Ironless transducer for measuring the mechanical properties of porous materials

Olivier Doutres (1, 2) , Nicolas Dauchez (1, 3) , Jean-Michel Génevaux (1) , Sylvain Mezil (1) , Guy Lemarquand (1)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans
2 UdeS - Université de Sherbrooke
3 LISMMA - Laboratoire d'Ingénierie des Systèmes Mécaniques et des MAtériaux

This paper presents a measurement set-up for determining the mechanical properties of porous materials at low and medium frequencies, by extending towards higher frequencies the quasistatic method based on a compression test. Indeed, classical quasi-static methods generally neglect the inertia effect of the porous sample and the coupling between the surrounding fluid and the frame: they are restricted to low fre- quency range (< 100 Hz) or specific sample shape. In the present method, the porous sample is placed in a cavity to avoid a lateral airflow. Then a specific electrodynamic ironless transducer is used to compress the sample. This highly linear transducer is used as actuator and sensor: the mechanical impedance of the porous sample is deduced from the measurement of the electrical impedance of the transducer. The loss factor and the Young's modulus of the porous material are estimated by inverse method based on the Biot's model. Experimental results obtained with a polymer foam show the validity of the method in comparison with quasistatic method. The frequency limit has been extended from 100 Hz to 500 Hz. Sensitivity of each input parameter is estimated in order to point out the limitations of the method.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Olivier Doutres, Nicolas Dauchez, Jean-Michel Génevaux, Sylvain Mezil, Guy Lemarquand. Ironless transducer for measuring the mechanical properties of porous materials. Journal of Applied Physics, 2010, pp.1. ⟨hal-00449742⟩