大型运输类飞机典型机身框段坠撞特性分析

Crashworthiness characteristics analysis of typical fuselage section of large transport aircraft

为了研究大型运输类飞机坠撞特性及失效模式,发展机身框段结构有限元建模及坠撞仿真技术,首先设计加工三框两段全尺寸机身框段试验件(含2套三联座椅和4个FAA混Ⅲ假人);其次通过开展坠撞试验获得其坠撞变形及响应特性;最后建立经试验验证的机身框段有限元模型,并进一步评估其撞击不同地面(混凝土地面和软土地面)时的响应特性。结果表明,在6.02 m/s坠撞速度下,客舱地板上部区域基本保持完整,客舱地板下部区域发生了较大变形与破坏,产生3处塑性铰;货舱地板横梁一侧在其与机身框连接处发生断裂,导致同侧的客舱地板峰值加速度明显大于另一侧,最大峰值加速度和撞击力分别为427.7 m/s^(2)和290.8 kN。有限元模型能够准确模拟客舱地板下部的3处塑性铰、货舱地板横梁与机身框连接处的失效情况等,且在速度、加速度等方面与试验结果吻合较好,仿真结果表明机身框是主要的吸能部件,占总吸能量的40.7%;当机身框段撞击不同地面时,由于软土地面发生变形并吸收了部分冲击能量,导致机身变形模式发生改变,并降低了传递给乘员的峰值加速度。

To study the crashworthiness characteristics and failure mode of large transport aircraft and develop the finite element modeling and crashworthiness simulation technology of fuselage structures,a three-frame and two-span full-scale fuselage section with two sets of triple seats installed and four FAA Hybrid III Anthropomorphic Test Devices(ATD)placed is firstly designed and manufactured;the crash deformation and response characteristics are then obtained by carrying out a drop test of the typical fuselage section;Finally,a finite element model of fuselage section is established and verified by the drop test results,and the crashworthiness characteristics are evaluated when hitting different grounds(concrete ground and soft grounds).The results show that at the vertical impact velocity of 6.02 m/s,the upper area of the cabin floor remains basically intact,and the sub-cabin structures are significantly deformed and damaged,resulting in three plastic hinges;the cargo floor beam breaks on one side where it joins the fuselage frame,resulting in a significantly faster peak acceleration of the cabin floor on the same side than on the other side,and the maximum acceleration peak value and impact force are 427.7 m/s^(2) and 290.8 kN,respectively.The finite element model can accurately simulate the three plastic hinges and the failure of the connection between the cargo floor beam and the fuselage frame,and it is in good agreement with the test results in terms of impact velocity and acceleration.The fuselage frame is the main energy-absorbing component,accounting for 40.7%of the total absorbed energy;when hitting different grounds,the partial impact energy is absorbed by the soft ground,resulting in slightly different failure modes of the fuselage section and a reduction in the peak acceleration transmitted to the occupants.