航空学报 > 2017, Vol. 38 Issue (7): 220553-220553   doi: 10.7527/S1000-6893.2017.220553

高温环境下二维正交编织C/SiC复合材料壁板振动模态演化

贺尔铭, 陈兵, 曹存显   

  1. 西北工业大学 航空学院, 西安 710072
  • 收稿日期:2016-06-22 修回日期:2016-10-19 出版日期:2017-07-15 发布日期:2017-04-01
  • 通讯作者: 贺尔铭,E-mail:heerming@nwpu.edu.cn E-mail:heerming@nwpu.edu.cn
  • 基金资助:

    国家自然科学基金(51675426);航天科技创新基金(2014KC010043)

Vibration mode evolution of 2D woven C/SiC composite panels in hot environment

HE Erming, CHEN Bing, CAO Cunxian   

  1. School of Aeronautics, Northwestern Polytechnical University, Xi'an 710072, China
  • Received:2016-06-22 Revised:2016-10-19 Online:2017-07-15 Published:2017-04-01
  • Supported by:

    National Natural Science Foundation of China (51675426);Aerospace Science and Technology Innovation Fund (2014KC010043)

摘要:

为了研究高温环境下二维正交编织C/SiC复合材料壁板的固有振动特性随温度的变化规律,进一步揭示模态跃迁和丢失现象。首先建立了二维正交编织复合材料的细观非均匀有限元模型,基于细观模型采用体积平均法计算得到了均匀化后材料的模量、热膨胀系数和热传导系数等宏观性能参数。在此基础上,分别研究了均匀温度和线性非均匀温度载荷下,四边简支复合材料板在屈曲前后固有频率及模态振型随温度的变化规律。研究结果表明:在均匀温度场下,如果仅考虑热载荷对材料模量的影响时,随着温度的升高,各阶固有频率逐渐降低,但降低的幅度不大;仅考虑热应力对结构刚度影响时,在临界屈曲温度后固有频率反而上升,并且随着温度的升高出现了频率交错,其对应振型发生了跃迁现象;当同时考虑热物性和热应力影响时,各阶频率值变化趋势与仅考虑热应力时类似,只是对应温度点的频率值有所下降。而在线性非均匀温度场下,通过对比不同工况下的模态振型发现,随着温度的升高某些模态振型还会出现丢失,并且这种丢失是从低阶到高阶依次发生的。

关键词: 二维C/SiC, 复合材料壁板, 热模态, 固有频率, 模态跃迁和丢失现象

Abstract:

To study the law of the variation of natural vibration frequencies of 2D woven C/SiC composite panels in hot environment, and further reveal the mode jumping and losing phenomena in the thermal mode test, the mechanics modules, thermal expansion coefficient and thermal conductivity of 2D woven C/SiC composite panels after homogenization are calculated by volume-averaged method based on its microscopic mechanics model. The vibration mode evolutions of the simply-supported rectangular panel under uniform temperature loads and linear non-uniform temperature loads are studied based on the macroscopic material properties obtained above, and the relationships between high temperature and the natural frequency, mode shapes are obtained from the mode analysis. The research results show that under the uniform temperature loads, when we consider only the effect of temperature on the elastic modulus, the natural frequency decrease slightly as the temperature increases. When the thermal stress caused by high temperature is considered separately, it is found that the natural frequency increases after the critical buckled temperature, and as the temperature increases, the mode shape being staggered which results in some mode shapes appear early, in other words, mode jumping occurs in those moments. If both of the two factors are considered, the natural frequency will be smaller at each temperature compared with only considering the thermal stress caused by high temperature. However, the trends are similar. Under the non-uniform high temperature loads, it shows that some modal shapes may be lost by comparing the mode shapes under different operating conditions, and the loss is not messy, but goes from low-order to high-order frequency.

Key words: 2D C/SiC, composite panel, thermal mode, natural frequency, mode jumping and losing phenomenna

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