Magnetostrictive twist guided wave sensor for rail bottom defect detection

[0021] The present invention will be further described below in conjunction with the drawings.

[0022] Such as figure 1 As shown, the present invention includes a bottom support plate 4, a left splint 2 and a right splint 6 with the same structure. The left splint 2 and the right splint 6 are respectively hinged on both sides of the bottom support plate 4, and the bottom support plate 4 is mounted on On the lower surface of the rail bottom of the rail 1, the left side splint 2 and the right side splint 6 are respectively installed on both sides of the rail 1 rail waist, the left side splint 2, the right side splint 6 are attached to the upper surface of the rail 1 rail waist and the rail bottom ;Such as figure 2 As shown, the left side splint 2, the right side splint 6 and the bottom support plate 4 all include a first support shell 7 and a second support shell 11. The first support shell 7 and the second support shell 11 are installed between Four comb-shaped arrays 16 uniformly spaced along the rail 1 direction; each comb-shaped array includes a magnetostrictive material layer 9, an excitation coil layer 10 and a permanent magnet layer 8. The excitation coil layer 10 is wrapped in the magnetostrictive material layer 9 The outer periphery is covered with a permanent magnet layer 8, the excitation coil layer 10 is wrapped around the periphery of the magnetostrictive material layer 9 and located on the inside, the permanent magnet layer 8 is located on the outside, and the second supporting shell 11 is located as an elastic wave transmission layer in the comb array 16 and Between the rails of the rail 1, the four excitation coil layers 10 in the left splint 2 and the corresponding excitation coil layers 10 in the bottom support plate 4 are connected by a soft cable, and the four excitation coil layers in the right splint 6 The coil layer 10 and the corresponding excitation coil layer 10 in the bottom support plate 4 are connected by a flexible cable 5.

[0023] The permanent magnet layer 10 is formed by arranging tile-shaped permanent magnets 13 uniformly spaced along the curve of the rail waist and bottom of the rail 1. The permanent magnet polarities 14 of the tile-shaped permanent magnets are arranged alternately and oppositely.

[0024] The bottom support board 4 is provided with a cable connection port 3, and the wires in the four excitation coil layers in the bottom support board 4 are drawn out and connected to the cable connection port 3.

[0025] The left side splint 2 and the right side splint 6 are respectively elastically hinged on both sides of the bottom support plate 4.

[0026] The distance between the two adjacent comb arrays 16 (that is, the comb array interval 17) is 1/4 of the guided wave wavelength excited by the sensor.

[0027] The contour of the second supporting shell 11 is the same as the surface curve on the rail waist and the rail bottom, and the material of the second supporting shell 11 is alumina.

[0028] The material of the magnetostrictive material layer 9 is FeCo alloy, FeGa alloy, Terfenol-D material or Ni.

[0029] Such as figure 1 As shown, the present invention is an open-close structure. When opened, the sensor can be installed from below the rail, and the left and right splints can be pushed to the middle to make the sensor closely adhere to and fix the bottom of the rail.

[0030] Such as image 3 As shown, the structure and arrangement of the comb-shaped array 16 in the bottom support plate 4 is the same as that of the left splint 2 and the right splint 6. The signal cable is connected to the cable interface 3, and the excitation coil layers 10 in the four comb-shaped arrays 16 The five-period sinusoidal current signals modulated by the Hanning window are respectively passed through, and the phases of the four sinusoidal signals are sequentially different by 90°; the magnetic field direction 12 and the current direction 15 in the magnetostrictive material layer are as Figure 4 As shown, the excitation coil current in the comb-shaped array generates an excitation magnetic field in the magnetostrictive material layer enclosed therein, the direction is along the rail extension direction, that is, perpendicular to the paper surface inward; the permanent magnet layer surrounded by the magnetostrictive material layer It is arranged by tile-shaped permanent magnets, and the N pole and S pole are placed in the direction in the figure. The excitation coil in the excitation coil layer 10 is energized in the magnetostrictive material layer to generate an alternating excitation magnetic field along the extension direction of the rail. The permanent magnet layer generates a bias magnetic field perpendicular to the excitation magnetic field and passes through the magnetostrictive material layer. The magnetic fields in the two directions are combined into a torsional magnetic field. The magnetostrictive material layer generates a torsional conduction based on the magnetostrictive effect under the action of the torsional magnetic field. The wave propagates along the bottom of the rail; such as Figure 5 As shown, the comb-shaped array interval 17 of the four comb-shaped arrays 16 in the first support shell 7 is 1/4 of the excited guided wave wavelength.

[0031] The implementation process of the present invention is as follows:

[0032] The left side splint 2 and the right side splint 6 of the magnetostrictive torsion guided wave sensor of the present invention are opened to both sides, so that the upper surface of the bottom support plate 4 is attached to the position to be installed on the bottom surface of the rail, and released The left splint 2 and the right splint 6 can make the sensor hug the bottom of the rail due to the spring action at the hinge. The signal cable is connected to the cable interface 3, and the excitation coil layers 10 in the four comb-shaped arrays 16 respectively pass through a 5-period sinusoidal current signal modulated by the Hanning window. The phases of the four sinusoidal signals are different by 90 degrees, and the four The position of the comb array 16 in the first support shell 7 is 1/4 wavelength. The four columns of guided waves excited in this way are focused in the bottom of the rail to produce a single mode due to the coherent effect of the guided waves. The twisted guided wave propagates forward along the bottom of the rail. During the propagation process of the guided wave at the bottom of the track, it will reflect when encountering defects, and the reflected echo will propagate in the opposite direction and be received by the sensor. The echo causes the magnetostrictive material layer in the sensor to deform. Due to the existence of the inverse magnetostrictive effect, the mechanical deformation will cause the change of the magnetic field. The changed magnetic field generates an electric field, which is reflected in the sensor as the voltage change in the excitation coil layer. Accurately calculate the transmission time of the excitation signal and the reception time of the defect echo. The time difference between them is multiplied by the wave speed of the torsion mode guided wave of this frequency to determine the precise position of the defect in the rail. The voltage of the echo signal reflects the defect size.

[0033] The foregoing implementations are only used to explain the present invention. Specific implementations of the present invention include but are not limited to those mentioned above. Any modification of the present invention within the scope of the claims of the present invention belongs to the protection scope of the present invention.