摘要
为评估现场时间截尾少样本故障数据的多台数控机床的可靠性,基于似然比检验理论,提出包括初步粗略评估和最终精确评估的数控机床可靠性指标的似然比检验两步区间减半评估方法,推导计算2参数Weibull分布评估模型参数及平均无故障工作时间、可靠寿命和可靠度等可靠性指标区间估计的迭代公式。应用该方法初步评估时,可先取较大计算步长,寻找评估指标上凸曲线的最大值和下凹曲线的最小值,计算结果可取至整数,不需要精确计算。在第二步精确评估时,在最大(小)值左右两区间分别取减半区间或更小区间,细化步长,重新计算,直至找到满足精度的精确估计值。结合一具体实例,给出2参数Weibull分布评估模型参数及可靠性指标的点估计和区间估计。结果显示该方法可减少计算量,提高迭代速度,适用于少样本数据的可靠性分析。
To evaluate reliability of multiple numerical control machine tools with field time truncated failure and small sample data,a two-step and bisectional interval method of likelihood ratio test is proposed,this method consist of firstly rough estimation and lastly accuracy estimation,and iterative formula of interval estimation for model parameters of 2-parameter Weibull distribution and reliability indices including mean time between failures,operational time given reliability and reliability at given time are all derived.In rough estimation process,a larger calculating step can be used to search maximum value of convex carve and minimum value of concave curve for assessment indices;At accuracy estimation stage,to obtain more accuracy computing results,bisectional interval of the two sides of maximum（minimum） value can be recalculated until the evaluation results meet the requirement of estimated accuracy.By using the proposed method,point estimation of model parameters and interval estimation of reliability indices for a detail example are presented.The results show that this method is suitable for reliability assessment to small sample data and can reduce computing and improve iterative speed.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2012年第2期9-15,22,共8页
Journal of Mechanical Engineering
基金
'高档数控机床与基础制造装备'科技重大专项资助项目(2009ZX04014-016)
