INFLUENCES OF SMALL CURVATURES ON THE MODAL CHARACTERISTICS OF THE JOINED HERMETIC SHELL STRUCTURES

摘要

From a practical engineering point of view, there is interest in understanding the influences of small curvatures on the modal characteristics of a plate-shell combination. However, research reports in this area are rarely found in literature. This paper is the first one to study the influences of small curvatures on free vibration of a plate-shell combined structure, consisting of a circular barrel-like shell and two spherically curved end plates, using the line receptance concepts and approximate frequency equations of barrel-shaped shell and spherically curved plate. It illustrates in detail information about natural frequencies and mode shapes of the combined structure under different geometric configurations. Consequently, it provides useful information for setting up criteria for designing hermetic plate-shell joined structures, such as the hermetic shell of a refrigeration compressor. The receptance method, which is basically a component mode synthesis technique, is adopted as the solution procedure in this study. It predicts the responses and frequencies of a combined system in terms of the responses and frequencies of its subsystems. This technique, for cases to which it can be applied successfully, is a powerful tool in creating an understanding of the physics of combined structures.