji numerycznej własności statycznych i dynamicznych łopaty. Sprzężenie typu zginanie-skręcanie zostało wprowadzone w konstrukcji łopaty poprzez dodtkowe zalaminowanie warstw kompozytów włóknistych jednokierunkowych po obu stronach łopaty pod dobranym kątem. Testy statyczne i dynamiczne zostały zrealizowane na sekcji dużej łopaty turbiny wiatrowej dostarczonej przez producenta Vestas Wind Systems A/S. W pracy przedstawiono i porównano wyniki badań oryginalnej sekcji łopaty oraz sekcji zmodyfikowanej. Analiza porównawcza wyników potwierdziła wyniki symulacji numerycznych. Wprowadznie dodatkowych warstw kompozytu włóknistego spowodowało powstanie w badanej łopacie mierzalnego sprzężenia typu zginanie-skręcanie. Sprzężenie to nie było obserwowane w oryginalnej łopacie przed modyfikacją.

4

Application of the finite element methods in long-term simulation of the multi physics systems with large transient response differences

Wittbrodt E., Kahsin M.

Journal of KONES

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2008

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Vol. 15, No. 1

227-233

EN

Application of the Finite Element Method (FEM) and the Multibody Dynamics Method (MBS) allows analyzing of complex physical systems. Complexity of the system could be related both to the geometry and the physical description of phenomenon. MBS is the excellent tool for analyzing statics or dynamics of the mechanical systems. MBS permits tracking of Multi Body System transient response for the long-term simulations and application of any arbitrary set of mechanical forcing functions. However, this method does not allow observing state of the continuum systems. Besides, applying forcing functions other than mechanical ones (i.e. general forces or displacements) is troublesome in MBS. In case of FEM most of algorithms encounter continuity conditions across the element boundaries , and thanks to this FEMis one of the most suitable calculation method for continua multi-physics systems (i.e. thermo-structural, electro-thermo-structural, magneto-thermo-structural, MEMS, etc.). Common problem with FEM is that there are major calculation difficulties when long-term simulation results are required and/or large relative motions are present in the system. Drawbacks of FEM and MBS could be overcome with use of algorithm based on the modifled Hybrid Finite Element Method presented further in this paper. Traditional Hybrid Finite Element Method model consists of rigid end deformable elements, system matrices derived for all compound elements are calculated concurrently. In this approach both advantages and disadvantages of FEM and MBS are transferred to the model. Proposed modified Hybrid Finite Element Method algorithm exploits two corresponding coupled discrete models, one containing FEM elements and the other MBS only. Both models are coupled by means of forcing functions. Such approach is applicable for the multi-physics systems with large transient response differences.

5

Analiza dynamiczna turbozespołu energetycznego jako podstawa do zmiany jego konstrukcji

Kahsin M., Olszewski H., Walczyk Z., Miścicki M.

Diagnostyka

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2004

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Vol. 30, T. 1

229--236

PL

W pracy badano wpływ rekonstrukcji naprawczych turbozespołu energetycznego dużej mocy na jego dynamiczne charakterystyki - częstości i postacie drgań własnych. W obliczeniach uwzględniono wpływ gruntu, w którym osadzona jest dolna płyta fundamentu. Wyniki symulacji komputerowych porównano z dynamicznymi charakterystykami turbozespołu i jego fundamentu wyznaczonymi eksperymentalnie. Przedmiotem badań był turbozespół energetyczny AEG TG-A w elektrowni Pomorzany.

EN

Influence constructional changes of high power turbo set on dynamical characteristics - natural frequencies and natural forms were analyzed in this paper. Influence of soil together with lower plate of foundation was included in calculations. Results of computer simulations were compared with dynamical characteristics of turbo set and turbine set foundation experimental specified. High power turbine set AEG TG-A at power plant Pomorzany was object of the analysis.