Made of polymer, metal, and polymer fibers of low melting point, a porous laminated composite material (PLCM) exhibits very highly sound absorption coefficient over the frequency of 500-2000 Hz with a relatively thin structure. In this paper we present two models to predict sound absorption characteristics for a PLCM. Firstly, we derive a semi-empirical model in which the flow resistivity of the PLCM is a function of the fibrous surface area under the assumption that most energy loss is due to the viscous loss consumed in the fibrous surface of a PLCM. Secondly, we propose an empirical model to predict the characteristic impedance and the propagation constant, which then is employed to determine the sound absorption coefficient for a new PLCM. Numerical predictions have been performed and experiments have been conducted to validate the two proposed models.
Curing Monitoring of Graphite/Epoxy Laminated Composite Material by Using Embedded Corrugated Long-Period Fiber Grating Sensor
