In this work we analyse basic characteristics of Love wave sensors implemented in waveguide structures composed of a lossy viscoelastic surface layer deposited on a lossless elastic substrate. It has to be noted that Love wave sensors working at ultrasonic frequencies have the highest mass density sensitivity $S_σ^(v_p )$ among all known ultrasonic sensors, such as QCM, Lamb wave or Rayleigh wave sensors. In this paper we have established an exact analytical formula for the mass density sensitivity $S_σ^(v_p )$ of the Love wave sensors in the form of an explicit algebraic expression. Subsequently, using this developed analytical formula, we compared theoretically the mass density sensitivity $S_σ^(v_p )$ for various Love wave waveguide structures, such as: (1) lossy PMMA surface layer on lossless Quartz substrate and (2) lossy PMMA on lossless Diamond substrate. The performed analysis shows that the mass density sensitivity $S_σ^(v_p )$ (real and imaginary part) for a sensor with a structure PMMA on Diamond is five times higher than that of a PMMA on Quartz structure. It was found that the mass density sensitivity $S_σ^(v_p )$ for Love wave sensors increases with the increase of the ratio: bulk shear wave velocity in the substrate to bulk shear wave velocity in the surface layer.

In the current study, investigations are made to control the MB truck cabin interior noise by reducing noise in the transmission path. The main sources of cabin noise include the engine, exhaust system, air inlet system, driveline system, and tyres (especially at higher speeds). Furthermore, vibrations of the body and interior parts of the truck may significantly impact the overall in-cabin sound level. Noise is transmitted into the cabin via air (airborne noise) and cabin structure (structure-borne noise). In the noise treatment phase, noise transmission paths are considered. A viscoelastic layer damping material is used to reduce the vibration amplitude of the cabin back wall. The overall loss factor and vibration amplitude reduction ratio for the structure treated is calculated. Computational results are then compared with the values obtained by the experimental modal analysis results. Choosing the suitable material and thickness can significantly reduce the vibration amplitude. A sound barrier, silicon adhesive, and foam are also utilised for noise control in the transmission path. The effectiveness of the mentioned acoustic materials on cabin noise reduction is evaluated experimentally. The experimental SPL values are reported in the frequency range of 20 Hz–20 kHz based on a 1/3 octave filter. The experimental results show that using acoustics materials reduces the overall in-cabin sound level for a wide range of frequencies.