超声波在粘弹性混凝土介质中传播机理研究

混凝土是一种含有骨料、水泥浆、钢筋、波纹管包裹的预应力孔道及空洞、孔隙的多相非均匀复合材料,作为一种粘弹性介质,超声在混凝土中传播机理比较复杂,常规的弹性声波方程不能确切地模拟超声传播方式。这里从粘弹性介质材料性质出发,推导了基于Kelvin粘弹性介质模型的高阶有限差分方程,通过建立几种粘弹性混凝土介质数值模型,模拟了超声波在混凝土中的传播过程,分析了含空洞、裂隙等不同缺陷的混凝土介质中超声波的波形特性,讨论了缺陷部位波形的变化规律,探讨了空洞、裂隙等不同缺陷对超声传播机理的影响以及能量分布的差异,为准确判断识别混凝土内部不同结构的缺陷提供科学借鉴。

The study on propagation of ultrasonic in concrete viscoelastic medium

As a kind of viscoelastic medium,the propagation mechanism of ultrasonic in concrete is complex. Conventional elastic acoustic wave equation can not exactly simulate the ultrasonic propagation mode. Based on the properties of viscoelastic materials,the higher-order finite difference equations based on the Kelvin viscoelastic medium model are deduced. Through the establishment of several numerical models of viscoelastic concrete,the propagation of ultrasonic wave in concrete is simulated. The wave characteristics of ultrasonic waves in concrete media with different defects such as voids and cracks were analyzed and the variation of the waveform of the defect was discussed. The effects of different defects such as cavities and fissures on the mechanism of ultrasonic propagation and the differences of energy distribution were discussed. It provides a scientific basis for accurately judging and identifying the defects of different structures in concrete.