Lucia Ciccarelli

Graduaton: Industrial Bioengineering at University of Naples Federico II

Supervisor: Prof. Simone Morganti

Thesis title: Coupled vibroacoustic finite element models for next-generation loudspeakers

Abstract: The rise of portable and wearable audio technologies has by far favoured integration of piezoelectric actuators rather than traditional dynamic speakers. Their greater suitability is enlightened by their ultra-thin, lightweight design and low power consumption, together with the ability to transform unconventional surfaces into audio speakers. On the other hand, piezoelectric speakers require accurate optimisation of parameters such as surface vibrational response, acoustic performance, sound and energy efficiency to drive any surface. However, available computational models often limit their study to either the vibrational response of the structure, or to acoustic modes generated in air-cavities, neglecting vibro-acoustic coupling effects. Therefore, although crucial for the design and performance evaluation of these devices, the investigation of coupled responses remains elusive. Considering the importance of developing coupled models to support the design of next generation loudspeakers, a robust computational framework integrating the electromechanical and the electro-mechano-acoustic modeling of simple and complex surfaces driven by multi-layered piezoceramic actuators is discussed. Experimental validations with interferometric and acoustic measurements confirm the reliability of the models, showing their ability to accurately capture out-of-plane displacements and sound pressure levels in all considered frequency ranges. These results constitute a generalised framework for investigating the vibro-acoustic response of complex structures such as over ear headphones or any other daily consumer products.