热环境下复合材料壁板的振动特性分析

针对飞行器中常见的壁板结构,运用能量原理和变分方法,建立了定常温度场下复合材料壁板振动的控制方程以及相应的有限元分析模型。分析了热环境对壁板振动特性影响的机理,同时提出了一种针对热环境下复合材料壁板振动特性分析的线性化计算方法。采用这种方法,热环境的影响以一个热刚度项和一个热载荷项的形式出现在常温下的振动运动方程中,由此可以较准确地模拟热效应对结构振动特性的影响。通过对热环境下复合材料壁板振动固有特性数值分析结果的对比,验证了本文方法的可行性和计算精度。同时分析结果表明,热效应产生的诱导应力对结构刚度的影响是导致壁板固有振动频率降低的主要原因。

Vibration Analysis to Composite Panels in Thermal Environment

Composite panels are commonly applied to high speed aircraft,where aerodynamic heating effect must be considered,thus the vibration analysis of composite panel in thermal environment is an attractive topic of aerothermoelasticity.A linearized finite element approach is proposed to determine the vibration characteristics of composite panels under thermal conditions.With the assumption of uncoupled thermal-structural properties and nonlinear von Karman large-deflection strain-displacement relationship,the vibration equation is established by Hamilton variation principle.To obtain the finite element equations of thermal vibration,the Mindlin plate element(MIN3) is used so that the transverse shear effect can be considered,and the thermal effect is represented by an equivalent thermal stiffness term and a thermal load term.Numerical examples are presented and the comparisons of the simulated results with existing ones confirm the validity and accuracy of this method.It is concluded that the natural frequencies of the composite panel lower mainly with the impact of thermal induced stiffness term rather than that of thermal induced variation of material properties.