Mobile magnetic adsorption steel structure curved surface non-uniform damage identification device and method

Abstract

The present invention provides a mobile magnetically adsorbed non-uniform damage identification device and method for curved surfaces of steel structures, the device comprising a magnetic telescopic probe, a signal cable, a micro-voltage and current acquisition device, and an industrial computer, wherein the telescopic probe comprises a telescopic probe array, a four-point magnetic seat, a fixed bracket plate, a terminal block integrated board, a fastener, and a fastening nut. The magnetic telescopic probe adopts a four-point magnetic adsorption method and can be moved on the steel structure to be tested. The damage identification probe adopts the form of a telescopic probe array, which can be well adapted to the application scenario of curved steel structures. Based on the method for identifying non-uniform damage to curved surfaces of steel structures in which the fixed bracket plate is in the form of a flat plate or a curved plate, the square four-probe method and the reference model method are adopted to realize local damage area calculation, local damage thickness identification analysis, residual strength analysis and safety assessment, thereby obtaining the safety of the steel structure, and providing a feasible and efficient solution for the health management of curved steel structures.

Description

Technical Field

[0001] The invention relates to a mobile magnetically adsorbed steel structure curved surface non-uniform damage identification device and an identification method. Background Art

[0002] Metal structures are widely used in energy engineering fields such as hydropower, water conservancy, shipbuilding and ocean, and oil pipelines. However, under specific working conditions, metal structures are not always used in a flat form. Curved structures such as curved hull panels, radial gates of hydropower stations, and pressure steel pipes are very common. These structures are usually subject to varying degrees of damage under complex environmental conditions, such as corrosion and wear, which are closely related to the structural and even engineering safety.

[0003] Metal structures often suffer from uniform damage and local damage. Uniform damage is easier to identify, and this part of damage is usually considered in the structural design stage. Local damage, also known as non-uniform damage, is often the main factor leading to structural failure and is difficult to identify. How to effectively locate the damage position of non-planar structures and evaluate the degree of non-uniform damage is a difficult problem encountered by metal structures during actual service. On the one hand, for the non-destructive testing of metal structures, the existing ultrasonic flaw detection technology is mature, but when it comes to curved structures, calibration is difficult and the deviation is large. In addition, since ultrasonic thickness measurement is a point-by-point measurement, it is easy to miss severely damaged areas. On the other hand, the invasive monitoring probe based on the resistance measurement principle does not directly measure the damage state of the metal structure itself, but uses homogeneous monitoring to reflect the degree of damage, which makes the measurement results have certain deviations. Summary of the invention

[0004] The purpose of the present invention is to provide a mobile magnetically adsorbed steel structure curved surface non-uniform damage identification device and identification method. The device adopts a four-point magnetic adsorption method and can be moved on the steel structure to be tested. The damage identification probe adopts a telescopic probe array, which can monitor the potential of the local area of ​​the steel structure to be tested by switching the current, and further locate the damage position and damage degree by the change of the micro-area potential, and then identify the remaining thickness of the steel structure within the regional range, thereby avoiding the problem that traditional damage monitoring methods are difficult to take into account both non-destructive monitoring and accurate analysis for non-planar steel structures, thereby realizing damage location and evaluation of non-planar steel structures.

[0005] To this end, according to the first aspect of the present invention, the present invention adopts the following technical solution:

[0006] A mobile magnetically adsorbed steel structure curved surface non-uniform damage identification device comprises a micro-voltage and current acquisition device, an industrial control computer and a signal cable; the identification device also comprises a magnetic telescopic probe; the magnetic telescopic probe comprises a telescopic probe array, a magnetic seat, a fixed bracket plate and a terminal integrated board; the telescopic probe comprises a copper needle tube, a copper needle head and a compression spring; the number of rows and columns of the telescopic probe array is equal, and the probe spacing is equal; the fixed bracket plate and the terminal integrated board press and fix the telescopic probe array through a fastening structure;

[0007] The magnetic telescopic probe adopts a four-point magnetic adsorption method and can move on the steel structure to be tested. The magnetic telescopic probe monitors the potential by switching the current, and then identifies the remaining thickness of the steel structure within the area. Four magnetic seats are set and configured as a four-point magnetic seat.

[0008] On the basis of adopting the above technical solutions, the present invention may also adopt the following further technical solutions, or use these further technical solutions in combination:

[0009] The fastening structure comprises a connecting rod and a fastening nut, wherein one end of the connecting rod is an externally threaded screw connected to the fastening nut; and the other end is an internally threaded screw hole connected to the magnetic suction seat.

[0010] The four magnetic seats of the four-point magnetic seat are respectively connected to the connecting rod by threads, and can be adjusted to magnetic seats of different lengths according to application scenarios; when the length of the magnetic seat is greater than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the convex surface to monitor the degree of damage on the concave side; if the length of the magnetic seat is less than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the concave surface to monitor the degree of damage on the convex side.

[0011] The fixed support plate is made of insulating material and has a certain strength. The fixed support plate is punched with holes arranged in an array, and the hole arrangement spacing is consistent with the telescopic probe array spacing.

[0012] The fixed bracket plate is in the form of a flat plate, and all the telescopic probes arranged thereon are parallel to each other; or, the fixed bracket plate is in the form of a curved plate matching the curved surface shape of the steel structure to be measured, and each telescopic probe arranged thereon is perpendicular to the surface of the steel structure to be measured.

[0013] The head of the telescopic probe array is in the form of a needle tip and can directly contact the steel structure to be measured.

[0014] After the telescopic probe array is fixed to the fixed bracket plate, the tail of the telescopic probe array is welded to the wiring terminal integrated board in sequence, and is connected to the signal cable through the rear connector of the wiring terminal integrated board.

[0015] The industrial computer collects the damage signal of the steel structure to be measured collected by the telescopic probe through the micro-voltage and current collection device by setting the collection program.

[0016] The current and voltage transmission path of the telescopic probe array is "steel structure to be tested-copper needle-copper needle tube-connection terminal-signal cable-collection device", and the surface of the compression spring is insulated and does not participate in the voltage and current measurement.

[0017] According to the second aspect of the present invention, the present invention adopts the following technical solution:

[0018] The steel structure curved surface non-uniform damage identification method based on the mobile magnetic adsorption steel structure curved surface non-uniform damage identification device, the telescopic probe array adopts ( m+1） ×( m+1） Root telescopic probe, surrounded by m × m The micro-area array is composed of micro-area units, and the area enclosed by 2×2 adjacent telescopic probes as vertices is defined as the micro-area unit. The non-uniform damage identification method for the steel structure curved surface to be tested includes the following steps:

[0019] (1) Calculation of the micro-area unit area in the micro-area array;

[0020] (2) Identification of micro-area unit damage thickness;

[0021] (3) Micro-area array residual strength analysis and safety assessment.

[0022] The damage distribution of the micro-area array can be divided according to the micro-area unit. The steel structure damage occurring on the micro-area unit is local damage. The micro-area unit area is calculated separately according to the two cases that the fixed support plate is a flat plate or a curved plate.

[0023] Case 1: For a fixed support plate in the form of a flat plate, if the telescopic probe array adopts ( m+1） ×( m+1） Root telescopic probe, surrounded by m × m A micro-cell array composed of micro-cell units. m is an even number, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the telescopic probe and the fixed bracket plate b The area enclosed by 2×2 adjacent telescopic probes as vertices is defined as a micro-unit. The steel structure damage occurring on the micro-unit is considered as local damage. The arc length of the micro-unit is calculated as for:

[0024]

[0025] for m× m indivual( m The micro-cell array is composed of micro-cell units (even number), the micro-cell unit with the same unit arc length at the center of the micro-cell array is defined as the central micro-cell unit, there are 4 of them, and the item (1) in the above formula is the calculation result of the arc length of the central micro-cell unit; the micro-cell unit with the same unit arc length outside the central micro-cell unit of the micro-cell array is defined as the central outer micro-cell unit, there are 12 of them, and the item (2) in the above formula is the calculation result of the arc length of the central outer micro-cell unit; the micro-cell unit with the same unit arc length at the outermost side of the micro-cell array is defined as the outermost micro-cell unit, there are 4m-4 of them, and the item (3) in the above formula is the calculation result of the arc length of the outermost micro-cell unit.

[0026] In addition, for the fixed support plate in the form of a flat plate, if the telescopic probe array adopts ( m+1） ×( m+1） Root telescopic probe, surrounded by m × m A micro-cell array composed of micro-cell units. m is an odd number, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the telescopic probe and the fixed bracket plate b , calculate the arc length of the micro-area unit for:

[0027]

[0028] for m × m indivual( m The micro-cell array is composed of micro-cell units (odd number), the micro-cell unit with the same unit arc length at the center of the micro-cell array is defined as the central micro-cell unit, there is 1 of them, and the item (1) in the above formula is the calculation result of the arc length of the central micro-cell unit; the micro-cell units with the same unit arc length outside the central micro-cell unit of the micro-cell array are defined as the central outer micro-cell units, there are 8 of them, and the item (2) in the above formula is the calculation result of the arc length of the central outer micro-cell unit; the micro-cell units with the same unit arc length at the outermost side of the micro-cell array are defined as the outermost micro-cell units, there are 4m-4 of them, and the item (3) in the above formula is the calculation result of the arc length of the outermost micro-cell unit.

[0029] Therefore, if the micro-area array is m × m An array of m is an even number, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the telescopic probe and the fixed bracket plate b , using the arc length formula, that is, the relationship between the length of an arc passing through two points on a circle and the radius and the central angle, we can calculate:

[0030] m × m The arc length distance of the actual monitoring surface of the central micro-cell unit of the micro-cell array l for

[0031]

[0032] Further, m × m ( m (even number) The arc length distance of the actual monitoring surface of the center outer micro-cell unit of the micro-cell array l for

[0033]

[0034] And so on, until m × m ( m (even number) The arc length distance of the actual monitoring surface of the outermost micro-cell unit of the micro-cell array l for

[0035]

[0036] In addition, if the micro-area array is m × m An array of m is an odd number, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the telescopic probe and the fixed bracket plate b , using the arc length formula, that is, the relationship between the length of an arc passing through two points on a circle and the radius and the central angle, we can calculate:

[0037] m × m The arc length distance of the actual monitoring surface of the central micro-cell unit of the micro-cell array l for

[0038]

[0039] Further, m × m ( m (odd number) The arc length distance of the actual monitoring surface of the center outer micro-cell unit of the micro-cell array l for

[0040]

[0041] And so on, until m × m ( m(odd number) The arc length distance of the actual monitoring surface of the outermost micro-cell unit of the micro-cell array l for

[0042]

[0043] Case 2: For the fixed support plate as a curved plate, the telescopic probe array adopts ( m+1） ×( m+1） Root telescopic probe, surrounded by m × m A micro-cell array composed of micro-cell units. m Regardless of whether it is an odd number or an even number, each telescopic probe is arranged perpendicular to the surface of the steel structure to be measured, and the distance between the vertices of the telescopic probes on the surface of the steel structure to be measured is c The projection area enclosed by the telescopic probe array is c × c , then according to the curvature of the target surface of the measured object θ , radius of curvature r , the arc length of the micro-area unit can be calculated for:

[0044]

[0045] In the above case, the fixed bracket plate is in the form of a curved plate. Considering that each telescopic probe is arranged perpendicular to the surface of the steel structure to be measured, the distance between the vertices of the telescopic probe and the surface of the steel structure to be measured can be directly obtained. c ,,The projection area enclosed by the telescopic probe array is c × c The main feature of the fixed bracket in the form of a curved plate is that for the curved surface structure to be measured with the same curvature, the arc length distance of each micro-area unit is l In order to know the arc length of the actual monitoring surface l and the area of ​​the actual monitored surface, then according to the curvature of the target surface of the measured object θ , radius of curvature r , we can calculate:

[0046]

[0047] Considering that damage may occur on the concave side or the convex side of the curved surface, the present invention is only applicable to the case where one side of the curved surface is damaged. Whether the concave side or the convex side of the curved surface is damaged, it is only necessary to replace the magnetic suction seat of different lengths, and the calculation method of the arc length of the micro-area unit on the curved surface is related to the odd and even numbers of the telescopic probe array.

[0048] Based on the above calculation process, the damage area of ​​the micro-unit can be obtained as l ×l , define the positioning coordinates of the micro-area unit in the micro-area array as ( i , j ), i , j are the row and column numbers of the micro-area array, respectively, and thus the damaged area of ​​the curved steel structure can be located. l × l Compared to the entire steel structure surface, it is very small. l × l The extent of metal damage within the area is considered to be the same.

[0049] Local damage thickness identification and analysis: In order to quantitatively obtain the non-uniform damage degree of curved steel structures, two damage thickness identification methods are used according to the curved surface structural characteristics of the object to be tested.

[0050] For the steel structure to be tested with the same curvature and curved surface structure, the local damage of the micro-area can be reflected by calculating the micro-area unit resistance of the minimum square array composed of the telescopic probe array. The micro-area unit resistance is calculated using the square four-probe method.

[0051] First, define the area enclosed by 2×2 adjacent telescopic probes as the vertices as a micro-unit, A, B, C, and D are the telescopic probes of the selected micro-unit, A and B are the current inflow and outflow points in the square four-probe method, D and C are the voltage measurement points in the square four-probe method, and A and C are arranged diagonally, and B and D are arranged diagonally. The current is measured at two points on the same side of the four points in the minimum square array ABCD ( I ) inflow (point A) and outflow (point B), and the potential under the corresponding current is monitored at two points on the other side (points C and D) ( V C , V D ), according to Ohm's law, the potential difference between points A and B is V 0 :

[0052]

[0053] In the above formula, l BC is the distance between the voltage test point C and the current outflow point B, q AC is the distance between the voltage measuring point C and the current inflow point A, d is the remaining thickness of the steel structure surface to be measured, d 0 is the initial thickness of the steel structure surface to be tested, is the damage thickness of the steel structure surface to be tested, Vis the potential difference between the two voltage measuring points D and C, V 0 is the initial potential difference between the two voltage measuring points D and C, is the density of the steel structure to be tested.

[0054] Preferably, considering that damage identification is mainly performed on micro-area units, and when the square array ABCD is a spherical square, considering that the area is small, it is approximate , so the above can be simplified to

[0055]

[0056] Therefore, if the thickness of the micro-unit on the steel structure surface to be tested is damaged , then the potential difference monitored at the instant can be expressed as

[0057]

[0058] Then, the micro-area unit damage thickness is obtained It can be calculated by the following formula

[0059]

[0060] For the steel structure to be tested with a deviation in the curvature of the curved surface structure, the micro-area curvature radius in different local areas is quite different and cannot be directly obtained by calculation. Therefore, the reference model comparison method is used to analyze the damage distribution and determine the degree of damage.

[0061] First, a reference model with the same size and process as the steel structure to be tested is made with reference to the steel structure to be tested, and the model will not suffer any damage. The reference model is subjected to four-probe potential current monitoring of the target area to obtain m × m Initial potential distribution cloud diagram of micro-area array U 0 ,

[0062]

[0063] Furthermore, in the actual damage identification of the steel structure to be tested, the micro-area array is used to monitor the potential cloud map of the same area, and the m × m Potential distribution cloud diagram of micro-area array U 1 ,

[0064]

[0065] By comparing the potential cloud map of the actual steel structure to be tested with the potential cloud map data of the reference model, when the micro-area unit ( i ,j ) shows a large increase in potential , which indicates that the micro-area unit has local damage.

[0066] .

[0067] in, The row and column numbers of the micro-area array under the reference model are ( i , j ) when the micro-area unit potential is The row and column numbers of the micro-area array under the actual steel structure to be tested are ( i , j ) when the micro-area unit potential is is the potential difference between the actual steel structure to be tested and the reference model.

[0068] In order to further quantitatively evaluate the damage thickness of the actual steel structure to be tested, the "potential amplification-damage thickness" relationship is established through numerical simulation. By constructing the virtual damage thickness of the micro-unit on the three-dimensional model, the damage potential distribution cloud map under the corresponding damage is obtained. In combination with the neural network algorithm, the potential cloud map data set that did not appear in the network training process is used to test the mapping relationship of the neural network. Finally, the potential cloud map of the actual steel structure to be tested is input into the trained neural network to obtain the damage thickness of the corresponding micro-unit.

[0069] Residual strength analysis and safety assessment: Based on the above calculation process, the local damage thickness of the steel structure to be tested is obtained. By inputting the corresponding damage thickness into the corresponding reference model, the structural strength calculation after damage reduction is performed to determine the safety and risk level of the steel structure to be tested.

[0070] The residual structural strength of the above micro-area array after damage reduction M , which is related to the initial thickness of the micro-unit and the damage thickness of the micro-unit, that is, it satisfies:

[0071]

[0072] in, On the one hand, the minimum residual structural strength can be calculated by reducing the maximum damage thickness of the micro-area array, that is:

[0073]

[0074] in, is the initial strength before damage occurs. On the other hand, the residual structural strength distribution of the micro-area array can be simulated and calculated through finite element numerical calculation, and then the safety risk assessment can be carried out.

[0075] In summary, the present invention has the following advantages:

[0076] 1. The present invention adopts the structural form of magnetic attraction and telescopic probe, which can be well adapted to the application scenario of curved steel structure.

[0077] 2. The present invention can effectively grasp the damage distribution of the micro-area array through the arrangement of the micro-area array.

[0078] 3. The present invention can accurately determine the degree of local damage by calculating or analyzing the damage thickness of the curved surface micro-area, and further obtain the residual strength and safety of the steel structure based on the local damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 This is a schematic diagram of the mobile magnetic adsorption steel structure curved surface non-uniform damage identification device system provided by the present invention;

[0080] Figure 2 A schematic diagram of a magnetic telescopic probe with a fixed support plate in the form of a curved plate;

[0081] Figure 3 A schematic diagram of a magnetic telescopic probe with a fixed support plate in the form of a flat plate;

[0082] Figure 4 is a cross-sectional view of the telescopic probe;

[0083] Figure 5 It is a side view of the magnetic telescopic probe;

[0084] Figure 6 A schematic diagram of a test form for measuring damage to a concave side steel structure when the number of rows and columns of a micro-area array is an odd number and the magnetic telescopic probe with a fixed support plate in the form of a flat plate is used;

[0085] Figure 7 A schematic diagram of a test form for measuring damage to a convex side steel structure when the number of rows and columns of a micro-area array is an odd number and the magnetic telescopic probe with a fixed support plate in the form of a flat plate is used;

[0086] Figure 8 A schematic diagram of a test form for measuring damage to a concave side steel structure when the number of rows and columns of a micro-area array is an even number and the magnetic telescopic probe with a fixed support plate in the form of a flat plate is used;

[0087] Fig. 9 A schematic diagram of a test form for measuring damage to a convex side steel structure when the number of rows and columns of a micro-area array is an even number and the magnetic telescopic probe with a fixed support plate in the form of a flat plate is used;

[0088] Fig.10 A schematic diagram of a test form for measuring damage to a concave side steel structure when the number of rows and columns of a micro-area array is an odd number and the magnetic telescopic probe with a fixed support plate in the form of a curved plate is used;

[0089] Fig.11 A schematic diagram of a test form for measuring damage to a convex side steel structure when the number of rows and columns of a micro-region unit array is an odd number and the fixing bracket plate is a magnetic telescopic probe in the form of a curved plate;

[0090] Fig.12 A schematic diagram of a test form for measuring damage to a concave side steel structure when the number of rows and columns of a micro-region unit array is an even number and the fixing bracket plate is a magnetic telescopic probe in the form of a curved plate;

[0091] Fig.13 It is a schematic diagram of a test form for measuring damage of a convex side steel structure when the number of rows and columns of the micro-area unit array is an even number and the fixing bracket plate is a magnetic telescopic probe in the form of a curved plate. DETAILED DESCRIPTION

[0092] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0093] like Figure 1 As shown, a mobile magnetically adsorbed and fixed steel structure curved surface non-uniform damage identification device system is mainly composed of a magnetic telescopic probe 1, a signal cable 2, a micro-voltage and current acquisition device 3, and an industrial computer 4. The magnetic telescopic probe adopts a four-point magnetic adsorption method and can be moved on the steel structure to be tested. This embodiment, combined with the accompanying drawings, illustrates the damage identification process of the back side of the panel of the arc steel gate structure 100. The industrial computer 4 collects the damage signal of the steel structure to be tested collected by the magnetic telescopic probe 1 through the micro-voltage and current acquisition device 3 by setting the acquisition program. The micro-voltage and current acquisition device can use a multi-channel micro-resistance meter to monitor the potential and current of the micro-area to be tested.

[0094] like Figure 2 and Figure 3 The figure is a schematic diagram of the structure of the magnetic telescopic probe 1. The magnetic telescopic probe 1 includes a telescopic probe array, a four-point magnetic seat 12, a fixed bracket plate 13, a terminal block integrated board 14, and a fastening structure; the number of rows and columns of the telescopic probe array is equal, and the probe spacing is equal; the fastening structure includes a fastener 15 and a fastening nut 16. Figure 2 and Figure 3 The difference between the magnetic telescopic probes shown is, Figure 3 The fixed support plate 13 is in the form of a flat plate. All the telescopic probes arranged in this form are parallel to each other. This design form is mainly used for steel structures to be tested with relatively simple curved surfaces, such as when the curvature radius of the area to be tested is basically the same; Figure 2The fixed bracket plate adopts the form of a curved plate consistent with the steel structure to be tested. Each telescopic probe arranged in this form is perpendicular to the surface of the steel structure to be tested. This design form is mainly used for steel structures to be tested with inconsistent surface curvature, such as the case where the micro-area curvature radius of different local areas is greatly different. The fixed bracket plate is made of insulating material and has a certain strength. The fixed bracket plate is punched with holes arranged in an array, and the hole arrangement spacing is consistent with the telescopic probe array spacing.

[0095] like Figure 4 The figure shows a cross-sectional view of the telescopic probe, which mainly includes a copper needle tube 111, a copper needle head 112, and a compression spring 113. The compression spring 113 is located inside the copper needle tube 111, and the tail of the copper needle head 112 is a clamp located inside the copper needle tube 111, which is slidably clamped in the copper needle tube 111 and supported by the compression spring 113. The copper needle head 112 is in sliding contact with the copper needle tube 111. The current and voltage transmission path of the telescopic probe array is "steel structure to be tested 100-copper needle head 112-copper needle tube 111-connection terminal-signal cable 2-micro voltage and current acquisition device 3". The surface of the compression spring is insulated and does not participate in the voltage and current measurement. The connection terminal is located on the connection terminal integrated board 14. The micro voltage and current acquisition device 3 is connected to the industrial computer 4 using 485 communication.

[0096] like Figure 5 The figure shows a side view of the magnetic telescopic probe. It can be seen from the figure that the head of each telescopic probe is in the form of a needle tip, which can directly contact the steel structure to be measured. At the same time, the fixed bracket plate 13 and the terminal integrated board 14 are arranged front and back, and the telescopic probe 11 is pressed and fixed by the fastener 15. The two end faces of the copper needle tube 111 of the telescopic probe 11 can be in contact and cooperate with the fixed bracket plate 13 and the terminal integrated board 14 respectively. The fastener 15 of the magnetic telescopic probe 1 adopts a connecting rod, and the connecting rod is located at the four corners of the magnetic telescopic probe 1. There are four connecting rods in total. The four magnetic seats of the four-point magnetic seat 12 are respectively connected to a connecting rod. The upper end of the connecting rod is an external threaded screw, which is connected to the fastening nut 16; the other end is an internal threaded screw hole, which is connected to the magnetic seat.

[0097] After the telescopic probe 11 is fixed to the fixed bracket plate 13, the tail of the telescopic probe is welded to the terminal integrated board 14 in sequence, and connected to the signal cable 2 through the back connector of the terminal integrated board 14. In order to ensure the connection reliability of the terminal, after the back connector of the terminal integrated board 14 is connected to the signal cable, the back of the entire integrated board can be encapsulated and poured with insulating epoxy resin.

[0098] The four-point magnetic seat is connected to the fastener through a thread, and the installation length of the magnetic seat includes two parts, namely the mating length of the threaded section and the working length of the non-threaded section, wherein the mating length of the threaded section is completely screwed into the fastener. Considering that there are actually two surfaces of the curved steel structure, one convex and one concave, in the actual service process of the steel structure, in some cases the convex surface is damaged, and in some cases the concave surface is damaged. The present invention will target the working condition where the unilateral curved surface is damaged. In order to realize the damage identification of the unilateral convex surface or the unilateral concave surface, in the structural design of the magnetic telescopic probe, magnetic seats of different lengths can be replaced according to the application scenario. That is, if the working length of the non-threaded section of the magnetic seat is greater than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the convex surface to monitor the degree of damage on the concave side; if the working length of the non-threaded section of the magnetic seat is less than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the concave surface to monitor the degree of damage on the convex side.

[0099] Furthermore, based on the mobile magnetically adsorbed and fixed steel structure curved surface non-uniform damage identification device, a steel structure curved surface non-uniform damage identification method can be specifically carried out for identification and analysis in the following manner according to whether the fixed bracket is a flat plate or a curved plate.

[0100] like Figure 6 and Figure 7 As shown, it is a schematic diagram of a test form in which the magnetic telescopic probe with a fixed bracket plate in the form of a flat plate is used to measure the damage of the concave side and the convex side of the steel structure when the number of rows and columns of the micro-area array is odd. Figure 8 , Fig. 9 The figure shows a schematic diagram of the test form of the magnetic telescopic probe used to measure the damage of the concave and convex sides of the steel structure when the number of rows and columns of the micro-area array is even when the fixed support plate is in the form of a flat plate. When the fixed support plate is in the form of a flat plate, all the telescopic probes are arranged parallel to each other, and the spacing of the micro-area units of the telescopic probe array can be directly obtained. b , the projected area of ​​the micro-region unit surrounded by the telescopic probe array is b × b , but the arc length distance of the actual monitoring micro-area unit surface is unknown l Therefore, it is impossible to know the actual monitoring area of ​​the micro-unit surface. The main feature of the fixed bracket in the form of a flat plate is that the telescopic probe array is easy to process and arrange, but the arc length distance of different micro-units is l Due to the different corresponding arcs, the calculation is more complicated. Considering the different numbers of micro-area units defined by the telescopic probe array, m × m ( m The arc length calculation method of the micro-area array (even or odd) is different.

[0101] like Figure 6 and Figure 7 As shown, if the micro-area array is m × m ( m is an odd number) array, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the telescopic probe and the fixed bracket plate b , we can calculate:

[0102] by 3 × 3 Take the micro-area array as an example, and select the arc length of a micro-area unit in the middle as , the arc length distance of the micro-cells on both sides is and , then according to the curvature of the target surface of the measured object , radius of curvature r , the arc length distance of the actual monitoring surface of the central micro-area unit for:

[0103]

[0104] Further, 3 × 3 The arc length distance of the surface actually monitored by the center and outer micro-cell units of the micro-cell array l for:

[0105]

[0106] And so on, until m × m ( m The arc length distance of the actual monitoring surface of the outermost micro-cell unit of the micro-cell array (odd number) l for

[0107]

[0108] like Figure 8 , Fig. 9 As shown, if the micro-area array is m × m ( m For an even number array, take a 6×6 array as an example, and select the arc length distance between the two middle micro-cell units as and , the arc length distance of the micro-zone unit outside the center is and , the arc length distance of the outermost micro-cell is and Therefore, the arc length distance of the central micro-area unit actually monitored the surface and for:

[0109]

[0110] Furthermore, the arc length distance of the surface actually monitored by the center outer micro-cell units of the 6×6 array is and for:

[0111]

[0112] And so on, until m × m ( m (even number) the arc length of the actual monitoring surface of the outermost micro-cell unit of the array l for

[0113]

[0114] like Fig.10 , Fig.11 and Fig.12 , Fig.13 As shown, for the fixed support plate in the form of a curved plate, the telescopic probe array adopts ( m+1） ×( m+1） Root telescopic probe, surrounded by m × m A micro-cell array composed of micro-cell units. m Regardless of whether it is an odd number or an even number, each telescopic probe is arranged perpendicular to the surface of the steel structure to be measured, and the distance between the vertices of the telescopic probes on the surface of the steel structure to be measured is c , the projected area of ​​the micro-region unit surrounded by the telescopic probe array is c × c The main feature of the fixed bracket in the form of a curved plate is that the micro-unit arc length distance is the same for the micro-units of the curved surface structure to be measured with the same curvature. l In order to know the arc length of the actual monitoring surface l and the area of ​​the actual monitored surface, then according to the curvature of the target surface of the measured object θ , radius of curvature r , the distance between the top of the telescopic probe and the surface of the steel structure to be tested c , we can calculate:

[0115]

[0116] Considering that damage may occur on the concave side or the convex side of the curved surface, the present invention is only applicable to the case where one side of the curved surface is damaged. Whether the concave side or the convex side of the curved surface is damaged, it is only necessary to replace the magnetic suction seat with different working lengths, and the calculation method of the arc length of the micro-area unit on the curved surface is related to the odd and even numbers of the telescopic probe array.

[0117] Furthermore, based on the above calculation process, the area of ​​the actual monitoring surface of the telescopic probe array can be obtained: l × l In order to quantitatively obtain the non-uniform damage degree of the curved steel structure, two damage degree identification methods are used according to the curvature uniformity of the curved surface structure of the object to be tested.

[0118] The first damage identification method is the square four-probe method of the present invention, which is mainly aimed at steel structures to be tested with relatively simple curved surfaces. If the radius of curvature of the tested area is not much different, the local damage of the micro-area can be reflected by calculating the micro-area unit resistance of the minimum square array composed of the telescopic probe array. The micro-area unit resistance is calculated using the square four-probe calculation method.

[0119] First, define the area enclosed by 2×2 adjacent telescopic probes as the vertices as a micro-unit, A, B, C, and D are the telescopic probes of the selected micro-unit, A and B are the current inflow and outflow points in the square four-probe method, D and C are the voltage measurement points in the square four-probe method, and A and C are arranged diagonally, and B and D are arranged diagonally. The current is measured at two points on the same side of the four points in the minimum square array ABCD ( I ) inflow (point A) and outflow (point B), and the potential under the corresponding current is monitored at two points on the other side (points C and D) ( V C , V D ), according to Ohm's law, the potential difference between points A and B is V 0 :

[0120]

[0121] In the above formula, l BC are the distances between the voltage test point C and the current outflow point B, q AC is the distance between the voltage measuring point C and the current inflow point A, d is the remaining thickness of the steel structure surface to be measured, d 0 is the initial thickness of the steel structure surface to be tested, is the damage thickness of the steel structure surface to be tested, V is the potential difference between the two voltage measuring points D and C, V 0 is the initial potential difference between the two voltage measuring points D and C, is the density of the steel structure to be tested.

[0122] Preferably, considering that damage identification is mainly measured for micro-area units, and when the square array ABCD is a spherical square, but considering that the area is small, it is approximate Therefore, the above can be simplified to

[0123]

[0124] Therefore, if the thickness of the micro-unit on the steel structure surface to be tested is damaged , then the potential difference monitored at the instant can be expressed as

[0125]

[0126] Then, the micro-area unit damage thickness is obtained It can be calculated by the following formula

[0127]

[0128] The second damage identification method is the reference model comparison method, which is mainly aimed at the steel structure to be tested with different curvatures of the surface. Since the micro-area curvature radius in different local areas is quite different and cannot be directly obtained by calculation, the reference model comparison method is used to analyze the damage distribution and determine the degree of damage.

[0129] First, a reference model with the same size and process as the steel structure to be tested is made with reference to the steel structure to be tested, and the model will not suffer any damage. The reference model is subjected to four-probe potential current monitoring of key areas to obtain m × m Potential distribution cloud diagram of micro-area array U 0 ,

[0130]

[0131] Furthermore, in the actual damage identification of the steel structure to be tested, the micro-area array is used to monitor the potential cloud map of the same area, and the m × m Potential distribution cloud diagram of micro-area array U 1 ,

[0132]

[0133] By comparing the potential cloud map of the actual steel structure to be tested with the initial potential cloud map data of the reference model, when the micro-area unit ( i , j ) shows a large increase in potential , which indicates that the micro-area unit has local damage.

[0134]

[0135] in, The row and column numbers of the micro-area array under the reference model are ( i , j ) when the micro-area unit potential is The row and column numbers of the micro-area array under the actual steel structure to be tested are ( i , j ) when the micro-area unit potential is is the potential difference between the actual steel structure to be tested and the reference model.

[0136] In order to further quantitatively evaluate the damage thickness of the actual steel structure to be tested, the "potential amplification-damage thickness" relationship is established through numerical simulation. By constructing the virtual damage thickness of the micro-unit on the three-dimensional model, the damage potential distribution cloud map under the corresponding damage is obtained. In combination with the neural network algorithm, the potential cloud map data set that did not appear in the network training process is used to test the mapping relationship of the neural network. Finally, the potential cloud map of the actual steel structure to be tested is input into the trained neural network to obtain the damage thickness of the corresponding micro-unit.

[0137] Based on the above calculation process, the local damage thickness of the steel structure to be tested is obtained, and the structural strength calculation after damage reduction is performed to determine the safety and risk level of the steel structure to be tested.

[0138] The residual structural strength of the above micro-area array after damage reduction M , which is related to the initial thickness of the micro-unit and the damage thickness of the micro-unit, that is, it satisfies:

[0139]

[0140] in, On the one hand, the minimum residual structural strength can be calculated by reducing the maximum damage thickness of the micro-area array, that is:

[0141]

[0142] in, is the initial strength before damage occurs. On the other hand, the residual structural strength distribution of the micro-area array can be simulated and calculated through finite element numerical calculation, and then the safety risk assessment can be carried out.

[0143] Based on the above-mentioned mobile magnetic adsorption-fixed steel structure curved surface non-uniform damage identification device and method, monitoring and analysis processes are carried out for curved surface structures with consistent curvature and structures with different curvatures.

[0144] When there are differences in the curvature of the curved surface of the steel structure to be tested, such as the large differences in the radius of curvature of the micro-units in different local areas, the curved panel fixed bracket form and the reference model method can be used to evaluate the damage of the steel structure. The specific process is as follows:

[0145] Step 1: Make a magnetic telescopic probe with a fixed bracket plate in the form of a curved plate, obtain the surface information of the steel structure to be measured by lofting and other methods, and then make a fixed bracket plate in the form of a curved plate by 3D printing, wherein the curvature of the curved plate is consistent with the surface curvature of the steel structure to be measured, and each telescopic probe is perpendicular to the surface of the steel structure to be measured.

[0146] Step 2: Select the working length of the magnetic base according to the curved surface direction of the steel structure to be tested. That is, if the telescopic probe array is arranged on the convex surface to monitor the damage degree on the concave side, the working length of the magnetic base is selected to be greater than the initial length of the telescopic probe; if the telescopic probe array is arranged on the concave surface to monitor the damage degree on the convex side, the working length of the magnetic base is selected to be less than the initial length of the telescopic probe.

[0147] Step 3: Place the magnetic telescopic probe at the tested part of the steel structure to carry out potential monitoring.

[0148] Step 4: According to the number of micro-cell units in the micro-cell array, choose to calculate the arc length of the micro-cell unit according to the odd and even numbers of rows and columns of the array.

[0149] Step 5: Using the reference model method, the damage area of ​​the micro-area unit is calculated by comparing the measured micro-area array potential cloud map with the reference model initial potential cloud map, and the damaged area of ​​the curved steel structure is located by the positioning coordinates in the micro-area array.

[0150] Step 6: Using the reference model method, the damage thickness of the micro-area unit is obtained by comparing the measured micro-area array potential cloud map with the reference model neural network training potential cloud map.

[0151] Step 7: Based on the micro-unit damage area and micro-unit damage thickness, calculate the residual strength of the steel structure to be tested and conduct a safety assessment.

[0152] When the curvature of the curved surface of the steel structure to be tested is consistent, the flat plate fixed bracket form and the square four-probe method of the present invention can be used to evaluate the structural damage. The specific process is as follows:

[0153] Step 1: Make a magnetic telescopic probe in the form of a flat plate fixing bracket, and arrange the telescopic probes on the flat plate fixing bracket at equal intervals.

[0154] Step 2: Select the working length of the magnetic base according to the curved surface direction of the steel structure to be tested. That is, if the telescopic probe array is arranged on the convex surface to monitor the damage degree on the concave side, the working length of the magnetic base is selected to be greater than the initial length of the telescopic probe; if the telescopic probe array is arranged on the concave surface to monitor the damage degree on the convex side, the working length of the magnetic base is selected to be less than the initial length of the telescopic probe.

[0155] Step 3: Place the magnetic telescopic probe at the tested part of the steel structure to carry out potential monitoring.

[0156] Step 4: According to the number of micro-cell units in the micro-cell array, choose to calculate the arc length of the micro-cell unit according to the odd and even numbers of rows and columns of the array.

[0157] Step 5: The square four-probe method of the present invention is used to calculate the damage area of ​​the micro-region unit, and the damage area of ​​the curved steel structure is located by the positioning coordinates in the micro-region array.

[0158] Step 6: Using the square four-probe method of the present invention, obtain the damage thickness of the micro-area unit.

[0159] Step 7: Based on the micro-unit damage area and micro-unit damage thickness, calculate the residual strength of the steel structure to be tested and conduct a safety assessment.

[0160] The above-mentioned specific implementation methods are used to explain the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A mobile magnetically adsorbed non-uniform damage identification device for curved steel structures, comprising a micro-voltage and current acquisition device, an industrial computer and a signal cable; the characteristics are: The identification device also includes a magnetic telescopic probe; the magnetic telescopic probe includes a telescopic probe array, a magnetic seat, a fixed bracket plate, and a terminal integrated board; the telescopic probe includes a copper needle tube, a copper needle head, and a compression spring; the number of rows and columns of the telescopic probe array is equal, and the probe spacing is equal; the fixed bracket plate and the terminal integrated board press and fix the telescopic probe array through a fastening structure; The magnetic telescopic probe adopts a four-point magnetic adsorption method and can move on the steel structure to be tested. The magnetic telescopic probe monitors the potential by switching the current, and then identifies the remaining thickness of the steel structure within the area. Four magnetic seats are provided, which are configured as four-point magnetic seats; The four magnetic seats of the four-point magnetic seat are respectively connected to the fastening structure by threads, and can be adjusted to magnetic seats of different lengths according to application scenarios; when the length of the magnetic seat is greater than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the convex surface to monitor the damage degree of the concave surface side; if the length of the magnetic seat is less than the initial length of the telescopic probe, it can be used to arrange a telescopic probe array at the concave surface to monitor the damage degree of the convex surface side; The head of the telescopic probe array is in the form of a needle tip and is in direct contact with the steel structure to be measured; After the telescopic probe array is fixed to the fixed bracket plate, the tail of the telescopic probe array is welded to the wiring terminal integrated board in sequence, and is connected to the signal cable through the rear connector of the wiring terminal integrated board.

2. The mobile magnetic adsorption steel structure curved surface non-uniform damage identification device according to claim 1 is characterized by: The fastening structure comprises a connecting rod and a fastening nut, wherein one end of the connecting rod is an externally threaded screw connected to the fastening nut; and the other end is an internally threaded screw hole connected to the magnetic suction seat.

3. The mobile magnetic adsorption steel structure curved surface non-uniform damage identification device according to claim 1 is characterized by: The fixed bracket plate is in the form of a flat plate, and all the telescopic probes arranged thereon are parallel to each other; or, the fixed bracket plate is in the form of a curved plate matching the curved surface shape of the steel structure to be measured, and each telescopic probe arranged thereon is perpendicular to the surface of the steel structure to be measured.

4. A method for identifying non-uniform damage on curved surfaces of steel structures based on the mobile magnetic adsorption non-uniform damage identification device for curved surfaces of steel structures according to claim 3, characterized in that: The telescopic probe array uses (m+1)×(m+1) telescopic probes to form a micro-area array consisting of m×m micro-area units on the surface of the steel structure to be measured. The area enclosed by 2×2 adjacent telescopic probes as vertices on the surface of the steel structure to be measured is defined as a micro-area unit. The non-uniform damage identification method for the surface of the steel structure to be measured includes the following steps: (1) Calculation of the unit area of ​​micro-area in micro-area array; (2) Identification of micro-area unit damage thickness; (3) Micro-area array residual strength analysis and safety assessment.

5. The method for identifying non-uniform damage on curved surfaces of steel structures of the mobile magnetically adsorbed non-uniform damage identification device for curved surfaces of steel structures according to claim 4 is characterized in that: The damage distribution of the micro-area array is divided according to the micro-area unit. The steel structure damage occurring on the micro-area unit is local damage. The micro-area unit area is calculated according to the two cases where the fixed bracket plate is a flat plate or a curved plate. For the fixed support plate in the form of a flat plate, if m is an even number, the arc length l of the micro-area unit is calculated based on the target surface curvature θ, the curvature radius r, and the spacing b of the telescopic probe on the fixed support plate: The micro-cell units with the same unit arc length at the center of the micro-cell array are defined as central micro-cell units, and there are 4 of them. The first item (1) in the above formula is the calculation result of the arc length of the central micro-cell unit; the micro-cell units with the same unit arc length outside the central micro-cell unit of the micro-cell array are defined as central outer micro-cell units, and there are 12 of them. The second item in the above formula is the calculation result of the arc length of the central outer micro-cell unit; the micro-cell units with the same unit arc length at the outermost side of the micro-cell array are defined as outermost micro-cell units, and there are 4m-4 of them. The third item in the above formula is the calculation result of the arc length of the outermost micro-cell unit; For the fixed support plate in the form of a flat plate, if m is an odd number, the arc length l of the micro-area unit is calculated based on the target surface curvature θ, the curvature radius r, and the spacing b of the telescopic probe on the fixed support plate: The micro-cell unit with the same unit arc length at the center of the micro-cell array is defined as the central micro-cell unit, and there is 1 of them. The first item (1) in the above formula is the calculation result of the arc length of the central micro-cell unit; the micro-cell unit with the same unit arc length outside the central micro-cell unit of the micro-cell array is defined as the central outer micro-cell unit, and there are 8 of them. The second item in the above formula is the calculation result of the arc length of the central outer micro-cell unit; the micro-cell unit with the same unit arc length at the outermost side of the micro-cell array is defined as the outermost micro-cell unit, and there are 4m-4 of them. The third item in the above formula is the calculation result of the arc length of the outermost micro-cell unit; For the fixed bracket plate in the form of a curved plate, whether m is an odd number or an even number, each telescopic probe is arranged perpendicular to the surface of the steel structure to be measured, the spacing between the vertices of the telescopic probes is c, and the projection area enclosed by the telescopic probe array is c×c. According to the target surface curvature θ and the curvature radius r of the measured object, the arc length l of the micro-area unit is calculated as: l = 2r arc sin (c / 2r), The damaged area of ​​the micro-area unit is l×l, and the positioning coordinates of the micro-area unit in the micro-area array are defined as (i, j), where i and j are the row and column numbers of the micro-area array, respectively. Considering that the damaged area l×l of the micro-area unit is very small relative to the entire steel structure surface, the degree of metal damage within the l×l area is considered to be the same.

6. The method for identifying non-uniform damage on curved surfaces of steel structures of the mobile magnetically adsorbed non-uniform damage identification device for curved surfaces of steel structures according to claim 5, characterized in that: Local damage thickness identification analysis includes the square four-probe method or the reference model comparison method; The damage thickness Δd of the micro-area unit by the square four-probe method is calculated by the following formula: Among them, A, B, C, and D are the telescopic probes of the selected micro-area unit, A and B are the current inflow point and outflow point in the square four-probe method, respectively, D and C are the voltage measurement points in the square four-probe method, and A and C are arranged diagonally, B and D are arranged diagonally, I is the constant current value flowing between A and B in the square four-probe method, l BC is the distance between the voltage measuring point C and the current outflow point B, q AC is the distance between the voltage measuring point C and the current inflow point A, d is the remaining thickness of the steel structure surface micro-unit to be measured, d0 is the initial thickness of the steel structure surface micro-unit to be measured, Δd is the damage thickness of the steel structure surface micro-unit to be measured, V is the potential difference between the two voltage measuring points D and C, V0 is the initial potential difference between the two voltage measuring points D and C, and ρ is the density of the steel structure to be measured; The reference model comparison method is to make a reference model with the same size and process as the steel structure to be tested, compare the potential cloud map of the actual steel structure to be tested with the initial potential cloud map data of the reference model, and when the potential of the micro-unit increases by ΔU i,j When it is greater than the threshold, it indicates that the local micro-area unit has local damage, that is: Among them, U i,j is the potential of the micro-cell when the row and column number of the micro-cell array is (i, j) under the reference model, U′ i,j is the potential of the micro-area unit when the row and column number of the micro-area array under the actual steel structure to be tested is (i, j), ΔU i,j is the potential difference between the actual steel structure to be tested and the reference model; The damage thickness of the actual steel structure to be tested is quantitatively evaluated. The "potential increase-damage thickness" relationship is established through numerical simulation. Combined with the neural network algorithm, the potential cloud map data set that did not appear in the network training process is used to test the mapping relationship of the neural network. Finally, the potential cloud map of the steel structure to be tested that is actually measured is input into the trained neural network to obtain the damage thickness of the corresponding micro-unit.

7. The method for identifying non-uniform damage on curved surfaces of steel structures of the mobile magnetically adsorbed non-uniform damage identification device for curved surfaces of steel structures according to claim 4, characterized in that: In step (3), the structural strength after damage reduction is calculated based on the micro-area unit damage thickness and the micro-area array damage distribution, so as to determine the safety and risk level of the steel structure to be tested.

Images