不同损伤模型下超高性能混凝土SHPB试验数值模拟对比

Comparison on Numerical Simulation of SHPB Test for Ultra-high Performance Concrete under Different Damage Models

目的探讨不同损伤模型下超高性能混凝土SHPB试验数值模拟效果的差异性。方法应用大型有限元程序LS-DYNA,结合UHPC材料特性,明确了KCC、HJC和CSC模型中关键参数的取值,建立了超高性能混凝土SHPB试验数值仿真模型。在此基础上,开展不同损伤模型下UHPC试件波形、动态应力-应变曲线、弹性模量和动力增大系数(DIF)值模拟结果与实测结果的对比,探讨不同损伤模型下超高性能混凝土SHPB试验动态破坏进程。结果CSC模型在低速冲击下能更好地模拟UHPC材料的实测波形和动态应力-应变曲线,而在中高应变率下KCC模型和HJC模型得到的计算波形以及动态应力-应变曲线与实测值吻合度更好;低应变率下三种损伤模型得到的DIF值相差不大,但随着应变率提高,CSC模型在一定程度上将低估UHPC材料的动力特性;UHPC试件破碎程度随应变率的增加而增大,相对于CSC模型在冲击破坏时表现出的核心存留现象,KCC模型和HJC模型分别表现出明显的整体塌陷和边缘塌陷现象。结论对于UHPC材料,CSC模型适用于低速冲击下SHPC试验数值模拟,而KCC模型和HJC模型适用于中高应变率下数值模拟。

To investigate the difference of numerical simulation effect of SHPB test on ultra high performance concrete under different damage models.Using LS-DYNA,a large finite element program,combined with UHPC material characteristics,the values of key parameters in KCC,HJC and CSC models were defined,and the numerical simulation model of SHPB test of ultra-high performance concrete was established.On this basis,the simulation results of UHPC specimen waveform,dynamic stress-strain curve,elastic modulus and dynamic increase coefficient(DIF)values under different damage models were compared with the measured results,and the dynamic failure process of ultrahigh performance concrete under SHPB test under different damage models was discussed.The CSC model can better simulate the measured waveforms and dynamic stress-strain curves of UHPC material at low speed impact,while the calculated waveforms and dynamic stress-strain curves obtained from KCC model and HJC model have better agreement with the measured values at medium and high strain rates.At low strain rate,the DIF values obtained by the three damage models have little difference,but with the increase of strain rate,the CSC model will underestimate the dynamic characteristics of UHPC material to a certain extent.The fracture degree of UHPC specimen increases with the increase of strain rate.Compared with the core retention phenomenon of CSC model during impact failure,KCC model and HJC model show obvious global collapse and edge collapse,respectively.For UHPC materials,CSC model is suitable for SHPC test numerical simulation under low speed impact,while KCC model and HJC model are suitable for numerical simulation under medium and high strain rate.