Energy Absorption Abilities of Members by Dynamic Loading

本研究基于理想塑性材料特性的塑性铰模型，对薄壁圆管和方管在冲击载荷作用下的轴向压缩吸能能力进行了理论分析。由于薄壁圆管的主要能量吸收是通过塑性铰上的弯曲功进行的，因此采用了我们以前研究中测得的动态弯矩与角速度之间的关系，而不是由拉伸试验得到的本构方程。在此基础上，计算了变形和吸收能量的时间历程，与实验结果吻合较好。在方管的情况下，理论上不能确定破碎周期，但在圆形管的情况下，可以确定。此外，考虑了理想塑性弯矩与塑料铰链弯曲角速度之间的动态关系，成功地实现了薄壁圆管的轴向挤压；另一方面，研究了碳纤维增强塑料(CFRP)薄壁圆筒在冲击载荷作用下破碎时的吸能能力。试验在冲击试验机上进行，十字头质量为21.5 kg，速度为8ms-1，温度范围为20~130ﾟC，铺层角度为15和75ﾟ，其尺寸为厚度1.2 mm，内径30 mm，长100 mm。将荷载-时间和位移-时间曲线转换为力和变形关系，体现了材料的吸能能力。试件产生两种不同的破碎模式和一定的恒定载荷水平，保持了较高的能量吸收能力。当温度高于60ﾟC时，样品的吸能能力和破碎方式发生变化。

In the present research, a theoretical mechanism analysis based on plastic hinge models with perfect plastic material properties is suggested in order to estimate the energy absorption abilities of thin-walled circular and square tubes by axial crushing under impact loading. The relationship between dynamic bending moments and angular velocities measured in our previous research is employed instead of the constitutive equations obtained from tensile tests because the main energy absorption in thin-walled tubes occurs by bending work at plastic hinges. On the basis of this procedure, the time histories of the deformation and the absorbed energy can be calculated with good agreement with the experimental results. Crushing periods could not be determined theoretically in the case of square tubes, but were determined in the case of circular tubes. In addition, the axial crushing of thin-welled tubes was carried out successfully taking into account the dynamic relationship between perfect plastic bending moments and bending angular velocities in plastics hinges.On the other hand, the energy-absorption abilities of thin-walled circular cylinders made from carbon-fiber-reinforced plastic (CFRP) during crushing under impact loading. The tests are carried out with an impact testing machine, the crosshead mass of which is 21.5kg, at a velocity of 8ms-1 under the temperature range 20 to 130ﾟC The ply angles of the specimens are 15 and 75ﾟ, their dimension are 1.2mm in thickness, 30mm in inner diameter and 100mm in length. Load-time and displacement-time profiles are converted to the force and deformation relationship, which manifests the energy-adsorption abilities. The specimens produce two different types of crushing mode and definite constant load levels which keep their energy-absorption ability high. The energy-absorption abilities and the crushing modes of the specimens change at temperatures above60ﾟC.