细长体飞行器自由边界热模态试验与仿真

随着耐热承载一体化材料在新型高超声速飞行器上的应用，承力结构的工作温度不断提高，各类热模态特性逐渐得到关注。针对非平面形状的细长体飞行器自由边界条件下的热模态特性开展了研究。通过研究模拟气动加热条件的圆筒形加热笼、模拟自由边界的耐高温柔性支撑、非接触激光多普勒测振、耐高温激振杆激励等试验方法，获得了细长体结构自由边界条件下随温度变化的前3阶模态变化情况。结果表明：对此类薄壁长圆筒类结构，温度升高对模态频率影响可以超过6 Hz。开展有限元仿真，并与试验取得的热模态结果的变化规律进行对比。结果表明：建立考虑温度对结构弹性模量、热应力影响的壳单元模型，能够较好地预测出前3阶模态频率在全部受热时间范围内的最大下降量，可为高超声速飞行器控制系统设计时的拉偏范围提供参考。

Thermo-modal test and simulation of spindly vehicle in free boundary conditions

As the use of more high temperature/high load durable materials in modern hypersonic vehicles requires load durable structures to work in increasingly higher temperature, much attention has been paid to thermo-modal characteristics of structures. This paper discusses the thermo-modal characteristics of a spindly vehicle with a non-planar shape in free flight boundary conditions. A cylindrical cage for aerodynamic heating simulation is studied. A free flight and flexible supporting boundary which is high temperature durable is simulated, a non-contact vibration measurement is conducted using laser Doppler, and a high temperature durable excitation pole is excited, obtaining the first 3-order modal variation of the spindly vehicle under free boundary conditions. The results show that temperature elevation can result in a 6 Hz decrease of the natural frequencies of such a thin and long cylindrical structure. A comparison of FE simulation results with test results shows that the shell element model which considers the effect of temperature on elastic module and thermo-stress of the structure can well predict the maximum decrease of the first 3-order natural frequencies in aerodynamic heating, and can thus provide some reference for the margin of the design of control system of hypersonic vehicles.