Fatigue Design Curve Construction for Test Data with Linear/Linearized and Universal Slope Characteristics

Fatigue testing and related fatigue life assessment are essential parts of the design and validation processes of vehicle components and systems. Fatigue bench test is one of the most important testing methods for durability and reliability assessment, and its primary function is to construct design curves based on a certain amount of repeated tests, with which recommendations on product design can be advised. How to increase the accuracy of predictions from test results, the associated life assessment, and to reduce the cost through reducing test sample size is an active and continuous effort. In this paper the current engineering practices on constructing design curves for fatigue test data are reviewed first. Subsequently, two new developments are reported: (1) Bayesian statistics based design curve construction method with the aim at reducing testing cost and time, (2) a design curve construction method for strain-based double-term power-law fatigue data with the focus on increasing assessment accuracy.