高速滚动轴承力学特性建模与损伤机理分析

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Rolling bearings are widely used in high-speed rotating machinery systems, such as, aero-engine rotors, high-speed CNC machine tool spindles and high-speed locomotive wheelsets. The mechanical properties and running states of bearings affect the accuracy, reliability, and life of the whole rotor system significantly. When a rotor-bearing system is rotating at high speed, the generated centrifugal forces and gyroscopic moments raise the loads on the bearings, meanwhile, the bearing inner rings expand radially due to the centrifugal force. In addition, with increase in the running time, the working temperature rises and thermal deformations appear in the rotor, bearings and other parts. Due to the combined effects of the centrifugal force and the rising working temperature, the geometric position relations of the parts inside bearings change, they lead to the change of bearing properties, such as, stiffness, stress and strain. Here, considering the effects of radial centrifugal expansion and thermal deformations on the geometric displacements in bearings, Jones＇s bearing model was improved and a mechanical model for a high-speed rolling bearing was proposed, it was used to predict contact angles, contact deformations and contact loads between rolling elements and bearing rings. The bearing stiffness was calculated with it as well. Based on the proposed mechanical model, the laws of contact loads and contact position in a bearing were investigated under different working conditions, i. e. , static loads, dynamic loads and high speeds. Afterwards, the damage mechanism and incipient damage locations of a bearing were analyzed on the basis of the fatigue failure theory of materials. The study results provided a theoretical reference for damage detection and fauh diagnosis of a high-speed rolling bearing.滚动轴承广泛应用于航空发动机转子、高速数控机床主轴、高速列车轮对等高速旋转机械系统中，其力学特性和运行状态对整个转子系统的精度、可靠性及寿命等具有重要的影响。当转子一轴承系统在高速旋转时，所产生的离心惯性力和陀螺力矩，使轴承负荷增加，高速旋转的轴承内圈还将发生径向离心膨胀变形；另外，随着运行时间的增长，工作温度将升高，转子、轴承等部件会发生热变形。在离心惯性力和工作温升的综合作用下，轴承结构元件的几何化段火系会发生改变，从而改变轴承的刚度、应力、应变等动态特性。考虑了旋转内圈离心膨胀和热膨胀变形对轴承内部儿何位移的影响，对Jones提出的轴承模型进行改进，建立了一种高速滚动轴承力学模型，可以预测滚动体与内圈、外圈之间的接触角、接触变形以及接触载荷等参数，并计算轴承刚度。在该轴承力学模型的基础上，研究了静载倚、动态载倚及高转速等工况下滚动轴承内部接触载荷、接触位置的变化规律，并基于材料疲劳失效理论对轴承的损伤机理和早期损伤部位进行了分析，为高速滚动轴承的损伤识别和故障诊断提供理论依据。