CN114623962B - Bolt transverse load distribution measurement method based on phased array ultrasonic rotary scanning - Google Patents

Abstract

The invention discloses a bolt transverse load distribution measuring method based on phased array ultrasonic rotary scanning, which comprises the following steps: s1, fixing phased array ultrasonic sensors with array elements circumferentially distributed and N array elements on the top of a bolt of a standard sample to be detected; s2, determining the aperture number M of the phased array sensor according to the echo of the bottom surface of the bolt; s3, obtaining a calibration coefficient by using the step loading of the transverse load; s4, traversing excitation by using the aperture M to measure the direction of the maximum transverse load; s5, carrying out transverse load measurement by utilizing the subtraction of the flight time of the symmetrical apertures; s6, sequentially selecting different array elements as centers according to the number sequence to obtain the transverse load distribution in the circumferential direction. The invention can directly eliminate the influence of the axial load on the measurement process without any auxiliary calibration; the test process does not need to carry out any movement and rotation on the sensor, thereby guaranteeing the stability and the test precision of the measurement.

Description

A Measurement Method of Bolt Transverse Load Distribution Based on Phased Array Ultrasonic Rotation Scanning

technical field

The invention relates to the field of ultrasonic stress measurement, in particular to a method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotational scanning.

Background technique

With the continuous application of advanced nuclear power and other major projects and major equipment, the fastener system with bolts as the main connection form bears more complex stress forms, including the combined effect of axial preload and non-uniform transverse shear force . The non-destructive stress measurement technology represented by ultrasonic has been widely used in the measurement of bolt pretension force. For example, the existing method (Application No. 20201094892.0) reports a method for simultaneously measuring axial force and shear force, but this solution requires sensors to be installed on both end faces of the bolt, and in most application scenarios, only one end face of the bolt can be used. At the same time, there is no good solution for the scene where the two load forms are coupled together with random directions and sizes. In the existing method (202111040614.9), in the process of testing the shear load, since the shear load has directionality, the sensor needs to be rotated during the measurement process to measure the shear load in a certain direction. During the rotation, the sensor not only The operation is complicated, and it will also bring coupling errors.

The invention provides an engineering site that is applied to nuclear power and other engineering sites that require high precision measurement, and mainly solves the following problems: (1) solves the interference problem of the bolt axial pretightening force on the measurement during the lateral load measurement process; (2) Solve the problem of cumbersome calibration and measurement process of the maximum load direction due to the randomness of the loading direction of the lateral load.

Contents of the invention

In order to solve the above problems, the present invention provides a method for measuring the transverse load of bolts based on phased array ultrasonic rotation scanning.

The object of the present invention is achieved through the following technical solutions:

A method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotary scanning, characterized in that it comprises the following steps:

Step S1, fix the phased array ultrasonic sensor with the array elements arranged in the circumferential direction and the number of array elements is N on the top of the standard bolt to be tested, and make a number P _i for the array elements, where i=1,2,3, ..., N;

Step S2, determining the aperture number M of the phased array sensor according to the echo of the bottom surface of the bolt;

Step S3, using the lateral load step loading to obtain the calibration coefficient;

Step S4, measuring the direction of the maximum lateral load with aperture M traversal excitation;

Step S5, using time-of-flight subtraction of symmetrical apertures to measure lateral loads;

Step S6 , sequentially selecting different array elements as the center according to the sequence of numbers, to obtain the lateral load distribution in the circumferential direction.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, in step S2, the phased array sensor is sequentially excited with progressive array numbers 1, 2, 3, ... N, and the bottom return of the bolt is observed. When the echo amplitude of the bottom wave reaches the set height of the full screen, stop advancing, and use the corresponding array element number M at this time as the aperture number M of the phased array sensor.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, step S3 performs calibration of the lateral load to obtain the calibration coefficient, specifically: the phased array sensor performs ultrasonic excitation and reception with the aperture number M, The stretching machine applies a transverse load to the bolts in steps of ΔF, records the ultrasonic flight time array and the stretching machine load array, and performs linear fitting to obtain the constant coefficients K1 and K2 of the transverse load.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, step S4 is specifically to perform ergodic excitation of the phased array sensor with the number of apertures as M, and first stimulate the array elements P ₁ to _PM , and then Stimulate array elements P ₂ ～PM ₊₁ until the excitation of the array elements in the entire circle is completed, record the flight time of each ultrasonic wave, find the number P _c of the array element corresponding to the maximum ultrasonic flight time, and record the orientation of the array element as horizontal The loading direction of the load.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, step S5 specifically includes:

Step S5-1. Take the array element P _c as the center, construct the aperture number M with the left and right adjacent array elements of the array element P _c , conduct the sending and receiving measurement of the ultrasonic signal, and record the time-of-flight change caused by the lateral and axial loads as t ₁ ;

Step S5-2. Take the symmetrical array element P _c1 of the array element P _c in the ring array as the center, construct the aperture number M with the adjacent array elements on the left and right sides of P _c1 , conduct the sending and receiving measurement of ultrasonic signals, and record the common values of lateral and axial loads. The resulting time-of-flight change is t ₂ ;

Step S5-3. Subtract the time-of-flight of the symmetrical aperture to eliminate the influence of the axial load, and record the time-of-flight difference as Δt=t1-t2;

Step S5-4. Using the calibration coefficient and the time-of-flight difference to calculate the lateral load F is:

F=(K ₁ *Δt+K ₂ )/2.

In the above method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, step S6 is to select different array elements as the center in sequence according to the numbering order, and repeat step 5 to obtain the lateral load distribution in the circumferential direction.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, the fixing methods of phased array ultrasonic sensors include using phased array probes and coupling agents, and using adhesive tape to paste piezoelectric sheets , and a way to prepare piezoelectric films directly on the surface of bolts using a coating method.

In the aforementioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotary scanning, the number of array elements of the phased array ultrasonic sensor is N≥32.

In the above-mentioned method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, the methods of exciting the phased array sensor include delayed focusing and electronic scanning.

The beneficial effect of the present invention is: the present invention adopts phased array ultrasonic rotation scanning to carry out the measurement of bolt transverse load, has the technical advantage: (1) take the bolt bottom surface echo as index, determine the array element quantity required for measurement (namely number of apertures), under the excitation of as few array elements as possible, the penetration ability of the ultrasonic emitted by the ultrasonic sensor is guaranteed, and the bolts with different lengths and attenuations are automatically adapted; Load size and distribution; (3) The method of subtracting the flight time of symmetrical array element combination can directly eliminate the influence of random axial load on the measurement process without any auxiliary calibration; (4) All the test processes adopt phase The principle of controlled array scanning does not require any movement and rotation of the sensor, thus ensuring the stability and accuracy of the measurement.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Figure 1 is a diagram of the array elements of a phased array ultrasonic sensor.

Figure 2 is the fitting curve of load and sound time.

Figure 3 is the array element traversal excitation rule for measuring the load angle.

Figure 4 is the array element symmetric excitation rule used to measure the size of the load.

Figure 5 is a diagram of the circumferential distribution of loads.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotation scanning, characterized in that it includes the following steps:

S1. Using the coating technology, fix the phased array ultrasonic sensor with the array elements arranged in the circumferential direction and the number of array elements is N=64 on the top of the standard bolt to be tested, and make a number P _i for the array elements (i=1, 2,3,...,64), as shown in Figure 1;

S2. Determine the number of apertures of the phased array sensor: use progressive array numbers (1, 2, 3, ...) to excite the phased array sensor by electronic scanning, and observe the echo at the bottom of the bolt. When the wave amplitude reaches 50% of the height of the full screen, stop advancing, and use the corresponding array element number M=7 at this time as the aperture number M=7 of the phased array sensor;

S3. Calibrate the lateral load: the phased array sensor performs ultrasonic excitation and reception with the aperture number M=7, the stretching machine applies a lateral load to the bolt with a step of ΔF=4KN, and records the ultrasonic time-of-flight array and the stretching machine The load array is used for linear fitting, as shown in Figure 2, and the lateral load constant coefficients K1 and K2 are obtained;

S4. Use ergodic excitation to measure the direction of the maximum lateral load: the ergodic excitation of the phased array sensor is carried out with the number of apertures M=7, first to excite the (1-7) array elements, and secondly to (2-8) array elements, …until all the array elements in the entire circle are excited, as shown in Figure 3, record the flight time of each ultrasonic wave, find the array element number P _c corresponding to the maximum ultrasonic flight time, and record the orientation of the array element as the loading direction of the lateral load;

S5. Lateral Load Measurement Using Symmetric Aperture Time-of-Flight Subtraction:

S5-1. Take the array element P _c as the center, construct the aperture number M with the left and right adjacent array elements of the array element P _c , and carry out the transmission and reception measurement of the ultrasonic signal, as shown in Figure 4, record the flight caused by the lateral and axial loads The time change is t ₁ ;

S5-2. Taking the symmetrical array element P _c1 of the array element P _c in the circular array as the center, the aperture number M is constructed with the adjacent array elements around P _c1 , and the ultrasonic signal is sent and received. As shown in Figure 4, the horizontal recording The time-of-flight change caused by the axial load is t ₂ ;

S5-3. Utilize the time-of-flight subtraction of symmetrical apertures to eliminate the influence of the axial load, and record the time-of-flight difference as Δt=t1-t2;

S5-4. Using the calibration coefficient and the flight time difference to calculate the lateral load F is:

F=(K ₁ *Δt+K ₂ )/2

S6. Select different array elements as the center in sequence according to the numbering order, and repeat step 5 to obtain the lateral load distribution in the circumferential direction, as shown in Fig. 5 .

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (5)

1. A bolt lateral load distribution measurement method based on phased array ultrasonic rotary scanning, is characterized in that, comprises the following steps: Step S1, fix the phased array ultrasonic sensor with the array elements arranged in the circumferential direction and the number of array elements is N on the top of the standard bolt to be tested, and make a number P _i for the array elements, where i=1,2,3, ..., N; Step S2, determining the aperture number M of the phased array ultrasonic sensor according to the echo of the bottom surface of the bolt; Step S3, using the lateral load step loading to obtain the calibration coefficient; Step S4, measuring the direction of the maximum lateral load with aperture M traversal excitation; Step S5, using time-of-flight subtraction of symmetrical apertures to measure lateral loads; Step S6, selecting different array elements as the center in turn according to the numbering sequence, to obtain the lateral load distribution in the circumferential direction; In step S2, the phased array ultrasonic sensor is excited in sequence with progressive array numbers 1, 2, 3, ... N, and the echo at the bottom of the bolt is observed. When the amplitude of the echo at the bottom reaches the set height of the full screen, stop transmitting advance, and use the corresponding array element number M at this time as the aperture number M of the phased array ultrasonic sensor; Step S3 calibrates the lateral load to obtain the calibration coefficient, specifically: the phased array ultrasonic sensor performs ultrasonic excitation and reception with the aperture number M, the stretching machine applies lateral load to the bolt in steps of ΔF, and records the ultrasonic time-of-flight array Carry out linear fitting with the tensile machine load array to obtain the lateral load calibration coefficients K ₁ and K ₂ ; In step S4, the ergodic excitation of the phased array ultrasonic sensor is carried out with the number of apertures as M, first stimulating the array elements P ₁ to _PM , and then stimulating the array elements P ₂ to _PM+1 , until all the array elements in the entire circle are excited. After the excitation is completed, record the flight time of each ultrasonic wave, find the number P _c of the array element corresponding to the maximum ultrasonic flight time, and record the orientation of the array element P _c as the loading direction of the lateral load; Step S5 specifically includes: Step S5-1. Take the array element P _c as the center, construct the aperture number M with the left and right adjacent array elements of the array element P _c , conduct the sending and receiving measurement of the ultrasonic signal, and record the time-of-flight change caused by the lateral and axial loads as t ₁ ; Step S5-2. Take the symmetrical array element P _c1 of the array element P _c in the ring array as the center, construct the aperture number M with the adjacent array elements on the left and right sides of P _c1 , conduct the sending and receiving measurement of ultrasonic signals, and record the common values of lateral and axial loads. The resulting time-of-flight change is t ₂ ; Step S5-3. Use the time-of-flight subtraction of symmetrical apertures to eliminate the influence of the axial load, and record the time-of-flight difference as Δt=t ₁ -t ₂ ; Step S5-4. Using the calibration coefficient and the time-of-flight difference to calculate the lateral load F is: F=(K ₁ *Δt+K ₂ )/2. 2. A method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotary scanning according to claim 1, wherein step S6 is to select different array elements successively according to the numbering order as the center, and repeat step S5 to obtain Lateral load distribution in the circumferential direction. 3. A kind of method for measuring bolt lateral load distribution based on phased array ultrasonic rotary scanning according to claim 1, characterized in that, the fixing mode of phased array ultrasonic sensor comprises the mode of using phased array probe and couplant, A method of pasting a piezoelectric sheet with an adhesive, and a method of directly preparing a piezoelectric film on the surface of a bolt by using a coating method. 4. A method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotational scanning according to claim 1, characterized in that the number of array elements of the phased array ultrasonic sensor is N≥32. 5 . A method for measuring the lateral load distribution of bolts based on phased array ultrasonic rotational scanning according to claim 2 , wherein the methods of exciting the phased array ultrasonic sensors include delayed focusing and electronic scanning. 6 .