Random Acoustic Fatigue Life Analysis Of Typical Fuselage Stucture

The aircraft fuselage is mainly used to load passengers,equipment and payloads.The fuselage is used as an essential part of the aircraft structure,which connects the various components of the aircraft together through various joints.As an essential part of the aircraft structure,the fatigue life of the fuselage under random acoustic loads is receiving more and more attention.In this thesis,a numerical simulation method is used to analyze a box segment of the fuselage structure which is regarded as the research object,and the acoustic fatigue life of the certain aircraft fuselage box segment is studied.In this thesis,the simulation analysis model of the certain aircraft fuselage box segment is established.Based on the modal analysis theory,the Abaqus/Standard implicit solver is used to solve the modal information of the typical fuselage box segment,including the natural frequency and mode of the structure.Combined with the basic theory of acoustics and random vibration theory,the indirect boundary element method is used to calculate the acoustic-vibration coupling of the structure in the Acoustics module of the dynamic analysis software LMS Virtual.Lab.The Miner's rule in the linear fatigue cumulative damage theory is used as the fatigue life estimation rule,and the average stress is corrected by the Goodman linear formula.Combined with the S-N curve of the material,the fatigue life of the structure is finally obtained in the Durability module of LMS Virtual.Lab.The area with serious damage is the skin and the peripheral skin on the fuselage box segment,and the damage at the bottom is the smallest.Finally,the effects of sound pressure level,structure type and structural damping on acoustic fatigue life are studied from the many factors affecting the acoustic fatigue life of the structure.The analysis results show that the sound pressure level after attenuation used as the acoustic load,the structure type of the tank and increasing the structural damping make the structural acoustic fatigue life increase,which provides a reference for the structural anti-acoustic fatigue design.