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Analysis of Rain Erosion of Coated Materials
Technical rept. Jun 1972-Jun 1973
MICHIGAN UNIV ANN ARBOR DEPT OF ENGINEERING MECHANICS
Pagination or Media Count:
The behavior of coat-substrate systems subjected to repeated impingements of liquid droplets was investigated. The system studied consisted of a thick homogeneous substrate covered by a single layer of homogeneous coating of arbitrary thickness. Based on the uniaxial stress wave model, the variations of the stresses with time were determined both in the coating and in the substrate. Employing the fatigue theorems established for the rain erosion of homogeneous materials, algebraic equations were derived which describe the incubation period, and the mass loss of the coating past the incubation period, in terms of the properties of the droplet, the coating and the substrate. The results were compared to available experimental data and good agreement was found between the present analytical results and the data. The differences between the uniaxial stress wave and the uniaxial strain wave models were also evaluated by calculating according to both models a the stress at the coat- liquid interface, b the stress that would occur in the substrate in the absence of the coating, and c the stress in the coating after the first wave reflection from the substrate.
APPROVED FOR PUBLIC RELEASE