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碳纤维/环氧复合材料由于其重量轻、比刚度高及可按承载情况进行优化设计等优点,已逐步为飞行器结构所采用。目前工艺上较成熟的是碳环氧加肋锥壳,但其机械性能对工艺因素较敏感。为解决产品的质量控制和动态响应分析等方面的问题,希望能用试验办法确定其动特性——即确定各阶固有频率、振型和阻尼。过去求锥壳结构动特性的传统的方法是用激振器、振动台或扬声器做正弦扫频激励,用布置在结构上的若干加速度计或应变计求出固有频率及振型,用突然停振的剩余响应确定阻尼。其缺点在于试验周期长,设备复杂且试验结果会受到传感器质量及激励器附加刚度、阻尼等的影响。
Carbon fiber / epoxy composites have been gradually adopted for aircraft structures due to their advantages of light weight, high specific stiffness and optimal design according to the bearing conditions. At present the more mature technology is carbon epoxy ribbed shell, but its mechanical properties are more sensitive to process factors. In order to solve the problems of product quality control and dynamic response analysis, it is hoped that the dynamic characteristics can be determined experimentally-that is, the determination of the natural frequency, mode shape and damping of each step. In the past, the traditional method to find the dynamic characteristics of the conical shell structure was to use a sine wave swept excitation with an exciter, a vibrating table or a loudspeaker. The natural frequencies and mode shapes were obtained from a number of accelerometers or strain gauges arranged on the structure, The remaining response of the vibration determines the damping. The disadvantage is that the test cycle is long, the device is complex and the test results will be affected by the sensor quality and additional stiffness, damping and other effects of the actuator.