RESEARCH ON DETAIL FATIGUE RATING METHOD FOR METAL STRUCTURES OF HIGH-SPEED AIRCRAFT CONSIDERING TEMPERATURE EFFECTS

The Detail Fatigue Rating (DFR) test method is applicable to the life verification of new aircraft types and the improvement and life assessment of in-service aircraft types. It is a key technical means for durability evaluation of critical aircraft structures. Existing DFR methods for civil and military aircraft are now well-established and sufficient to ensure the assessment of fatigue life in complex environments. In contrast, research on DFR methods for high-speed aircraft is still immature, and constructing a complete DFR test method for high-speed aircraft is a core task for the advancement of this field. This study systematically investigated the influence of temperature factors on the DFR method, and based on the basic assumptions of this method, derived the DFR expression that incorporates temperature influence coefficient correction. Fatigue tests on various titanium alloy materials at high and room temperature environments were designed and conducted, in order to verify the accuracy of the expressions. The experimental results show that the relative error between the formula-predicted values and the experimental results is less than 10%, confirming the validity of the proposed temperature modification model. This research directly addresses the core issues of insufficient consideration of temperature factors in current DFR methods and the lack of fatigue performance data for advanced materials. A novel DFR framework applicable to high temperature conditions is established, providing theoretical and technical support for the design of next-generation aircraft.