超高韧性水泥基复合材料的波传播试验研究

Experimental study on stress wave propagation in ultra high toughness cementitious composites

为了研究超高韧性水泥基复合材料(UHTCC)中应力波的传播特性,采用Hopkinson杆加载UHTCC试件,测得UHTCC在0.2、0.3、0.4、0.5 MPa冲击气压下的应力波信号.通过对比入射杆波形,验证相同加载条件下加载波形的一致性.分别采用两点法和峰值法计算每种冲击气压下UHTCC中应力波的波速,结果显示,两点法适用性较广,计算结果较稳定,利用峰值法测波速则需要入射杆和试件波阻抗相近.计算结果显示,UHTCC中应力波波速、衰减系数随冲击气压均无明显变化,平均波速为3.060 km/s,平均衰减系数为2.777 m^−1.可以利用朱-王-唐本构模型参数表达材料中应力波的波速和衰减,也可以利用实测的波速和衰减系数将UHTCC的朱-王-唐冲击本构模型表示为只含单个准静态参数的方程,从而提供通过试验直接确定UHTCC动态本构的方法.

The ultra high toughness cementitious composite(UHTCC)specimens were loaded with Hopkinson bar,and the stress wave signals in UHTCC under impact pressure of 0.2,0.3,0.4,0.5 MPa were measured,in order to study the propagation characteristics of stress waves in UHTCC.The consistency of the loading waveforms under the same loading conditions was verified by comparing the incident bar waveforms.The stress wave speeds in UHTCC under different impact pressures were calculated by two methods,i.e.two point method and peak value method.Results show that the two point method is more applicable and the calculation results are relatively stable.However,the peak value method requires similar wave impedance of the incident bar and the specimen.Calculation results show that the stress wave speed and attenuation coefficient in UHTCC do not change significantly with the impact pressure,and the average wave speed is 3.060 km/s,as well as the average attenuation coefficient is 2.775 m^−1.The wave speed and attenuation of stress waves in material can be expressed by parameters of Zhu-Wang-Tang constitutive model.Correspondingly,the measured wave speed and attenuation coefficient can represent the Zhu-Wang-Tang impact constitutive model of UHTCC as an equation with a single quasi-static parameter.An experimental method to determine the dynamic constitutive of UHTCC directly is provided.