Composite vertical fin main box section spar root joint considering damage safety, and design method thereof

Abstract

The invention provides a composite vertical fin main box section spar root connecting area structure considering damage safety, and a design method thereof, and relates to the technical field of aircraft design. The composite vertical fin main box section spar joint structure can improve the damage safety performance of the root of a composite vertical fin main box section spar, improve the load transfer reliability, reduce the part processing and assembling workload, improve the raw material utilization rate and reduce the cost on the premise of not changing the joint structure load transferform. The connecting method considers the damage safety performance of the joint structure on the premise of not changing the load transferring form of the joint structure, and the integrated titanium alloy joint is split into two-piece type back-to-back titanium alloy joints; the vertical fin main box section spar is connected with a rear fuselage through a left pair of two-piece titanium alloyjoints and a right pair of two-piece titanium alloy joints; the two-piece type titanium alloy joints are connected with a spar web to form a double-shear connecting structure, and the reliability of the connecting structure is improved. The connecting area structure is suitable for connection design of the root of the composite vertical fin main box section spar.

Description

【Technical field】 [0001] The invention relates to the technical field of aircraft design, in particular to a composite material vertical tail main box section spar root connection area structure and design method in consideration of damage safety. 【Background technique】 [0002] The aerodynamic load, control load and inertial load on the vertical tail of commercial aircraft are all transmitted to the rear fuselage by the butt joint structure at the root of the main box section of the vertical tail. According to the relevant requirements of CCAR25, the docking structure must be able to bear the limit load without permanent deformation, and must adopt a damage safety design, so that it can still bear the limit load when any single joint or structural element is damaged, and must be used during the entire service life of the aircraft To avoid catastrophic failure due to fatigue, corrosion or accidental damage, maintainability and interchangeability requirements must be met. Th...

AI Technical Summary

Problems solved by technology

However, there are obvious shortcomings. The thickened design of the joint places higher requirements on the laying process and molding process. Once the overall joint is damaged, it is very difficult to replace and repair, and it is not conducive to the guarantee of the damage safety design requirements.

In 2001, in New York, USA, flight AA587 (Airbus A300) was due to damage to one of the integral joints at the root of the vertical tail. After the load was redistributed, the vertical tail completely fell off, resulting in the death of 251 passengers and 9 crew members on board.

[0009] In the existing connection scheme at the root of the rear beam of the vertical tail main box section, from the perspective of damage safety design, once the integral joint 2 is damaged or cracked somewhere, it is likely to lead to the overall failure of the joint under the action of high cycle fatigue load. Therefore, the damage safety performance is not good; the beam web and joint vertical reinforcement are single-shear connection structures, and the reliability of load transmission is poor; Titanium alloy joint 2 connection increases the workload of parts manufacturing and assembly steps, and increases the manufacturing cost and assembly cost

At the same time, for this solution, the size of the titanium alloy integral joint at the root of the back beam is large, the overall joint process is difficult to manufacture, the product scrap rate is high, the required blank size is large, and the material utilization rate is low, which further increases the manufacturing cost.

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