Dynamic load characteristics and performance degradation of CFRP wing-body connection lugs under elevated temperature wet conditions

Abstract

The elevated temperature wet (ETW) conditions have a significant impact on the mechanical properties of the CFRP main load-bearing components in all-carbon fiber aircraft, thereby influencing the aircraft’s service life. This paper utilizes a full-scale CFRP wing-body connection structure to study its static load characteristics under elevated temperature wet conditions and its fatigue performance under flight loads. Under ETW conditions (71°C, 85% RH) for 35 days, the average moisture content reached 0.5707%. Structural stiffness decreased by 49.67% under static load in ETW conditions, with displacement exhibiting a two-stage behavior in both environments. During the full load spectrum test, the stiffness degradation rate under ETW conditions increased by 47.3%. In the constant peak load test, structural stiffness exhibited three stages: initial enhancement-gradual reduction-rapid reduction following local damage. Numerical calculations identified the fillet transition and opening positions as weak points. The fatigue safety factor based on strength criteria significantly decreased under high-temperature and humid conditions, showing an inverse relationship with the load value.