钢花管中低频纵向导波模态传播特性的数值仿真

Steel floral pipe is one of the key load-carrying components of advanced pipe supporting structures. Propagation characteristics and inspection potential of low frequency longitudinal guided wave modes in steel floral pipes were investigated by using finite element analysis. Finite element model of low frequency longitudinal guided wave mode propagation in steel floral pipe distributing small grouting holes was established. L(0, 2) mode at 30 kHz was optimized for the inspection of steel floral pipes. The change of hole number had no significant effect on the amplitudes of the first and second end-reflected echoes of L(0, 2) mode at 30 kHz when the diameter of small grouting hole was kept to be 10 mm. However, group velocity of this mode linearly decreases with the increase of the hole and to be 0.76 m/s with the increase of every hole. The effect of hole diameter on propagation velocity of longitudinal guided waves mode was also simulated when the hole number kept constant. It was shown that the change of hole diameter had limited effect on the energy propagation of this mode. Number and diameter of holes less affect to the amplitude of end-reflected echo. It was shown that low frequency longitudinal guided waves had potentials to inspect long range steel floral pipes nondestructively. However, with the increase of the hole diameter, group velocity of this mode will decrease gradually in varying degree. These simulation results provide a basic foundation for nondestructive inspection of steel floral pipes by using low frequency longitudinal guided wave modes.