Deformation of a viscoelastic coating under the action of convective pressure fluctuations

The measurement method for complex compliance of viscoelastic coatings based on direct determination of deformation amplitude and pressure fluctuations was suggested. The value of dynamic deformation was about 0.02%. The frequency range was from 200 Hz to 2 kHz. Complex compliance of a viscoelastic coating measured was experimentally compared with calculations made on the basis of the measured modulus of elasticity and loss factor of the coating material. The resonance frequency was shown to not depend on the ratio between the diameter of the contact area and the coating thickness. According to the suggested explanation, coating deformation is defined by a stationary wave with an oscillation node on solid basement and loop on the coating outside. Analysis showed that to obtain maximum coating deformation under the action of pressure fluctuations, two conditions should be satisfied and the influence frequency should be equal to resonance the frequency of the coating (time factor). The length scale of convective pressure wave should also be equal to quadruple the thickness of the coating (spatial factor).