舰载飞机起落架突伸时外筒应力陡增分析

Analysis of stress steep increase in outer cylinder during sudden extension of an carrier-based aircraft landing gear

分析了某舰载飞机斜板滑跃起飞试飞时,前起落架在机轮出斜板而卸载后,缓冲器外筒轴向应力未减小反而陡增的现象。在介绍缓冲器结构、工作原理和受力数学模型的基础上,建立了缓冲器外筒轴向应力的计算模型;结合对实测数据的分析,揭示了缓冲器外筒应力陡增的原因。结果表明:外筒轴向应力与缓冲器的行程和活塞运动速度相关,起落架出斜板后外筒应力陡增的主要原因是起落架突伸时,活塞杆高速伸出引起油液阻尼力大幅增加及高速伸出的起落架的下部质量在反阻活门关闭瞬间对外筒底面的撞击。

Structural stress and load measurement flight test is a basic task to ensure the safety of aircraft flight test,demonstration and the improvement of aircraft design.A phenomenon that the axial stress of the buffer outer cylinder does not decrease but increase sharply after the ski-jump ramp exit is described.Based on the introduction of the structure,working principle and force mathematical model of the buffer,the mathematical expression of the axial stress of the buffer outer cylinder is established.Combined with the analysis of the flight data,the reason for the buffer outer cylinder stress steep increase is revealed.Results obtained show that the axial stress of the outer cylinder is related to the stroke of the buffer and the piston motion speed,the high-speed extension of the piston rod causes a great increase in the oil damping force,and impact of the lower mass of the high-speed extension landing gear on the outer cylinder bottom at the moment of the reverse retardation valve closing is the main reasons for the stress steep increase in the outer cylinder during the landing gear sudden extension after the ski-jump ramp exit.