含孔隙混凝土的动态压缩数值模拟

Numerical simulation of dynamic compression of concrete with pores

为研究孔隙大小、数量及位置分布对混凝土动态压缩力学性能的影响,文章通过ANSYS参数化设计语言编程创建含随机分布球形孔隙的混凝土有限元模型,利用ANSYS/LS-DYNA有限元软件对孔隙混凝土的分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)试验进行数值模拟;提出一个预测不同孔隙率、不同孔隙数目混凝土在不同应变率下动态抗压强度的经验方程。研究结果表明:对于含单个球形孔隙的混凝土,孔隙尺寸越大,抗压强度越小,但内部孔隙位置发生变化时,抗压强度基本没有变化;相同孔隙率下,孔隙数目增加,混凝土抗压强度呈指数衰减,并最终趋于一个稳定值;孔隙率越低,混凝土抗压强度趋于稳定值时的孔隙数目越少,孔隙率为1.11%时,多孔隙混凝土的抗压强度与单个孔隙时无显著差别,可按单孔隙计算;提出的经验方程预测结果与仿真试验结果有很好的一致性。

In order to study the influence of pore size,quantity and location distribution on dynamic compressive mechanical properties of concrete,the finite element model of concrete with randomly distributed spherical pores was established by ANSYS parametric design language,and the split Hopkinson pressure bar(SHPB)test of concrete with pores was numerically simulated by ANSYS/LS-DYNA.An empirical equation for predicting dynamic compressive strength of concrete with different porosity and number of pores under different strain rates was proposed.The results show that the compressive strength of concrete with single spherical pore decreases with the increase of pore size.However,when the positions of internal pores change,the compressive strength is basically unchanged.With the same porosity,the compressive strength of concrete decreases exponentially with the increase of the number of pores,and finally tends to a stable value.The lower the porosity,the smaller the number of pores when the compressive strength of concrete tends to a stable value.When the porosity is 1.11%,there is no significant difference between the compressive strength of porous concrete and that of single pore,which can be calculated according to single pore.The prediction results of the empirical equation are in good agreement with the simulation results.