Vibro-acoustic response of flexible Micro-Perforated Plates: impact of the boundary condition at the perforation walls

This paper investigates the vibro-acoustic behavior of flexible micro-perforated plates through a finite element method approach, in which each single orifice can be modeled independently. The role of the vibrations on the local orifice impedance values is included in the numerical model and analyzed for the case of PVC perforated plates with different orifice sizes. Two expressions for the modified local orifice impedance are compared, depending on the extension of the correction to the attached mass of air at the orifice ends or not. The effect on the global plate absorption properties is quantified. It is found that accounting for the orifice impedance alteration through the structural motion is more important for larger orifice diameters and at low frequency. This effect is nevertheless rather limited for the investigated micro-perforated plates and can be neglected in first instance.