Innovation in sound source technology gives to the applied acoustics field new opportunities for advanced methods and for modern approaches in non-destructive testing. Specific requirements in the experimental practice orient the research towards smarter and more performing instruments. The researchers look for those technological solutions that guarantee the easiest measuring conditions, are not time consuming while providing very accurate data, or obtain punctual results on non-homogeneous materials, and allow the monitoring of their conservation state through periodic tests. Last generation acoustic sources have been selected for this study, a parametric array operating in air and two plane wave flat panels; their sound emission properties were analyzed, i.e. the width of the characteristic frequency band and the pressure field. These sources are small sized transducers characterized by a very narrow directivity pattern, particularly interesting for field (on site) applications. The objective of the characterization of these sources is the assessment of their suitability for the integration into some measuring systems, in particular those for the determination of the sound absorbing properties of heterogeneous materials and structures. Two specific applications directed both the initial choice of the sources' typology and the final evaluation criteria. The first one is related to a non-invasive diagnostic method of paintings like frescoes, ceramics and panel paintings, for revealing detachments of the pictorial film from the support. Some examples of in situ investigation are presented, where a commercial parametric array is integrated in the experimental apparatus. The second application aims at the determination of the sound absorbing properties of road pavements and acoustic barriers. The authors briefly review the critic aspects of some international standards such as the ADRIENNE method (UNI ISO 13472-1:2004), for which the plane wave flat panels have been selected. In this case, on the basis of the characterization's outcomes, the potential use of the plane wave source is considered, while at present the realization of field measurements are still under examination with other potential partners.
limitaL'innovazione tecnologica delle sorgenti acustiche offre al settore dell'acustica applicata sempre nuove opportunità per l'avanzamento dei metodi di misura e per approcci innovativi nei controlli non distruttivi. Esigenze specifiche nella pratica delle indagini orientano la ricerca verso strumenti più performanti, che semplificano le condizioni di misura, forniscono dati con un'accuratezza adeguata in tempi più brevi, o risultati puntuali di materiali e strutture non omogenei, e ne monitorano periodicamente lo stato di conservazione. Per questo studio sono state selezionate alcune sorgenti di ultima generazione, una sorgente parametrica in aria e due elementi ad onde piane, e sono state analizzate le loro proprietà di emissione acustica, ampiezza della banda di frequenza e il campo di pressione. Le sorgenti sono altamente direttive pur presentando delle dimensioni contenute, caratteristiche queste particolarmente interessanti per l'esecuzione di misure sul campo. Specifiche applicazioni hanno orientato sia la scelta iniziale delle sorgenti, sia la valutazione finale della loro adeguatezza. La prima applicazione riguarda un metodo diagnostico non invasivo di dipinti, usato dagli autori per rilevare distacchi del film pittorico dal supporto. In questo lavoro sono mostrati esempi di analisi realizzate in situ con la sorgente parametrica integrata nel sistema di misura. La seconda applicazione riguarda l'uso di metodi normalizzati per la determinazione delle proprietà di assorbimento delle pavimentazioni stradali e delle barriere acustiche, per la quale sono stati studiati gli elementi ad onde piane. In questo caso, in base ai risultati della caratterizzazione, è solo analizzato il potenziale utilizzo di tali elementi, mentre misure in campo sono ancora in via di definizione assieme ad altri soggetti potenzialmente interessati.
Caratterizzazione di sorgenti acustiche non convenzionali per l'impiego dei test non distruttivi
Sara De Simone;Lucilla Di Marcoberardino;Paola Calicchia
2013
Abstract
Innovation in sound source technology gives to the applied acoustics field new opportunities for advanced methods and for modern approaches in non-destructive testing. Specific requirements in the experimental practice orient the research towards smarter and more performing instruments. The researchers look for those technological solutions that guarantee the easiest measuring conditions, are not time consuming while providing very accurate data, or obtain punctual results on non-homogeneous materials, and allow the monitoring of their conservation state through periodic tests. Last generation acoustic sources have been selected for this study, a parametric array operating in air and two plane wave flat panels; their sound emission properties were analyzed, i.e. the width of the characteristic frequency band and the pressure field. These sources are small sized transducers characterized by a very narrow directivity pattern, particularly interesting for field (on site) applications. The objective of the characterization of these sources is the assessment of their suitability for the integration into some measuring systems, in particular those for the determination of the sound absorbing properties of heterogeneous materials and structures. Two specific applications directed both the initial choice of the sources' typology and the final evaluation criteria. The first one is related to a non-invasive diagnostic method of paintings like frescoes, ceramics and panel paintings, for revealing detachments of the pictorial film from the support. Some examples of in situ investigation are presented, where a commercial parametric array is integrated in the experimental apparatus. The second application aims at the determination of the sound absorbing properties of road pavements and acoustic barriers. The authors briefly review the critic aspects of some international standards such as the ADRIENNE method (UNI ISO 13472-1:2004), for which the plane wave flat panels have been selected. In this case, on the basis of the characterization's outcomes, the potential use of the plane wave source is considered, while at present the realization of field measurements are still under examination with other potential partners.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.