大直径分离式霍普金森压杆试验中的波形整形技术研究

采用直径100 mm分离式霍普金森压杆(SHPB)试验装置，以碳纤维混凝土(CFRC)的SHPB试验为例，就试验过程中的波形整形技术展开研究，内容包括：波形整形器的设计、近似恒应变率的估算、最佳近似恒应变率的确定以及应力均匀性分析。结果表明：厚度为1 mm，直径分别为20 mm、22 mm、25 mm、27 mm、30 mm的H62黄铜波形整形器对入射波形有明显的改善效果，可将入射脉冲上升沿的升时延长1～1.6倍；应变率对于波形整形器的直径很敏感，随着整形器直径的增大，最佳近似恒应变率也在增加，一个几何尺寸的波形整形器只能对应于一个最佳近似恒应变率．且与整形器的直径之间满足线性函数关系；应力不均匀系数能够有效地描述混凝土材料SHPB试验的应力均匀性。

Pulse Shaping Techniques for Large-diameter Split Hopkinson Pressure Bar Test

Carbon fiber reinforced concrete (CFRC) specimens were tested by 100 mm diameter split Hopkinson pressure bar (SHPB) apparatus. An improved method for obtaining dynamic stress equilib?rium and nearly constant strain rate loading was proposed, containing pulse shaper design, nearly con?stant strain rate estimation, the optimum average strain rate determination and dynamic stress equilib?rium analysis. The experimented results obtained from pulse shaped SHPB tests with CFRC specimens show that H62 brass pulse shapers of ?20 mm x I mm, ?22 mm x I mm, ?25 mm x I mm,?27 mm x I mm and ?30 mm X I mm can increase rise time of incident pulse by up to 100% ?160% ; one pulse shaper of a certain diameter can just offer one optimum nearly constant strain rate, and the relationship between them is approximately linear; dynamic stress nonequilibrium coefficient can describe stress equilibrium during SHPB tests effectively.