Dynamic compliance of viscoelastic coatings used to reduce hydrodynamic friction
V. M. Kulik
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: coating, compliance, steady state, transition period, viscoelastic properties
Abstract
The paper describes the response of a viscoelastic layer glued onto a solid base to a non-stationary convective pressure wave. A complete equation of motion of coating material particles in the case of two-dimensional deformations is derived and it takes into account the viscosity of the medium. A system of equations for calculating the longitudinal and transverse dynamic compliance, determined by the ratio of the displacement components to the applied pressure, is obtained. The derived equations allow the description of not only stationary oscillations of the coating, but also the process of their stabilization. It is noted that, in addition to viscosity and Poisson ratio, stationary and dynamic compliances depend only on two parameters: the ratio of the disturbance wave velocity to the propagation velocity of shear oscillations in the coating and the ratio of the wavelength to the coating thickness. An example of calculating stationary compliance for a typical case of a silicone rubber coating is given. Attention is drawn to the need to take into account the transition period of the forced oscillation stabilization, since the coating cannot swing instantly due to inertia and viscosity. Known attempts to calculate this process have been analyzed.
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