Energy Absorption Abilities of Members by Dynamic Loading

本文提出了一种基于塑性铰模型的理论机理分析方法，以评估薄壁圆管和方管在冲击载荷作用下的轴向破碎吸能能力。由于薄壁管的主要能量吸收是通过塑性铰处的弯曲功产生的，因此本文采用了以往研究中实测的动弯矩与角速度的关系，而不是拉伸试验得到的本构方程。在此基础上，可以计算出变形和吸收能量的时程，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。考虑了塑料铰链中理想塑性弯矩与弯曲角速度之间的动态关系，成功地进行了薄壁管材的轴向破碎。另一方面，研究了碳纤维增强塑料（CFRP）薄壁圆柱在冲击载荷下破碎时的吸能能力。试验采用十字头质量为21.5kg，速度为8ms-1的冲击试验机，温度范围为20 ~ 130 C，试样的厚度为15 75，尺寸为1.2mm，内径为30mm，长度为100mm。载荷-时间和位移-时间曲线转化为力-变形关系，体现了吸附能的能力。试样产生两种不同的破碎模式和确定的恒载水平，保持了较高的吸能能力。当温度高于60℃时，试样的吸能能力和破碎模式发生变化。

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.