声/热/静联合载荷下钛板结构响应特性研究

Study on Response Characteristcs of Titanium Panel under Combined Thermal/Acoustic/Static Loadings

关键词:  钛板  固有频率  热屈曲  热噪声载荷  动态响应

Key words:  Titanium panel  Natural frequency  Thermal buckling  Thermal-acoustic loading  Dynamic response

摘要:

复杂耦合载荷环境是导致高速飞行器进气道等部件破坏的重要因素。为预测静力、噪声、热等联合载荷作用下进气道壁板结构的响应特性，进而指导其结构设计及试验，以四边简支典型钛合金壁板结构为研究对象，由薄板大挠度运动方程出发，结合有限元法计算得到钛合金板的热屈曲系数、热模态特性以及预应力作用下的模态特性，利用顺序耦合方法计算壁板的热声响应。利用Newmark时间积分方法对计算进行非线性处理，分析得到壁板中心处的频率响应特性，采用蒙特卡洛法生成时域随机载荷，在此基础上计算得到钛合金壁板在静力、热、噪声联合载荷下的时域响应特性曲线。结果表明:热声载荷作用下，四边简支钛合金壁板结构的临界屈曲温度较低，容易产生屈曲，屈曲后结构的模态和频率均发生改变，其热声响应呈现复杂的非线性特征，静力、热、噪声联合条件下，由于静力的刚度硬化/弱化效应，壁板的热声跳变持续时间较短，且较快进入后屈曲状态。

Abstract:

Complex coupled loading environment is the main reason that lead to destruction of the hypersonic inlet structures. With the purpose to predict the behavior of the inlet structures subjected to combined mechanical，thermal and acoustic loading，thus guiding the structure design and test，we studied the thermal-acoustic dynamic response characteristics for the titanium panel simply supported on four sides. Firstly，according to large deflection hypotheses of thin plate，the thermal buckling coefficients and the thermal mode characteristics are obtained with the combination of finite element method. The thermal-acoustic response is calculated by ordinal coupling method for the panel. The nonlinear processing of the computation is carried out by Newmark time integration method and the frequency response property of the center of panel is obtained. The time domain response curve of titanium panel under combined static pressure，thermal and acoustic loading is calculated based on the random sound pressure load obtained by the Monte Carlo method. The results show that the critical buckling temperature of titanium panel simply supported on four sides is lower under the thermal-acoustic loadings and it is more easier to buckling. After thermal buckled，both the mode shape and frequency are changed and the complex nonlinear characteristics is presented in the thermal-acoustic response. Under the combined loads of static，thermal and intensive acoustic，the snap-through duration of the panel becomes shorter and gets into post-buckling faster due to static stiffness hardening / weakening effects.