NOISE AND VIBRATION OF A FLUID-FILLED ELASTIC PIPE COATED WITH AN ABSORPTIVE LAYER ON THE INNER SIDE OF THE WALL

In previous work it has been found that there is a large discrepancy between lossless theory and experiments on vibration and noise levels of a water filled elastic pipe at high frequencies. This problem is investigated theoretically in this paper. Absorption due to the mixture layer on the inner wall of the pipe is taken into account. This layer is treated as a special coupling layer with high damping, but the shell and the water are still treated as lossless. The vibration of the shell is coupled via the absorptive layer with the interior water. A mathematical model is presented and expressions are simplified. Numerical results are given: they agree well with experiments.