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中文核心期刊

热环境下多种材料圆柱壳动特性畸变相似研究

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

  • 摘要: 受试验条件和成本限制, 大尺寸圆柱壳的热振动测试依赖于缩比模型试验. 然而, 各种先进复合材料在圆柱壳上的应用, 导致传统缩比模型设计面临厚度和材料特性无法缩尺的相似畸变难题. 对此, 文章首次面向多种复合材料, 对热环境下圆柱壳的动特性畸变相似进行研究. 分析了复合材料导致的相似畸变因素, 基于作者近期提出的能量相似修正法(ESCM)对各向同性材料、层合复合材料、传统功能梯度材料(FGM)、夹层功能梯度材料和功能梯度碳纳米管增强材料(FG-CNTRCs)等进行了动特性相似的适用性分析, 推导了多种材料的固有频率相似关系, 改进了能量相似修正法的应用, 使其适用范围从单一的各向同性材料拓展为诸多类型的复合材料, 最后建立了通用相似畸变模型. 利用相似关系设计缩比模型, 通过数值算例对多种材料的固有频率相似关系进行了验证. 结果表明, 所建立通用相似畸变模型是准确的, 能够适用于各种先进复合材料的圆柱壳热振动缩比模型试验; 基于ESCM设计的畸变相似模型中, 原型与模型的壁厚、材料及温度条件等均保持一致时, 动特性相似关系不受材料对象的影响. 研究成果可为将来各种大尺寸新材料圆柱壳在缩比模型试验中的设计和评估提供技术支撑.

     

    Abstract: 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.

     

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