金属壁板结构在热声环境下的动态响应.docxVIP

壁板结构在热声环境下的动态响应计算与分析学 院动力与能源工程学院专 业飞行器动力工程班 级7404101学 号200704041035姓 名赵宇指导教师沙云东负责教师沙云东沈阳航空航天大学2011年6月摘 要针对薄壁结构在热声载荷作用下的动态响应问题，本文利用理论分析及数值模拟相结合的方法研究了薄壁结构在热声载荷作用下的非线性动态响应。首先建立了热声载荷作用下薄板振动的非线性大挠度方程，基于该方程建立Miles单自由度杜芬型模态方程，讨论非线性恢复力项对结构自由振动的影响，计算屈曲温度、热屈曲幅值，并分析了热屈曲前后刚度变化及应力应变响应统计特性。建立薄壁结构有限元模型，考虑几何非线性，结合有限元软件，对高温结构施加模拟的声载荷进行动响应计算，根据屈曲前后薄壁中点应力及横向位移概率分布，分析热及噪声载荷造成的结构几何非线性对结构刚度的影响。最后计算了三种典型壁板结构，平板，开孔板，加肋板在热噪声载荷作用下的动态响应，预测到了三种类型的跳变运动，计算了均方应力、均方应变、应力及应变功率谱密度。分析了温度和噪声对薄板刚度及热应力和应变分布的影响，不同结构对相应的影响。本文所研究的航空薄壁结构在热声载荷作用下非线性动态响应的计算和分析方法，以及所计算的结构应力/应变，对认识高速飞行器表面结构非线性动态响应及进行抗疲劳设计有着重要的参考价值。 关键词：壁板结构；热声疲劳；动态响应；热屈曲；跳变响应CALCULATION AND ANALYSIS OF DYNAMIC RESPONSE OF THIN-WALLED STRUCTURE UNDER THERMAL-ACOUSTIC LOADINGSAbstractAiming at the dynamic responses of thin-walled structures under complex loadings, with theoretical analysis and numerical simulation employed, nonlinear response of thin-walled structure under thermo-acoustic loading is investigated.The nonlinear large deflection governing equation of motion for thin plate under thermo-acoustic loading is established firstly. The simplest case, a single DOF equation is then obtained. The influence of the nonlinear term of restoring force on free vibration is discussed. The critical temperature and static deflection of thermal buckling are calculated.A flat plate, a stiffened plate and a plate with a circular hole in its center with clamped edge condition are selected. Finite element models are built in commercial code ANSYS. With geometric nonlinearity and pre-stress effect considered, the dynamic response of plates under different temperatures and sound pressure levels are computed, assuming that the acoustic load is truncated Gaussian white noise and the thermal load is uniformly distributed. Based on the time histories of displacement and stress, the power spectral density, probability density function and statistics are obtained.The method and results presented have certain value to the research of the nonlinear response of thin