As product structure becomes more and more complex, the fault mode presents a diversified trend, and it is more difficult to determine the causes of system failure for a complex product. The main objective of this study is to provide an effective failure analysis method based on the combination of fault trees analysis (FTA) and generalized grey relation analysis (GGRA) for complex product. In this method, the product system failure is defined and the fault tree is constructed by FTA methodology firstly; and then GGRA is employed to identify the correlations between each fault mode and the system failure; finally, the main causes of system failure are identified and the corresponding measures can be made. A case study of a WD615 Steyr engine is conducted throughout the text to verify the validity of this method. The present study would help facilitate the failure and reliability analysis for complex product and benefit designers for the product improvement.

Engine is the core of auto parts. It has great economic and social benefits for retired engines and their parts by remanufacturing. However, in recycling process, the uncertainty of quality status of retired engines leads to the uncertainty of life cycle cost, which makes it difficult for technicians to evaluate the cost. In order to address the problem mentioned, this study sets up a nonlinear model between the life cycle cost, service time and the quality level of used engine parts by considering damage degree in recycling process of used engine parts as a research index and takes 50 heavy-duty engine connecting rods as an example, which provides a theoretical basis for remanufacturing enterprises to evaluate the cost and determine the remanufacturing process accurately.