关键词: 超声, 非线性声学, 非线性系数, 水泥

Abstract: A stable, high repeatability acoustic nonlinearity parameter experimental procedures and data process system is deployed to track the damage evolution in cement-based specimens using RAM 5000 of RITEC Inc. Three kinds of cement specimens with different diameters of grain are measured by this system to obtain relative nonlinearity parameters. In order to reduce the influence of third harmonics, highlight the second harmonics, 40 levels of voltages input have been tested by 3 groups of high frequency transducers to observe change of the second and third harmonics combined with pulse-inversion technique usage. Linear correlation coefficients are proposed to evaluate the stability of the system. System stability and repeatability is verified by 86.5 h within 175 times testing using above mentioned system. Consequently relative nonlinearity parameter change and velocity change of cement specimens are acquired during the process of water saturation.

Key words: Cement-based material, Nonlinearity acoustics, Nonlinearity parameter, Ultrasonic