A computational model for a high speed vehicle with early defects in its axle box roller bearings was established using the dynamic package SIMPACK.It was assumed that there only exist interactions between outer ring and inner one for a bearing,so bearing rollers were directly equivalent to several force elements.Then,the effects of early defects located at inner and outer rings and roller surfaces on the vertical vibration features of the vehicle system were analyzed.The simulation results showed that the axle box bearing defects make the axle box vibration acceleration increase significantly,but they have little effect on the bogie frame acceleration;when the defect sizes of the three kinds of defects are equal,the defect located at outer ring has the largest influence on the amplitude of the axle box acceleration,but the defects at roller surfaces have the least effect;with increase in defect width,the amplitudes of the axle box accelerations under three kinds of defects all increase gradually;the bearing early defects can cause high-frequency vibrations of the axle box,but they have little effect on the vehicle ride comfort.%采用 SIMPACK 动力学软件，建立了一高速车辆出现轴箱轴承早期缺陷的动力学计算模型，将轴承假设为只有外圈和内圈两者之间的相互作用，轴承中的滚子直接等效成若干个力元，分别考虑了轴承的内、外圈以及滚子表面早期缺陷对车辆垂向振动特性的影响。仿真结果表明：当轴承表面出现早期缺陷时，轴箱振动加速度显著增大，而构架的加速度变化不大；当内外圈以及滚子缺陷尺寸（缺陷宽度和深度）相等时，轴承外圈缺陷对轴箱的加速度幅值影响最大，轴承滚子缺陷对轴箱加速度幅值影响最小；随着早期缺陷宽度的增加，3种轴承缺陷下的轴箱加速度幅值均逐渐变大；轴承早期缺陷能够引起轴箱的高频振动，但对车辆的平稳性影响甚微。
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