关键词: 幂律过程, 样本容量, 试验时间, 数控机床, 可靠性评估

Abstract: According to the requirement of cumulative Mean Time Between Failures(MTBF)and interval estimation precision of reliability for Numerical Control(NC)machine tools,the minimal testing truncated time and sample size of reliability assessment test were given by using Fisher information matrix method for failure process that described by power law process model.Thus the problem of determining sample size and testing time of reliability assessment test for NC machine tools was resolved.The results showed that the log ratio of upper bound to lower bound and confidence level of reliability indices interval were the main factors for truncated time and sample size.The minimal sample size increased significantly with the improvement of required precision of interval estimation and confidence level of reliability indices,but the minimal testing truncated time was less affected by these two factors.

Key words: power law process, sample size, testing time, numerical control machine tool, reliability assessment