Propagation of acoustic wave’s motion in orthotropic Cylinders of infinite length

We report, in the present work, a numerical method for investigating guided waves propagation in a homogeneous infinite cylinder composed of elastic material. This method makes use of Legendre polynomials series and harmonic function to express different displacement components which are introduced into the equation of motion. The advantage of this method is the possibility to incorporate the stress-free boundary conditions directly into the equations of motion by assuming position-dependent elastic constants and mass density. The solution of the wave equations can be reduced to an eigenvalue problem. Numerical results are presented and compared with those published earlier in order to validate our polynomial approach. For certain specific modes, dispersion curves and field profiles such as mechanical displacements, normal stresses are presented. The developed software is capable of dealing efficiently and accurately with a variety of homogeneous and inhomogeneous cylinders

Generalized thermoelastic wave response in a hollow cylinder with temperature-dependent properties based on the memory-dependent derivative of the heat conduction model

High-temperature pipelines are susceptible to defects due to the long-term service in high-temperature environments. The guided wave technology is promising for online non-destructive testing. Before implementing it in engineering, it is essential to better understand guided wave characteristics, especially attenuation, which significantly decreases the test distance and the resolution. However, describing the large attenuation is challenging due to the strong thermoelastic coupling, resulting in limitations of available models. To address these limitations, this paper aims to introduce a memory-dependent generalized thermoelastic model for investigating guided waves propagating in a hollow cylinder with temperature-dependent material properties. The analytical solutions are obtained using the Legendre polynomial method. The influence of the memory-dependent effect, temperature variation, and boundary conditions are studied. Some interesting findings are revealed: (1) The time delay factor is more dominant when adjusting κ and n to accurately describe guided wave propagation at high temperatures. (2): The mode conversion is accompanied by the attenuation and group velocity jump when the adjacent flexural torsional and longitudinal modes intersect, which is advisable to avoid when choosing the excitation frequency. (3) The relationship between phase velocity and attenuation versus temperature for quasi-elastic modes is nonlinear, while that for thermal modes is approximately linear

Mapped orthogonal functions method applied to acoustic waves-based devices

This work presents the modelling of acoustic wave-based devices of various geometries through a mapped orthogonal functions method. A specificity of the method, namely the automatic incorporation of boundary conditions into equations of motion through position-dependent physical constants, is presented in detail. Formulations are given for two classes of problems: (i) problems with guided mode propagation and (ii) problems with stationary waves. The method’s interest is demonstrated by several examples, a seven-layered plate, a 2D rectangular resonator and a 3D cylindrical resonator, showing how it is easy to obtain either dispersion curves and field profiles for devices with guided mode propagation or electrical response for devices with stationary waves. Extensions and possible further developments are also given

Synthesis, structural and crystallographic characterization of new hydrosoluble thymol derivatives with a comparative study of enhanced antioxidant activity

In this study, we synthesized two new Thymol derivatives obtained by reacting Thymol sulfonic acid with respectively two amines: aniline and diethylamine. Spectroscopic analysis by FT-IR, mass spectrometry, (1H, 13C) NMR and XRD elucidated the chemical structure of these two new Thymol derivatives identified as: Diethylammonium 4-hydroxy-5-isopropyl-2-methylbenzenesulfonate (P.1) and Benzenaminium 4-hydroxy-5-isopropyl-2-methylbenzenesulfonate (P.2) obtained respectively with 98% and 52% reaction yields. They match two new Thymol organic salts with specific ionic crystalline form. We investigated a comparative antioxidant activity study based on the DPPH test versus Butyl hydroxy toluene (BHT) as control and Thymol as strating material. The results show that boat synthesized compounds (P.1) and (P.2) are significantly more active with IC50 value 3,44 µg/mL for (P.2) and 6,76 µg/mL for (P.1) versus 21,7 µg/mL for (BHT) and 178.03 µg/mL for Thymol. More interestingly, these two compounds are water soluble and the compound (P.1) was obtained in a good yield reaction (98%)