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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reducció de vibracions residuals en moviments transitoris. Definició de lleis de moviment per mitjà de corbes B-spline

Veciana, Joaquim M. (Joaquim Maria) 14 November 2007 (has links)
Molts sistemes mecànics existents tenen un comportament vibratori funcionalment perceptible, que es posa de manifest enfront d'excitacions transitòries. Normalment, les vibracions generades segueixen presents després del transitori (vibracions residuals), i poden provocar efectes negatius en la funció de disseny del mecanisme.El mètode que es proposa en aquesta tesi té com a objectiu principal la síntesi de lleis de moviment per reduir les vibracions residuals. Addicionalment, els senyals generats permeten complir dues condicions definides per l'usuari (anomenats requeriments funcionals). El mètode es fonamenta en la relació existent entre el contingut freqüencial d'un senyal transitori, i la vibració residual generada, segons sigui l'esmorteïment del sistema. Basat en aquesta relació, i aprofitant les propietats de la transformada de Fourier, es proposa la generació de lleis de moviment per convolució temporal de polsos. Aquestes resulten formades per trams concatenats de polinomis algebraics, cosa que facilita la seva implementació en entorns numèrics per mitjà de corbes B-spline. / Many mechanical systems have a vibratory behavior, functionally noticeable, which can be raised when transient excitations happen. Usually, such generated vibrations remain in the system after this transient (residual vibrations), and may imply negative effects in the mechanism's intended function.The method proposed in this thesis has as main objective, the synthesis of excitation signals for mechanical systems in order to reduce residual vibrations. In addition, generated signals are able to achieve two conditions defined by the user related to function of the mechanism (called functional requirements). This method is based on the relationship between the frequency contents of the transient signal and the residual vibration generated, depending on the system damping. From this relation, and taking advantage of the Fourier transform properties, motion laws are generated through the pulses' time convolution. Resultant laws are made up of algebraic polynomial pieces linked together, which makes them very suitable for implementation with numerical calculus through B-spline curves.

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