碳/碳复合材料薄壁结构在热声载荷作用下的动态响应

Dynamic response of C/C composite thin-walled structure under thermo-acoustic loadings

高速飞行器中大量使用复合材料薄壁结构,高温和强噪声联合作用的工作环境使复合材料薄壁结构表现出强非线性振动响应特性和复杂的运动形式。以四边固支碳/碳(C/C)复合材料薄壁结构为研究对象,采用有限元法计算了其在不同温度和声压级(SPL)组合下的振动响应。得到了典型的振动响应运动形式,包括屈曲前的随机振动、屈曲后的跳变运动和围绕一个平衡位置的随机振动。结合振动响应的概率密度、功率谱密度,随着温度和声压级的变化,对振动响应的非线性特性进行了分析。结果表明,热载荷和声载荷对响应非线性特性的影响方式不同,强噪声载荷引起的间歇跳变降低了结构的刚度。

A great amount of composite material of thin-walled structure is used in the high-speed flight vehicles, which presents strong nonlinear characteristics and complex forms of exercise in the working environ- ment of high temperatures and intense noises. The object of this paper is C/C composite material structures with clamping. This paper utilizes the finite element method to calculate the nonlinear random response of thin composite panels at various combinations of sound pressure levels and temperatures, and obtains the typical thermo-acoustic motion, including the random vibration before buckling, jumping and the random vibration around a balance position. By analyzing the change of probability densities and power spectrum densities with the change of temperature and sound pressure level, this paper studies the nonlinear characteristics of dynamic response. Results show that acoustic loadings and thermal loadings influence the nonlinear characteristics of dynamic response in different ways and the intermittent jump caused by strong acoustic loadings reduces structure stiffness.