Reliability growth assessment under several operating stress conditions

Developed by the common research program of CNES and SAFRAN-SNECMA, this paper presents a new methodology for reliability growth model during development tests plan in which the reliability is estimated on the rocket engine by integrating the operating conditions. The proposed method evaluates the reliability of mechanical systems under variable constraints which contain the information of failure modes observed on the materials, the condition of repairs, the operating data linked to each development test. Applying to rocket engines data provided by SAFRAN-SNECMA society, the new reliability growth model gives better performance than the case of classical reliability growth model. The obtained result by a case study simulation illustrates the impact of operational data to estimate the reliability growth of system. The estimations obtained on real data on rocket engines allowed to emphasize the results of reliability estimated during operational flights. This reliability growth estimation method is thus valued in term of industrial application.