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首先基于Hamilton原理建立旋翼系统动力学模型,计算旋翼的振频和振型,然后对稳定悬停状态下的桨叶进行某阶模态的激励,并在旋翼重新达到稳定状态后停止激励,截取旋翼系统自由振动信号,用移动矩形窗法计算旋翼系统的模态阻尼。这种计算系统模态阻尼的数值方法能够对旋翼系统在不同工况下的各阶模态阻尼进行仿真,而且在仿真过程中可以根据桨叶振型将激励按相同相位施加于各自由度上,使桨叶只按该阶振型振动。使用该方法可以突破旋翼动力学试验中激振位置、激振频率与相位的限制,获得旋翼系统更全面的动力学特性。
First of all, based on the principle of Hamilton, the dynamics model of the rotor system is established to calculate the rotor vibration frequency and vibration mode. Then the blade in a stable hovering state is excited in a certain mode. After the rotor reaches a steady state again, the excitation is stopped. Rotor system free vibration signal, using the moving rectangular window method to calculate the modal damping of the rotor system. The numerical simulation of modal damping in this calculation system can simulate the modal damping of rotor system under different operating conditions. In the process of simulation, the excitation can be applied in the same phase to each degree of freedom according to the blade mode , So that the blade only vibration of the vibration mode. The method can break through the limits of excitation position, excitation frequency and phase in rotor dynamics test to obtain more comprehensive dynamic characteristics of rotor system.