Еstimation of integrated characteristics of materials of rail concrete structures by the method of surface wave

• Дата: 2018
• Автори: Vusatiuk, A.Ye., Fareniuk, G.G.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: Kyiv National University of Construction and Architecture 2018
• Теми: non-destructive testing; Rayleigh waves; Lamb waves; dispersion curve; integral characteristics; неруйнівні методи; хвилі Релея; хвилі Лемба; дисперсійна крива; інтегральні характеристики
• Онлайн доступ: https://es-journal.in.ua/article/view/155962
• Назва журналу: Environmental safety and natural resources

The basis of the method for evaluating the integral characteristics of materials of building structures is the parameters of the surface wave of the acoustic frequency range when vibrations in the construction are excited by the impulse load. Surface wave method is the complicated method for theoretical solutions, technology of measurements, methods of information procession and their further interpretation. But this complexity is justified by the advantages in obtaining integral characteristics of materials of building constructions. The integral acoustic characteristic of a planar construction (plate) is the velocity of surface wave (Rayleigh wave). The analysis and comparison of theoretical and experimental dispersion curves forms allows us to estimate the uniformity of the thickness of construction, as well as to determine this thickness. For the practical construction of experimental dispersion curves, the efficient method for measuring the phase velocity of bending waves in building constructions excited by the impulse load was developed. The problem of propagation of planar harmonic Rayleigh waves on the boundary of a rigid isotropic ideal-elastic half-space with a vacuum that can be used for determination of mechanical properties of materials of reinforced concrete plates is analyzed. The wave number, calculated voltages and displacements in the Lamb waves in each point of plate are determined. To construct the dispersion curves, the mathematical package Mathcad 13 was used. The construction of the dispersion curves takes place in three stages. The velocity of the Rayleigh surface wave is determined from the bicubic equation for the given values of the velocities of the longitudinal and transverse wave. A sequence of values of the variable x is chosen, for which the corresponding equations are solved in accordance to the phase velocity с. The dispersion curve based on the values of the phase velocity с is constructed. It is shown that the value of Rayleigh wave velocities has a nonlinear relationship with the mechanical properties of plate materials. At the rate of decline of the dispersion curves it is possible to estimate the thickness of the reinforced concrete plates. The Poisson coefficient and the density of concrete practically do not affect the character of the dispersion curves. If some of input parameters are unknown during the numerical simulation of the real plate, you can consider them to be equal to their average statistical values. In this case the maximal deviation of both the velocity of the Rayleigh waves and other points of the dispersion curve does not exceed 4%.