基于HGERT网络模型的退化型失效可靠性评估

针对退化型失效的复杂装备系统,提出基于隐图解评审技术(hidden graphic evaluation and review technique,HGERT)网络模型来进行系统可靠性预计和评估的方法。图解评审法(graphic evaluation and review technique,GERT)网络中的节点代表装备失效过程中正常状态到失效状态的转移,通过传感器将反映系统隐性状态的性能特征参数进行量化输入,从而将GERT网络中的各个劣化状态节点进行展开。应用Viterbi算法对模型参数进行解码和学习,确定退化型失效系统状态转移概率。将装备运行中所处的工作应力、环境载荷等影响性能衰退的因素作为输入,将关键性能指标退化量作为输出,建立装备性能退化的一般控制模型并将其作为GERT网络活动传递的随机变量。借助于信号流图理论对参数进行解析,监测系统处于不同状态时的性能退化水平,为故障预测和装备健康管理提供支持。案例通过对铣床性能退化量的分析,证明所构模型的可行性和合理性。

Reliability evaluation of degradation failure based on HGERT network model

A method based on hidden graphic evaluation and review technique (HGERT) for system reliability prediction and assessment is proposed for complex equipment with degradation failure. Nodes in GERT network represents state transmission from a normal state to a failure state in a failure process. The performance-characteristic-parameters of hidden states in the system are quantized and input through the sensors, so that each deteriorated state node in GERT network can be expanded. Viterbi algorithm is used to decode and study the model parameters, and then the state transition probability of degradation failure system is determined. Working stress, environment load and other factors which influence the performance of equipment operation are considered as input, performance degradation of critical indicators as output, a general control model reflecting equipment performance degradation can be established and then we use degradation as a random variable transmitted between nodes in GERT network. The parameters are analyzed by means of signal flow graph-theory, the performance degradation level in different states can be monitored, which provides support for fault prognosis and health management. Feasibility and rationality of the model is proved by analyzing the performance degradation of a milling machine.