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为了研究导波在半埋地护栏立柱结构中的传播特性,并从中选择适合检测立柱长度的导波模态和频率,在弹性动力学理论基础上,分别对立柱未埋地部分和埋地部分的导波群速度、衰减和频散进行计算分析。结果表明:80~130 kHz的纵向模态L(0,2)在未埋地部分和埋地部分中的群速度相同,衰减程度最小,传播距离可以满足检测要求,可以用来对半埋地立柱埋深进行检测;试验验证结果和理论分析相吻合,所获得的端面回波信号清晰,有较高的信噪比,测量的最大相对误差小于0.8%,可以满足工程实际要求。
In order to study the propagation characteristics of the guided wave in the semi-buried fence column structure and select the guided mode and frequency suitable for testing the length of the column, based on the theory of elastic dynamics, The guided wave group velocity, attenuation and dispersion are calculated and analyzed. The results show that the group velocities of the longitudinal mode L (0,2) at 80 ~ 130 kHz are the same in the unburied part and the buried part, the attenuation is the smallest and the propagation distance can meet the detection requirements. The depth of the column is tested. The experimental verification results are in good agreement with the theoretical analysis. The obtained end surface echo signals are clear and have high signal-to-noise ratio. The maximum relative error of the measurement is less than 0.8%, which can meet the actual engineering requirements.