Finite element modelling of acoustic waves propagation in stone masonry

The paper deals with the finite element modelling of acoustic waves propagation through a stone masonry specimen. In the last decades major efforts have been devoted to improve Sonic and Ultrasonic analysis of structural members and provide suitable correlations between acoustic wave features and the material parameters. This paper concerns the ultrasonic analysis of a masonry specimen made of trachyte blocks and cement mortar, including an inner void as an anomaly supposed to be detected by the analysis. The tests were performed with several equipments accordingly to the Direct Transmission Technique, transmitting an ultrasound signal by a piezoelectric transducer and detecting and analysing the signal received on the opposite side by another transducer. Basically the transmission time of the signal through an ideal path from the emitting and receiving transducers and the resulting wave speed are regarded as the main phenomenological measurements for non-homogeneity and anomalies detection. The presented finite element modelization is a first attempt for providing an inner insight of the propagation of the acoustic wave through a masonry specimen. For this purpose the test has been simulated in the structural field with no regard to the piezoelectric transducer modelization. The specimen with its anomaly has been modelled in details in the elastic field and subjected to a mechanical concentrated action, while displacements have been measured in the corresponding nodes on the opposite side. The analysis have been performed in the transient domain and the resulting displacement measurements have been regarded as the signal received by the transducers, susceptible to the same signal post-processing.