铝蜂窝结构的冲击动力学性能的试验及数值研究

EXPERIMENTAL AND NUMERICAL STUDIES ON ALUMINUM HONEYCOMB STRUCTURE WITH VARIOUS CELL SPECIFICATIONS UNDER IMPACT LOADING

通过分析蜂窝胞元中取出的Y型单元,推导了正六边形蜂窝胞元的相对密度计算公式,并分析了蜂窝的典型动态压溃过程;通过自制刀具切割蜂窝板得到了外径为Φ100的三种规格(0.06 mm(胞元壁厚t)×4mm(胞元边长l)×60mm(试件高h)、0.06mm(t)×6mm(l)×30mm(h)和0.06mm(t)×10mm(l)×50mm(h))的蜂窝试件,并在标准冲击试验机上得到了它们在5m/s名义初始压溃速度下的应力-应变曲线;在保证与试验条件相同的前提下,简化蜂窝单元为Y型单元,辅以适当的边界条件,通过数值方法研究了此三种蜂窝试件的动态压溃过程,并将得到的应力-应变曲线与试验得到的应力-应变曲线作了比较,发现它们吻合的很好;最后将理论得到的弹性坍塌应力和塑性坍塌应力与相应的试验值和仿真值进行了对比,发现塑性坍塌应力的仿真值和试验值比较接近,而理论值则小于它们。最后结合蜂窝片标准冲击试验结果设计出可用于着陆缓冲装置着陆缓冲的蜂窝减振器,试验结果表明缓冲后加速度的试验值和设计值吻合的较好。

Through analyzing an Y-shaped cross-section structure of honeycomb cell,the formula for calculating relative density of honeycomb with regular hexagon cell shape was derived.The typical dynamic collapse process of honey- comb was illuminated.Three kinds of aluminum alloy (3003) honeycomb specimens for experiment were attained by cut- ting honeycomb plate using the self-made cutting tool.These specimens' size specifications are 0.06mm(cell foil thickness t)×4mm(cell sides length l)×60mm(specimen height h),0.06mm(t)×6mm(l)×30mm(h) and 0.08mm(t)×10mm(l)×50mm(h) respectively.Impact experiment using a drop-hammer apparatus (Instron dynatup 9250HV),in which the initial mean impact velocity is 5m/s and the drop mass is 14.6687kg,and the corresponding quasi-static test were both performed.Then the stain-stress curves of the three kinds of specimens under dynamic and quasi-static states were recorded.Assuring the same load conditions in experiment and simplifying the honeycomb cell as an Y-shaped cross- section column,numerical simulations for these three kinds of honeycomb's compression collapse processes under impact loading were carried out by using FEM code LS-DYNA.Then the strain-stress curves obtained by experiment and numeri- cal simulation were compared.It is shown that the result of the numerical simulation well coincides with that of the experi- ment.The elastic and plastic collapse stress by theory,experiment and simulation were compared and the result shows that the plastic collapse stress of simulation is fairly well-matched with that of the experiment while the theoretical stress is less than others.At last,an aluminum honeycomb buffer which can be used in the Landing Gear's primary/auxiliary legs was designed.And the test result shows that the designed buffered acceleration is in accordance with the test value.