logo SBA


Digital archive of theses discussed at the University of Pisa


Thesis etd-11272015-152823

Thesis type
Tesi di dottorato di ricerca
email address
Thesis title
Sviluppo di tecniche automatizzate per la caratterizzazione dinamica sperimentale di macchine rotanti.
Academic discipline
Course of study
tutor Prof. Bertini, Leonardo
relatore Prof. Santus, Ciro
relatore Dott. Monelli, Bernardo Disma
  • analisi modale
  • analisi risposta armonica
  • Caratterizzazione dinamica macchine rotanti
  • diagramma SAFE
  • monitoraggio danneggiamento
  • ruote palettate
Graduation session start date
Bladed wheels are crucial components in many rotating machinery, which are widely used in several industrial fields. Product development often leads the machine to work in really severe conditions. The resulting cyclic load can have catastrophic results on the main components, causing efficiency loss, noise, fatigue failures and expensive plant shut down. A deep knowledge of bladed wheels dynamic behavior is then needed in order to face all these issues. At design stage, some tools are needed to predict dangerous working conditions or possible resonances. Once the wheels are designed and machined, a validation step is also needed to ensure the specification fulfillment in terms of vibrational response. Finite element analysis are surely useful, but experimental analysis are also essential. Modal analysis can be conducted in order to validate FE results, and harmonic response analysis can help to estimate the component response under specific simulated working conditions. In this dissertation a study of the commonly adopted resonance prediction methods for bladed wheels is firstly presented. Then, two test bench are described along with experimental results: a robotic station for automatic modal analysis and a test bench for harmonic response analysis. The whole activity was conducted in cooperation with GE Oil&Gas, a worldwide leading company whose core business is represented by rotating machinery design and production. The research was a part of the program “Bando Unico Ricerca e Sviluppo 2012” (POR CReO FESR 2007-2013_REGIONE TOSCANA), set in the framework of the Regione Toscana funded project ATENE: “Advanced Technologies for ENergy Efficiency”. In this dissertation the whole activity is reported, starting from a description of the two mainly used methods for resonance prediction. The setup of a robotic station for fully automated experimental modal analysis is then presented, along with some results obtained testing two different bladed wheels of the shrouded and un-shrouded type respectively. Furthermore, a wide range harmonic response analysis test bench is described, able to simulate operational conditions by controlling the load spatial distribution in the frequency range 1 - 10 kHz. The design of the exciters and of the stinger system involved is also presented, along with some preliminary results. A method for bladed wheels online monitoring is also presented. The method was studied and developed during a research activity in cooperation with LMS - Siemens (Leuven, Blegium), which is a leading company in the field of the design of software and hardware for experimental dynamic analysis. Finally, some conclusions are presented: the whole activity is summarized and remarks about the main results are drawn. All the described activity were also presented in several research papers, from which most parts of the dissertation are drawn.