CN111208207A - Bolt stress detection method - Google Patents
Bolt stress detection method Download PDFInfo
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- CN111208207A CN111208207A CN202010119781.1A CN202010119781A CN111208207A CN 111208207 A CN111208207 A CN 111208207A CN 202010119781 A CN202010119781 A CN 202010119781A CN 111208207 A CN111208207 A CN 111208207A
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- bolt
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- detection method
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- 238000001514 detection method Methods 0.000 title claims abstract description 24
- 239000000523 sample Substances 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 9
- 238000009864 tensile test Methods 0.000 claims description 7
- 238000005259 measurement Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 239000007822 coupling agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/25—Measuring force or stress, in general using wave or particle radiation, e.g. X-rays, microwaves, neutrons
- G01L1/255—Measuring force or stress, in general using wave or particle radiation, e.g. X-rays, microwaves, neutrons using acoustic waves, or acoustic emission
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4418—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a model, e.g. best-fit, regression analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/01—Indexing codes associated with the measuring variable
- G01N2291/011—Velocity or travel time
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02827—Elastic parameters, strength or force
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/26—Scanned objects
- G01N2291/269—Various geometry objects
- G01N2291/2691—Bolts, screws, heads
Abstract
The invention relates to a bolt stress detection method, which comprises the following steps: step S1: establishing a relation model of ultrasonic time difference and bolt stress; step S2: a piezoelectric wafer is stuck on one end face of the bolt, an ultrasonic emission probe is placed on the other end face of the bolt to measure an ultrasonic time difference-bolt stress relation curve, unknown parameters in the relation model are solved, and a determined relation model is obtained; step S3: and detecting the stress of the bolt by using the determined relation model. Compared with the prior art, the energy loss of sound waves is reduced, the received waveform signals are more obvious, and the detection result is more accurate.
Description
Technical Field
The invention relates to the field of bolt stress measurement, in particular to a bolt stress detection method.
Background
In the flange service process, leakage failure of the bolt flange joint caused by insufficient bolt force is one of main reasons for failure of the flange joint, the flange joint has long service time and is more easy to cause bolt force attenuation under external factors, but most bolt force detection technologies in engineering are not suitable for the bolt flange joint or damage the bolt force, so that a nondestructive bolt force online detection method is needed.
The phenomenon that the ultrasonic wave speed changes with the change of the stress state of the propagation medium is called an acoustic elasticity phenomenon. Both in the elastic range and in the nonlinear stress-strain range. The phenomenon provides a force theoretical basis for an ultrasonic stress measurement technology, and the material stress measurement method based on the phenomenon is an acoustic-elastic method.
When the stress of the bolt is measured by using the acoustic elasticity method, the accuracy of the result is often influenced by the size of the received sound wave.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a bolt stress detection method.
The purpose of the invention can be realized by the following technical scheme:
a bolt stress detection method comprises the following steps:
step S1: establishing a relation model of ultrasonic time difference and bolt stress;
step S2: a piezoelectric wafer is stuck on one end face of the bolt, an ultrasonic emission probe is placed on the other end face of the bolt to measure an ultrasonic time difference-bolt stress relation curve, unknown parameters in the relation model are solved, and a determined relation model is obtained;
step S3: and detecting the stress of the bolt by using the determined relation model.
The relationship model is as follows:
wherein σ is bolt stress, Δ S is ultrasonic time difference, C0The ultrasonic sound velocity is the ultrasonic sound velocity in the stress-free state, E is the elastic modulus of the bolt, r' is the equivalent stress length of the bolt, K is the material coefficient of the bolt, and K is the unknown parameter.
The equivalent stress length r' of the bolt is as follows:
r ═ the distance between the nut and the bolt head + the screw diameter.
The process of measuring the relation curve comprises the following steps:
step S21: sticking a piezoelectric wafer serving as an ultrasonic receiver on one end face of the bolt;
step S22: placing an ultrasonic emission probe on the other end face of the bolt, and fixing the ultrasonic emission probe through a clamp;
step S23: the piezoelectric wafer is connected with the processor, and the ultrasonic transmitting probe is connected with the waveform generator through the power amplifier;
step S24: measuring the initial ultrasonic receiving time length without tensile force;
step S25: stretching the bolt by a tensile testing machine, and recording the magnitude of the tensile force and the ultrasonic receiving time corresponding to different tensile forces;
step S26: and obtaining a relation curve according to the magnitude of the tensile force, the ultrasonic receiving time length corresponding to different tensile forces and the initial ultrasonic receiving time length.
The process of obtaining the determined relationship model comprises the following steps:
step S27: performing linear fitting on the relation curve to obtain a fitting linear line;
step S28: and obtaining the material coefficient of the bolt by utilizing the fitted straight line so as to obtain a determined relation model.
In step S23, the processor is an oscilloscope, the piezoelectric chip is connected to one channel of the oscilloscope, and the waveform generator is connected to the other channel of the oscilloscope.
And verifying the determined relation model by using a strain gauge, wherein the strain gauge is adhered to the screw rod and is connected with a strain gauge.
The process of detecting the stress of the bolt by using the determined relation model comprises the following steps:
step S31: measuring the initial ultrasonic receiving time length in the stress-free state;
step S32: applying pretightening force to the bolt, and recording the corresponding ultrasonic receiving time length;
step S33: obtaining a detection ultrasonic time difference by using the initial ultrasonic receiving time length and the ultrasonic receiving time length corresponding to the pretightening force;
step S34: and detecting the ultrasonic time difference and determining a relation model to obtain the bolt stress.
Compared with the prior art, the invention has the following advantages:
(1) compared with the original two-pass method (the ultrasonic wave is excited from one end of the bolt and is received from the other end), the method adopting the one-pass method (namely the ultrasonic wave is excited from one end of the bolt and is received from the other end of the bolt) reduces the energy loss of the sound wave, and makes the received waveform signal more obvious, and the received waveform signal is an important basis for calculating the time difference of the ultrasonic wave.
(2) The method for calibrating by adopting the tensile testing machine improves the measurement precision of the stress of the bolt, and further improves the measurement precision by considering the sound velocity change and the material length change in the stretching process of the bolt.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of the ultrasonic time difference-bolt stress relationship curve measurement of the present invention;
FIG. 3 is a schematic view of the bolt stress detection of the present invention;
FIG. 4 is an ultrasonic waveform received by an oscilloscope of the present invention;
FIG. 5 is a fitted line of ultrasonic moveout versus bolt stress for the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Examples
The present embodiment provides a bolt stress detection method, as shown in fig. 1, including:
step S1: establishing a relation model of ultrasonic time difference and bolt stress;
step S2: a piezoelectric wafer is stuck on one end face of the bolt, an ultrasonic emission probe (longitudinal wave ultrasonic probe) is placed on the other end face of the bolt, an ultrasonic time difference-bolt stress relation curve is measured, unknown parameters in a relation model are solved, and a determined relation model is obtained;
step S3: and detecting the stress of the bolt by using the determined relation model.
Specifically, the method comprises the following steps:
the ultrasonic time difference is a difference between an initial ultrasonic receiving time length when the bolt is unstressed and an ultrasonic receiving time length when the bolt is stressed.
The method comprises the following steps: and establishing a relation model of the ultrasonic time difference and the bolt stress. Due to the existence of bolt stress, not only the change of sound velocity causes the change of ultrasonic time difference, but also the change of material length caused by the stress causes the change of ultrasonic time difference, so the influence of the stress on the material length and the sound velocity must be analyzed simultaneously. The relationship between the bolt stress sigma and the ultrasonic time difference delta S is obtained through theoretical derivation as follows:
in the formula: the units of sigma are MPa and Delta S are S, C0The unit of the ultrasonic sound velocity in the stress-free state is m/s, E is the elastic modulus of the bolt, the unit is MPa, r 'is the equivalent stress length of the bolt, the unit is m, r' is the distance between the nut and the bolt head plus the diameter of the screw rod, K is the material coefficient of the bolt, and K is an unknown parameter.
The method comprises the following steps of obtaining a relation model, calibrating a schematic diagram of a system as shown in figure 2, wherein a tensile testing machine, a strain gauge, a waveform generator, a power amplifier, an oscilloscope, an ultrasonic emission probe, a piezoelectric crystal and the like are needed, the piezoelectric crystal is connected with a channel CH2 of the oscilloscope and used for receiving ultrasonic signals, the waveform generator CH1 is connected with a channel CH1 of the oscilloscope and used as a comparison, the waveform generator CH2 is connected with the power amplifier and connected with the ultrasonic emission probe, the piezoelectric crystal is pasted at the center of the end face of the bottom of the bolt and used as an ultrasonic receiver, the ultrasonic emission probe is placed on the end face of the top of the bolt and coated with a coupling agent and fixed through a clamp, the piezoelectric crystal is connected with a channel CH2 of the oscilloscope and used for receiving ultrasonic signals, the waveform generator CH1 is connected with the oscilloscope and used as a comparison reference of ultrasonic emission time, the waveform generator CH2 is connected with the power amplifier and connected with the ultrasonic emission probe, the initial ultrasonic receiving time duration (no tensile force or no tensile force is obtained) is measured, the bolt is installed at the position of the tensile testing machine, the tensile testing machine is started, the linear stress curve is obtained, the linear stress curve of the tensile testing machine, the linear stress curve is obtained, the linear stress curve obtained, the time difference obtained, the linear stress curve obtained by using the linear stress curve obtained, the linear stress curve obtained by the linear stress of the linear stress curve obtained by.
Step three: and detecting the stress of the bolt according to the determined relation model. A schematic diagram of the detection system is shown in fig. 3. The method comprises the following specific steps: firstly, acquiring a waveform in an unstressed state to obtain initial ultrasonic receiving time in an unstressed state; applying pretightening force to the bolt, re-collecting waveforms, and recording corresponding ultrasonic receiving time length; obtaining a detection ultrasonic time difference by using the initial ultrasonic receiving time length and the ultrasonic receiving time length corresponding to the pretightening force; and detecting the ultrasonic time difference and determining a relation model to obtain the bolt stress.
In the embodiment, the relation determining model is verified by using the strain gauge, the strain gauge is adhered to the screw rod and is connected with the strain gauge, and the stress of the bolt is measured by the strain gauge as comparison; and comparing the bolt stress obtained by utilizing the determined relation model with the bolt stress measured by the strain gauge to obtain the measurement accuracy of the determined relation model.
Claims (8)
1. A bolt stress detection method is characterized by comprising the following steps:
step S1: establishing a relation model of ultrasonic time difference and bolt stress;
step S2: a piezoelectric wafer is stuck on one end face of the bolt, an ultrasonic emission probe is placed on the other end face of the bolt to measure an ultrasonic time difference-bolt stress relation curve, unknown parameters in the relation model are solved, and a determined relation model is obtained;
step S3: and detecting the stress of the bolt by using the determined relation model.
2. The bolt stress detection method according to claim 1, wherein the relationship model is as follows:
wherein σ is bolt stress, Δ S is ultrasonic time difference, C0The ultrasonic sound velocity is the ultrasonic sound velocity in the stress-free state, E is the elastic modulus of the bolt, r' is the equivalent stress length of the bolt, K is the material coefficient of the bolt, and K is the unknown parameter.
3. The bolt stress detection method according to claim 2, wherein the bolt equivalent stress length r' is:
r ═ the distance between the nut and the bolt head + the screw diameter.
4. The bolt stress detection method according to claim 1, wherein the process of measuring the relation curve comprises the following steps:
step S21: sticking a piezoelectric wafer serving as an ultrasonic receiver on one end face of the bolt;
step S22: placing an ultrasonic emission probe on the other end face of the bolt, and fixing the ultrasonic emission probe through a clamp;
step S23: the piezoelectric wafer is connected with the processor, and the ultrasonic transmitting probe is connected with the waveform generator through the power amplifier;
step S24: measuring the initial ultrasonic receiving time length without tensile force;
step S25: stretching the bolt by a tensile testing machine, and recording the magnitude of the tensile force and the ultrasonic receiving time corresponding to different tensile forces;
step S26: and obtaining a relation curve according to the magnitude of the tensile force, the ultrasonic receiving time length corresponding to different tensile forces and the initial ultrasonic receiving time length.
5. The bolt stress detection method according to claim 4, wherein the process of obtaining the determined relation model is as follows:
step S27: performing linear fitting on the relation curve to obtain a fitting linear line;
step S28: and obtaining the material coefficient of the bolt by utilizing the fitted straight line so as to obtain a determined relation model.
6. The bolt stress detection method according to claim 4, wherein in step S23, the processor is an oscilloscope, the piezoelectric chip is connected to one channel of the oscilloscope, and the waveform generator is connected to the other channel of the oscilloscope.
7. The bolt stress detection method according to claim 1, wherein the relationship-determining model is verified by using a strain gauge, the strain gauge is adhered to the screw, and the strain gauge is connected with a strain gauge.
8. The bolt stress detection method according to claim 1, wherein the process of performing bolt stress detection by using the deterministic relationship model comprises:
step S31: measuring the initial ultrasonic receiving time length in the stress-free state;
step S32: applying pretightening force to the bolt, and recording the corresponding ultrasonic receiving time length;
step S33: obtaining a detection ultrasonic time difference by using the initial ultrasonic receiving time length and the ultrasonic receiving time length corresponding to the pretightening force;
step S34: and detecting the ultrasonic time difference and determining a relation model to obtain the bolt stress.
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| CN202010119781.1A CN111208207A (en) | 2020-02-26 | 2020-02-26 | Bolt stress detection method |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112179553A (en) * | 2020-09-09 | 2021-01-05 | 西南交通大学 | Method for ultrasonically and synchronously measuring axial force and shearing force of bolt |
| CN112461429A (en) * | 2020-11-10 | 2021-03-09 | 西南交通大学 | Ultrasonic pretightening force measurement method for low-elasticity-modulus material bolt |
| CN113155357A (en) * | 2021-03-11 | 2021-07-23 | 中国长江电力股份有限公司 | Ultrasonic measurement calibration experiment table and method for axial tensile stress of large bolt |
| CN113176031A (en) * | 2021-04-30 | 2021-07-27 | 中车青岛四方机车车辆股份有限公司 | Bolt pretightening force monitoring equipment, method and device |
| CN113588414A (en) * | 2021-08-03 | 2021-11-02 | 重庆大学 | Bolt axial stress detection method based on ultrasonic frequency spectrum energy attenuation |
| CN113932958A (en) * | 2021-10-25 | 2022-01-14 | 南京惟真智能管网科技研究院有限公司 | Pipeline stress nondestructive testing method and system based on ultrasound |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112179553A (en) * | 2020-09-09 | 2021-01-05 | 西南交通大学 | Method for ultrasonically and synchronously measuring axial force and shearing force of bolt |
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| CN112461429A (en) * | 2020-11-10 | 2021-03-09 | 西南交通大学 | Ultrasonic pretightening force measurement method for low-elasticity-modulus material bolt |
| CN112461429B (en) * | 2020-11-10 | 2022-05-27 | 西南交通大学 | Ultrasonic pretightening force measurement method for low-elasticity-modulus material bolt |
| CN113155357A (en) * | 2021-03-11 | 2021-07-23 | 中国长江电力股份有限公司 | Ultrasonic measurement calibration experiment table and method for axial tensile stress of large bolt |
| CN113176031A (en) * | 2021-04-30 | 2021-07-27 | 中车青岛四方机车车辆股份有限公司 | Bolt pretightening force monitoring equipment, method and device |
| CN113588414A (en) * | 2021-08-03 | 2021-11-02 | 重庆大学 | Bolt axial stress detection method based on ultrasonic frequency spectrum energy attenuation |
| CN113932958A (en) * | 2021-10-25 | 2022-01-14 | 南京惟真智能管网科技研究院有限公司 | Pipeline stress nondestructive testing method and system based on ultrasound |
| CN113932958B (en) * | 2021-10-25 | 2024-03-01 | 南京惟真智能管网科技研究院有限公司 | Pipeline stress nondestructive testing method and system based on ultrasound |
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Application publication date: 20200529 |