Random incidence energy transmission of bending waves at junctions

Abstract

This paper describes analytical expressions and numerical results for the random incidence transmission efficiencies of bending wave at typical types of junctions. Analyzed junctions are formed by semi-infinite flat plates, perpendicularly intersecting with each other, for which arbitrary plate thickness and material property are permitted. To obtain a basic formula of transmission efficiency, the analysis for oblique incidence energy transmission at the cross-type junction is carried out, and the total transmission efficiency is expressed by the sum of partial transmission efficiencies among the incident and each transmitting plates. The above basic formula can utilize for other types of junctions, L and T types, by omitting some arguments in the formula, corresponding to each junction. As numerical examples, the transmission and the reflection losses for oblique incidence at each incident angle are calculated for L-, T-, and X-type junctions as a function of the plate thickness ratio, and the average transmission loss for each type junction is obtained from the results of oblique incidence. These calculated average transmission losses for L, T, and X types completely agree with the Cremer's results for the case when plate thickness ratio is unity, and increases around 2–4 dB more than that in the normal incidence over the same range of thickness ratio.