The laboratory is equipped with measurement instrumentation to perform mechanical, physical and acoustic material testing, by means of experimental measurements and developing prediction models.
MEASURED PARAMETERS
The airflow resistivity quantifies the "resistance" met by an airflow passing through a certain material. It is measured with a continuous airflow, according to ISO 9053-1, or alternatively by means of alternated airflow generated by a rigid piston with a frequency of 2 Hz according to EN ISO 9053-2.
The porosity is defined as the ratio of the volume of the fluid within the pores to the total volume of the sample. The method, based on the general gas equation, directly determines the volume of the solid frame of the material.
The tortuosity is a parameter to describe the path of the acoustic wave propagating inside the material. Physically, it describes the complexity of the pores of the material. The measurement method is based on the evaluation of the phase velocity high-frequency limit.
- Normal incidence sound absorption
Transfer function method: the measurement method allows the evaluation of the sound absorption coefficient, the surface impedance and the complex reflection coefficient for normal incidence, according to the EN ISO 10534-2 (2001) standard.
Reverberation time method: the normal incidence sound absorption coefficient is determined from the reverberation time measured into an impedance tube with a circular cross-section. the method can be applied to a single material or to coupled systems. The test rig is constituted of a tube with a circular cross-section equipped with two moving sample holders. The tube is laterally connected to a box hosting the sound source. The sound pressure inside the tube is measured with a microphone.
- Mechanical parameters of homogenous or composite structures
Different techniques, based on the dynamic response of structures excited with an electro-dynamic shaker or an instrumented hammer, are employed for the determination of their elastic and damping properties. Such methods can be applied to homogeneous isotropic or orthotropic structures, visco-elastic materials and composite systems.
