Absolute stress detection system and method for in-service curved steel components

Abstract

The present invention relates to a system and method for detecting absolute stress of in-service curved steel components. The system comprises an ultrasonic generator, an annular curvature sensor, a digital oscilloscope, and a host computer. The annular curvature sensor comprises a first transmitting ultrasonic probe, a second transmitting ultrasonic probe, a third transmitting ultrasonic probe, a first receiving ultrasonic probe, a second receiving ultrasonic probe, a third receiving ultrasonic probe, and a fixed mold. Each transmitting ultrasonic probe and each receiving ultrasonic probe are mounted on the fixed mold. The ultrasonic generator is connected to the annular curvature sensor, stimulating each transmitting ultrasonic probe of the annular curvature sensor to generate an ultrasonic longitudinal wave signal. Each receiving ultrasonic probe receives a critically refracted longitudinal wave signal corresponding to the ultrasonic longitudinal wave signal passing through the in-service curved steel component and transmits the signal to the digital oscilloscope and the host computer. The present invention achieves nondestructive detection of absolute stress of in-service curved steel components with high detection accuracy.

Description

Technical Field

[0001] The present invention relates to the field of stress detection of steel components, and in particular to an absolute stress detection system and method for in-service curved steel components. Background Art

[0002] Structural steel is widely used in construction and bridge engineering due to its advantages such as high strength, good plasticity and toughness, and good assembly. In particular, high-rise steel structures and large-span structures often use steel components as the main load-bearing components. As an important component in steel structures, the safety performance of curved steel components plays an important role in the construction, use and maintenance of the entire structure. Under the influence of environmental erosion, fatigue loads and natural disasters, curved steel components may produce stress redistribution due to local deformation or damage. Detecting the internal stress of curved steel components can efficiently and accurately find the damage inside the curved steel components, and take corresponding preventive measures to avoid accidents. Therefore, the internal stress information of curved steel structures is an important indicator for evaluating the safety status of structures, and it is necessary to master the detection technology of the internal stress status of in-service curved steel structures.

[0003] Currently, in order to understand the stress state and mechanical properties of steel components, it is common to test the absolute stress of steel components to detect stress concentration and damage points of the components.

[0004] Existing stress nondestructive testing methods include strain gauges, fiber Bragg gratings, X-rays, neutron diffraction, magnetism, and ultrasonics. These methods, among others, suffer from low accuracy, limited applicability, and high costs, due to their limited ability to measure stress changes in steel components over a period of time, complex and expensive equipment that can cause radiation contamination, and limitations due to factors such as the grain size, microcracks, voids, carbon content, and ambient electromagnetic noise of the steel component being tested.

[0005] Ultrasonic stress detection technology, particularly critically refracted longitudinal waves, is widely used due to its high stress sensitivity, excellent signal stability, and independence from structural geometry. However, existing ultrasonic stress detection methods primarily measure the absolute stress of flat steel components and cannot be directly applied to curved ones. Because these methods fail to consider the influence of curvature on the propagation of critically refracted longitudinal waves, they can produce significant deviations in stress detection results, limiting their practical applicability.

[0006] Therefore, there is an urgent need for an absolute stress detection system and method for in-service curved steel components. Summary of the Invention

[0007] (1) Technical issues to be resolved

[0008] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a system and method for detecting absolute stress of in-service curved steel components, which can realize non-destructive detection of the absolute stress of in-service curved steel components, and solve the technical problems of large deviation in detection accuracy due to curvature and low applicability in practical applications.

[0009] (2) Technical solution

[0010] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] In a first aspect, an embodiment of the present invention provides an absolute stress detection system for an in-service curved steel member, comprising:

[0012] Ultrasonic generator, annular curvature sensor, digital oscilloscope, host computer;

[0013] The annular curvature sensor includes: a first transmitting ultrasonic probe, a second transmitting ultrasonic probe, a third transmitting ultrasonic probe, a first receiving ultrasonic probe, a second receiving ultrasonic probe, a third receiving ultrasonic probe, and a fixed mold;

[0014] The first transmitting ultrasonic probe, the second transmitting ultrasonic probe, the third transmitting ultrasonic probe, the first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe are installed on the fixed mold;

[0015] The fixed mold is a hollow circular ring, the line connecting the first transmitting ultrasonic probe and the first receiving ultrasonic probe coincides with the diameter of the fixed mold, the line connecting the second transmitting ultrasonic probe and the second receiving ultrasonic probe coincides with the diameter of the fixed mold, and the line connecting the third transmitting ultrasonic probe and the third receiving ultrasonic probe coincides with the diameter of the fixed mold;

[0016] The ultrasonic generator is connected to the annular curvature sensor to stimulate each transmitting ultrasonic probe of the annular curvature sensor to generate an ultrasonic longitudinal wave signal. Each receiving ultrasonic probe receives the critical refracted longitudinal wave signal corresponding to the ultrasonic longitudinal wave signal passing through the in-service curved steel component and transmits it to the digital oscilloscope and the host computer.

[0017] Optionally, the angle between the first transmitting ultrasonic probe and the first receiving ultrasonic probe set on the fixed mold is θ 0° =27.6°;

[0018] The angle between the second transmitting ultrasonic probe and the second receiving ultrasonic probe set on the fixed mold is Wherein, L is the preset straight-line distance between the second transmitting ultrasonic probe and the second receiving ultrasonic probe, and R is the curvature radius of the curved steel member surface;

[0019] The angle between the third transmitting ultrasonic probe and the third receiving ultrasonic probe set on the fixed mold is Wherein, L is a preset straight-line distance between the third transmitting ultrasonic probe and the third receiving ultrasonic probe, and R is a curvature radius of the surface of the curved steel member.

[0020] Optionally, the distance between the first transmitting ultrasonic probe and the second transmitting ultrasonic probe is the same as the distance between the second transmitting ultrasonic probe and the third transmitting ultrasonic probe;

[0021] The distance between the first receiving ultrasound probe and the second receiving ultrasound probe is the same as the distance between the second receiving ultrasound probe and the third receiving ultrasound probe.

[0022] Optionally, the ultrasonic generator excites the first transmitting ultrasonic probe, the second transmitting ultrasonic probe, and the third transmitting ultrasonic probe to transmit ultrasonic longitudinal wave signals at 0°, 45°, and 90° respectively; the ultrasonic longitudinal wave signals are refracted on the surface of the in-service curved steel member and converted into critical refracted longitudinal wave signals at 0°, 45°, and 90°;

[0023] The first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe respectively receive the critical refracted longitudinal wave signals at 0°, 45°, and 90°, and obtain three-way receiving signals;

[0024] The digital oscilloscope is used to receive three-way receiving signals and perform signal conversion on the three-way receiving signals to obtain three-way digital receiving signals;

[0025] The host computer is used to receive and calculate the time of the three-way digital reception signal, obtain the three-way propagation sound time difference, input the three-way propagation sound time difference into a predefined curved steel component absolute stress detection equation, and obtain the absolute stress of the curved steel component to be tested.

[0026] Optionally, the receiving and calculating the time of the three-way digital reception signal to obtain the three-way propagation sound time difference includes:

[0027] The host computer receives and calculates the time of the three-way digital reception signal, the time being the three-way acoustic time of the three-way critically refracted longitudinal wave signal, and subtracts the three-way acoustic time from the three-way acoustic time in the zero-stress replica to obtain a three-way acoustic time difference;

[0028] The three-way propagation of sound in the zero-stress replica is set in advance.

[0029] In a second aspect, the present invention provides a method for detecting absolute stress of an in-service curved steel member, comprising:

[0030] S10, collecting the three-way propagation sound of the critical refracted longitudinal wave signal in the curved steel member to be measured;

[0031] S20, subtracting the three-way acoustic propagation time of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way acoustic propagation time of the zero stress state collected in the replica of the curved steel member to be measured to obtain the three-way acoustic propagation time difference;

[0032] S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured, inputting the three-way acoustic transit time and the stress-acoustic transit time coefficient into a predefined curved steel member absolute stress detection equation, and obtaining the absolute stress of the curved steel member to be measured.

[0033] Optionally, the S30 includes:

[0034] The three-way acoustic transit time and stress-acoustic transit time coefficient are input into the following formula to obtain the absolute stress of the curved steel component to be measured:

[0035]

[0036] Where ρ1 is the maximum normal stress detection value, ρ2 is the minimum normal stress detection value, θ is the angle between the propagation direction of the critical refracted longitudinal wave and the main plane of the measuring point, Δt1 is the propagation time difference of the critical refracted longitudinal wave in the 0° curved steel member, Δt2 is the propagation time difference of the critical refracted longitudinal wave in the 45° curved steel member, Δt3 is the propagation time difference of the critical refracted longitudinal wave in the 90° curved steel member, and K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction;

[0037] The expression of stress-acoustic transit time coefficient is:

[0038]

[0039] Among them, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic time difference coefficient perpendicular to the stress direction, R is the curvature radius of the curved steel component, d is the measurement depth, V0 is the propagation velocity of the three-way critical refraction longitudinal wave signal in the zero-stress steel component material, λ and μ are the Lamé constants of the steel component material, and l and m are the Murnaghan constants of the steel component material.

[0040] Optionally, in S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured includes:

[0041] S31, performing stress loading at different stress gradients on the replica of the curved steel member to be tested, collecting critical refracted longitudinal wave signals of the replica of the curved steel member to be tested under different stress gradients, and obtaining the three-way acoustic transit time of each stress gradient;

[0042] S32. Fit the three-way acoustic transit time of each stress gradient to obtain a stress-acoustic transit time coefficient.

[0043] Optionally, the replica of the curved steel member to be measured is prepared in advance, and the replica of the curved steel member to be measured has the same specifications, material, surface curvature and surface roughness as the curved steel member to be measured.

[0044] Optionally, the S31 further includes:

[0045] performing data preprocessing on the critical refracted longitudinal wave signal;

[0046] The data preprocessing of the critical refracted longitudinal wave signal comprises:

[0047] Using a bandpass filter to filter noise in the critical refracted longitudinal wave signal;

[0048] The passband of the bandpass filter is ±2 MHz of the center frequency of the first transmitting ultrasonic probe, the second transmitting ultrasonic probe and the third transmitting ultrasonic probe.

[0049] (3) Beneficial effects

[0050] The present invention has the following beneficial effects: a system and method for detecting absolute stress of an in-service curved steel member of the present invention adopts an annular curvature sensor, which includes a first transmitting ultrasonic probe, a second transmitting ultrasonic probe, a third transmitting ultrasonic probe, a first receiving ultrasonic probe, a second receiving ultrasonic probe, a third receiving ultrasonic probe, and a fixed mold, thereby generating critical refracted longitudinal wave signals in three directions in the curved steel member to be tested. Compared with the existing technology, the system has a simple structure, convenient installation, fast detection speed, high efficiency, little time and scene restrictions, high feasibility, high detection accuracy, and relatively stable detection results.

[0051] The method is based on the above-mentioned absolute stress detection system and can be applied to the absolute stress detection of curved steel components in steel structures under construction and existing buildings. It is simple, fast, easy to implement, and has high detection efficiency and accuracy. In addition, the absolute stress detection equation for curved steel components provided by the present invention takes into account the influence of curvature on detection, further improving the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of the structure of the absolute stress detection system for in-service curved steel members in Example 1 of the present invention;

[0053] Figure 2 This is a schematic structural diagram of an annular curvature sensor in the absolute stress detection system of Example 1 of the present invention being fixed on a curved steel member;

[0054] Figure 3 Schematic diagram of the propagation path of the critical refracted longitudinal wave signal on the curved steel member in Example 1 of the present invention;

[0055] Figure 4 This is a schematic flow chart of a method for detecting absolute stress of an in-service curved steel member according to Example 2 of the present invention;

[0056] Figure 5 Schematic diagram of the process of detecting the absolute stress of an in-service curved steel member using the absolute stress detection system in Example 2 of the present invention;

[0057] Figure 6 Schematic diagram of a critical refracted longitudinal wave signal in Example 3 of the present invention;

[0058] Figure 7 Schematic diagram of a curved steel member to be tested in Example 3 of the present invention;

[0059] Figure 8 for Figure 7 A copy of the curved steel member to be tested;

[0060] Figure 9 Schematic diagram of fitting the three-way acoustic transit time of each stress gradient and the corresponding critical refracted longitudinal wave signal in Example 3;

[0061] Figure 10 This is a diagram showing the arrangement of ultrasonic testing measuring points for the curved steel member to be tested in Example 3 of the present invention. DETAILED DESCRIPTION

[0062] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0063] The present invention proposes a system and method for detecting absolute stress on in-service curved steel structures. Using an annular curvature sensor consisting of three transmitting and three receiving ultrasonic probes and a fixed mold, the system detects critically refracted longitudinal wave signals in three directions on the curved steel structure. Furthermore, the system uses a predefined absolute stress detection equation for curved steel structures that accounts for the influence of curvature on detection to determine the absolute stress of the curved steel structure. The system's detection process is simple and fast, with minimal time and scenario constraints, high feasibility, and reliable, stable results.

[0064] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0065] Specific embodiment description part

[0066] Example 1

[0067] See also Figure 1 , an absolute stress detection system for an in-service curved steel member according to an embodiment of the present invention comprises: an ultrasonic generator, an annular curvature sensor, a digital oscilloscope, and a host computer;

[0068] The annular curvature sensor includes: a first transmitting ultrasonic probe, a second transmitting ultrasonic probe, a third transmitting ultrasonic probe, a first receiving ultrasonic probe, a second receiving ultrasonic probe, a third receiving ultrasonic probe, and a fixed mold;

[0069] The first transmitting ultrasonic probe, the second transmitting ultrasonic probe, the third transmitting ultrasonic probe, the first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe are installed on the fixed mold;

[0070] The fixed mold is a hollow ring, the line connecting the first transmitting ultrasonic probe and the first receiving ultrasonic probe coincides with the diameter of the fixed mold, the line connecting the second transmitting ultrasonic probe and the second receiving ultrasonic probe coincides with the diameter of the fixed mold, and the line connecting the third transmitting ultrasonic probe and the third receiving ultrasonic probe coincides with the diameter of the fixed mold;

[0071] The ultrasonic generator is connected to the annular curvature sensor to stimulate each transmitting ultrasonic probe of the annular curvature sensor to generate an ultrasonic longitudinal wave signal. Each receiving ultrasonic probe receives the critical refracted longitudinal wave signal corresponding to the ultrasonic longitudinal wave signal passing through the in-service curved steel component and transmits it to the digital oscilloscope and the host computer.

[0072] In this embodiment, the depth of each transmitting ultrasonic probe and each receiving ultrasonic probe in the fixed mold is determined by actual application conditions and the depths are the same.

[0073] In this embodiment, each transmitting ultrasonic probe and each receiving ultrasonic probe are ultrasonic probes of the same specification.

[0074] In the specific implementation process, see Figure 2 The angle between the first transmitting ultrasonic probe and the first receiving ultrasonic probe set on the fixed mold is θ 0° =27.6°;

[0075] The angle between the second transmitting ultrasonic probe and the second receiving ultrasonic probe set on the fixed mold is Wherein, L is the preset straight-line distance between the second transmitting ultrasonic probe and the second receiving ultrasonic probe, and R is the curvature radius of the curved steel member surface;

[0076] The angle between the third transmitting ultrasonic probe and the third receiving ultrasonic probe set on the fixed mold is Wherein, L is a preset straight-line distance between the third transmitting ultrasonic probe and the third receiving ultrasonic probe, and r is a curvature radius of the surface of the curved steel member.

[0077] In this embodiment, the distance between the first transmitting ultrasonic probe and the second transmitting ultrasonic probe is the same as the distance between the second transmitting ultrasonic probe and the third transmitting ultrasonic probe;

[0078] The distance between the first receiving ultrasound probe and the second receiving ultrasound probe is the same as the distance between the second receiving ultrasound probe and the third receiving ultrasound probe.

[0079] In a specific implementation process, the distance between the first transmitting ultrasonic probe and the second transmitting ultrasonic probe is determined by actual application conditions, and the distance between the first transmitting ultrasonic probe and the second transmitting ultrasonic probe is the same as the distance between the first receiving ultrasonic probe and the second receiving ultrasonic probe.

[0080] In this embodiment, see Figure 3 The ultrasonic generator excites the first transmitting ultrasonic probe, the second transmitting ultrasonic probe, and the third transmitting ultrasonic probe to transmit ultrasonic longitudinal wave signals at 0°, 45°, and 90° respectively; the ultrasonic longitudinal wave signals are refracted on the surface of the in-service curved steel member and converted into critical refracted longitudinal wave signals at 0°, 45°, and 90°;

[0081] The first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe respectively receive the critical refracted longitudinal wave signals at 0°, 45°, and 90°, and obtain three-way receiving signals;

[0082] In the specific implementation process, the ultrasonic generator generates a 200V square wave pulse electrical signal to excite the first transmitting ultrasonic probe, the second transmitting ultrasonic probe, and the third transmitting ultrasonic probe fixed on the fixed mold to transmit ultrasonic longitudinal wave signals of 0°, 45°, and 90° respectively.

[0083] A digital oscilloscope is used to receive three-way receiving signals, perform signal conversion on the three-way receiving signals, and obtain three-way digital receiving signals;

[0084] The host computer is used to receive and calculate the time of the three-way digital receiving signal, obtain the three-way propagation time difference, input the three-way propagation time difference into the pre-defined absolute stress detection equation of the curved steel component, and obtain the absolute stress of the curved steel component to be tested.

[0085] Receiving and calculating the time of three-way digital reception signals and obtaining the three-way propagation sound time difference includes:

[0086] The host computer receives and calculates the time of the three-way digital receiving signal, which is the three-way propagation acoustic time of the three-way critical refracted longitudinal wave signal. The three-way propagation acoustic time is subtracted from the three-way propagation acoustic time in the zero-stress replica to obtain the three-way propagation acoustic time difference.

[0087] The three-way propagation of sound in the zero-stress replica is set in advance.

[0088] In this embodiment, the absolute stress detection system may further include a signal amplifier for increasing the amplitude of the critical refracted longitudinal wave signal.

[0089] In the specific implementation process, the host computer can be any electronic device such as a computer that can perform the above operations.

[0090] The absolute stress detection system for in-service curved steel components, according to an embodiment of the present invention, uses an annular curvature sensor to generate and collect critically refracted longitudinal wave signals in three directions within the curved steel component. Simultaneously, using a digital oscilloscope and a host computer, the absolute stress of the curved steel component is calculated using a predefined absolute stress detection equation for curved steel components. The system boasts a simple structure, fast detection speed, high efficiency, minimal time and scenario constraints, high feasibility, high detection accuracy, and stable deviations in detection results.

[0091] Example 2

[0092] See also Figure 4 , an absolute stress detection method for an in-service curved steel member according to an embodiment of the present invention comprises:

[0093] Step S10, collecting the three-way propagation sound of the critical refracted longitudinal wave signal in the curved steel component to be measured;

[0094] Step S20, subtracting the three-way acoustic time difference of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way acoustic time difference of the zero stress state collected in the replica of the curved steel member to be measured;

[0095] Step S30: Obtain the stress-acoustic transit time coefficient of the curved steel member to be tested, input the three-way acoustic transit time and the stress-acoustic transit time coefficient into a predefined absolute stress detection equation for the curved steel member to obtain the absolute stress of the curved steel member to be tested.

[0096] In this embodiment, step S30 includes:

[0097] Input the three-way acoustic transit time and stress-acoustic transit time coefficient into the following formula to obtain the absolute stress of the curved steel component to be tested:

[0098]

[0099] Where ρ1 is the maximum normal stress detection value, ρ2 is the minimum normal stress detection value, θ is the angle between the propagation direction of the critical refracted longitudinal wave and the main plane of the measuring point, Δt1 is the propagation time difference of the critical refracted longitudinal wave in the 0° curved steel member, Δt2 is the propagation time difference of the critical refracted longitudinal wave in the 45° curved steel member, Δt3 is the propagation time difference of the critical refracted longitudinal wave in the 90° curved steel member, and K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction.

[0100] In the specific implementation process, since most of the in-service curved steel components are non-detachable, the pre-defined absolute stress detection equation of the curved steel component is usually obtained by performing different loading stress tests on the replicas of the curved steel component to be tested.

[0101] In this embodiment, the expression of the stress-acoustic time difference coefficient is:

[0102]

[0103] Among them, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic time difference coefficient perpendicular to the stress direction, R is the curvature radius of the curved steel component, d is the measurement depth, V0 is the propagation velocity of the three-way critical refraction longitudinal wave signal in the zero-stress steel component material, λ and μ are the Lamé constants of the steel component material, and l and m are the Murnaghan constants of the steel component material.

[0104] In step S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured includes:

[0105] Step S31: Stress loading with different stress gradients is performed on the replica of the curved steel member to be tested, critical refracted longitudinal wave signals of the replica of the curved steel member to be tested under different stress gradients are collected, and the three-way propagation acoustic time difference of each stress gradient is obtained;

[0106] Step S32: Fit the three-way acoustic transit time of each stress gradient to obtain the stress-acoustic transit time coefficient.

[0107] In this embodiment, a replica of the curved steel member to be tested is prepared in advance, and the replica of the curved steel member to be tested has the same specifications, material, surface curvature and surface roughness as the curved steel member to be tested.

[0108] Optionally, step S31 further includes:

[0109] Perform data preprocessing on critical refracted longitudinal wave signals;

[0110] Data preprocessing of critical refraction longitudinal wave signals includes:

[0111] A bandpass filter is used to filter out the noise in the critical refracted longitudinal wave signal;

[0112] The passband of the bandpass filter is ±2 MHz of the center frequency of the first transmitting ultrasonic probe, the second transmitting ultrasonic probe, and the third transmitting ultrasonic probe.

[0113] In the specific implementation process, the preparation process of the replica of the curved steel component to be tested is as follows:

[0114] The manufacturer collects the specifications, material, surface curvature, and surface roughness of the curved steel structure to be measured, and then produces a nearly identical replica of the curved steel structure with the same specifications, material, surface curvature, and surface roughness. To increase the accuracy of the measurement data, the replica is then subjected to internal stress elimination.

[0115] In this example, a replica of the curved steel component under test was subjected to gradient axial compression loading using a universal testing machine. The stress gradient ranged from 0 MPa to 160 MPa, with each gradient increasing by 10 MPa. After the stress reached the target value, an annular curvature sensor was used to transmit an ultrasonic longitudinal wave signal and receive a critically refracted longitudinal wave signal. The critically refracted longitudinal wave signals under different stress conditions were stored.

[0116] The specific operation is: use the universal testing machine to load and transmit and receive the critical refracted longitudinal wave signal at the same time, release the constraint of the universal testing machine on the replica after loading is completed, and store the critical refracted longitudinal wave signal under different stress conditions. Figure 5 As shown, an annular curvature sensor is coupled to a replica, and the replica is subjected to gradient axial compression loading using a universal testing machine. For example, when measuring propagation sound on a replica under 0 MPa (no stress), the replica is then subjected to stress loading at 10 MPa, 20 MPa, 30 MPa, 150 MPa, and 160 MPa, acquiring the critical refracted longitudinal wave signals of the replica under different stress loading conditions.

[0117] In this embodiment, the replica should be kept at the same stress gradient for at least 5 minutes.

[0118] In this embodiment, the curvature of the annular curvature sensor is the same as the curvature of the curved steel member to be measured.

[0119] In this embodiment, the preferred surface curvature radius is 400-600 mm, which is applicable to a wide range of application scenarios. In addition to being applicable to curved steel components, the method provided by the present invention is also highly applicable to absolute stress detection of other curved metal components.

[0120] The absolute stress detection method for an in-service curved steel member proposed in this embodiment can be applied to the absolute stress detection of curved steel structures in steel structures under construction and already built. The method is simple, fast, and easy to implement, and has high detection efficiency and accuracy.

[0121] Example 3

[0122] For example, if Figure 7 As shown, Figure 7 The specimen in the test is the Q355B steel round steel pipe column specimen to be tested. Figure 8 A replica of the specimen.

[0123] Figure 7 Test piece and Figure 8 The replicas have the same specifications, materials, surface curvature and surface roughness.

[0124] In this embodiment, a method for detecting absolute stress of a curved steel member includes:

[0125] Step S10, collecting the three-way propagation sound of the critical refracted longitudinal wave signal in the curved steel component to be measured;

[0126] Step S20, subtracting the three-way acoustic time difference of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way acoustic time difference of the zero stress state collected in the replica of the curved steel member to be measured;

[0127] Step S30: Obtain the stress-acoustic transit time coefficient of the curved steel member to be tested, input the three-way acoustic transit time and the stress-acoustic transit time coefficient into a predefined absolute stress detection equation for the curved steel member to obtain the absolute stress of the curved steel member to be tested.

[0128] In this embodiment, when the target curved steel component to be tested is a Q355B steel round steel pipe specimen, a suitable location on the specimen is selected as the test area, and the surface of the test area is polished. A coupling agent is applied to the monitoring area and the annular curvature sensor is fixed. After all the above connections are prepared, the absolute stress detection system is adjusted to the appropriate parameters for normal operation.

[0129] The annular curvature sensor transmits ultrasonic longitudinal wave signals in three directions and receives critical refracted longitudinal wave signals, and uses a digital oscilloscope to collect the critical refracted longitudinal wave signals. The critical refracted longitudinal wave signals are as follows: Figure 6 As shown, the host computer collects the three-way propagation time of the critical refracted longitudinal wave signal in the curved steel member to be measured; and subtracts the three-way propagation time of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way propagation time of the zero stress state collected in the replica of the curved steel member to be measured to obtain the three-way propagation time difference;

[0130] The measured three-way propagation time difference of sound is substituted into the predefined absolute stress detection equation of the curved steel component to obtain the absolute stress of the specimen.

[0131] In step S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured includes:

[0132] Step S31: Stress loading with different stress gradients is performed on the replica of the curved steel member to be tested, critical refracted longitudinal wave signals of the replica of the curved steel member to be tested under different stress gradients are collected, and the three-way propagation acoustic time difference of each stress gradient is obtained;

[0133] Step S32: Fit the three-way acoustic transit time of each stress gradient to obtain the stress-acoustic transit time coefficient.

[0134] In this example, a replica was coupled and fixed to an annular curvature sensor. The replica was then subjected to axial compression using a universal testing machine, with a stress gradient of 10 MPa ranging from 0 to 160 MPa. Critically refracted longitudinal wave signals were collected and processed under various stress conditions to obtain the three-way acoustic transit time differences under these conditions.

[0135] The stress-acoustic time difference coefficient fitting diagram is obtained by fitting the loading stress and the three-way propagation acoustic time difference. Figure 9 shown.

[0136] In this embodiment, the specimen to be tested is fixed on the loading test bench, and the vertical actuator and horizontal actuator are controlled to load it respectively. The two sides of the round steel pipe are symmetrical. One side is ultrasonically measured by the annular curvature sensor, and the other side is stress measured by the three-axis strain gauge. Four strain gauge measurement areas are arranged on the round steel pipe, with a total of 128 strain gauge measurement points. The measurement points are arranged as follows: Figure 10 shown.

[0137] The three-way acoustic transit time and stress-acoustic transit time coefficient of the original steel column to be tested are obtained and substituted into the absolute stress test equation for curved steel components to obtain the absolute stress of the in-service curved steel components. The test results are shown in the table below.

[0138]

[0139]

[0140]

[0141] According to the above table, the relative deviation of Mises stress between ultrasonic detection stress value and strain gauge detection stress value can be calculated as follows:

[0142]

[0143] It can be seen from this that the absolute stress detection method of an in-service curved steel member of this embodiment has a small relative error and high detection accuracy.

[0144] The absolute stress detection method for an in-service curved steel member proposed in this embodiment can be applied to the absolute stress detection of curved steel structures in steel structures under construction and already built. The method is simple, fast, and easy to implement, and has high detection efficiency and accuracy.

[0145] Example 4

[0146] An absolute stress detection method for an in-service curved steel member according to an embodiment of the present invention includes:

[0147] Step S10, collecting the three-way propagation sound of the critical refracted longitudinal wave signal in the curved steel component to be measured;

[0148] Step S20, subtracting the three-way acoustic time difference of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way acoustic time difference of the zero stress state collected in the replica of the curved steel member to be measured;

[0149] Step S30: Obtain the stress-acoustic transit time coefficient of the curved steel member to be tested, input the three-way acoustic transit time and the stress-acoustic transit time coefficient into a predefined absolute stress detection equation for the curved steel member to obtain the absolute stress of the curved steel member to be tested.

[0150] In this embodiment, the predefined absolute stress detection equation for curved steel components is:

[0151]

[0152] Wherein, σ1 is the maximum normal stress detection value, σ2 is the minimum normal stress detection value, θ is the angle between the propagation direction of the critical refracted longitudinal wave and the main plane of the measuring point, Δt1 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 0°, Δt2 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 45°, Δt3 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 90°, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥is the stress-acoustic transit time coefficient perpendicular to the stress direction.

[0153] In this embodiment, the process of obtaining the absolute stress detection equation of the curved steel member is as follows:

[0154] A1. Calculate the speed of sound when the critical refracted longitudinal wave propagates in directions parallel to and perpendicular to the stress:

[0155] According to the principle of acoustoelasticity, when the propagation direction of the critical refracted longitudinal wave is parallel to the stress, the sound velocity is calculated as shown in formula (1):

[0156]

[0157] According to the principle of acoustoelasticity, when the propagation direction of the critical refracted longitudinal wave is perpendicular to the stress, the sound velocity is calculated as shown in formula (2):

[0158]

[0159] Among them, σ || is the absolute stress of the steel member parallel to the propagation direction of the critical refracted longitudinal wave, σ ⊥ is the absolute stress of the steel member perpendicular to the propagation direction of the critical refracted longitudinal wave, V || V is the propagation velocity of the critical refracted longitudinal wave when it is parallel to the stress direction; ⊥ is the propagation velocity of the critical refracted longitudinal wave when it is perpendicular to the stress direction; V0 is the propagation velocity of the critical refracted longitudinal wave when the stress is zero; k || 、k ⊥ is the acoustoelastic coefficient, which is related to the Lamé constant and Murnaghan constant of the material.

[0160] A2. Calculation of three-way acoustic time difference under different stress conditions when the acoustic path is fixed:

[0161] When the sound path is fixed, the critical refracted longitudinal wave propagation velocity can be converted into propagation sound time. Differentiating both sides of formula (1) and formula (2), the relationship between the velocity change and the stress change can be obtained:

[0162] 2V || dV || =k || dσ || ,

[0163] 2V ⊥ dV ⊥ =k ⊥ dσ ⊥ (3),

[0164] V || V is the propagation velocity of the critical refracted longitudinal wave when it is parallel to the stress direction; ⊥is the propagation velocity of the critical refracted longitudinal wave when it is perpendicular to the stress direction; V0 is the propagation velocity of the critical refracted longitudinal wave when the stress is zero; k || 、k ⊥ is the acoustoelastic coefficient.

[0165] If the propagation distance of the critical refracted longitudinal wave is a fixed value L, then the relationship between the sound velocity and the acoustic time, as well as the relationship between the change in sound velocity and the change in acoustic time can be expressed by formula (4):

[0166]

[0167] Substituting formula (4) into formula (3), we can obtain:

[0168]

[0169] Where L is the propagation distance of the critical refracted longitudinal wave, t || is the propagation time of the critical refracted longitudinal wave in the direction parallel to the stress under a fixed sound path L; t ⊥ k is the propagation time of critical refracted longitudinal wave in the direction perpendicular to stress under fixed sound path L, || 、k ⊥ is the acoustoelastic coefficient, σ || is the absolute stress of the steel member parallel to the propagation direction of the critical refracted longitudinal wave, σ ⊥ is the absolute stress of the steel member perpendicular to the propagation direction of the critical refracted longitudinal wave.

[0170] Compared with the propagation time t0 under zero stress, the change of the propagation time under stress is very small, and we can approximate t≈t0. Then Equation (5) can be simplified to:

[0171]

[0172] t || is the propagation time of the critical refracted longitudinal wave in the direction parallel to the stress under a fixed sound path L; t ⊥ k is the propagation time of critical refracted longitudinal wave in the direction perpendicular to stress under fixed sound path L, || 、k ⊥ is the acoustoelastic coefficient, σ || is the absolute stress of the steel member parallel to the propagation direction of the critical refracted longitudinal wave, σ ⊥ is the absolute stress of the steel member perpendicular to the propagation direction of the critical refracted longitudinal wave.

[0173] In equation (6), dt is the change in the acoustic time of the critical refracted longitudinal wave, i.e., the acoustic time difference Δt. Since the initial stress is 0, the stress change is the absolute stress value inside the component during measurement. Therefore, the relationship between the critical refracted longitudinal wave acoustic time difference and the absolute stress under a fixed acoustic path is:

[0174] Δt=K || σ || +K ⊥ σ ⊥ (7),

[0175] Among them, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction, σ || is the absolute stress of the steel member parallel to the propagation direction of the critical refracted longitudinal wave, σ ⊥ is the absolute stress of the steel member perpendicular to the propagation direction of the critical refracted longitudinal wave.

[0176] The expression of the stress-acoustic time difference coefficient is:

[0177]

[0178] Among them, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic time difference coefficient perpendicular to the stress direction, R is the curvature radius of the curved steel component, d is the measurement depth, V0 is the propagation velocity of the three-way critical refraction longitudinal wave signal in the zero-stress steel component material, λ and μ are the Lamé constants of the steel component material, and l and m are the Murnaghan constants of the steel component material.

[0179] A3. Absolute stress detection equation for curved steel components based on three-dimensional sound:

[0180] According to formula (7), when the propagation direction of the critical refracted longitudinal wave and the principal plane of the plane stress at the measuring point have a certain angle, formula (9) can be obtained:

[0181] Δt=K || (σ1cos 2 θ+σ2sin 2 θ)+K ⊥ (σ1sin 2 θ+σ2cos 2 θ) (9),

[0182] Where σ1 is the first principal stress of the plane stress at the measuring point, σ2 is the second principal stress of the plane stress at the measuring point, θ is the angle between the propagation direction of the critical refraction longitudinal wave and the principal plane of the measuring point, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction.

[0183] Taking the axial direction of the curved steel member as the 0° reference direction, rotating 45° and 90° counterclockwise, respectively, and measuring the critical refracted longitudinal wave propagation time difference in three directions, the equation group (10) can be obtained:

[0184]

[0185] Among them, Δt1, Δt2, and Δt3 are the three-way propagation sound time differences in the directions of 0°, 45°, and 90° respectively.

[0186] By solving the equation group (10), we can obtain the absolute stress detection equation of curved steel components based on three-dimensional sound:

[0187]

[0188] Wherein, σ1 is the maximum normal stress detection value, σ2 is the minimum normal stress detection value, θ is the angle between the propagation direction of the critical refracted longitudinal wave and the main plane of the measuring point, Δt1 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 0°, Δt2 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 45°, Δt3 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 90°, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction.

[0189] The reference direction is preferably the axial direction of the curved steel member. In practical applications, a suitable direction can be selected as the reference direction based on actual conditions, and there is no limitation here.

[0190] In an absolute stress detection method for an in-service curved steel member according to an embodiment of the present invention, the influence of curvature on detection is taken into account in the absolute stress detection equation provided, thereby further improving the detection accuracy.

[0191] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0192] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0193] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0194] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0195] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An absolute stress detection system for in-service curved steel components, characterized in that: include: Ultrasonic generator, annular curvature sensor, digital oscilloscope, host computer; The annular curvature sensor includes: a first transmitting ultrasonic probe, a second transmitting ultrasonic probe, a third transmitting ultrasonic probe, a first receiving ultrasonic probe, a second receiving ultrasonic probe, a third receiving ultrasonic probe, and a fixed mold; The first transmitting ultrasonic probe, the second transmitting ultrasonic probe, the third transmitting ultrasonic probe, the first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe are installed on the fixed mold; The fixed mold is a hollow circular ring, the line connecting the first transmitting ultrasonic probe and the first receiving ultrasonic probe coincides with the diameter of the fixed mold, the line connecting the second transmitting ultrasonic probe and the second receiving ultrasonic probe coincides with the diameter of the fixed mold, and the line connecting the third transmitting ultrasonic probe and the third receiving ultrasonic probe coincides with the diameter of the fixed mold; The ultrasonic generator is connected to the annular curvature sensor, and stimulates each transmitting ultrasonic probe of the annular curvature sensor to generate an ultrasonic longitudinal wave signal. Each receiving ultrasonic probe receives a critical refracted longitudinal wave signal corresponding to the ultrasonic longitudinal wave signal and passing through the in-service curved steel member, and transmits the signal to a digital oscilloscope and a host computer. The angle between the first transmitting ultrasonic probe and the first receiving ultrasonic probe set on the fixed mold is θ 0° =27.6°; The angle between the second transmitting ultrasonic probe and the second receiving ultrasonic probe set on the fixed mold is Wherein, L is the preset straight-line distance between the second transmitting ultrasonic probe and the second receiving ultrasonic probe, and R is the curvature radius of the curved steel member surface; The angle between the third transmitting ultrasonic probe and the third receiving ultrasonic probe set on the fixed mold is Wherein, L is the preset straight-line distance between the third transmitting ultrasonic probe and the third receiving ultrasonic probe, and R is the curvature radius of the surface of the curved steel member; The ultrasonic generator excites the first transmitting ultrasonic probe, the second transmitting ultrasonic probe, and the third transmitting ultrasonic probe to transmit ultrasonic longitudinal wave signals at 0°, 45°, and 90° respectively; the ultrasonic longitudinal wave signals are refracted on the surface of the in-service curved steel member and converted into critical refracted longitudinal wave signals at 0°, 45°, and 90°; The first receiving ultrasonic probe, the second receiving ultrasonic probe, and the third receiving ultrasonic probe respectively receive the critical refracted longitudinal wave signals at 0°, 45°, and 90°, and obtain three-way receiving signals; The digital oscilloscope is used to receive three-way receiving signals and perform signal conversion on the three-way receiving signals to obtain three-way digital receiving signals; The host computer is used to receive and calculate the time of the three-way digital reception signal, obtain the three-way propagation sound time difference, input the three-way propagation sound time difference into a predefined curved steel component absolute stress detection equation, and obtain the absolute stress of the curved steel component to be tested.

2. The absolute stress detection system for in-service curved steel members according to claim 1, characterized in that: The distance between the first transmitting ultrasonic probe and the second transmitting ultrasonic probe is the same as the distance between the second transmitting ultrasonic probe and the third transmitting ultrasonic probe; The distance between the first receiving ultrasound probe and the second receiving ultrasound probe is the same as the distance between the second receiving ultrasound probe and the third receiving ultrasound probe.

3. The absolute stress detection system for in-service curved steel members according to claim 1, characterized in that: The receiving and calculating the time of the three-way digital reception signal to obtain the three-way propagation sound time difference includes: The host computer receives and calculates the time of the three-way digital reception signal, the time being the three-way acoustic time of the three-way critically refracted longitudinal wave signal, and subtracts the three-way acoustic time from the three-way acoustic time in the zero-stress replica to obtain the three-way acoustic time difference; The three-way propagation of sound in the zero-stress replica is set in advance.

4. An absolute stress detection method based on the absolute stress detection system according to any one of claims 1 to 3, characterized in that: include: S10, collecting the three-way propagation sound of the critical refracted longitudinal wave signal in the curved steel member to be measured; S20, subtracting the three-way acoustic propagation time of the critical refracted longitudinal wave signal in the curved steel member to be measured from the three-way acoustic propagation time of the zero stress state collected in the replica of the curved steel member to be measured to obtain the three-way acoustic propagation time difference; S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured, inputting the three-way acoustic transit time and the stress-acoustic transit time coefficient into a predefined absolute stress detection equation for curved steel members, and obtaining the absolute stress of the curved steel member to be measured; The S30 includes: The three-way acoustic transit time and stress-acoustic transit time coefficient are input into the following formula to obtain the absolute stress of the curved steel component to be measured: Wherein, σ1 is the maximum normal stress detection value, σ2 is the minimum normal stress detection value, θ is the angle between the propagation direction of the critical refracted longitudinal wave and the main plane of the measuring point, Δt1 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 0°, Δt2 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 45°, Δt3 is the propagation time difference of the critical refracted longitudinal wave in the curved steel member at 90°, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic transit time coefficient perpendicular to the stress direction; The expression of stress-acoustic transit time coefficient is: Among them, K || is the stress-acoustic transit time coefficient parallel to the stress direction, K ⊥ is the stress-acoustic time difference coefficient perpendicular to the stress direction, R is the curvature radius of the curved steel component, d is the measurement depth, V0 is the propagation velocity of the three-way critical refraction longitudinal wave signal in the zero-stress steel component material, λ and μ are the Lamé constants of the steel component material, and l and m are the Murnaghan constants of the steel component material.

5. The absolute stress detection method for an in-service curved steel member according to claim 4, characterized in that: In the step S30, obtaining the stress-acoustic transit time coefficient of the curved steel member to be measured includes: S31, performing stress loading at different stress gradients on the replica of the curved steel member to be tested, collecting critical refracted longitudinal wave signals of the replica of the curved steel member to be tested under different stress gradients, and obtaining the three-way acoustic transit time of each stress gradient; S32. Fit the three-way acoustic transit time of each stress gradient to obtain a stress-acoustic transit time coefficient.

6. The absolute stress detection method for an in-service curved steel member according to claim 5, characterized in that: The replica of the curved surface steel component to be measured is prepared in advance, and the replica of the curved surface steel component to be measured has the same specifications, the same material, the same surface curvature and the same surface roughness as the curved surface steel component to be measured.

7. The absolute stress detection method for an in-service curved steel member according to claim 5, characterized in that: The S31 further includes: performing data preprocessing on the critical refracted longitudinal wave signal; The data preprocessing of the critical refracted longitudinal wave signal comprises: Using a bandpass filter to filter noise in the critical refracted longitudinal wave signal; The passband of the bandpass filter is ±2 MHz of the center frequency of the first transmitting ultrasonic probe, the second transmitting ultrasonic probe and the third transmitting ultrasonic probe.

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