Energy Absorption System of Thin-Walled Members by Dynamic Crushing Due to Impact Loading

本文试图建立一台冲击试验机和一套测试系统，以评估薄壁构件在冲击载荷作用下的吸能能力。质量为18公斤的十字头，在重力和气压的作用下，可以加速到16米/秒，并粉碎各种类型的构件。利用该系统对钢、铝等金属材料和纤维增强塑料（FRP）材料的圆柱形和多边形试件进行了吸能试验，研究了试件形状和材料对吸能性能的影响。结果表明，铝和非金属材料试样的静态和冲击破碎行为差异不大，而钢试样的静态和冲击破碎行为受冲击速度的影响较大。钢试件的动态破碎吸能能力明显高于静态破碎吸能能力。但由于应变率效应、惯性力、缺陷敏感性等因素的影响，静态和动态破碎试验中的破碎行为存在很大差异，钢试件的吸能绝对高于铝试件，而单位质量吸收的能量显示出对铝的优势，因为铝的质量密度是钢的三分之一。然而，从FRP试样的单位质量的能量吸收能力显示甚至比铝更高，它被揭示，FRP将能够作为能量吸收材料的更强大的候选人。

The construction of an impact testing machine and a system for measurement are attempted to estimate the energy absorption abilities of thin-walled members by impact loadings. The cross-head, of which mass is 18kg, can be accelerated up to 16m/s by both gravity and air pressure, and crushes various types of members. This testing system provides precise measurements of loads applied to the members and the crusing distances.By using this system, circular and polygonal cylinder specimens of metallic materials such as steel or aluminium and fiber reinforced plastics (FRP) are tested in order to study the influences of the shape and the material of specimen on the energy absorption abilities. And also some of the results are compared with those from static crushing tests in order to clarigy the strain rate effect.The difference between the static and impact crushing behaviors of aluminium and non-metallic material specimens is found to be not significant, while the results of steel specimens are strongly affected by the impact velocity. The energy absorption ability of steel specimens by dynamic crushing indicates absolutely much higher than that by static crushing. However it is difficult to determine the dynamic to static ratios in energy absorption abilities because the crushing behaviors in static and dynamic crushing tests show a considerable difference each other which may come from the strain rate effect, inertia force, imperfection sensitivity and so on.The absorbed energy by steel specimens is absolutely higher than aluminium specimens, while the absorbed energy by unit mass shows the advantage to aluminium because the mass density of aluminium is one third of steel. However the energy absorption abilities by unit mass from FRP specimens show higher than even aluminium and it is revealed that FRP will be able to be much more powerful candidate as energy absorption materials.