简谐激励下柔性卡箍支承管路系统响应

Responses of pipe system with flexible clamp under harmonic excitation

针对柔性卡箍支承航空发动机管路系统振动问题,研究了柔性卡箍的刚度特性及其对管路系统响应特性的影响。建立了包含管路和柔性卡箍的管路系统流固耦合有限元模型,给出了系统时域响应的Newmark积分方法。采用解析推导和试验测试两种方法对柔性卡箍刚度特性进行了研究,研究结果表明:柔性卡箍的刚度具有明显的分段线性特性。通过对基础简谐激励作用下管路系统时域受迫响应分析,研究了柔性卡箍支承刚度对系统非线性行为的影响。发现柔性卡箍刚度的不对称性较大时,系统的幅频响应特性曲线出现明显的非线性突跳现象;在特定频率范围,响应中存在激励频率的亚谐和超谐分量;随着流体流速和压力的增加,系统固有频率减小。

For analysis of vibration of aero-engine pipe system with flexible clamp,the stiffness characteristics of a flexible clamp and the effect of the flexible clamp on the pipe system response were studied,respectively.Considering the fluid-structure interaction,a dynamic model with pipe and flexible clamp was proposed based on the finite element model.The Newmark numerical integration was then utilized to obtain the time-domain responses.The stiffness of the flexible clamp was derived analytically and verified by the test.The result showed that the stiffness of the flexible clamp was piecewise linear stiffness.Responses of a pipe system with flexible clamp under harmonic base excitation were simulated,and the effects of the flexible clamp stiffness on the nonlinear dynamic behavior of the system were also discussed in detail.The results show that the amplitude-frequency curves of the responses become obviously nonlinear with the increase of the flexible clamp stiffness asymmetry.Within certain excitation frequency ranges,both sub-harmonic and multi-harmonic responsescould be found in the system responses.The natural frequencies decreases with the increase of flow velocity and pressure.