Φ100mm SHPB应力均匀及恒应变率加载试验技术研究  

STUDY ON 100-MM-DIAMETER SHPB TECHNIQUES OF DYNAMIC STRESS EQUILIBRIUM AND NEARLY CONSTANT STRAIN RATE LOADING

作　　者：李为民[1] 许金余[1] 沈刘军[1] 李庆[1] 

机构地区：[1]空军工程大学工程学院机场建筑工程系,西安710038

出　　处：《振动与冲击》2008年第2期129-132,共4页Journal of Vibration and Shock

基　　金：空军工程大学工程学院优秀博士学位论文创新基金(BC07002)

摘　　要：大直径分离式霍普金森压杆（SHPB）试验装置被越来越多地应用于混凝土等脆性材料的高应变率力学性能研究，试件在破坏前，满足应力均匀分布要求，且保持恒应变率加载，是保证SHPB试验有效性及试验结果可靠性的关键。以提高试验结果准确性为研究目标，以C50素混凝土的SHPB试验为例，采用Ф100mmSHPB试验装置，对试验中的应力均匀及恒应变率加载技术进行研究，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检验。结果表明：厚度为1mm，直径分别为20mm、25mm、30mm、35mm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1～2倍，且波形呈半正弦状；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。A large-diameter split Hopkinson pressure bar(SHPB) apparatus is widely used to investigate dynamic mechanical properties of brittle materials subjected to high strain rate loading.It is vital to obtain dynamic stress equilibrium and a nearly constant strain rate over most of the test duration.To ensure the reliability of SHPB tests,H62 brass pulse shapers with different geometries are designed to improve incident waveforms.C50 plain concrete specimens are tested using a 100-mm-diameter SHPB apparatus.An improved method for obtaining dynamic stress equilibrium and nearly constant strain rate loading is proposed,including designing pulse shapers,estimating nearly constant strain rate,determining the optimal average strain rate and verifying dynamic stress equilibrium.Experimental results obtained from pulse shaped SHPB tests with concrete specimens show that H62 brass pulse shapers of Φ20mm×1mm,Φ25mm×1mm,Φ30mm×1mm and Φ35mm×1mm increase the rising time of incident pulse up to 100%~200%,which becomes a half-sine wave.Besides,one pulse shaper of a certain diameter can only offer an optimal nearly constant strain rate,and the relationship between the strain rate and the diameter is approximately linear.

关 键 词：Ф100mm SHPB试验装置 波形整形技术 应力均匀 近似恒应变率加载 

分 类 号：O348[理学—固体力学]