Modelling of a clamped-pinned pipeline conveying fluid for vibrational stability analysis

Recent developments in materials and cost reduction have led the study of the vibrational stability of pipelines conveying fluid to be an important issue. Nowadays, this analysis is done both by means of simulation with specialized softwares and by laboratory testing of the preferred materials. The former usually requires of complex modelling of the pipeline and the internal fluid to determine if the material will ensure vibrational stability; and in the latter case, each time there is a mistake on the material selection is necessary to restart all the process making this option expensive. In this paper, the classical mathematical description of the dynamic behavior of a clamped-pinned pipeline conveying fluid is presented. Then, they are approximated to a Hamiltonian system through Garlekin’s method being modelled as a simple linear system. The system stability has been studied by means of the eigenvalues of the linear system. From this analysis, characteristic expressions dependent on material constants has been developed as inequalities, which ensures the stability of the material if it matches all expressions. This new model provides a simplified dynamical approximation of the pipeline conveying fluid depending on material and fluid constants that is useful to determine if it is stable or not. It is worth to determine that the model dynamics does not correspond with the real, but the global behaviour is well represented. Finally, some simulations of specific materials have been use to validate the results obtained from the Hamiltonian model and a more complex model done with finite element software.Postprint (published version

Stability of a pipeline hydraulic fluid with one end fixed

The dynamics and stability of pipes conveying fluid has been studied thoroughly in the last decades. In this paper we study the stability in the Liapunov sense, of a clamped-pinned pipe conveying fluid at a low speed. After describing the motion of the system by partial differential equations we solve equations using finite element method testing solutions by means of ANSYS, we analyze the characteristic equation and its eigenvalues in order to obtain the stability conditionsPreprin

Stability analysis of a clamped-pinned pipeline conveying fluid

Increasing advances in materials engineering and cost reduction in their testing have lead to the study of the stability of vibration of pipes conveying fluid an important problem to deal with. Currently, such analysis is done either by means of simulation with costly specialized software or by making laboratory tests of the selected material. One of the main issues with the last process is that if appears any trouble on the material selection, it is necessary to restart all the process, and it is happening each time there is a mistake on the material selection. In order to avoid such costly tests, a general mathematical description of the dynamic behavior of a clamped-pinned pipeline conveying fluid is presented. The system stability has been studied by means of the eigenvalues of a Hamiltonian linear system associated. From this analysis, characteristic expressions dependent on material constants have been developed as inequalities, which ensure the stability of the material if it matches all expressions. Finally, some specific materials are introduced as study cases to compare the mathematical description proposed with the results obtained from specialized software as ANSYS, in order to validate the resultsPostprint (published version

Input Observability Analysis of Fixed Speed Wind Turbine

This paper deals with the concept of input observability in a fixed speed wind turbine. A linear system has been calculated from the nonlinear equations of the squirrel cage induction generator, supposing it connected directly to the grid and assuming a steady state operating point. The observability of the input from the output of the system could be an interesting way to know if its possible to develop some new controls without introduce special sensors in the system. Furthermore, it is interesting to analyse which is the parameter variation margin of the wind turbine from input-observable state to non-input observable, in order to obtain some restrictions to design future controllers, or limit the operating points.Postprint (published version

Analysis of support structure of wind turbine tower

Wind turbines are being used to generate electricity as an alternative energy source to conventional fossil fu- els, and it is well known that wind towers must to sus- tain continuous vibration forces throughout their opera- tional life. In this paper, a stability analysis of bending deflection of a wind turbine steel tower is presented. The wind turbine is modelled as the structure of a sim- plified beam-column by a switched system. It is mod- elled by using a Hamiltonian system, which simplifies the system under study and allows to analyze the sta- bility dynamics of the system. An eigenvalue analysis have been done in order to analyze the stability of the system; finally, also, some transient simulations of the system are presented to verify the results obtainedPostprint (published version

Análisis y simulación del comportamiento de una tubería para el transporte de fluidos mediante un modelo de elementos finitos

El presente proyecto surge del inter´es por analizar la estabilidad de una tuber´ıa para el transporte de fluidos desde su enfoque matem´atico y estructural. Se pretende analizar la afectaci´on de las condiciones de contorno y de los materiales utilizados en la fabricaci´on de tuber´ıas sobre la estabilidad. Para ello en la primera parte del proyecto se realizar´a una modelizaci´on matem´atica mediante un modelo de elementos finitos y se calcular´an las zonas de estabilidad del sistema. El resultado del an´alisis matem´atico ser´a utilizado para aplicarlo al estudio de un problema fluido-estructural, concretamente al estudio de la estabilidad y la vibraci´on de una tuber´ıa. La segunda parte del proyecto se basar´a en la simulaci´on num´erica de los diferentes tipos de tuber´ıa, utilizando para ello el programa ANSYS que se basa en el m´etodo de los elementos finitos. Con los c´alculos realizados en la primera parte de este estudio se podr´a verificar si la simulaci´on del comportamiento de la tuber´ıa es fiable y se aproxima a la realidad. A partir de los datos obtenidos se podr´an conocer las zonas de estabilidad del sistema analizado, as´ı como los materiales para tuber´ıas que tienen un mejor comportamiento frente a vibraciones estructurales. De manera que el proyecto se concluye con una propuesta de un rango de materiales ´optimos para el caso de estudio

Análisis y simulación del comportamiento de una tubería para el transporte de fluidos mediante un modelo de elementos finitos

El presente proyecto surge del inter´es por analizar la estabilidad de una tuber´ıa para el transporte de fluidos desde su enfoque matem´atico y estructural. Se pretende analizar la afectaci´on de las condiciones de contorno y de los materiales utilizados en la fabricaci´on de tuber´ıas sobre la estabilidad. Para ello en la primera parte del proyecto se realizar´a una modelizaci´on matem´atica mediante un modelo de elementos finitos y se calcular´an las zonas de estabilidad del sistema. El resultado del an´alisis matem´atico ser´a utilizado para aplicarlo al estudio de un problema fluido-estructural, concretamente al estudio de la estabilidad y la vibraci´on de una tuber´ıa. La segunda parte del proyecto se basar´a en la simulaci´on num´erica de los diferentes tipos de tuber´ıa, utilizando para ello el programa ANSYS que se basa en el m´etodo de los elementos finitos. Con los c´alculos realizados en la primera parte de este estudio se podr´a verificar si la simulaci´on del comportamiento de la tuber´ıa es fiable y se aproxima a la realidad. A partir de los datos obtenidos se podr´an conocer las zonas de estabilidad del sistema analizado, as´ı como los materiales para tuber´ıas que tienen un mejor comportamiento frente a vibraciones estructurales. De manera que el proyecto se concluye con una propuesta de un rango de materiales ´optimos para el caso de estudio

Análisis y simulación del comportamiento de una tubería para el transporte de fluidos mediante un modelo de elementos finitos

El presente proyecto surge del inter´es por analizar la estabilidad de una tuber´ıa para el transporte de fluidos desde su enfoque matem´atico y estructural. Se pretende analizar la afectaci´on de las condiciones de contorno y de los materiales utilizados en la fabricaci´on de tuber´ıas sobre la estabilidad. Para ello en la primera parte del proyecto se realizar´a una modelizaci´on matem´atica mediante un modelo de elementos finitos y se calcular´an las zonas de estabilidad del sistema. El resultado del an´alisis matem´atico ser´a utilizado para aplicarlo al estudio de un problema fluido-estructural, concretamente al estudio de la estabilidad y la vibraci´on de una tuber´ıa. La segunda parte del proyecto se basar´a en la simulaci´on num´erica de los diferentes tipos de tuber´ıa, utilizando para ello el programa ANSYS que se basa en el m´etodo de los elementos finitos. Con los c´alculos realizados en la primera parte de este estudio se podr´a verificar si la simulaci´on del comportamiento de la tuber´ıa es fiable y se aproxima a la realidad. A partir de los datos obtenidos se podr´an conocer las zonas de estabilidad del sistema analizado, as´ı como los materiales para tuber´ıas que tienen un mejor comportamiento frente a vibraciones estructurales. De manera que el proyecto se concluye con una propuesta de un rango de materiales ´optimos para el caso de estudio

Stability analysis of a wind turbine tower using reachability properties of switched systems

Wind turbines are increasingly installed to generate electricity around the whole, as an alternative energy source to conventional fossil fuels in order to reduce fossil fuel energy dependence and environment impact. It is well known that wind towers must be designed to sustain continuous vibration forces throughout their operational life, which are more critical at offshore locations. The paper aims to analyze the structural stability of a wind turbine tower made of steel. The wind turbine tower is modeled as the addition of various (infinitesimal) simplified beamcolumns, which mathematically can be represented by a switched system. Each beam-column section is equivalently modeled as a Hamiltonian system, which allows simplifying the system and providing the stability general response. An eigenvalue analysis has been done in order to analyze the stability of the system; finally, also, some transient simulations of the system are presented to verify the results obtained.Peer ReviewedPostprint (author's final draft

Modelling of a clamped-pinned pipeline conveying fluid for vibrational stability analysis

Recent developments in materials and cost reduction have led the study of the vibrational stability of pipelines conveying fluid to be an important issue. Nowadays, this analysis is done both by means of simulation with specialized softwares and by laboratory testing of the preferred materials. The former usually requires of complex modelling of the pipeline and the internal fluid to determine if the material will ensure vibrational stability; and in the latter case, each time there is a mistake on the material selection is necessary to restart all the process making this option expensive. In this paper, the classical mathematical description of the dynamic behavior of a clamped-pinned pipeline conveying fluid is presented. Then, they are approximated to a Hamiltonian system through Garlekin’s method being modelled as a simple linear system. The system stability has been studied by means of the eigenvalues of the linear system. From this analysis, characteristic expressions dependent on material constants has been developed as inequalities, which ensures the stability of the material if it matches all expressions. This new model provides a simplified dynamical approximation of the pipeline conveying fluid depending on material and fluid constants that is useful to determine if it is stable or not. It is worth to determine that the model dynamics does not correspond with the real, but the global behaviour is well represented. Finally, some simulations of specific materials have been use to validate the results obtained from the Hamiltonian model and a more complex model done with finite element software