CN114636504A - Method for detecting axial stress of bolt of train braking system - Google Patents

Method for detecting axial stress of bolt of train braking system Download PDF

Info

Publication number
CN114636504A
CN114636504A CN202210151743.3A CN202210151743A CN114636504A CN 114636504 A CN114636504 A CN 114636504A CN 202210151743 A CN202210151743 A CN 202210151743A CN 114636504 A CN114636504 A CN 114636504A
Authority
CN
China
Prior art keywords
bolt
axial stress
state
ultrasonic
wave
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202210151743.3A
Other languages
Chinese (zh)
Other versions
CN114636504B (en
Inventor
张济民
张楠飞
许立超
周和超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tongji University
Original Assignee
Tongji University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tongji University filed Critical Tongji University
Priority to CN202210151743.3A priority Critical patent/CN114636504B/en
Publication of CN114636504A publication Critical patent/CN114636504A/en
Application granted granted Critical
Publication of CN114636504B publication Critical patent/CN114636504B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/24—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed
    • G01L5/246—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed using acoustic waves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention relates to a method for detecting axial stress of a bolt of a train braking system, which comprises the following steps: deducing a calculation formula of the axial stress of the bolt in a calibration state by adopting an ultrasonic pulse reflection method based on the acoustic elasticity principle; based on the stress relation between the bolt in the zero-load initial state and the bolt in the calibration state and the bolt in the measurement state, combining the effective clamping length of the bolt, and deducing a calculation formula of the axial stress of the bolt in the measurement state by adopting an ultrasonic wave speed temperature compensation correction mode; and measuring material parameters, structural data and ultrasonic longitudinal and transverse wave measurement data corresponding to the actual bolt, and calculating to obtain the axial stress of the actual bolt by combining a bolt axial stress calculation formula in a calibration state and a bolt axial stress calculation formula in a measurement state. Compared with the prior art, the method and the device realize the purpose of carrying out quantitative analysis on the axial stress of the bolt, and can efficiently and conveniently detect the axial stress of the bolt.

Description

Method for detecting axial stress of bolt of train braking system
Technical Field
The invention relates to the technical field of bolt stress detection, in particular to a method for detecting axial stress of a bolt of a train braking system.
Background
Along with the rapid development of rail transit, the requirements on the stability, safety and reliability of a train are gradually improved, the train must rely on a braking system to adjust the running speed of the train in high-speed running so that the train can be stopped accurately in time, and the train braking system is the fundamental guarantee of the train running safety.
At present, a train braking system mostly adopts a disc braking mode, compared with other braking modes, disc braking has larger braking force, the size and the mass under the same braking torque are smaller, the thermal stability is high, and the application is wider. In a disc brake structure, a brake disc is generally fixed to an axle by a plurality of high-strength bolts, and thus, the bolts are one of core fasteners of the brake disc. However, when a train runs, the brake disc can follow the wheel pair to run at a high speed, and meanwhile, the brake disc is influenced by heat generated by friction braking and track vibration, so that the axial stress of the fastening bolt of the brake disc is limited by various factors, and the service life of the bolt is further influenced.
Therefore, the evaluation of the prior art for the bolt life health mainly depends on the anti-loosening marking method: for bolted connections of a size greater than M8, check marks are made on the nut and bolt head and on the fastened piece in contrasting colors (e.g., red and blue) using a marker. The method can directly observe the loosening condition, has low cost, but has the following defects:
firstly, the anti-loosening mark can only be qualitatively judged, the offset of the bolt cannot be quantitatively analyzed, and the bolt loosening condition can only be judged by a professional according to experience, so that a misjudgment space exists;
secondly, the operation is inconvenient, the user needs to check the marks at fixed intervals, the workload is large, and the automation is difficult to realize.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for detecting the axial stress of a bolt of a train braking system, so that the quantitative analysis of the axial stress of the bolt is realized, and the axial stress of the bolt can be detected efficiently and conveniently.
The purpose of the invention can be realized by the following technical scheme: a method for detecting axial stress of a bolt of a train braking system comprises the following steps:
s1, deducing a calculation formula of the axial stress of the bolt in a calibration state by adopting an ultrasonic pulse reflection method based on the principle of acoustic elasticity;
s2, deriving a calculation formula of the axial stress of the bolt in the measuring state by combining the effective clamping length of the bolt and adopting an ultrasonic wave speed temperature compensation correction mode based on the stress relation between the bolt in the zero-load initial state and the calibration state and the bolt in the measuring state;
and S3, measuring material parameters, structural data and ultrasonic longitudinal and transverse wave measurement data corresponding to the actual bolt, and calculating to obtain the axial stress of the actual bolt by combining a bolt axial stress calculation formula in a calibration state and a bolt axial stress calculation formula in a measurement state.
Further, the step S1 specifically includes the following steps:
s11, regarding the stress state of the bolt as a unidirectional stress state, and determining the relation between the propagation speed of ultrasonic longitudinal waves and transverse waves in the bolt and the material coefficient and the axial stress of the bolt based on the acoustic-elastic principle;
and S12, further deducing a calculation formula of the axial stress of the bolt in a calibration state according to the relation between the propagation speeds of the ultrasonic longitudinal wave and the ultrasonic transverse wave in the bolt and the coefficient of the bolt material and the axial stress of the bolt.
Further, the relation among the propagation speed of the ultrasonic longitudinal wave in the bolt, the material coefficient of the bolt and the axial stress of the bolt is as follows:
Figure BDA0003510650520000021
wherein, VzIs the propagation speed of ultrasonic longitudinal wave in the bolt, alpha is the Lame elastic constant, mu is the shear modulus, rho0Is the density of the bolt material, σ is the axial stress of the bolt, Vz0The propagation speed of the ultrasonic longitudinal wave of the bolt is not under the condition of axial stress;
the relation among the ultrasonic transverse wave propagation speed in the bolt, the bolt material coefficient and the bolt axial stress is as follows:
Figure BDA0003510650520000022
wherein, VhIs the propagation velocity of ultrasonic transverse wave in the bolt, Vh0The propagation speed of the ultrasonic transverse wave is the propagation speed of the ultrasonic transverse wave when the bolt is not under the axial stress.
Further, the calculation formula of the axial stress of the bolt in the calibration state is specifically as follows:
Figure BDA0003510650520000031
Figure BDA0003510650520000032
Figure BDA0003510650520000033
Figure BDA0003510650520000034
Figure BDA0003510650520000035
wherein σ1For the axial stress of the bolt in the calibration state, M0And MσA first relevant parameter for the material of the bolt in a state of no axial stress and in a state of axial stress,
Figure BDA0003510650520000036
and
Figure BDA0003510650520000037
the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is not subjected to axial stress is respectively,
Figure BDA0003510650520000038
and
Figure BDA0003510650520000039
respectively the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is subjected to axial stress, KzAnd KhThe second related parameters of the material corresponding to the ultrasonic longitudinal wave and the ultrasonic transverse wave respectively, E is Young modulus, AzAnd AhThe propagation proportionality coefficients of the ultrasonic longitudinal wave and the ultrasonic transverse wave are respectively.
Further, the step S2 specifically includes the following steps:
s21, determining the effective fastening length of the bolt;
s22, deducing a calculation formula of the axial stress of the bolt in the measurement state before correction according to the relation among the stress of the bolt in the zero-load initial state, the calibration state and the measurement state and the fastening effective length of the bolt;
s23, deducing a wave velocity temperature compensation formula when ultrasonic waves propagate in the bolt according to the fact that the wave velocity of the ultrasonic waves and the temperature are in a direct proportion relation;
and S24, combining the wave speed temperature compensation formula with the bolt axial stress calculation formula under the measurement state before correction to obtain the bolt axial stress calculation formula under the measurement state containing temperature compensation.
Further, the effective fastening length of the bolt in the step S21 is the bolt clamping length plus 1/2 bolt diameter plus 1/3 bolt diameter.
Further, the calculation formula of the axial stress of the bolt in the measurement state before the correction in the step S22 is specifically as follows:
Figure BDA00035106505200000310
wherein σ2For correcting the axial stress of the bolt in the measured state before correction,/0Is the original length of the bolt in the initial state, l1、lk1、le1Respectively the length, the clamping length and the fastening effective length of the bolt in a calibration state2For measuring the length of the bolt in the state, d is the boltDiameter.
Further, the wave speed temperature compensation formula is specifically as follows:
Vbc＝(-0.0001b)·T+(1+0.0001b)·Vb
wherein, VbcFor the ultrasonic velocity temperature compensation value, Vb、TbThe wave velocity and the temperature in a calibration state are respectively, and T is the temperature of the test point.
Further, the calculation formula of the axial stress of the bolt in the measurement state containing the temperature compensation is specifically as follows:
Figure BDA0003510650520000041
wherein σ2 ’For measuring the axial stress, T, of the bolt in the state of measurement with temperature compensation2For measuring the actual temperature in the state, t2The propagation time of the ultrasonic wave in the bolt under the state is measured.
Further, the step S3 specifically includes the following steps:
s31, randomly taking out part of samples to perform a calibration experiment aiming at the same batch of bolts so as to obtain the bolt material parameters: lame elastic constant alpha, shear modulus mu and bolt material density rho0Young's modulus E;
s32, measuring the original length l of the bolt to be measured0And a bolt diameter d;
s33, applying a set torque to the bolt to be tested to enable the bolt to be tested to enter a calibration state from an initial state, carrying out ultrasonic longitudinal and transverse wave measurement on the bolt in the calibration state, calculating to obtain the axial stress applied to the bolt to be tested in the calibration state based on a bolt axial stress calculation formula in the calibration state, and recording the length and the clamping length of the bolt to be tested in the calibration state;
s34, determining the temperature and the ultrasonic wave speed in a calibration state through tests;
and S35, measuring the actual temperature and the propagation time of the ultrasonic waves in the bolt, and calculating the axial stress of the actual bolt based on a bolt axial stress calculation formula under the measurement state with temperature compensation by combining the relevant parameters obtained in the steps S31-S34.
Compared with the prior art, the method has the advantages that the ultrasonic bolt axial stress calculation formula based on the acoustoelastic principle is gradually deduced according to the bolt axial stress by combining the initial state, the calibration state and the measurement state of the bolt, so that technical innovation from qualitative analysis to quantitative analysis is realized, the operability is high, a data base can be provided for further quantitative index analysis, and the bolt axial stress can be efficiently and conveniently detected;
in addition, because the bolt material and each parameter of the bolt in the initial and calibration states can be determined in advance, the axial stress can be directly calculated after the data in the bolt measurement state is measured, the method is efficient and rapid, and the automation is convenient to realize;
the bolt has the advantage of high universality, can show good applicability to bolts of different materials, lengths and application working conditions, and has a wide application range.
Drawings
FIG. 1 is a schematic flow diagram of the process of the present invention;
FIG. 2 is a flow chart illustrating the derivation of the calculation of axial stress of the bolt according to the embodiment;
FIG. 3 is a schematic diagram showing the length change of the bolt in the initial state, the calibration state and the measurement state;
FIG. 4 is a diagram illustrating a specific process applied in the example;
FIG. 5 is a fitting curve of the axial stress detection result of the bolt and the actual value in the embodiment.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in FIG. 1, the method for detecting the axial stress of the bolt of the train braking system comprises the following steps:
s1, deducing a calculation formula of the axial stress of the bolt in a calibration state by adopting an ultrasonic pulse reflection method based on the principle of acoustic elasticity, specifically:
s11, regarding the stress state of the bolt as a unidirectional stress state, and determining the relation between the propagation speed of the ultrasonic longitudinal wave and the propagation speed of the transverse wave in the bolt and the coefficient of the bolt material and the axial stress of the bolt based on the principle of acoustic elasticity, wherein the relation between the propagation speed of the ultrasonic longitudinal wave in the bolt and the coefficient of the bolt material and the axial stress of the bolt is as follows:
Figure BDA0003510650520000051
in the formula, VzIs the propagation speed of ultrasonic longitudinal wave in the bolt, alpha is the Lame elastic constant, mu is the shear modulus, rho0Is the density of the bolt material, σ is the axial stress of the bolt, Vz0The propagation speed of the ultrasonic longitudinal wave of the bolt is not under the condition of axial stress;
the relation among the ultrasonic transverse wave propagation speed in the bolt, the bolt material coefficient and the bolt axial stress is as follows:
Figure BDA0003510650520000052
in the formula, VhIs the propagation velocity of ultrasonic transverse wave in the bolt, Vh0The propagation speed of ultrasonic transverse waves of the bolt is not influenced by the axial stress state;
s12, further deducing a calculation formula of the axial stress of the bolt in a calibration state according to the relation between the propagation speeds of the ultrasonic longitudinal wave and the ultrasonic transverse wave in the bolt and the coefficient of the bolt material and the axial stress of the bolt:
Figure BDA0003510650520000061
Figure BDA0003510650520000062
Figure BDA0003510650520000063
Figure BDA0003510650520000064
Figure BDA0003510650520000065
in the formula, σ1For the axial stress of the bolt in the calibration state, M0And MσFirst relevant parameters of the material of the bolt in a state of no axial stress and in a state of axial stress are respectively provided,
Figure BDA0003510650520000066
and
Figure BDA0003510650520000067
the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is not subjected to axial stress is respectively,
Figure BDA0003510650520000068
and
Figure BDA0003510650520000069
respectively the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is subjected to axial stress, KzAnd KhThe second related parameters of the material corresponding to the ultrasonic longitudinal wave and the ultrasonic transverse wave respectively, E is Young modulus, AzAnd AhThe propagation proportionality coefficients of the ultrasonic longitudinal wave and the ultrasonic transverse wave are respectively;
s2, based on the stress relation between the bolt in the zero-load initial state and the calibration state and the bolt in the measurement state, combining the effective clamping length of the bolt, and adopting an ultrasonic wave speed temperature compensation correction mode, deriving a calculation formula of the axial stress of the bolt in the measurement state, specifically:
s21, determining the effective fastening length of the bolt, wherein the effective fastening length of the bolt is the bolt clamping length plus 1/2 bolt diameter plus 1/3 bolt diameter;
s22, according to the relation among the bolt stresses in the zero-load initial state, the calibration state and the measurement state, combining the fastening effective length of the bolt, deducing a calculation formula of the bolt axial stress in the measurement state before correction:
Figure BDA00035106505200000610
in the formula, σ2For correcting the axial stress of the bolt in the measured state before correction,/0Is the original length of the bolt in the initial state, l1、lk1、le1Respectively the length, clamping length and fastening effective length of the bolt in a calibration state2D is the bolt diameter for the length of the bolt in the measuring state;
s23, deriving a wave velocity temperature compensation formula when the ultrasonic wave propagates in the bolt according to the fact that the ultrasonic wave velocity and the temperature are in a direct proportion relation:
Vbc＝(-0.0001b)·T+(1+0.0001b)·Vb
in the formula, VbcFor the ultrasonic velocity temperature compensation value, Vb、TbRespectively the wave velocity and the temperature in a calibration state, and T is the temperature of the test point;
s24, combining the wave speed temperature compensation formula with the bolt axial stress calculation formula under the measurement state before correction to obtain the bolt axial stress calculation formula under the measurement state containing temperature compensation:
Figure BDA0003510650520000071
in the formula, σ2 ’For measuring the axial stress, T, of the bolt in the state of measurement with temperature compensation2For measuring the actual temperature in the state, t2Measuring the propagation time of ultrasonic waves in the bolt in a measuring state;
s3, determining material parameters, structural data and ultrasonic longitudinal and transverse wave measurement data corresponding to the actual bolt, and calculating to obtain the axial stress of the actual bolt by combining a bolt axial stress calculation formula in a calibration state and a bolt axial stress calculation formula in a measurement state, specifically:
s31, randomly taking out part of samples to perform a calibration experiment aiming at the same batch of bolts so as to obtain the bolt material parameters: lame elastic constant alpha, shear modulus mu and bolt material density rho0Young's modulus E;
s32, measuring the original length l of the bolt to be measured0And a bolt diameter d;
s33, applying a set torque to the bolt to be tested to enable the bolt to be tested to enter a calibration state from an initial state, carrying out ultrasonic longitudinal and transverse wave measurement on the bolt in the calibration state, calculating the axial stress applied to the bolt to be tested in the calibration state based on a bolt axial stress calculation formula in the calibration state, and recording the length and the clamping length of the bolt to be tested in the calibration state;
s34, determining the temperature and the ultrasonic wave speed in a calibration state through tests;
and S35, measuring the actual temperature and the propagation time of the ultrasonic wave in the bolt, combining the relevant parameters obtained in the steps S31-S34, and calculating the axial stress of the actual bolt based on a bolt axial stress calculation formula under the measurement state with temperature compensation.
In this embodiment, as shown in fig. 2, the above technical solution is mainly included:
the method comprises the following steps: based on the principle of acoustic elasticity, namely that the stress in a solid is related to the sound velocity, a pulse reflection method in an ultrasonic measurement method is selected, and a corresponding relation between the bolt axial stress and the ultrasonic longitudinal and transverse wave propagation time of a specific material in a calibration state is deduced according to the relation between the propagation velocity of the ultrasonic longitudinal and transverse waves and the axial stress and the material. The method specifically comprises the following steps:
a) regarding the stress state of the bolt as a unidirectional stress state, V0Indicates no axial stress in the bolt (σ ═ i)0) Velocity of propagation of ultrasonic longitudinal wave in time, VσRepresents the propagation velocity of ultrasonic longitudinal wave when axial stress (sigma > 0) exists in the bolt, and can obtain (alpha, mu, rho) according to the acoustic elasticity principle0And E are material coefficients):
Figure BDA0003510650520000081
Figure BDA0003510650520000082
in the formula: alpha-Laume elastic constant; μ — shear modulus; rho0-bolt material density; E-Young's modulus;
further obtain
Figure BDA0003510650520000083
Figure BDA0003510650520000084
The "-" in the formula indicates that the velocity of the ultrasonic longitudinal wave propagating along the tensile stress direction decreases as the stress increases, wherein a is a proportionality coefficient.
At the same time, the length of the bolt also changes under the effect of the stress, which changes have an effect on the time for which the ultrasonic waves propagate in the bolt. If L is used0And LσWhen σ is 0 and σ > 0, respectively, the length of the bolt is expressed as:
Figure BDA0003510650520000085
the time required for the ultrasonic longitudinal wave to reciprocate once along the whole length of the bolt is t when the sigma is 0 and the sigma is more than 0 respectively0And tσThen, there are:
Figure BDA0003510650520000086
Figure BDA0003510650520000087
and the relative time rate of change:
Figure BDA0003510650520000088
both experimental results and theoretical analysis indicate that A is a very small constant and that A σ < 1. Therefore, 1 σ ≈ 1 can be approximately assumed, if let K1/E + A, one can obtain:
Figure BDA0003510650520000089
or
Figure BDA00035106505200000810
b) In order to avoid the problem that the length of a part of a fastening bolt under the stress-free condition is difficult to measure, the method (a) is extended to an ultrasonic longitudinal and transverse wave measuring method, namely, the method is popularized to ultrasonic longitudinal waves and transverse waves, and the following steps are obtained:
Figure BDA0003510650520000091
Figure BDA0003510650520000092
Figure BDA0003510650520000093
Figure BDA0003510650520000094
subscripts z and h in the formula represent longitudinal and transverse waves, respectively, and subscripts 0 and σ represent axially unstressed and stressed states, respectively, of the bolt.
Defining a material-related parameter M of a bolt in an axially unstressed state and in an axially stressed state0And Mσ:
Figure BDA0003510650520000095
Figure BDA0003510650520000096
Substituting the formula to obtain:
Figure BDA0003510650520000097
in practical application, the propagation time of the ultrasonic transverse wave in the bolt under the calibration state is measured
Figure BDA0003510650520000098
And propagation time of ultrasonic longitudinal wave in bolt
Figure BDA0003510650520000099
The axial stress of the bolt in the calibration state can be calculated according to the formula.
Step two: and (3) deducing a calculation formula of the axial stress of the bolt in the measuring state based on the stress relation between the bolt in the zero-load initial state and the calibration state and the bolt in the measuring state by combining the effective clamping length of the actual bolt. The method specifically comprises the following steps:
a) calculating effective bolt length
In the case of a screw-nut connection or a blind-hole connection, the effective bolt-fastening length is defined by the bolt-clamping length plus 1/2 bolt diameter plus 1/3 bolt diameter.
b) The bolt to be tested is divided into three states (as shown in fig. 3): an initial state when not subjected to axial stress, a calibration state when subjected to known axial stress, and a measurement state when subjected to unknown axial stress.
Assume that the original length of the bolt is l0The bolt is not subjected to any axial stress at this time. In a calibration state, a certain torque is applied to the bolt, so that the bolt is subjected to a certain axial stress sigma1And the length of the bolt is l1Clamping length is lk1Fastening effective length of le1. Under the measuring state, the bolt can be subjected to axial stress sigma during normal working2And the length of the bolt is l2Clamping length is lk2Fastening effective length of le2. The acoustic elasticity principle can be used as follows:
Figure BDA0003510650520000101
Figure BDA0003510650520000102
further, it can be obtained:
Figure BDA0003510650520000103
according to the bolt length variation relation, considering a bolt effective length calculation method, the following steps are obtained:
le2＝le1-l1+l2
le1＝lk1+5d/6
substituting the formula as follows:
Figure BDA0003510650520000104
c) ultrasonic wave speed temperature compensation correction
Test data show that the ultrasonic wave speed is reduced by 1% for every 100 ℃ rise of the thermal state material. As can be seen from an empirical model between the ultrasonic wave velocity and the temperature, the ultrasonic wave velocity and the temperature are in a direct proportional relationship, and therefore, an assumption can be made.
Recording the wave velocity in the calibration state as VbAt a temperature of TbThe ultrasonic wave velocity after temperature compensation in the solid medium is VbcAnd the temperature of the test point is T, and the following assumptions are provided:
Vbc＝kbc·+B
in the formula, kbcAnd B are two constants. And k can be obtained from the above assumptionsbcExpression:
Figure BDA0003510650520000105
will be the wave velocity V under the calibration statebAnd temperature TbBy substituting the above formula, the following can be obtained simultaneously:
B＝0.0001·Vb·b+Vb
further, a wave speed temperature compensation formula when the ultrasonic waves are transmitted in the bolt can be deduced;
Vbc＝(-0.0001b)·T+(1+0.0001b)·Vb
substituting the wave speed temperature compensation formula into the formula obtained in the step b) to obtain a bolt axial stress calculation formula which is actually applied;
Figure BDA0003510650520000106
step three: as shown in FIG. 4, the parameters required by calculation are measured in engineering application, and axial stress calculation is completed.
a) Aiming at the same batch of bolts, randomly taking out part of sample pieces to carry out a calibration experiment to obtain the material parameters alpha, mu and rho of the bolts0、E。
b) Determination of the original length l of the bolt0And bolt diameter d.
c) Applying a certain torque to the bolt to enter the calibrationStatus. Recording ultrasonic echo time by an ultrasonic longitudinal and transverse wave measuring method, and solving the axial stress sigma to which the bolt is subjected according to a formula obtained in the step one1. Note that the length of the bolt is l at this time1Clamping length is lk1. Meanwhile, the temperature T under the calibration state is determined through experimentsbAnd the ultrasonic wave velocity Vb。
d) Substituting the measured data of the steps a), b) and c) into a derivation calculation formula to obtain the temperature T which is actually measured2And the propagation time t of the ultrasonic wave in the bolt2And (4) a related calculation formula of axial stress of the bolt.
e) Measuring the actual temperature T2And the propagation time t of the ultrasonic wave in the bolt2And obtaining an axial stress algorithm of the bolt after ultrasonic wave speed temperature compensation, and obtaining a calculation result.
To verify the algorithm accuracy of the present invention, the present embodiment was verified by a torque tightening method. A10.9-grade carbon steel bolt with a bolt M14 multiplied by 110mm commonly used in a braking system is selected as a research object, an axial force is applied to the bolt through a digital display torque wrench, and the actual axial stress is calculated. Then, under the same axial force condition, the axial stress of the bolt is also measured by using an ultrasonic bolt axial stress algorithm based on the acoustic elasticity principle, the experimental results of the two detection methods are compared (as shown in table 1), and curve fitting is performed in MATLAB.
TABLE 1
Figure BDA0003510650520000111
As can be seen from the comparison of the data in table 1, when the axial stress of the bolt is small, the error of the algorithm is large, because when the axial stress of the bolt is small in the initial stage, the dislocation and the slippage in the bolt do not form a certain scale, and the change of the microstructure is not enough to be detected; when the axial stress of the bolt is increased to a certain degree, the error is obviously reduced, and when the axial stress is greater than 150MPa, the algorithm error is always within 5 percent, so that the requirement of actual detection is met. As can be seen from the fitting straight line of FIG. 5, the calculated value fitting curve of the ultrasonic bolt axial stress algorithm provided by the invention is approximately coincident with the actual value fitting curve of the bolt axial stress obtained by the experiment, and the accuracy of the method provided by the invention is fully proved.

Claims (10)

1. The method for detecting the axial stress of the bolt of the train braking system is characterized by comprising the following steps of:
s1, deducing a calculation formula of the axial stress of the bolt in a calibration state by adopting an ultrasonic pulse reflection method based on the principle of acoustic elasticity;
s2, deriving a calculation formula of the axial stress of the bolt in the measuring state by combining the effective clamping length of the bolt and adopting an ultrasonic wave speed temperature compensation correction mode based on the stress relation between the bolt in the zero-load initial state and the calibration state and the bolt in the measuring state;
and S3, measuring material parameters, structural data and ultrasonic longitudinal and transverse wave measurement data corresponding to the actual bolt, and calculating to obtain the axial stress of the actual bolt by combining a bolt axial stress calculation formula in a calibration state and a bolt axial stress calculation formula in a measurement state.
2. The method for detecting the axial stress of the bolt of the train braking system according to claim 1, wherein the step S1 specifically comprises the following steps:
s11, regarding the stress state of the bolt as a unidirectional stress state, and determining the relation between the propagation speed of ultrasonic longitudinal waves and transverse waves in the bolt and the material coefficient and the axial stress of the bolt based on the acoustic-elastic principle;
and S12, further deducing a calculation formula of the axial stress of the bolt in a calibration state according to the relation between the propagation speeds of the ultrasonic longitudinal wave and the ultrasonic transverse wave in the bolt and the coefficient of the bolt material and the axial stress of the bolt.
3. The method for detecting the axial stress of the bolt of the train braking system according to claim 2, wherein the relation among the propagation speed of the ultrasonic longitudinal wave in the bolt, the material coefficient of the bolt and the axial stress of the bolt is as follows:
Figure FDA0003510650510000011
wherein, VzIs the propagation speed of ultrasonic longitudinal wave in the bolt, alpha is the Lame elastic constant, mu is the shear modulus, rho0Is the density of the bolt material, σ is the axial stress of the bolt, Vz0The propagation speed of the ultrasonic longitudinal wave of the bolt is not under the condition of axial stress;
the relation among the ultrasonic transverse wave propagation speed in the bolt, the bolt material coefficient and the bolt axial stress is as follows:
Figure FDA0003510650510000012
wherein, VhIs the propagation velocity, V, of ultrasonic transverse waves in the bolth0The propagation speed of ultrasonic transverse wave is the propagation speed of the ultrasonic transverse wave when the bolt is not under the axial stress state.
4. The method for detecting the axial stress of the bolt of the train braking system according to claim 3, wherein the calculation formula of the axial stress of the bolt in the calibration state is specifically as follows:
Figure FDA0003510650510000021
Figure FDA0003510650510000022
Figure FDA0003510650510000023
Figure FDA0003510650510000024
Figure FDA0003510650510000025
wherein σ1For the axial stress of the bolt in the calibration state, M0And MσFirst relevant parameters of the material of the bolt in a state of no axial stress and in a state of axial stress are respectively provided,
Figure FDA0003510650510000026
and
Figure FDA0003510650510000027
the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is not subjected to axial stress is respectively,
Figure FDA0003510650510000028
and
Figure FDA0003510650510000029
respectively the propagation time of ultrasonic transverse wave and ultrasonic longitudinal wave in the bolt under the condition that the bolt is subjected to axial stress, KzAnd KhThe second related parameters of the material corresponding to the ultrasonic longitudinal wave and the ultrasonic transverse wave respectively, E is Young modulus, AzAnd AhThe propagation proportionality coefficients of the ultrasonic longitudinal wave and the ultrasonic transverse wave are respectively.
5. The method for detecting the axial stress of the bolt of the train braking system according to claim 1, wherein the step S2 specifically comprises the following steps:
s21, determining the effective fastening length of the bolt;
s22, deducing a calculation formula of the axial stress of the bolt in the measurement state before correction according to the relation among the stress of the bolt in the zero-load initial state, the calibration state and the measurement state and the fastening effective length of the bolt;
s23, deducing a wave velocity temperature compensation formula when ultrasonic waves propagate in the bolt according to the fact that the wave velocity of the ultrasonic waves and the temperature are in a direct proportion relation;
and S24, combining the wave speed temperature compensation formula with the bolt axial stress calculation formula under the measurement state before correction to obtain the bolt axial stress calculation formula under the measurement state containing temperature compensation.
6. The method for detecting axial stress of a bolt of a train brake system according to claim 5, wherein the effective fastening length of the bolt in the step S21 is the bolt clamping length plus 1/2 bolt diameter plus 1/3 bolt diameter.
7. The method for detecting the axial stress of the bolt of the train braking system according to claim 6, wherein a calculation formula of the axial stress of the bolt in the measurement state before the correction in the step S22 is specifically as follows:
Figure FDA00035106505100000210
wherein σ2For correcting the axial stress, σ, of the bolt in the measured state1For the axial stress of the bolt in the calibration state, /)0Is the original length of the bolt in the initial state, l1、lk1、le1Respectively the length, the clamping length and the fastening effective length of the bolt in a calibration state2To measure the length of the bolt in the state, d is the bolt diameter.
8. The method for detecting the axial stress of the bolt of the train braking system according to claim 7, wherein the wave speed temperature compensation formula is specifically as follows:
Vbc＝(-0.0001Vb)·T+(1+0.0001Tb)·Vb
wherein, VbcFor the ultrasonic velocity temperature compensation value, Vb、TbRespectively wave velocity in the calibration state andand the temperature T is the temperature of the test point.
9. The method for detecting the axial stress of the bolt of the train braking system according to claim 8, wherein a calculation formula of the axial stress of the bolt in the measurement state with the temperature compensation is specifically as follows:
Figure FDA0003510650510000031
wherein, σ'2For measuring the axial stress, T, of the bolt in the state of measurement with temperature compensation2For measuring the actual temperature in the state, t2The propagation time of the ultrasonic wave in the bolt under the state is measured.
10. The method for detecting the axial stress of the bolt of the train braking system according to claim 5, wherein the step S3 specifically comprises the following steps:
s31, randomly taking out part of samples to perform a calibration experiment aiming at the same batch of bolts so as to obtain the bolt material parameters: lame elastic constant alpha, shear modulus mu and bolt material density rho0Young's modulus E;
s32, measuring the original length l of the bolt to be measured0And a bolt diameter d;
s33, applying a set torque to the bolt to be tested to enable the bolt to be tested to enter a calibration state from an initial state, carrying out ultrasonic longitudinal and transverse wave measurement on the bolt in the calibration state, calculating the axial stress applied to the bolt to be tested in the calibration state based on a bolt axial stress calculation formula in the calibration state, and recording the length and the clamping length of the bolt to be tested in the calibration state;
s34, determining the temperature and the ultrasonic wave speed in a calibration state through tests;
and S35, measuring the actual temperature and the propagation time of the ultrasonic wave in the bolt, combining the relevant parameters obtained in the steps S31-S34, and calculating the axial stress of the actual bolt based on a bolt axial stress calculation formula under the measurement state with temperature compensation.
CN202210151743.3A 2022-02-18 2022-02-18 Method for detecting axial stress of bolts of train braking system Active CN114636504B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210151743.3A CN114636504B (en) 2022-02-18 2022-02-18 Method for detecting axial stress of bolts of train braking system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210151743.3A CN114636504B (en) 2022-02-18 2022-02-18 Method for detecting axial stress of bolts of train braking system

Publications (2)

Publication Number Publication Date
CN114636504A true CN114636504A (en) 2022-06-17
CN114636504B CN114636504B (en) 2023-08-29

Family

ID=81946215

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210151743.3A Active CN114636504B (en) 2022-02-18 2022-02-18 Method for detecting axial stress of bolts of train braking system

Country Status (1)

Country Link
CN (1) CN114636504B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115342955A (en) * 2022-08-03 2022-11-15 哈尔滨工业大学 Stress high-precision measurement method and system based on echo amplitude adaptive weighting compensation

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4899591A (en) * 1987-09-11 1990-02-13 Sps Technologies, Inc. Ultrasonic load indicating member, apparatus and method
CN2226289Y (en) * 1995-03-28 1996-05-01 同济大学 Ultrasonic measurer for axial fastening stress of bolt
RU2146818C1 (en) * 1999-06-22 2000-03-20 Чургель Анатолий Олегович Method determining characteristics of stress-deformed state of structural materials
CN110967143A (en) * 2019-11-12 2020-04-07 北京理工大学 Portable bolt fastening force ultrasonic detection coefficient calibration device
CN111693190A (en) * 2020-08-06 2020-09-22 浙江中自庆安新能源技术有限公司 Bolt axial stress measuring device and method based on ultrasonic waves
CN113701930A (en) * 2021-09-06 2021-11-26 哈尔滨工业大学 High-strength bolt shear stress detection method based on ultrasonic transverse waves

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4899591A (en) * 1987-09-11 1990-02-13 Sps Technologies, Inc. Ultrasonic load indicating member, apparatus and method
CN2226289Y (en) * 1995-03-28 1996-05-01 同济大学 Ultrasonic measurer for axial fastening stress of bolt
RU2146818C1 (en) * 1999-06-22 2000-03-20 Чургель Анатолий Олегович Method determining characteristics of stress-deformed state of structural materials
CN110967143A (en) * 2019-11-12 2020-04-07 北京理工大学 Portable bolt fastening force ultrasonic detection coefficient calibration device
CN111693190A (en) * 2020-08-06 2020-09-22 浙江中自庆安新能源技术有限公司 Bolt axial stress measuring device and method based on ultrasonic waves
CN113701930A (en) * 2021-09-06 2021-11-26 哈尔滨工业大学 High-strength bolt shear stress detection method based on ultrasonic transverse waves

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
江泽涛, 张少钦, 胡景春, 朱士明: "微机化的纵横波螺栓轴向应力检测仪研制", 固体力学学报, no. 04 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115342955A (en) * 2022-08-03 2022-11-15 哈尔滨工业大学 Stress high-precision measurement method and system based on echo amplitude adaptive weighting compensation

Also Published As

Publication number Publication date
CN114636504B (en) 2023-08-29

Similar Documents

Publication Publication Date Title
US11131579B2 (en) Piezoelectric patch-based real-time and high-precision bolt preload detection method and system
US7360435B2 (en) Ultrasonic control of bolt tightening
US4333351A (en) Method and apparatus for measuring the residual tension in a stud or a bolt
CN113701930B (en) High-strength bolt shear stress detection method based on ultrasonic transverse waves
US20090235748A1 (en) Acoustic method and system of measuring material loss from a solid structure, uses thereof and a software product
Fukuoka et al. Acoustoelastic stress analysis of residual stress in a patch-welded disk: Sing-around measurements of transit time of ultrasonic shear waves are used to measure residual-stress distributions in a patch-welded circular plate made of mild steel
CN111208207A (en) Bolt stress detection method
GB2037430A (en) Method of indirect measurement of bolt or screw pre- stressing
Johnson et al. An ultrasonic method for determining axial stress in bolts
CN114636504A (en) Method for detecting axial stress of bolt of train braking system
CN111693190A (en) Bolt axial stress measuring device and method based on ultrasonic waves
Doyle An experimental method for determining the location and time of initiation of an unknown dispersing pulse
US6672141B2 (en) Viscoelastic characteristic value-measuring apparatus and method of measuring viscoelastic characteristic value
CN107490446B (en) Ultrasonic nondestructive testing method for stress of high-speed rail wheel pair tread
CN116956644B (en) Rail longitudinal stress detection method based on ultrasonic guided wave characteristics
JP4088342B2 (en) Method for determining the axial load of an elongated member
CN117077441B (en) Bolt axial stress double-wave calculation method
JPH11218452A (en) Method and apparatus for measuring axial tension
CN115855350B (en) Bolt axial force measuring method based on combination of primary trailing wave and transverse wave
JPH01131422A (en) Detecting method for loosed bolt
RU2112235C1 (en) Method for measuring attenuation variables of elastic waves
CN114878042A (en) Device and method for measuring axial stress of circular tube based on torsional mode ultrasonic guided waves
JPH10153585A (en) Surface layer evaluating method and apparatus therefor
JPH11166870A (en) Axial stress measuring method and device
JP3632084B2 (en) Ultrasonic thickness measurement method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant