摘要
The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.
通常采用二维当量地面共振模型来分析直升机地面共振稳定性。主要原因是该模型概念清楚，计算也相对简便．其当量质量、当量刚度与当量阻尼均来自机体的模态特性．为了验证该模型，本文分别采用三维空间立体模型及当量地面共振模型计算了同一型号直升机的地面共振稳定性．计算结果表明，两者有完好的一致性，说明当量地面共振模型用于计算地面共振稳定性其结果是可靠的．计算地面共振稳定性时所采用的量旋翼阻尼一般根据减摆器的力学特性，采取迭代的过程导出。由于粘弹性减摆器复模量的实部转换成线性速度阻尼的过程极为繁琐，本文直接采用复模量导出地面共振稳定性运动方程，故简化了计算过程，并使计算结果更加可靠。
