Flexural wave propagation in coated poroelastic cylinders with reference to fretting fatigue

Abstract

Fretting is a contact fatigue phenomenon, but the bulk stresses and material properties contribute to final failure. The near-surface state of stress developed under oscillatory contact between machine elements plays a major role in deciding the severity of fretting. It is common to coat the core or provide surface treatment. The coating material is chosen to give good tribological properties. Such coatings exert a larger influence on the near-surface state of stress. It is possible to enhance tribological properties by coating the surface. Flexural wave propagation in coated poroelastic cylinders of infinite extent is investigated employing Biot’s theory. The coated poroelastic cylinder consists of two poroelastic cylinders of different poroelastic materials bonded at the curved surface. Each material is taken to be homogeneous and isotropic. A perfect bond is assumed at the interface and outer boundary of the coated cylinder is treated as traction free. Frequency equations of coated poroelastic cylinders are derived both for pervious and impervious surfaces. At the interface of the core and coating, the stresses and displacements are continuous. The nondimensional phase velocity for propagating modes is computed as a function of the propagation constant in the absence of dissipation. The results are presented graphically for two types of coated poroelastic cylinders and then discussed.