【作者】 孙涛；

【导师】 张春巍； 李冀龙；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2011， 硕士

【摘要】 低屈服点钢具有比普通结构用钢更低的屈服强度,更好的塑性,其冲击韧性也良好,本文尝试探讨低屈服点钢在通过塑性变形来耗散爆炸冲击能量方面所可能具有的优势。对国产225MPa低屈服点钢AQ225进行了准静态与SHPB实验研究,拟合得到相应的Johnson-Cook动态本构模型,并通过对SHPB实验数值模拟验证模型参数的准确性,进而对低屈服点钢制方板结构在爆炸冲击荷载作用下的动态响应进行数值模拟研究。主要内容包括以下几个方面:首先,运用Instron材料试验机和分离式霍普金森压杆(SHPB)实验装置对AQ225进行了准静态和动态实验研究。得到AQ225在准静态应变率和高应变率下的应力应变曲线,由实验数据拟合得到JC动态模型参数,并估算SHPB实验过程中绝热温升效应的影响程度。其次,对SHPB实验进行数值模拟研究。确定了较为合理的单元尺寸和接触刚度罚因子,将仿真得到的波形与实验波形进行对比,验证低屈服点钢JC模型的准确性。最后,对低屈服点钢用于抗爆吸能方面的可行性进行数值模拟研究。分别利用简化冲击荷载方法和流固耦合方法,得到不同钢材(HQ600、Q345和AQ225)制方板结构的动态力学响应,并运用能量方法对结果进行了分析比较,确定了低屈服点钢通过塑性变形吸收爆炸冲击能量所具有的优势。更多还原

【Abstract】 Based on Low Yield Point (LYP) steel’s lower yield strength, better plastic performance and better impact toughness than general structural steel, its advantages of dissipating explosion or impact energy through the plastic deformation were explored in this paper. Domestic 225MPa class LYP steels named AQ225 were tested by quasi-static and split Hopkinson pressure bar (SHPB) experiment. Corresponding Johnson-Cook dynamic constitutive model was obtained by fitting experimental data, and the accuracy of the model parameters was verified through numerical simulation of SHPB experiment. Then dynamic response of LYP steel square plate structure subjected to explosive loads was studied by numerical simulation.The main contents of this dissertation include the following aspects: First, specimens made of AQ225 were tested using Instron material testing machine and SHPB apparatus, and corresponding stress-strain curves under quasi-static strain rate and high strain rate were obtained. Based on the experimental data, JC model parameters were fitted. Then influence degree of adiabatic temperature rise effect in the SHPB experiment process was estimated.Second, numerical simulation of SHPB experiment was carried out. Reasonable element size and contact stiffness penalty factor were determined, and then JC model parameters were verified to be accurate and reliable by comparing with the waveforms obtained from simulation and experiments.Finally, the prospect of AQ225 used for absorbing explosion or impact energy was studied by a series of numerical simulations. Using simplified impact load method and fluid-structure coupling method respectively, the dynamic mechanical responses of square plates subjected to same blast loads were analyzed. Then the results of plates made of different steel (HQ600, Q345 and AQ225) were analyzed and compared through energy analysis method. At last, LYP steel’s advantages of absorbing explosion or impact energy through the plastic deformation were confirmed.更多还原