This thesis deals with the modeling of a piezoelectric ultrasonic micro-transducer with electro-mechanical-acoustic coupling. Taking into consideration a device owned by STMicroelectronics, the performance of audio efficiency and comparison with other previously performed simulations were investigated. The laws governing the electro-mechanical problem for piezoelectric laminate plates and the fluid-structure interaction by harmonic oscillation of the solid part within a fluid domain governed by the Navier-Stokes equations were used to describe the multi-physical problem, from which is derived the the wave equation characterizing the acoustic problem. The results, obtained with the commercial software ABAQUS 2018, first refer to the 3-D models of stratified plate, compared with the analytical solutions, in order to verify the correctness of the results and the practicality of the different modeling alternatives, and then switch to analyze the actual pMUT model. Various analyzes were then developed also considering the fluid-structure coupling, comparing the results obtained with other simulations carried out on the commercial software COMSOL Multiphysics 5.2 and ANSYS Academic 17.2. Subsequently, models were created that are even more in line with the actual case of use for a micro-transducer like the one under examination, going to compare the results obtained with the experimental tests carried out by STMicroelectronics operators. Finally, the response in the membrane's time domain was investigated, performing an implicit analysis with direct integration over time. In this way it was also possible to study the behavior of the membrane, ie whether this was Hard Spring or Soft Spring. The results obtained for each type of analysis are extremely satisfactory as the software chosen is very user-friendly, without affecting the quality and computational skills. In particular, the comparison with other software showed lower analysis times and in some cases even greater precision.
La presente tesi tratta la modellazione di un micro-trasduttore ultrasonico piezoelettrico con accoppiamento elettro-meccanico-acustico. Prendendo in considerazione un dispositivo dell’azienda STMicroelectronics si sono indagate le prestazioni di efficienza acustica e confrontati i risultati con altre simulazioni precedentemente effettuate. Per descrivere il problema multi-fisico sono state usate le leggi che governano il problema elettro-meccanico per piastre laminate piezoelettriche e l’interazione fluido-struttura per oscillazione armonica della parte solida all’interno di un dominio fluido governato dalle equazioni di Navier-Stokes, da cui si ricava l’equazione delle onde che caratterizza il problema acustico. I risultati, ottenuti con il software commerciale ABAQUS 2018, fanno dapprima riferimento a dei modelli 3-D semplificati di piastra stratificata, confrontabili con soluzioni analitiche, in modo da verificare la correttezza dei risultati ottenuti e la praticità delle diverse alternative di modellazione, per poi passare al modello effettivo di pMUTs. Si sono quindi sviluppate le varie analisi considerando anche l’accoppiamento fluido-struttura, andando a confrontare i risultati ottenuti con altre simulazioni effettuate sui software commerciali COMSOL Multiphysics 5.2 e ANSYS Academic 17.2. Successivamente, sono stati realizzati dei modelli ancor più aderenti alla reale situazione di utilizzo per un micro-trasduttore come quello in esame, andando a confrontare i risultati ottenuti con le prove sperimentali effettuate dagli operatori di STMicroelectronics. Infine, si è andato ad indagare la risposta nel dominio del tempo della membrana, andando ad effettuare un’analisi implicita con integrazione diretta nel tempo. In questo modo si è anche potuto studiare il comportamento della membrana, ovvero se questo fosse Hard Spring o Soft Spring. I risultati ottenuti per ogni tipo di analisi sono estremamente soddisfacenti essendo il software scelto molto user-friendly, senza incidere sulle qualità e capacità computazionali. In particolare, il confronto con altri software ha mostrato tempi di analisi inferiori e in alcuni casi anche maggiore precisione.
Analisi dinamiche di trasduttori piezoelettrici in campo lineare e non lineare
OLIVIERI, ALESSANDRO MARIA
2018/2019
Abstract
This thesis deals with the modeling of a piezoelectric ultrasonic micro-transducer with electro-mechanical-acoustic coupling. Taking into consideration a device owned by STMicroelectronics, the performance of audio efficiency and comparison with other previously performed simulations were investigated. The laws governing the electro-mechanical problem for piezoelectric laminate plates and the fluid-structure interaction by harmonic oscillation of the solid part within a fluid domain governed by the Navier-Stokes equations were used to describe the multi-physical problem, from which is derived the the wave equation characterizing the acoustic problem. The results, obtained with the commercial software ABAQUS 2018, first refer to the 3-D models of stratified plate, compared with the analytical solutions, in order to verify the correctness of the results and the practicality of the different modeling alternatives, and then switch to analyze the actual pMUT model. Various analyzes were then developed also considering the fluid-structure coupling, comparing the results obtained with other simulations carried out on the commercial software COMSOL Multiphysics 5.2 and ANSYS Academic 17.2. Subsequently, models were created that are even more in line with the actual case of use for a micro-transducer like the one under examination, going to compare the results obtained with the experimental tests carried out by STMicroelectronics operators. Finally, the response in the membrane's time domain was investigated, performing an implicit analysis with direct integration over time. In this way it was also possible to study the behavior of the membrane, ie whether this was Hard Spring or Soft Spring. The results obtained for each type of analysis are extremely satisfactory as the software chosen is very user-friendly, without affecting the quality and computational skills. In particular, the comparison with other software showed lower analysis times and in some cases even greater precision.| File | Dimensione | Formato | |
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Descrizione: Tesi Laurea Magistrale di Alessandro Olivieri
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https://hdl.handle.net/10589/148786