不同相对密度泡沫铝填充对民机适坠性的影响

Effect of different relative density of aluminum foam filling on crashworthiness of civilian aircrafts

摘要

为满足民机适坠性的要求，提出使用泡沫铝作为机身段填充材料的方法，并在此基础上研究了填充不同相对密度泡沫铝的机身结构能量吸收特性和冲击响应特性。首先，通过电子万能试验机和高速动力加载系统对低、中、高 3 种不同相对密度的泡沫铝进行了准静态和中低应变率下（0.001～100 s^–1）的压缩实验。其次，建立不同相对密度的泡沫铝等效有限元模型，通过实验结果验证模型的有效性。最后，将泡沫铝等效模型应用于民机适坠性分析中，研究置入不同相对密度泡沫铝的机身段破坏模式、能量吸收情况和客舱地板处的加速度-时间历程。结果表明：泡沫铝的平台应力、体积比吸能随相对密度的增大而升高，致密应变则相反。增加泡沫铝填充能量吸收结构后，较好地平衡了机身框各部件的吸能比例，且随着相对密度的增大，泡沫铝材料的吸能贡献逐渐提高，客舱地板处的峰值加速度降低，表明高相对密度泡沫铝缓冲吸能性能更强，能够有效改善机身结构的适坠性。

Abstract

In order to satisfy the requirements of civil aircraft crashworthiness，a method of using aluminium foam as fuselage section filling material is proposed，and on this basis the energy absorption characteristics and impact response characteristics of fuselage structures filled with different relative densities of aluminium foam are investigated. Firstly，quasi-static and medium strain rate (0.001～100 s^–1) compression tests are carried out on aluminium foams with low，medium， and high relative densities，using an electronic universal testing machine and high-speed power loading systems. Secondly， an equivalent finite element model for different relative densities of aluminium foam is established and the validity of the model is verified by comparing the results of the model analysis with the experiments. Finally，the aluminium foam equivalent model is applied to the analysis of civil aircraft crashworthiness and the damage pattern，energy absorption， and acceleration time course of the fuselage section in the passenger cabin floor after placing aluminium foam of different relative densities are analyzed. The results show that the platform stress and volume specific energy absorption of the aluminium foam increase with increasing relative density，while the opposite is true for densified strain. The addition of aluminium foam-filled energy-absorbing structures better balances the energy absorption rate of the fuselage frame components than classic frame construction. At the same time，as the relative density increases，the energy absorption of the aluminium foam gradually increases and the peak acceleration of the cabin floor decreases，indicating that high relative density aluminium foam has a stronger cushioning and energy absorption properties than low and middle relative density aluminium foam，and these provide theoretical support for the application of aluminium foam to the crashworthiness design of civil aircraft.

关键词

泡沫铝 / 相对密度 / 应变率 / 吸能 / 民机适坠性

Key words

aluminium foam / relative density / strain rate / energy absorption / crashworthiness of civil aircraft

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