DISTORTED DYNAMIC SIMILITUDE OF CYLINDRICAL SHELLS WITH VARIOUS MATERIALS IN A THERMAL ENVIRONMEN

Thermal vibration testing of large-size cylindrical shells relies on scaled model tests due to test conditions and cost constraints. However, the application of various advanced composite materials on cylindrical shells has led to the difficulty of similitude distortion in the traditional scaled model design, which cannot be scaled down in terms of thickness and material properties. In this regard, this paper is the first to investigate the similitude distortion of the dynamic properties of cylindrical shells in thermal environments for a variety of composite materials. In this paper, the similitude distortion factors caused by composite materials are analyzed, and based on the energy similitude correction method (ESCM) recently proposed by the authors, the applicability of the dynamic characteristics similitude is analyzed for isotropic materials, laminated composites, conventional functional gradient materials (FGM), sandwich FGM, and functionally gradient carbon nanotube-reinforced materials (FG-CNTRCs), and the natural frequencies of the materials are deduced and the similitude relationship is improved. the similitude relationship is derived, the application of the energy the similitude correction method is improved to expand its scope of application from a single isotropic material to many types of composite materials, and finally a generalized similitude distortion model is established. The similitude relationship is utilized to design the scaled model, and the similitude relationship of the natural frequencies of various materials is verified by numerical examples. The results show that the generalized similitude distortion model is accurate and can be applied to the thermal vibration scaled model tests of cylindrical shells of various advanced composites; in the similitude distortion model designed based on ESCM, the similitude relationship of the dynamic characteristics is not affected by the material objects when the conditions of wall thickness, material, and temperature conditions of the prototype and the model are kept the same. This study may provide technical support for the design and evaluation of large-size cylindrical shells with new materials in scaled model tests.