磨损与冲击耦合的随机振动系统的可靠性与灵敏度研究

For dynamic and evolutive behavior of reliability caused by coupling effect of wear and vibration, a gear transmission system is taken as research object under the working condition of overload and shock, combining theory analysis, system simulation and experiment. The research is to study the influence rule of coupled wear and shock on gradual change process of system dynamics, to explore constitutive relations among the original design parameters, wear and dynamic behavior, to extract the fault signature of structural components and to reveal the internal mechanism of failure generated by wear and shock. Then, the random distribution rule of random parameters are explored, dynamic model with random distribution parameters is established, and random characters are concluded from dynamic response for time-varying and cumulative gradual characteristics of random parameters. Finally, based on the probabilistic perturbation method and reliability theory, the highly effective numerical approach is studied to calculate the dynamic reliability sensitivity of complex nonlinear mechanical system. The quantitative analysis is used into dynamic reliability theory with gradual parameters. After probing the variation trend of reliability in product’s life cycle and putting forward a method to assess the influence index of random parameters on reliability of random dynamic system and design method of reliability sensitivity, the enhanced design criterion of system’s and key components’ reliability will be obtained. All above provides scientific theory support for safe reliable operation of machinery.

针对磨损和冲击耦合作用导致可靠性的动态演变行为，以齿轮传动系统为研究对象，在重载和冲击等恶劣工况下，通过理论分析、系统仿真和试验相结合的方法，研究磨损与冲击耦合作用对系统动力学行为渐变过程的影响规律，探索初始设计参数与磨损以及系统动力学特征的本质关系，提取结构部件的故障特征，揭示诱发磨损和冲击失效的内部机理；针对随机参数的时变特性与累计渐变性，探索随机变量的随机分布规律，建立参数化的随机分布动力学模型，提取动态响应的随机特征；基于随机摄动技术、可靠性相关理论，研究非线性复杂机械系统的动态可靠性灵敏度的高效计算方法，形成系统及关键零部件动态渐变的可靠性定量分析理论，探索整个寿命周期内可靠性变化趋势，提出评价基本设计参数对随机动态系统的可靠性影响指标以及可靠性灵敏度设计方法，建立系统及关键零部件可靠性增强设计准则，为保障机械产品安全可靠运行提供科学理论支撑。

项目针对采煤装备中截割传动系统的重载、冲击、磨损等恶劣工况，考虑了采煤机截齿的截割过程是连续的，是小块碎屑崩落与大块煤屑从煤体上崩落不间断的交替过程。各煤块单元连续随机的崩落，引起截齿载荷的随机波动，将该过程视为平稳随机过程，得到了截割力随机载荷谱。研究了重载载荷和冲击载荷对动力学参数的影响程度，提取变化较大的参数作为理论研究中的设计参数；针对重载条件下冲击与摩擦磨损问题，应用赫兹接触理论与摩擦磨损理论，建立了多自由度齿轮摩擦磨损模型，讨论了齿轮传动系统结构参数和材料特性参数与冲击及摩擦磨损的关系。考虑结构、载荷、材料相关的初始设计参数是随机分布并且概率密度分布未知的情况下，基于Kriging方法和ANN方法，建立了具有随机参数的齿轮磨损代理模型。基于渐变失效模式和表征功能函数，应用以矩法为代表的解析法、以蒙特卡洛为代表的数值模拟法，建立了具有渐变参数的可靠性模型，对随机过程系统进行了可靠性计算，描述了整个寿命阶段系统的可靠性变化规律。结果表明，采煤机截割传动系统的主要失效模式为冲击疲劳和磨损，基于Kriging方法、Edgeworths级数、四阶矩法可以快速准确的得到可靠性的变化趋势，并预测系统寿命。该项目进一步丰富了机械振动系统可靠性模型的有关理论与方法，提出了一套切实可行的、对实际生产有指导意义的设计准则。