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摘要:
针对现有适于宽幅值范围的黏弹减摆器模型一般含有动幅值参量，不便用于幅值变化的直升机旋翼/机体耦合动稳定性时域分析的问题，给出了小摆振阻尼比时，黏弹减摆器在单频及双频条件下动幅值参量的计算方法，运用该方法计算系统在收敛、中性稳定及发散3种情况下的幅值曲线，较好地反映了响应幅值在时域上的变化趋势。将改进的黏弹减摆器模型用于直升机地面共振非线性时域分析，为准确获取旋翼摆振后退型响应，给出了所需桨叶激振力矩的计算方法，在不同转速不同复模量状态下，采用该方法确定的激振力矩对桨叶进行激振激出的响应幅值与预期值误差不超过6%。对摆振后退型响应进行分析可知，系统稳定时，与线性化结果相比，计入黏弹减摆器非线性后，旋翼摆振后退型响应衰减更快，其模态阻尼在时域上呈增加趋势。
Abstract:The existing elastomeric damper models commonly introduce dynamic amplitude parameter for applying to wide amplitude situation. It is inconvenient to time domain analysis of helicopter rotor-fuselage coupled dynamic stability on account of the dynamic amplitude changing in time domain. Aimed at this problem, the calculation methods of dynamic amplitude parameter were given for single and double frequency excitation cases while the lagging damping ratio is little. The amplitude curves calculated by the method describe the response amplitudes well while the system is in the state of convergence, neutral stable, or divergence. The improved model of elastomeric damper was used for nonlinear time domain analysis of helicopter ground resonance. The calculation method of excitation moment at blade was given for exciting the regressive lagging mode responses accurately. For different rotor speeds and complex modulus states, the response amplitudes excited by the excitation moment determined by the moment calculation method were compared with the desired values, and the maximum error is under 6%. After the regressive lagging mode responses are analyzed, it is known that the regressive lagging mode responses decay faster than the linearization results, and its modal damping increases in time domain due to the elastomeric damper nonlinearity while system is stable.
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Key words:
- helicopter /
- elastomeric damper /
- nonlinear /
- time domain analysis /
- ground (air) resonance
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图 1 不同稳定情况下的单频时域响应
Figure 1. Single frequency response in time domain at different stable situations
图 2 不同稳定情况下的双频时域响应
Figure 2. Double frequency response in time domain at different stable situations
图 3 黏弹减摆器时域响应计算流程
Figure 3. Calculation flow of elastomeric damper time domain response
图 10 旋翼摆振后退型阻尼随时间变化情况
Figure 10. Variation of rotor regressive lagging modal damping with time
表 1 直升机主要参数
Table 1. Main parameters of helicopter
参数 数值 桨叶片数 4 桨叶质量/kg 42.3 桨叶对摆振铰静矩/(kg·m) 123.7 桨叶对摆振铰惯性矩/(kg·m2) 457 摆振铰外伸量/m 0.23 减摆器到摆振铰距离/m 0.35 机体纵向当量质量/kg 2 000 机体纵向固有频率/Hz 1 机体纵向当量阻尼/(N·s·m-1) 1 000 机体横向当量质量/kg 800 机体横向固有频率/Hz 1.5 机体横向当量阻尼/(N·s·m-1) 500 
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