The big-mass equipment under the car has an important influence on the vehicle's modal characteristics and ride comfort.The mathematical model of a 9-freedom rigid-elastic coupling vehicle system was established.And the effect of the equipment on the vertical vibration of the vehicle was investigated by analysing the acceleration FRFs at some reference points.The vehicle acceleration frequency response characteristics at certain vertical bending vibration frequencies were obtained considering the factors of geometric filtering effect,equipment installation type (rigid,flexible),and running speed.Finally,the influences of equipment mass and damping ratio on the vehicle body vibration level were studied.The results show that:the elastic suspension can effectively reduce the vibration of the car body.The geometric filtering effect is quite obvious when the speed is lower than 150 krn/h.It is necessary to take the geometric filtering effect into account to reduce the vibration when the equipment mass and damping ratio are chosen reasonably.%车下设备因其质量较大,对车体的振动模态特性和车辆乘坐舒适性都有着重要影响.建立了9自由度的车体-设备刚柔耦合数学模型,获得了车体中部、构架上方三个参考点的加速度频率响应函数表达式,研究了车下设备对车辆垂向振动的影响规律.考虑了在几何滤波效应、设备的安装方式(刚性、弹性)、运行速度等因素作用下,车体的三个参考点在垂向弯曲频率下的振动加速度响应特性,最后讨论了设备的质量以及吊挂阻尼比对车体振动水平的影响.研究结果表明,设备弹性悬挂能有效降低车体振动水平,在速度低于150 km/h,几何滤波效应对车辆的振动影响较大,在此速度范围内设备悬挂参数设计应该充分考虑几何滤波效应的影响,合理的选择设备质量和阻尼比能有效控制车体的振动.
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