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主减速器齿轮啮合产生的中高频谐波振动是直升机舱内噪声的主要来源之一,通过抑制该振动向机体的传递可达到舱内降噪的目的。基于金属/橡胶周期结构,提出了一种适用于直升机舱内降噪的串/并联复合型主减周期撑杆,不仅具有宽频减振特性,而且能够满足直升机对撑杆的强度和刚度要求。为指导这种周期撑杆的设计,首先采用谱单元法建立了复合型主减周期撑杆的动力学模型,进一步建立了该周期撑杆的刚度和强度分析模型;在此基础上,分析得到了该周期结构的主要设计参数对减振特性、刚度及强度的影响规律;最后,以某轻型直升机为背景机设计了复合型主减周期撑杆,对其减振特性、刚度及强度特性进行了仿真研究,结果表明:所提出的设计方案可满足该直升机对主减撑杆的刚度和强度要求,且撑杆两端位移传递率在500~2 000Hz频率范围内的最大振动衰减超过60dB,验证了本文所提出复合型周期撑杆方案的可行性。
The intermediate-high frequency harmonic vibration generated by the gear meshing of the final drive is one of the main sources of noise in the helicopter cabin. The purpose of noise reduction in the cabin can be achieved by suppressing the transmission of the vibration to the airframe. Based on the periodic structure of metal / rubber, a serial / parallel main reduction cycle strut suitable for noise reduction in helicopter cabin is proposed, which not only has the characteristics of wideband vibration reduction but also meets the requirements of helicopter strength and stiffness. In order to guide the design of this kind of periodic strut, firstly, the dynamic model of composite main reduction period strut was established by spectral element method, and then the stiffness and strength analysis model of this strut was established. On this basis, The main design parameters of the periodic structure of the damping characteristics, stiffness and strength of the law; Finally, a light helicopter as the background machine designed composite main reduction period strut, its vibration characteristics, stiffness and strength characteristics The simulation results show that the proposed design can satisfy the requirements of the helicopter on the rigidity and strength of the main down-strut, and the maximum vibration attenuation of displacement transfer rate at both ends of the strut in the frequency range from 500 to 2 000 Hz is more than 60 dB. The feasibility of the composite periodic strut proposed in this paper is verified.