摘要:
针对典型民用飞机机身下部结构加装辅助燃油箱，分别进行1.53m/s，2.78m/s以及5.96m/s的垂直坠撞试验，研究了不同速度下加装辅助燃油箱对机身下部结构触地冲击响应、结构变形和破坏模式的影响。通过仿真与试验结果的相关性分析，验证了加装辅助燃油箱的机身下部结构有限元模型的有效性，并通过仿真结果分析了垂直坠撞过程中的结构吸能形式。结果表明：在1.53m/s轻微坠撞工况下，机身下部结构以弹性变形为主，仅有轻微的塑性变形；在2.78m/s冲击下，机身框、蒙皮及货舱地板T形支撑件以弯曲变形为主，整体结构压缩程度较小，货舱地板T形支撑件与左侧地板滑轨连接失效后翘起，未触及油箱；在5.96m/s冲击下，机身下部结构压缩变形严重，左侧斜支撑受压发生断裂，辅助燃油箱下沉至货舱地板；仿真分析可以有效的模拟不同垂直冲击速度下坠撞过程中的结构变形和破坏情况，坠撞触地撞击力与典型位置加速度趋势与试验吻合较好，分析结果表明对于加装辅助燃油箱的机身下部结构坠撞，机身框是主要的变形吸能部件，蒙皮和辅助燃油箱是次要参与变形吸能的结构；随着辅助燃油箱装油质量增加，仿真得到的辅助燃油箱及机身下部结构组件吸收冲击能量增加，即破坏程度更严重。本文的研究成果可为民用飞机加装辅助燃油箱结构的抗坠撞设计、分析及验证提供支持。
Abstract:
A study was conducted to investigate the crash impact response of the lower fuselage structure of a typical civil aircraft with an auxiliary fuel tank installed. The results of vertical crash tests under the impact of 1.53 m/s, 2.78 m/s, and 5.96 m/s were obtained, including the influence of installing auxiliary fuel tanks on the impact response data, structural deformation and damage of the lower fuselage structure. The validity of the finite element model of the fuselage structure with an auxiliary fuel tank installed was verified through a correlation analysis between the simulation results and the test results. The impact energy absorption form at the vertical crash process was analyzed through simulation results.The results show that the structure mainly deforms elastically with only slight plastic deformation under the 1.53 m/s impact condition. Under the impact 2.78 m/s condition, the fuselage frames, skin, and T-shaped support components of the cargo floor are mainly deformed by bending, and the total structures were slightly compressed. The T-shaped support components connected to the left cargo floor slide rails extended upward and didn’t touch the fuel tank. Under the 5.96 m/s impact condition, the lower fuselage structures were seriously compressed and the left diagonal brace fractured under pressure. The auxiliary fuel tank sank down to the cargo floor. The simulation analysis can effectively simulate the deformation and damage of the structure in the vertical crash process under different impact velocities. The impact force on the ground and the trend of acceleration at typical locations obtained by analysis are in good agreement with the test results. The analysis results show that the fuselage frame is the main deformation and energy absorption component in the crash of the lower fuselage structure with auxiliary fuel tanks installed. The skin and auxiliary fuel tank are the secondary structures that participate in deformation and energy absorption. As the auxiliary fuel tank is filled with more fuel, the simulation results show that the energy absorption capacity of the auxiliary fuel tank and the lower fuselage structure components increases, i.e., the degree of damage becomes more serious. The research results can provide support for the anti-crash design, analysis, and verification of the fuselage structure of civil aircraft with auxiliary fuel tanks installed.
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