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。 In order to study the variation of natural vibration characteristics of two-dimensional orthogonal woven C / SiC composite panel with temperature under high temperature, the phenomenon of mode transition and loss is further revealed. First, the mesoscopic non-uniform finite element model of two-dimensional orthogonal braided composites was established. Based on the mesoscopic model, the macro-performance parameters such as modulus, thermal expansion coefficient and thermal conductivity of the homogenized material were calculated by the volume average method. On this basis, the variation regularity of natural frequency and mode shape with temperature of the simply supported composite plate under flexural stress under uniform temperature and linear non-uniform temperature loading are studied respectively. The results show that when the thermal load only affects the material modulus under uniform temperature field, the natural frequency of each step decreases gradually with the increase of temperature, but the magnitude of decrease is insignificant. Considering the effect of thermal stress on the structure When the stiffness is affected, the natural frequency increases after the critical buckling temperature, and as the temperature increases, the frequency alternation occurs and the corresponding mode transition occurs. When both the thermal properties and the thermal stress are taken into account, The trend of change is similar to that of thermal stress, except that the frequency corresponding to the temperature decreases. However, under the condition of linear inhomogeneous temperature, comparing with the mode shapes under different operating conditions, it is found that some mode shapes will be lost as the temperature increases, and the loss is from low order to high order Happen in turn