RELIABILITY ASSURANCE METHOD OF PRODUCT MADE OF BRITTLE MATERIAL, MANUFACTURING METHOD, RELIABILITY ASSURANCE DEVICE, AND RELIABILITY ASSURANCE PROGRAM

PROBLEM TO BE SOLVED: To perform life prediction being a relationship between a load and a breaking probability after a predetermined period with a reduced frequency of tensile test, and guarantee the reliability, in a product made of a brittle material such as an optical fiber in which strength distribution comprises a mixed system of two Weibull distributions of a high strength area and a low strength area.SOLUTION: A reliability assurance method is characterized by including: a step of inputting data of the breaking strength showing tensile test results of multiple products; a step of finding non-reliability corresponding to multiple data and calculating a cumulative hazard value; a step of applying a set of the multiple data and the cumulative hazard value to a cumulative hazard function of a high strength area, and estimating a geometry parameter and a scale parameter to estimate the cumulative hazard function of the high strength area; and a step of calculating the relationship between a load and the breaking probability after a predetermined period based on the cumulative hazard function of the high strength area, and estimating a calculable range capable of predicting the breaking probability based on the input data of the breaking strength in the relationship. 【課題】強度分布が高強度域と低強度域との２つのワイブル分布の混合系からなる光ファイバ等の脆性材料製の製品において、少ない引張り試験の回数で、負荷と所定期間後の破断確率との関係である寿命予測を行うとともに、信頼性を保証する。【解決手段】複数の製品の引張り試験の結果を示す破断強度のデータを入力するステップと、複数のデータについて対応する不信頼度を求め累積ハザード値を算出するステップと、複数のデータと累積ハザードの値との組を、高強度域の累積ハザード関数に当てはめ、形状パラメータ及び尺度パラメータを推定して、高強度域の累積ハザード関数を推定するステップと、高強度域の累積ハザード関数に基づいて、負荷と所定期間後の破断確率との関係を算出すると共に、当該関係における入力した破断強度のデータに基づいて破断確率を予測できる予測可能範囲を推定するステップと、を含むことを特徴とする信頼性保証方法である。【選択図】図１２