Theoretical-Experimental Method for Determining the Parameters of Damping Based on the Study of Damped Flexural Vibrations of Test Specimens. 1. Experımental Basıs

Theoretical-Experimental Method for Determining the Parameters of Damping Based on the Study of Damped Flexural Vibrations of Test Specimens. 3. Identification of the Characteristics of Internal Damping

“…The frequency of the first flexural mode of free vibrations of cantilever test specimens in vacuum can be found from the known relations written for the base and a sandwich bar with external layers made of a rubber, respectively. As is known (see, for example, [4][5][6][7]), vibration frequencies w weakly depend on the parameters of internal and external (aerodynamic) damping, which was also completely confirmed by the experimental investigations performed in [1]. Therefore, assuming in formulas (1.12) and (1.13) that the frequencies w are equal to those found experimentally ( w 0exp for the base and w exp for the sandwich specimen), to determine the elastic moduli of base material E 0 and rubber E r , we come to the relations (1.14)…”

“…The test specimens (considered in [1] and recommended in [2]) of single-layer structure of thickness h 0 , used as the base, and of a sandwich structure with layers made of a soft material (a rubber of thickness h r ), glued on both sides of the base, were cantilever plates of width b , length L , and thicknesses h h = 0 and h h h r = + 0 2 , respectively. The vibrations of such plates according to flexural modes with small amplitudes, to a high degree of accuracy due to h h b r , < , and b L << , can be described by an equation of motion based on the classical Kirchhoff-Love model.…”

“…kg/m 3 . If the aerodynamic component d a is subtracted from the parameter d exp , found experimentally in [1], thereby determining the parameter δ * , the damped vibrations of a test specimen in vacuum can be described by the equation …”

Damping Oriented Design of Thin-Walled Mechanical Components by Means of Multi-Layer Coating Technology

“…Moreover, starting from the results of the present work, identification tools based on experimental dynamical measurements of simple specimens must also be developed to estimate most of the unknown layer parameters associated with the manufacturing technology, i.e., the ones related to inter-layer coupling, making it possible to extend the design optimization research stage. An experimental dynamical measurement test activity made on bi-layer specimens, mainly differing by means of the PVD, CVD, or hot melting deposition technology adopted, the substrate material, the surface finish texture, and the coating thickness, can be performed by properly designing an experimental test apparatus, following the indications reported in [27][28][29][30][31]. Test data can be used to evaluate the unknown interlaminar dissipation viscosity and thickness values by means of a robust, numerical identification technique, since only two unknown parameters have to be identified, following the approach developed by our research group in [11].…”

Постановка Геометрически Нелинейной Задачи Об Изгибе Трехслойной Пластины С Трансверсально-Мягким Заполнителем

“…Применение в качестве заполнителя материалов с низкими массовыми характеристиками позволяет при сравнительно небольшом увеличении веса конструкции существенно повысить изгибную жесткость. Тем самым трехслойные конструкции нашли широкое применение в качестве несущих и управляющих поверхностей летательных аппаратов, обтекателей, теплозащитных и силовых экранов, разного рода панелей и других конструктивных элементов [4][5][6].…”