Modelling of the acoustical properties of hemp particles

This paper focuses on the acoustical properties of mixes of hemp particles. A physical analysis of the experimental data revealed that acoustical dissipation in this material is governed by inter-particle pores in the tested frequency range. The evolution of the acoustical parameters of mixes of hemp particles is studied as a function of density and it was found that these parameters are strongly affected by the parallelepipedal shape of the particles. The relationships existing between these acoustical parameters and basic parameters of the material, such as the apparent density of the mix, the particle apparent density, the characteristic dimension of the particles and their shape factor are investigated. It is shown first that these basic parameters can be directly used to model the acoustical properties of the mixes, then that acoustical data can be very useful to characterize the shape and microstructure of these hemp aggregates.

► The acoustical dissipation in loose hemp particles is governed by the interparticle pores.
► Double porosity approach is used to model their acoustical properties.
► Shiv have higher tortuosities and smaller viscous lengths than spherical particles.
► Acoustical parameters can be computed from basic parameters of shiv.
► Acoustical measurements enable to characterize the key properties of shiv.