基于导波技术的螺柱轴力无损检测

Guided wave nondestructive testing of axial stress in the stud

根据弹性动力学理论，采用纵向导波与弯曲导波相结合的方法对螺柱所受轴向应力进行无损检测。计算了M22螺柱中纵向导波和弯曲导波的群速度频散曲线。根据频散曲线，确定了采用导波对螺柱轴向应力进行无损检测的最优检测信号频率范围（50～80kHz），此频率范围的纵向导波与弯曲导波模态单一，并且频散性较低。分别计算了不同轴向应力σ作用下，多种频率的纵向导波和和弯曲导波在螺柱中传播的群速度值c＂WL和c＂WF。结果表明,随着轴向应力的增大，同频率纵向导波和弯曲导波的群速度皆呈线性递减趋势。利用纵向导波和弯曲导波群速度与轴向应力的线性关系及纵向导波和弯曲导波在轴向应力作用螺柱端面的反射时间l＂L和l＂F，可以迅速确定螺柱所受轴向应力值。

Longitudinal guided wave and flexural guided wave are used to nondestructively test axial stress in the stud. Based on the theory of elastodynamics, the longitudinal guided wave and flexural guided wave group velocity dispersion curves for M22 stud were calculated. And the optimum frequencies of excitation wave for testing axial stress were obtained, which are ranging from 50 kHz to 80kHz. In this frequency domain, only two guided wave modes exist. L（0, 1） and F（1,1） and the dispersion properties for those two mode are weak. The propagation velocities of longitudinal guided wave and flexural guided wave with different frequencies in the stud under axial stress o were also calculated. The results show that both longitudinal and flexural guided wave group velocities decrease linearly with the increasing of axial stress in the stud. By testing the time that longtitudinal and flexural guided wave spend propagating in the stud which is under axial stress, the value of axial stress can be determined easily.