CN117268618A - Double-probe device for transverse and longitudinal wave bolt stress detection and detection method thereof - Google Patents

Abstract

The invention relates to a double-probe device for transverse and longitudinal wave bolt stress detection and a detection method thereof, belonging to the technical field of ultrasonic nondestructive detection equipment. The problem that in the practical use process of transverse-longitudinal wave double-probe stress detection, the positioning accuracy of the double probes and the constant pressure between the double-probe and a bolt to be detected are difficult to ensure is solved. The device comprises a shell, a longitudinal wave probe pretightening force adjusting piece, a transverse wave probe pretightening force adjusting piece, a first spring, a second spring, a longitudinal wave probe, a transverse wave probe, a base and a magnet, wherein the longitudinal wave probe pretightening force adjusting piece, the first spring and the longitudinal wave probe are sequentially arranged in the shell, the transverse wave probe pretightening force adjusting piece, the second spring and the transverse wave probe are sequentially arranged in the shell, the shell is detachably connected with the base, and the detection ends of the longitudinal wave probe and the transverse wave probe extend into the base. The invention can well fix the position of the transverse and longitudinal wave double probes and ensure the stress measurement precision; the invention is convenient to use and adjust, and can keep constant pressure with the bolt to be measured.

Description

A dual-probe device for transverse and longitudinal wave bolt stress detection and its detection method

Technical field

The invention relates to a dual-probe device and a detection method thereof, and belongs to the technical field of ultrasonic non-destructive testing equipment.

Background technique

With the increase in global energy consumption, the pace of research and development of new energy sources is also accelerating. New technologies such as hydropower, solar power, biopower, and wind power have made breakthrough progress and have begun to be vigorously promoted and implemented. , in the field of new energy, we also vigorously support the transmission of electricity into the grid, and vigorously promote the construction of new energy through the implementation of price subsidies. Wind energy is a clean, pollution-free renewable energy source. Wind power generation is green and environmentally friendly. In recent years, as energy shortages and environmental pollution problems have intensified, people have paid more attention to wind power generation. In addition, the competitive advantage of wind power compared with other new energy sources continues to increase, promoting the rapid development of the wind power industry.

With the continuous development of wind power technology and the continuous increase of wind power installed capacity, it has posed considerable challenges to the maintenance and upkeep of wind turbine units. It is necessary to continuously accelerate the transformation and application of research and development technology in the wind power field. At present, ultrasonic non-destructive testing technology has been applied in stress testing of fastening bolts of wind turbine blades. However, in actual testing, bolts will have different lengths due to manufacturing differences and the size of internal stress. The traditional single longitudinal wave method has a complicated calibration process. , and changes in the length of the measured bolts will cause great measurement errors, and the applicable range and measurement accuracy cannot be guaranteed.

Therefore, it is proposed that bolt stress measurement based on transverse and longitudinal waves can in principle eliminate the influence of length on stress measurement, and the measurement accuracy is high. It can detect the stress of fastening bolts on wind turbine blades and replace them in time for repair to avoid irreversible damage. Has wider application prospects. However, during actual use of transverse and longitudinal wave dual probe stress detection, it is difficult to ensure the positioning accuracy of the dual probes and the constant pressure between the dual probes and the bolts to be tested.

Therefore, there is an urgent need to propose a dual-probe device and a detection method for transverse and longitudinal wave bolt stress detection to solve the above technical problems.

Contents of the invention

The purpose of the present invention is to solve the problem that it is difficult to ensure the positioning accuracy of the dual probes and the constant pressure between the dual probes and the bolt to be tested during actual use of the transverse and longitudinal wave dual probe stress detection, and to provide a dual probe for transverse and longitudinal wave bolt stress detection. Device and detection method thereof. A brief summary of the present invention is given below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention.

Technical solution of the present invention:

A dual-probe device for transverse and longitudinal wave bolt stress detection, including a shell, a longitudinal-wave probe pre-tightening force adjustment member, a transverse-wave probe pre-tightening force adjustment member, a first spring, a second spring, a longitudinal-wave probe, a transverse-wave probe, a base and a magnet , the casing is provided with a longitudinal wave probe preload adjuster, a first spring, and a longitudinal wave probe arranged in sequence. The casing is also provided with a shear wave probe preload adjuster, a second spring, and a shear wave probe arranged in sequence. The casing and the base can be Disassemble the connection and extend the detection ends of the longitudinal wave probe and shear wave probe into the base.

Preferred: The sides of the cylindrical longitudinal wave probe preload adjuster and the shear wave probe preload adjuster have external threads, and the longitudinal wave probe preload adjuster and the shear wave probe preload adjuster are provided with six screws at their axes. Side countersunk hole.

Preferably: it also includes a shear wave probe fixing component. The shear wave probe fixing component includes an outer sleeve and screws. The side of the outer sleeve is provided with a number of equidistantly arranged threaded holes. The outer sleeve is sleeved on the end of the shear wave probe, and the screws are inserted into the threads. The hole allows the screw to be threadedly connected to the outer sleeve, and the extending end of the screw presses against the outer wall of the shear wave probe.

Preferably: the outer shell is processed with a first cavity and a second cavity that penetrate in the axial direction, one end of the first cavity and the second cavity is processed with threads, and one end of the base is processed with a thread corresponding to the first cavity and the second cavity. The first detection hole and the second detection hole are provided correspondingly in the two cavities. The other end of the base is processed with a detection groove that matches the bolt to be tested. The longitudinal wave probe is arranged in the first cavity, and the detection end of the longitudinal wave probe is arranged in the first detection hole. In the hole, a first spring is provided at the end of the longitudinal wave probe. The longitudinal wave probe pre-tightening force adjustment member is threadedly connected to the first cavity. The shear wave probe fixing assembly and the tightening shear wave probe are set in the second cavity to tighten the shear wave probe. The detection end is arranged in the second detection hole, the end of the shear wave probe fixing assembly is provided with a second spring, and the shear wave probe preload adjustment member is threadedly connected to the second cavity.

Preferably: the magnet includes a first magnet and a second magnet, two mounting holes are processed on the base, and the first magnet and the second magnet are arranged in the mounting holes.

A detection method of a dual-probe device for transverse and longitudinal wave bolt stress detection, including the following steps:

Step 1: Fit the end of the shear wave probe with the shear wave probe fixing component, and fix the shear wave probe with the shear wave probe fixing component by adjusting the screws at each position;

Step 2: Put the longitudinal wave probe and the shear wave probe into the casing respectively, then put the first spring and the second spring, rotate the longitudinal wave probe preload adjuster and the shear wave probe preload adjuster to connect and tighten them with the casing. The first spring, the second spring, and the detection ends of the longitudinal wave probe and the shear wave probe extend from the housing;

Step 3: According to the specifications of the bolt to be tested, select the base of the corresponding specifications and place the first magnet and the second magnet into the mounting holes of the base;

Step 4: Align the detection ends of the longitudinal wave probe and the shear wave probe with the first detection hole and the second detection hole respectively, and then connect the shell and base through bolts;

Step 5: Put the base on the bolt to be tested, and the magnet on the base will adsorb the dual probe device for transverse and longitudinal wave bolt stress detection to the bolt to be tested;

Step 6: Adjust the pre-tightening force between the longitudinal-wave probe, shear-wave probe and the bolt to be measured by rotating the longitudinal-wave probe pre-tightening force adjustment piece and the shear-wave probe pre-tightening force adjusting piece;

Step 7: From the nonlinear acoustic theory, it can be known that the sound speed of ultrasonic waves in the medium has an approximately linear relationship with the temperature change ΔT. From this, the longitudinal wave sound speed v (L, T) and the transverse wave sound speed v _{(S, T )} at a certain temperature T can be obtained ₎ ’s expression is

v _{(L, T)} = v _L (1-α _L ·ΔT) (10)

v _{(S, T)} = v _S (1-α _S ΔT) (11)

Combined with the thermal expansion coefficient β, the transit time of longitudinal and transverse waves t _{(Lσ, T)} and t _{(Sσ, T)} after the temperature of the bolt changes ΔT under a certain stress can be expressed as

t _{(Lσ, T)} = (1+β·ΔT)·t _Lσ /(1-α _L ·ΔT) (12)

t _(Sσ·T) = (1+β·ΔT·t _Sσ /(1-α _S ·ΔT) (13)

In the formula: α _L and α _S are the temperature influence coefficients of longitudinal and transverse waves propagating in the bolt respectively;

The sound time ratio detected and collected when the temperature changes is t _{(Lσ, T)} /t _{(sσ, T)} . The actual sound time ratio t _Lσ /t _sσ required to be obtained can be expressed as

Combining formulas (10) and (11), we can get

In the formula: t _{(L, T)} , t _{(S, T)} are the transit times of longitudinal waves and transverse waves respectively at a certain temperature; t _L is the longitudinal wave transit time when the longitudinal wave sound is heard, which can be determined by the signal received by the longitudinal wave probe. The cross-correlation is obtained; t _S is the shear wave sound, and the shear wave transit time can be obtained by cross-correlation of the signals received by the shear wave probe;

It can be seen from equations (15) and (16) that the calibration of α _L and α _S can be achieved by fitting the linear relationship between the change rate of the ultrasonic wave transit time after the temperature changes and the temperature change ΔT; let O = (1 -α _L ΔT)/(1-α _S ΔT) is called the temperature acoustic time correction factor. O is only related to ΔT. After substituting it into equation (14), the expression of stress σ _T at a certain temperature is obtained:

In the formula: xT is the square of the ratio of the transit time of longitudinal waves and transverse waves in the detection bolt at a certain temperature;

According to equation (17), it can be seen that after calibrating a ₁ , a ₂ , a ₃ and o through experiments, the axial stress can be detected by simply collecting the ratio of the longitudinal wave and transverse wave transit time of the bolt. At the same time, since a ₁ , a ₂ , a ₃ are only related to the material properties of the bolt, ο is only related to the material properties of the bolt and ΔT, so the above four parameters are suitable for stress detection and temperature correction between bolts of different lengths of the same material.

The invention has the following beneficial effects:

The invention can well fix the position of the transverse and longitudinal wave dual probes and ensure the accuracy of stress measurement;

The invention is easy to use and adjust, and can keep the pressure between the bolt to be measured constant, the measurement parameters of the transverse and longitudinal wave dual probes remain unchanged, and does not require frequent calibration, and can be used for real-time monitoring of the stress of the fastening bolts of wind turbine blades;

The invention greatly reduces the number of manual regular inspections, saves a lot of manpower, material and financial resources, and has very good application prospects and application value.

Description of the drawings

Figure 1 is a perspective view of a dual-probe device used for transverse and longitudinal wave bolt stress detection;

Figure 2 is a cross-sectional view of a dual-probe device used for transverse and longitudinal wave bolt stress detection;

Figure 3 is an exploded view of a dual-probe device used for transverse and longitudinal wave bolt stress detection.

In the picture: 1-casing, 2-longitudinal wave probe preload adjuster, 3-shear probe preload adjuster, 4-first spring, 5-second spring, 6-shear probe fixing component, 7-longitudinal wave probe , 8-shear wave probe, 9-first magnet, 10-second magnet, 11-base.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is described below through the specific embodiments shown in the drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. Furthermore, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily confusing the concepts of the present invention.

Specific Embodiment 1: This embodiment will be described with reference to Figures 1-3. This embodiment is a dual probe device for transverse and longitudinal wave bolt stress detection, including a housing 1, a longitudinal wave probe pre-tightening force adjustment member 2, and a transverse wave probe pre-tensioner. The force adjusting member 3, the first spring 4, the second spring 5, the longitudinal wave probe 7, the shear wave probe 8, the base 11 and the magnet are arranged in the housing 1. The longitudinal wave probe preload adjusting member 2, the first spring 4, Longitudinal wave probe 7, the shell 1 is also provided with a shear wave probe preload adjustment member 3, a second spring 5, and a shear wave probe 8 arranged in sequence. The shell 1 is detachably connected to the base 11 through bolts, and the longitudinal wave probe 7 and the shear wave probe 8 are detachably connected. The detection end extends into the base 11; the invention can well fix the positions of the transverse and longitudinal wave dual probes and ensure the stress measurement accuracy. Due to the use of springs and preload adjustment nuts (preload adjusters for longitudinal wave probes or preload adjusters for transverse wave probes), it is easy to use and adjust, and can maintain a constant pressure with the bolt to be measured. The measurement parameters of the transverse and longitudinal wave dual probes are not the same. Variable and does not require frequent calibration, it can be used for real-time monitoring of the stress of wind turbine blade fastening bolts, which can greatly reduce the number of manual regular inspections and save a lot of manpower, material and financial resources; this device can not only be used in wind turbine blade fastening In the stress measurement of bolts, it can also be used in all fields of stress measurement and stress monitoring of fastening bolts such as hydropower generation. It has very good application prospects and application value.

Specific Embodiment 2: This embodiment is described with reference to Figures 1-3. This embodiment is a dual-probe device for transverse and longitudinal wave bolt stress detection, a cylindrical longitudinal wave probe pre-tightening force adjustment member 2, a transverse wave probe pre-tightening force The sides of the adjusting member 3 have external threads, and hexagonal counterbore holes are provided at the axes of the longitudinal wave probe preload adjusting member 2 and the shear wave probe preload adjusting member 3.

Specific Embodiment 3: This embodiment will be described with reference to Figures 1-3. A dual-probe device for transverse and longitudinal wave bolt stress detection in this embodiment also includes a transverse-wave probe fixing assembly 6. The transverse-wave probe fixing assembly 6 includes an outer sleeve. and screws. The side of the outer sleeve is provided with a number of equidistantly arranged threaded holes. The outer sleeve is set on the end of the shear wave probe 8. The screws (or fastening screws) are inserted into the threaded holes to connect the screws to the outer sleeve. The screws The extension end of the shear wave probe 8 is pressed against the outer wall of the shear wave probe 8; when in use, put the shear wave probe and the longitudinal wave probe into the corresponding probe holes of the fixture base respectively. Since the cross section of the shear wave probe is large, it is difficult to fix and the stability is not high. Therefore, the shear wave probe fixing assembly is designed, which includes the probe fixing shell and fastening screws. The probe fixing shell is placed on the shear wave probe, and the probe fixing shell and the shear wave probe are fixed with the fastening screws. The preload adjustment nut is The clamp shell (shell 1) and the spring are fixed to the clamp base (base 11) through screws, and then the clamp base is placed on the bolt to be tested. The magnet on the clamp base will firmly adsorb the clamp to the bolt to be tested. By adjusting the pre-tightening force adjustment nut on the fixture housing, the pre-tightening force between the probe and the bolt to be measured can be adjusted.

Specific Embodiment 4: This embodiment will be described with reference to Figures 1-3. This embodiment is a dual probe device for transverse and longitudinal wave bolt stress detection. The housing 1 is processed with a stepped first step that penetrates along the axial direction. Cavity and second cavity, one end of the first cavity and the second cavity is processed with threads, and the cross-sectional area of the other end of the first cavity and the second cavity is smaller than that of the first cavity and the second cavity at other positions. Cross-sectional area, one end of the base 11 is processed with a first detection hole and a second detection hole corresponding to the first cavity and the second cavity, and the other end of the base 11 is processed with a detection slot that matches the bolt to be tested, for different diameter sizes When detecting the bolt stress, only the clamp bases of different diameters need to be processed, which will greatly increase the applicable scope of the clamp. The first detection hole and the second detection hole are connected with the detection groove. The longitudinal wave probe 7 is set in the first cavity, and the longitudinal wave probe 7 is installed in the first cavity. The detection end of the probe 7 is arranged in the first detection hole. The end of the longitudinal wave probe 7 is provided with a first spring 4. The longitudinal wave probe preload adjustment member 2 is threadedly connected to the first cavity and compresses the first spring. The transverse wave probe The fixed component 6 and the pressing shear wave probe 8 are arranged in the second cavity. The detection end of the pressing shear wave probe 8 is arranged in the second detection hole. The end of the shear wave probe fixing component 6 is provided with a second spring 5. The shear wave probe The preload adjustment member 3 is threadedly connected to the second cavity and compresses the second spring; the outer wall of the shear wave probe fixing assembly 6 is provided with a protrusion, and the threaded hole is provided at the protrusion, in the second cavity of the housing 1 The outer wall is provided with grooves, and the protrusions are provided correspondingly to the grooves.

Specific Embodiment 5: This embodiment will be described with reference to Figures 1-3. In this embodiment, a double probe device is used for transverse and longitudinal wave bolt stress detection. The magnet includes a first magnet 9 and a second magnet 10. The base 11 is processed with Two mounting holes, the first magnet 9 and the second magnet 10 are provided in the mounting holes.

Specific Embodiment 6: This embodiment will be described with reference to Figures 1-3. The detection method of a dual-probe device for transverse and longitudinal wave bolt stress detection in this embodiment adopts a dual-probe device for transverse and longitudinal wave bolt stress detection. , including the following steps:

Step 1: Fit the end of the shear wave probe 8 with the shear wave probe fixing assembly 6, and fix the shear wave probe 8 and the shear wave probe fixing assembly 6 by adjusting the screws at each position;

Step 2: Put the longitudinal wave probe 7 and the shear wave probe 8 into the housing 1 respectively, then put the first spring 4 and the second spring 5, and rotate the longitudinal wave probe preload adjusting member 2 and the shear wave probe preload adjusting member 3 so that It is connected with the housing 1 and presses the first spring 4 and the second spring 5, and the detection ends of the longitudinal wave probe 7 and the shear wave probe 8 extend from the housing 1;

Step 3: According to the specifications of the bolt to be tested, select the base 11 of the corresponding specifications and place the first magnet 9 and the second magnet 10 into the mounting holes of the base;

Step 4: Align the detection ends of the longitudinal wave probe 7 and the shear wave probe 8 with the first detection hole and the second detection hole respectively, and then connect the shell 1 and the base 11 through bolts;

Step 5: Place the base 11 on the bolt to be tested, and the magnet on the base will firmly attach the dual probe device for transverse and longitudinal wave bolt stress detection to the bolt to be tested;

Step 6: By rotating the longitudinal wave probe pre-tightening force adjustment piece 2 and the shear wave probe pre-tightening force adjusting piece 3, adjust the pre-tightening force between the longitudinal wave probe 7, shear wave probe 8 and the bolt to be tested to complete the clamping and positioning of the bolt to be tested to ensure The positioning accuracy of the dual probes and the pressure between the bolts to be tested are constant, and the longitudinal wave probe 7 and the shear wave probe 8 are used for non-destructive testing;

Step 7: Stress measurement and temperature compensation; considering that the service process of bolts is usually accompanied by environmental temperature changes within a certain range, and temperature will have a certain impact on the propagation speed of ultrasonic waves, so the acoustic time error caused by temperature needs to be corrected. ; On the other hand, since the temperature does not change much, the effect of temperature on the bolt material properties is not considered for the time being; according to the nonlinear acoustic theory, the sound speed of ultrasonic waves in the medium has an approximately linear relationship with the temperature change ΔT, so it can be obtained The expressions of longitudinal wave sound speed v _{(L, T)} and transverse wave sound speed v _{(S, T)} at a certain temperature T are:

v _{(L, T)} = v _L (1-α _L ·ΔT) (10)

v _{(S, T)} = v _S (1-α _S ΔT) (11)

The propagation sound speed v _L and v _S of longitudinal and transverse waves in materials under zero stress;

Combined with the thermal expansion coefficient β, the transit time of longitudinal and transverse waves t _{(Lσ, T)} and t _{(Sσ, T)} after the temperature of the bolt changes ΔT under a certain stress can be expressed as

t _{(Lσ, T)} = (1+β·ΔT)·t _Lσ /(1-α _L ·ΔT) (12)

t _{(Sσ, T)} = (1+β·ΔT)·t _Sσ /(1-α _S ·ΔT) (13)

In the formula: α _L and α _S are the temperature influence coefficients of longitudinal and transverse waves propagating in the bolt respectively;

The sound time ratio detected and collected when the temperature changes is t _{(Lσ, T)} / t _{(Sσ, T)} . The transit times of longitudinal and transverse waves under stress σ are t _Lσ and t _Sσ . The actual sound time ratio t needs to be obtained. _Lσ /t _Sσ can be expressed as

Combining formulas (10) and (11), we can get

In the formula: t _{(L, T)} , t _{(S, T)} are the transit time of longitudinal wave and transverse wave respectively at a certain temperature; t _L is the longitudinal wave transit time when the longitudinal wave sound is heard, which can be determined by the signal received by the longitudinal wave probe. The cross-correlation is obtained; t _S is the shear wave sound, and the shear wave transit time can be obtained by cross-correlation of the signals received by the shear wave probe;

It can be seen from equations (15) and (16) that the calibration of α _L and α _S can be achieved by fitting the linear relationship between the change rate of the ultrasonic wave transit time after the temperature changes and the temperature change ΔT; let ο = (1 -α _L ΔT)/(1-α _S ΔT) is called the temperature acoustic time correction factor. ο is only related to ΔT. After substituting it into equation (14), the expression of stress σ _T at a certain temperature is obtained:

In the formula: xT is the square of the ratio of the transit time of longitudinal waves and transverse waves in the detection bolt at a certain temperature;

According to equation (17), it can be seen that after calibrating a ₁ , a ₂ , a ₃ , o through experiments, the axial stress can be detected by simply collecting the ratio of the longitudinal wave and transverse wave transit time of the bolt. At the same time, because a ₁ , a ₂ , a and ₃ are only related to the material properties of the bolt, and ο is only related to the material properties of the bolt and ΔT. Therefore, the above four parameters are suitable for stress detection and temperature correction between bolts of different lengths of the same material, and can effectively shorten the time required for engineering applications. The preliminary preparation time for stress testing of large batches of bolts; the acoustic time (transit time) is calculated through the cross-correlation algorithm based on the echo signals of the probes (longitudinal wave probe 7, shear wave probe 8); the temperature compensation coefficient is obtained through calibration experiments; The test environment temperature is measured by the device temperature sensor;

It solves the problem that the currently disclosed transverse and longitudinal wave detection models are relatively complex. Most of them approximate the parameters and do not directly establish the relationship between the transverse and longitudinal wave transit time ratio and the axial stress on the bolt, which makes the engineering application of these detection models More complex issues. The detection model provided by the present invention directly establishes the relationship between the above two, and at the same time can correct the influence of temperature on acoustic time according to the change of the detection temperature relative to the calibration temperature, making its engineering application more convenient.

It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention no longer applies to the permuted and combined technical solutions. Although explained one by one, it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. A two probe devices for transverse and longitudinal wave bolt stress detection, its characterized in that: including shell (1), longitudinal wave probe pretightning force regulating part (2), transverse wave probe pretightning force regulating part (3), first spring (4), second spring (5), longitudinal wave probe (7), transverse wave probe (8), base (11) and magnet, set up longitudinal wave probe pretightning force regulating part (2), first spring (4), longitudinal wave probe (7) that arrange in order in shell (1), still set up transverse wave probe pretightning force regulating part (3), second spring (5), transverse wave probe (8) that arrange in order in shell (1), shell (1) can dismantle with base (11) and be connected, the detection end of longitudinal wave probe (7), transverse wave probe (8) stretches into base (11).

2. The dual probe apparatus for shear and longitudinal wave bolt stress detection of claim 1, wherein: the side surfaces of the cylindrical longitudinal wave probe pretightening force adjusting piece (2) and the transverse wave probe pretightening force adjusting piece (3) are respectively provided with external threads, and hexagonal counter bores are formed in the axial centers of the longitudinal wave probe pretightening force adjusting piece (2) and the transverse wave probe pretightening force adjusting piece (3).

3. The dual probe apparatus for shear and longitudinal wave bolt stress detection of claim 1, wherein: the transverse wave probe fixing assembly (6) comprises an outer sleeve and screws, a plurality of equally-spaced threaded holes are formed in the side face of the outer sleeve, the outer sleeve is sleeved at the end portion of the transverse wave probe (8), the screws are inserted into the threaded holes to enable the screws to be in threaded connection with the outer sleeve, and the extending ends of the screws are tightly propped against the outer side wall of the transverse wave probe (8).

4. A dual probe apparatus for shear wave bolt stress detection according to claim 3, the method is characterized in that: the utility model discloses a high-speed ultrasonic transducer, including shell (1), shell (1) is last to be processed has first cavity, the second cavity of following the axial and run through, the one end processing of first cavity, the second cavity has the screw thread, base (11) one end processing have with first cavity, the second cavity corresponds the first detection hole that sets up, the second detection hole of setting, base (11) other end processing have with the bolt complex that awaits measuring detect the groove, longitudinal wave probe (7) set up in first cavity, the detection end setting of longitudinal wave probe (7) is in first detection hole, the tip of longitudinal wave probe (7) is provided with first spring (4), longitudinal wave probe pretightning force regulating part (2) and first cavity threaded connection, transverse wave probe fixed subassembly (6), tight transverse wave probe (8) set up in the second cavity, the detection end setting of tight transverse wave probe (8) is in the second detection hole, the tip of transverse wave probe fixed subassembly (6) is provided with second spring (5), transverse wave probe pretightning force regulating part (3) and second cavity threaded connection.

5. The dual probe apparatus for shear and longitudinal wave bolt stress detection as defined in claim 4, wherein: the magnet comprises a first magnet (9) and a second magnet (10), two mounting holes are formed in the base (11), and the first magnet (9) and the second magnet (10) are arranged in the mounting holes.

6. A detection method of a double-probe device for detecting transverse and longitudinal wave bolt stress is characterized by comprising the following steps of: a dual probe apparatus for shear and longitudinal wave bolt stress detection as defined in any one of claims 1 to 5, comprising the steps of:

step one: sleeving a transverse wave probe fixing assembly (6) at the end part of a transverse wave probe (8), and fixing the transverse wave probe (8) and the transverse wave probe fixing assembly (6) by adjusting screws at all positions;

step two: a longitudinal wave probe (7) and a transverse wave probe (8) are respectively arranged in the shell (1), a first spring (4) and a second spring (5) are arranged in the shell, the longitudinal wave probe pretightening force adjusting piece (2) and the transverse wave probe pretightening force adjusting piece (3) are rotated to be connected with the shell (1) and compress the first spring (4) and the second spring (5), and the detection ends of the longitudinal wave probe (7) and the transverse wave probe (8) extend out of the shell (1);

step three: according to the specification of the bolt to be tested, a base (11) with corresponding specification is selected to put the first magnet (9) and the second magnet (10) into the mounting hole of the base;

step four: aligning the detection ends of the longitudinal wave probe (7) and the transverse wave probe (8) with the first detection hole and the second detection hole respectively, and connecting the shell (1) and the base (11) through bolts;

step five: sleeving a base (11) on a bolt to be detected, wherein a magnet on the base can adsorb a double-probe device for detecting the transverse and longitudinal wave bolt stress on the bolt to be detected;

step six: the pretightening force between the longitudinal wave probe (7), the transverse wave probe (8) and the bolt to be tested is regulated by rotating the longitudinal wave probe pretightening force regulating piece (2) and the transverse wave probe pretightening force regulating piece (3);

step seven: as known from nonlinear acoustic theory, the sound velocity of ultrasonic wave in medium and the temperature variation DeltaT are approximately in linear relation, so that the longitudinal wave sound velocity v at a certain temperature T can be obtained _(L，T) Transverse wave sound velocity v _(S，T) The expression of (2) is

υ _(L，T) ＝υ _L (1-α _L ·ΔT) (10)

υ _(S，T) ＝υ _S (1-α _S ΔT) (11)

The transition time T of longitudinal wave and transverse wave after the temperature change delta T of the bolt under certain stress is combined with the thermal expansion coefficient beta _(Lσ，T) ，t _(Sσ，T) Can be expressed as

Wherein: alpha _L ，α _S The temperature influence coefficients of longitudinal wave and transverse wave propagating in the bolt are respectively;

when the temperature changesThe sound-time ratio of detection and acquisition is t _(Lσ，T) /t _(Sσ，T) Ratio t of sound to time actually required to be acquired _Lσ /t _Sσ Can be expressed as

The combination of (10), (11) can obtain

Wherein: t is t _(L，T) ，t _(S，T) The transit time of longitudinal wave and transverse wave at a certain temperature; t is t _L When the signal is longitudinal wave sound, the transition time of the longitudinal wave can be obtained by cross-correlation of signals received by a longitudinal wave probe; t is t _S When the transverse wave sound is the transverse wave sound, the transverse wave transit time can be obtained by cross-correlation of signals received by a transverse wave probe;

from equations (15) and (16), it can be seen that α can be achieved by fitting a linear relationship between the rate of change of the ultrasonic transit time after the temperature change and the temperature change amount DeltaT _L ，α _S Is calibrated; let omic= (1-alpha) _L ΔT)/(1-α _S Δt), called temperature sound time correction factor, wherein omicron is related to Δt alone, and substituting it into (14) to obtain stress σ at a certain temperature _T The expression of (2) is

In which x is _T The square of the ratio of the transit time of the longitudinal wave and the transverse wave in the detection bolt at a certain temperature;

from equation (17), a is calibrated by the test ₁ ，a ₂ ，a ₃ After omicron, the detection of axial stress can be realized only by collecting the ratio of the transition time of longitudinal wave and transverse wave of the bolt, and simultaneously, the stress is detected due to a ₁ ，a ₂ A3 is only related to the material property of the bolt, omicron is only related to the material property of the bolt and delta T, so the 4 parameters are applicable to stress detection and temperature correction between bolts of the same material and different lengths.