Gearbox fault detection method based on full-field reconstruction of structural acceleration response

Abstract

A gearbox fault detection method based on full-field reconstruction of structural acceleration response is disclosed. In the method, the acceleration responses of all nodes of the gearbox housing are obtained based on the acceleration responses of finite measuring points and a transformation matrix; a full-field acceleration response nephogram of the gearbox housing is drawn according to the coordinates of each node and the color of each node; real-time full-field response inversion reconstruction is carried out and the full-field acceleration response nephogram of the gearbox housing under the working state is monitored; the numerical distribution of the acceleration response, the numerical value of the maximum full-field acceleration response, and the position of the node with the maximum acceleration response are compared to determine whether the gearbox has a fault; the fault-sensitive measuring points of the gearbox are determined based on the full-field acceleration response reconstructing the typical fault characteristic frequency components of the gearbox housing, and whether the gearbox has a typical fault corresponding to the typical fault characteristic frequency is judged according to whether there is an obvious change in the fault characteristic frequency information in the response of the sensitive measuring points.

Description

Technical Field

[0001] The invention belongs to the technical field of gearbox housing state monitoring and fault diagnosis, and in particular to a gearbox fault detection method based on full-field reconstruction of structural acceleration response. Background Art

[0002] Gearbox is a key component of the transmission system of many mechanical equipment. Once a fault occurs, the machine cannot work properly, or even cause a tragic accident with the machine destroyed and people killed. At present, the gearboxes on many equipment, such as helicopter gearboxes and gearboxes of integrated transmission systems of tanks and armored vehicles, are difficult to disassemble during routine maintenance. If they are disassembled rashly without knowing the status, human failure may be introduced. However, the transmission systems of major equipment are mostly in complex and harsh working environments with heavy loads, high speeds, large instantaneous shocks during speed changes, or high temperatures. With the increase of working time of the gearbox and the influence of the harsh external environment, the gearbox will inevitably fail. Therefore, in order to ensure the healthy operation of the machinery, it is of great practical significance to conduct efficient and accurate status monitoring and fault diagnosis of the gearbox. In view of the fact that the number and position of sensors are limited in the actual gearbox status monitoring process, the structural response of the gearbox body as a whole or at key positions can be identified through the vibration signals measured by a small number of sensors, which has great theoretical and engineering value.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0004] In response to the problems existing in the prior art, the present invention proposes a gearbox fault detection method based on full-field reconstruction of the structural acceleration response, which solves the difficult problem that limited measuring points in practice can only measure the limited acceleration response of the gearbox body and thus cannot perform efficient, accurate and comprehensive status detection of the gearbox. It also has the advantage of simultaneously reconstructing the dynamic acceleration response of the inaccessible measuring points on the surface and inside of the body.

[0005] The purpose of the present invention is to achieve the following technical solution: a gearbox fault detection method based on full-field reconstruction of structural acceleration response includes:

[0006] In the first step, a three-dimensional finite element model of the gearbox housing is established, and the modal parameters and node coordinates of the three-dimensional finite element model are extracted. The first n nodes of the three-dimensional finite element model are extracted by modal analysis. s Order modal parameters, modal frequency f i and size n dof ×1 displacement mode shape φ i , construct the full-field displacement mode matrix of the gearbox housing , size is n dof ×n s , where n s represents the number of vibration multimodes, i represents the modal order, n dof represents the number of degrees of freedom of the three-dimensional finite element model, n dof =3n no , n no represents the number of nodes of the three-dimensional finite element model;

[0007] In the second step, an optimized layout scheme of the acceleration sensors is determined, including the number and installation positions of the acceleration sensors, wherein the acceleration sensors are arranged in a candidate set of measuring points, the displacement modal vibration shape of each candidate measuring point in the candidate set of measuring points is extracted, and a measuring point candidate matrix of the displacement modal vibration shape is constructed. , size is n c ×n s , where φ i * is the i-th order main vibration displacement mode shape of the candidate measuring point in the measuring point candidate set, n c Indicates the number of candidate measurement points in the measurement point candidate set, from the measurement point candidate matrix Φ p Randomly select n at The size of the measuring point structure with acceleration sensors is n at ×n s The displacement modal vibration matrix Φ of the measuring point at , and calculate its matrix condition number w, this random process is repeated L times, and the acceleration sensor layout scheme with the smallest condition number w is selected as the acceleration sensor optimization layout scheme;

[0008] In the third step, the conversion matrix between the acceleration response of the finite measurement points and the full-field acceleration response of the gearbox body is established, T A =Φ×Φ at -1 , size is 3n no ×n at ; where Φ at -1 It is the inverse matrix of the displacement modal vibration matrix of the measuring point, and its size is n at ×n s ;

[0009] In the fourth step, n is arranged based on the acceleration sensor optimization layout scheme. at The acceleration sensor obtains the actual measured finite point acceleration response of the gearbox housing. where a m * (t) represents the acceleration response measured by the mth acceleration sensor of the system, which is converted into the acceleration response of the finite measurement point through the conversion matrix TA Obtain the acceleration response A(t) = T of all nodes A A at (t), where

[0010]

[0011] where a i，x (t) represents the acceleration response in the x - direction of the i - th node of the gearbox housing, a i，y (t) represents the acceleration response in the y - direction of the i - th node of the gearbox housing, a i，z (t) represents the acceleration response in the z - direction of the i - th node of the gearbox housing;

[0012] In the fifth step, assign colors to the nodes according to the numerical magnitudes of the acceleration responses of the nodes, and draw the full - field acceleration response nephogram of the gearbox housing based on the node coordinates and node colors to visually display the reconstructed full - field acceleration response of the gearbox housing;

[0013] In the sixth step, based on the limited - measurement - point acceleration response A at (t) obtained in real - time, obtain the real - time acceleration response A(t) of all nodes of the gearbox housing via the transformation matrix T A and generate the real - time full - field acceleration response nephogram of the gearbox housing;

[0014] In the seventh step, compare the full - field acceleration response nephogram of the gearbox housing under the real - time working state with the full - field acceleration response nephogram of the gearbox housing under normal working conditions. Among them, compare the numerical distribution of the acceleration responses, the numerical value of the full - field maximum acceleration response, and the position of the node with the maximum acceleration response to determine whether the gearbox has a fault.

[0015] In the gearbox fault detection method based on full - field reconstruction of structural acceleration responses, in the first step, the node coordinates are coor no = [no, cx, cy, cz], where no represents the node number, cx represents the x - coordinate of the node, cy represents the y - coordinate of the node, and cz represents the z - coordinate of the node.

[0016] In the gearbox fault detection method based on full - field reconstruction of structural acceleration responses, in the second step, the relationship between the number of acceleration sensors n at and the number of vibration multi - modes n s is: n at ≥n s .

[0017] In the gearbox fault detection method based on full - field reconstruction of structural acceleration responses, in the fifth step, divide the numerical range R of the acceleration responses of each node of the housing at time t0 into 9 equal - sized intervals Ri (1 ≤ i ≤ 9), each interval corresponds to a color. According to the numerical value of the node acceleration response, add the color corresponding to the interval to which the node acceleration response belongs to each node. Draw a scatter plot of the reconstructed acceleration response field based on the extracted coordinates and colors of each node to visually display the reconstructed full-field acceleration response.

[0018] In the gearbox fault detection method based on the full-field reconstruction of the structural acceleration response, mark the node with the maximum acceleration response as MAX in the scatter plot.

[0019] In the gearbox fault detection method based on the full-field reconstruction of the structural acceleration response, in the fifth step, draw an indicator bar to clearly show the magnitude and distribution of the full-field acceleration response. Divide the line segment with the starting endpoint as a min and the ending endpoint as a max into 9 equal parts on average. Mark the numerical values a min and a max at the endpoints and each equal division point respectively, and add the color corresponding to the numerical interval to each small line segment. Among them, a min represents the minimum value of all node acceleration responses, a max represents the maximum value of all node acceleration responses, |R| represents the magnitude of the numerical range R, j represents the j-th equal division point, and the scatter plot and the indicator bar together constitute the full-field acceleration response cloud map of the gearbox housing at time t0.

[0020] In the gearbox fault detection method based on the full-field reconstruction of the structural acceleration response, it also includes,

[0021] In the eighth step, use a band-pass filter to retain the response A at of the gearbox typical fault characteristic frequency f0 component in the measurement responses of n at0 acceleration sensors. Based on the response A at0 , reconstruct the full-field acceleration response of the gearbox housing for the typical fault characteristic frequency f0 component. Find the measurement point with the maximum acceleration response in the measurement point candidate set as the gearbox fault-sensitive measurement point. Monitor and analyze the measurement point response of the sensitive measurement point, compare it with the measurement point response under normal conditions, and judge whether the gearbox has a typical fault corresponding to the typical fault characteristic frequency f0 according to whether there is an obvious change in the fault characteristic frequency information in the sensitive measurement point response.

[0022] In the gearbox fault detection method based on the full-field reconstruction of the structural acceleration response, in the eighth step, use a band-pass filter to retain the response A at of the gearbox typical fault characteristic frequency f0 component in the measurement responses of the n at0 acceleration sensors. Based on the response A obtained after filtering,at0 , via the transformation matrix T A , reconstruct the full-field acceleration response A0(t) of the typical fault characteristic frequency f0 component of the gearbox housing.

[0023] In the gearbox fault detection method based on full-field reconstruction of structural acceleration response, in the eighth step, for the full-field acceleration response A0(t) of the typical fault characteristic frequency f0 component of the gearbox housing, find the candidate set Φ of measurement points p The measurement point with the maximum acceleration response in it, and the corresponding node number is n a0_max , which is the gearbox fault-sensitive measurement point d0, and monitor the response of the fault-sensitive measurement point d0 For the response of the fault-sensitive measurement point Carry out FFT analysis to generate the spectrum diagram of the response of the fault-sensitive measurement point , and compare it with the spectrum diagram of the response of this measurement point under the normal working conditions of the gearbox. If the fault characteristic frequency information in the spectrum diagram of the response of the fault-sensitive measurement point changes significantly, it is determined that the gearbox has a typical fault corresponding to the typical fault characteristic frequency f0, otherwise, it is determined that the gearbox does not have a typical fault corresponding to the typical fault characteristic frequency f0.

[0024] Compared with the prior art, the present invention has the following advantages: The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to the present invention can realize the inverse reconstruction of the full-field acceleration response of the gearbox housing only by using the acceleration responses of limited measurement points. It can not only realize the reconstruction of the acceleration response on the surface of the gearbox housing, but also realize the reconstruction of the acceleration response of the internal nodes of the housing. The transformation matrix constructed between the acceleration responses of the limited measurement points and the full-field acceleration response is independent of frequency, time, and even boundary conditions. It realizes the visualization of the acceleration response field of the gearbox housing. The calculation process of this method is simple, and it can realize on-line real-time condition monitoring and fault diagnosis, and determine the typical fault-sensitive measurement points of the gearbox. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The accompanying drawings in the specification are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. And throughout the drawings, the same reference numerals are used to represent the same components.

[0026] In the drawings:

[0027] Figure 1It is a schematic flow chart of a preferred example of a gearbox fault detection method based on full-field reconstruction of structural acceleration response provided by the present invention;

[0028] Figures 2(a) to 2(b) It is a gearbox housing model in an embodiment. Among them, Fig. 2(a) is the geometric model of the housing, and Fig. 2(b) is the finite element model of the housing;

[0029] Figures 3(a) to 3(e) It is the first five-order displacement mode shape diagrams of a gearbox housing in an embodiment. Among them, Fig. 3(a) is the first-order displacement mode shape diagram, Fig. 3(b) is the second-order displacement mode shape diagram, Fig. 3(c) is the third-order displacement mode shape diagram, Fig. 3(d) is the fourth-order displacement mode shape diagram, and Fig. 3(e) is the fifth-order displacement mode shape diagram;

[0030] Figures 4(a) to 4(c) It is a candidate set of acceleration sensor measurement points in an embodiment. Among them, Fig. 4(a) is the candidate set of X-direction acceleration sensor measurement points, Fig. 4(b) is the candidate set of Y-direction acceleration sensor measurement points, and Fig. 4(c) is the candidate set of Z-direction acceleration sensor measurement points;

[0031] Figures 5(a) to 5(c) It is a comparison of the reconstructed acceleration response time-domain waveform of node 2500 of a gearbox housing in an embodiment and the acceleration response time-domain waveform in the simulation. Among them, Fig. 5(a) is the comparison of the X-direction time-domain waveform, Fig. 5(b) is the comparison of the Y-direction time-domain waveform, and Fig. 5(c) is the comparison of the Z-direction time-domain waveform;

[0032] Figures 6(a) to 6(c) It is a comparison of the reconstructed acceleration response time-domain waveform of node 25815 of a gearbox housing in an embodiment and the acceleration response time-domain waveform in the simulation. Among them, Fig. 6(a) is the comparison of the X-direction time-domain waveform, Fig. 6(b) is the comparison of the Y-direction time-domain waveform, and Fig. 6(c) is the comparison of the Z-direction time-domain waveform;

[0033] Figure 7 It is the acceleration response nephogram of a gearbox housing in a normal working state in an embodiment;

[0034] Figures 8(a) to 8(b) It is a schematic diagram of a gearbox with typical faults in an embodiment. Among them, Fig. 8(a) is a schematic diagram when a bolt of the gearbox housing fails and the constraint is damaged, and Fig. 8(b) is a schematic diagram of the gearbox housing under abnormal excitation;

[0035] Figures 9(a) to 9(b) It is the full-field acceleration response nephogram of a gearbox housing when a typical fault occurs in an embodiment. Among them, Fig. 9(a) is the full-field acceleration response nephogram of the gearbox housing when a bolt fails and the constraint is damaged, and Fig. 9(b) is the full-field acceleration response nephogram of the gearbox housing under abnormal excitation;

[0036] Figures 10(a) to 10(b) It is a schematic diagram of the sensitive measurement point positions and the FFT analysis results of the measurement point response signals. Among them, Fig. 10(a) is the schematic diagram of the sensitive measurement point positions, and Fig. 10(b) is the frequency spectrum diagram of the acceleration response of the sensitive measurement points under abnormal excitation;

[0037] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments. Specific embodiments

[0038] The following will refer to the attached Figures 1 to 10(b) The specific embodiments of the present invention will be described in more detail. Although specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0039] It should be noted that in the description of the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. The specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "comprising" or "including" is an open-ended term and should be interpreted as "including but not limited to". The subsequent description of the specification is for the purpose of implementing the preferred embodiments of the present invention, but the description is for the general purpose of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the scope defined by the appended claims.

[0040] For the convenience of understanding the embodiments of the present invention, the following will take specific embodiments as examples and make further explanatory descriptions in conjunction with the accompanying drawings, and each drawing does not constitute a limitation on the embodiments of the present invention.

[0041] For better understanding, as Figure 1 shown, the gearbox fault detection method based on the full-field reconstruction of the structural acceleration response includes,

[0042] In the first step S1, a three-dimensional finite element model of the gearbox housing is established, and the modal parameters and the coordinates of each node of the three-dimensional finite element model are extracted;

[0043] In the second step S2, an optimized layout scheme for acceleration sensors is determined, including the number and installation positions of the acceleration sensors;

[0044] In the third step S3, a conversion matrix between the acceleration response of finite measurement points and the full-field acceleration response of the gearbox housing is established;

[0045] In the fourth step S4, the acceleration response of the finite measurement points on the gearbox housing is obtained based on the acceleration sensor, and the acceleration response of all nodes of the gearbox housing is obtained based on the acceleration response of the finite measurement points and the conversion matrix;

[0046] In the fifth step S5, colors are assigned to the nodes according to the numerical magnitudes of the node acceleration responses, and the full-field acceleration response cloud map of the gearbox housing is drawn based on the coordinates and colors of the nodes, visually displaying the reconstructed full-field acceleration response of the gearbox housing;

[0047] In the sixth step S6, based on the method described in step 4, the real-time obtained acceleration response A at (t) of the finite measurement points passes through the conversion matrix T A to obtain the real-time acceleration response A(t) of all nodes of the gearbox housing, and a real-time full-field acceleration response cloud map of the gearbox housing is generated based on the method described in step 5;

[0048] In the seventh step S7, the full-field acceleration response cloud map of the gearbox housing under the working state is compared with the full-field acceleration response cloud map of the gearbox housing under normal working conditions, with a focus on comparing the numerical distribution of the acceleration responses, the maximum numerical value of the full-field acceleration response, and the positions of the nodes with the maximum acceleration response, to determine whether the gearbox has a fault;

[0049] In the eighth step S8, the full-field acceleration response of the typical fault characteristic frequency components of the gearbox is reconstructed, the measurement point with the maximum acceleration response in the candidate measurement point set is found, and this measurement point is defined as the fault-sensitive measurement point of the gearbox. The response of the fault-sensitive measurement point is monitored and analyzed, compared with the response of this measurement point under normal conditions, and based on whether there are obvious changes in the fault characteristic frequency information in the response of the sensitive measurement point, it is determined whether the gearbox has a typical fault corresponding to the typical fault characteristic frequency f0.

[0050] The contributions of different vibration modes to the response of the gearbox housing vary greatly. Generally, the first several modes contribute more to the system vibration, and other modes, mainly high-order modes, can be ignored. Based on the modal reduction and expansion theory, the present invention inversely reconstructs the overall acceleration response of the gearbox housing through the vibration acceleration response of finite measurement points, only considering the first few modes of the gearbox housing to participate in the analysis of the housing structure vibration response. The core is to establish the conversion matrix between the acceleration response of finite measurement points on the gearbox housing and the full-field acceleration response. When the structure of the gearbox housing is damaged, or abnormal vibration excitation occurs due to damage to gears, bearings, shafts, etc. in the gearbox, it will cause abnormal changes in the full-field acceleration response of the gearbox housing. By comparing with the acceleration response nephogram of the gearbox housing under normal working conditions, the fault monitoring of the gearbox can be realized, reconstruct the full-field acceleration response of the typical fault characteristic frequency components of the gearbox, determine the typical fault sensitive measurement points, and judge whether the gearbox has a typical fault corresponding to the typical fault characteristic frequency based on whether the fault characteristic information of the fault sensitive measurement points is significant.

[0051] In the method described above, in the first step S1, the first n s modal parameters, modal frequencies f i and displacement modal shapes φ dof of size n i ×1 of the three-dimensional finite element model of the gearbox housing are extracted through modal analysis, and the full-field displacement modal shape matrix of the gearbox housing is constructed, with a size of n dof ×n s , where n s represents the number of vibration multimodes, i represents the modal order, n dof represents the number of degrees of freedom of the finite element model of the gearbox housing, n dof = 3n no , and n no represents the number of nodes of the finite element model of the gearbox housing.

[0052] In an embodiment of the method described above, in the first step S1, the coordinates coor no = [no, cx, cy, cz] of each node of the finite element model are extracted, where no represents the node number, cx represents the x coordinate of the node, cy represents the y coordinate of the node, and cz represents the z coordinate of the node.

[0053] In an embodiment of the method described above, in the second step S2, the relationship between the number n at of acceleration sensors and the number n s of vibration multimodes is: n at ≥n s .

[0054] In an embodiment of the described method, in the second step S2, the acceleration sensors should be arranged on a set of candidate positions that meet certain initial selection conditions. The principles for the set of candidate positions for arranging the acceleration sensors are as follows: 1 The set of candidate positions for measurement points should fully reflect the overall characteristics of the elastic modal deformation of the structure and have an obvious vibration response; 2 The set of candidate positions for measurement points should be convenient for arranging, replacing sensors, and detecting data; 3 The vibration signals of the set of candidate positions for measurement points have a high signal-to-noise ratio.

[0055] In an embodiment of the described method, in the second step S2, extract the displacement modal shapes of each candidate measurement point in the set of candidate measurement points, and construct a candidate matrix of measurement points for the displacement modal shape , with a size of n c ×n s , where φ i * is the i-th order main vibration displacement modal shape of the candidate measurement points in the set of candidate measurement points, and n c represents the number of candidate measurement points in the set of candidate measurement points. Randomly select n p measurement points from the candidate matrix Φ at to construct a measurement point displacement modal shape matrix Φ at ×n s of size n at , and calculate its matrix condition number w. This random process is repeated L times, and select the acceleration sensor arrangement scheme when the condition number w is the smallest, and use this as the optimal acceleration sensor arrangement scheme.

[0056] In an embodiment of the described method, in the third step S3, construct a conversion matrix T A = Φ×Φ at -1 of size 3n no ×n at ; where Φ at -1 is the inverse matrix of the measurement point displacement modal shape matrix, with a size of n at ×n s .

[0057] In an embodiment of the described method, in the fourth step S4, use the optimally arranged n at acceleration sensors to obtain the actual vibration acceleration response signal of the gearbox housing where a m * (t) represents the measured acceleration response of the m-th acceleration sensor of the system.

[0058] In an embodiment of the described method, in the fourth step S4, based on the conversion matrix T Aand the acceleration response signal A collected by the acceleration sensor at (t). The acceleration responses of all nodes on the gearbox housing are calculated by the formula A(t) = T a A at (t). Among them,

[0059]

[0060] represents the acceleration responses in three directions of all nodes on the surface and inside of the gearbox housing; among them, a i，x (t) represents the acceleration response in the x direction of the i-th node on the gearbox housing, a i，y (t) represents the acceleration response in the y direction of the i-th node on the gearbox housing, a i，z (t) represents the acceleration response in the z direction of the i-th node on the gearbox housing.

[0061] In one embodiment of the method described above, in the fifth step S5, the numerical range R of the acceleration responses of each node on the housing at a certain moment t0 is divided into 9 equal-sized intervals R i (1 ≤ i ≤ 9). Each interval corresponds to a color. According to the magnitude of the node acceleration response, the color corresponding to the interval to which the node acceleration response belongs is added to each node. According to the coordinates coor no of each node and the color of each node, a scatter plot of the reconstructed acceleration response field is drawn. At the same time, the node with the maximum acceleration response in the scatter plot is specially marked with MAX to realize the visual display of the reconstructed full-field acceleration response;

[0062] In one embodiment of the method described above, in the fifth step S5, an indicator bar is drawn to clearly display the magnitude and distribution of the full-field acceleration response of the gearbox housing. A line segment with a starting endpoint of a min and an ending endpoint of a max is evenly divided into 9 parts. The numerical magnitudes a min , a max are marked at the endpoints and each equal division point respectively, and the color corresponding to this numerical interval is added to each small line segment. Among them, a min represents the minimum value of the acceleration responses of all nodes, a max represents the maximum value of the acceleration responses of all nodes, |R| represents the magnitude of the numerical range R, and j represents the j-th equal division point. The scatter plot and the indicator bar together constitute the full-field acceleration response cloud map of the gearbox housing at the moment t0;

[0063] In one embodiment of the method described above, in the sixth step S6, based on the full-field reconstruction of the acceleration response and the visual response field, the full-field response inversion reconstruction is carried out in real time and the full-field acceleration response cloud map of the gearbox housing under the working state is monitored;

[0064] In one embodiment of the described method, in the seventh step S7, the full-field acceleration response contour map of the structure in the working state is compared with the acceleration response contour map K of the gearbox housing under normal working conditions, with a focus on comparing the acceleration response numerical distribution, the full-field maximum acceleration response value a max and the position of the node n a_max with the maximum acceleration response, and determining whether there are obvious changes in the several fault identification indicators, so as to determine whether the gearbox has a fault;

[0065] In one embodiment of the described method, in the eighth step S8, a band-pass filter is used to retain the response A at of the typical fault characteristic frequency f0 component of the gearbox in the responses measured by the n at0 acceleration sensors. Using the method described in step (4), based on the filtered response A at0 , through the conversion matrix T A , the full-field acceleration response A0(t) of the typical fault characteristic frequency f0 component of the gearbox housing is reconstructed.

[0066] In one embodiment of the described method, in the eighth step S8, for the full-field acceleration response A0(t) of the typical fault characteristic frequency f0 component of the gearbox housing, find the measuring point candidate set Φ p and find the measuring point with the maximum acceleration response in it. The corresponding node number is n a0_max , which is the gearbox fault-sensitive measuring point d0, and monitor the response of the fault-sensitive measuring point d0 of the fault-sensitive measuring point carry out FFT analysis on the response of the fault-sensitive measuring point to generate the spectrogram of the response of the fault-sensitive measuring point , and compare it with the spectrogram of the response of this measuring point under the normal working conditions of the gearbox. If there are significant changes in the fault characteristic frequency information in the spectrogram of the response of the fault-sensitive measuring point

[0067] Figures 1 to 10(b) The following combines the attached

[0068] Figure 1 and uses a specific simulation example to further describe the present invention and illustrate the changes in the full-field acceleration response contour map of the gearbox housing under different fault types. It should be emphasized that the following description is only exemplary, and the application object of the present invention is not limited to the following examples.FIG. 0 is a schematic flow chart of a gearbox fault detection method based on full-field reconstruction of structural acceleration response. This method constructs the conversion relationship between the finite acceleration sensor measurement points on the gearbox housing and the acceleration response of all nodes in the field based on modal reduction and extension theory to realize the full-field acceleration response reconstruction of the gearbox housing. Each node is assigned a color according to the numerical value of the node acceleration response, and a scatter plot of the gearbox housing is drawn based on the coordinates and colors of each node to realize the visual display of the reconstructed full-field acceleration response of the gearbox housing. The fault-sensitive measurement points are determined according to the full-field response of the reconstructed fault characteristic frequency components, and then the working state monitoring and fault diagnosis of the gearbox are realized. The specific steps of the method are as follows:

[0069] 1. Establish the geometric model and finite element model of the gearbox housing, and extract the coordinates of each node of the three-dimensional finite element model: Refer to Figures 2(a) to 2(b) , establish the geometric model of the gearbox housing according to the actual gearbox housing model parameters, and use ANSYS finite element analysis software to establish the finite element model of the gearbox housing. The material is structural steel, and the density is 7850 Kg / m 3 , the elastic modulus is 2×10 11 Pa, and the Poisson's ratio is 0.3. The finite element element type is Solid186 element, the mesh size is 12 mm, the total number of elements is 79025, the total number of mesh nodes is 128699, and fixed constraints are applied to the four bolt hole surfaces of the gearbox to simulate the constraint conditions during the operation of the gearbox housing;

[0070] Use ANSYS finite element software to obtain the first 5 modal parameters, that is, n s =5; the modal frequency f i and the displacement modal shape φ dof with a size of n i ×1, where the first 5 modal frequencies are f1 = 345.61 Hz, f2 = 672.37 Hz, f3 = 695.11 Hz, f4 = 747.08 Hz, f5 = 880.97 Hz; construct the full-field displacement modal shape matrix with a size of n dof ×n s , and the displacement modal shape diagram is shown in Figures 3(a) to 3(e) ; i represents the modal order, n dof =386097 represents the number of degrees of freedom of the finite element model of the gearbox housing; the displacement of each node contains 3 displacement components u x , u y , u z , that is, each node has 3 displacement modal shapes, that is, n dof =3n no , n no =128699 represents the number of nodes of the finite element model of the gearbox housing.

[0071] 2. To determine the acceleration sensor layout plan, we must first select a candidate set of acceleration sensor measurement points that meet certain preliminary selection conditions based on the measurement point location selection principle. The principles of the location candidate set for the acceleration sensor layout are: 1. The measurement point location candidate set should fully reflect the overall characteristics of the structural elastic modal deformation, and the vibration response should be obvious; 2. The measurement point location candidate set should be convenient for arranging, replacing sensors and detecting data; 3. The vibration signal of the measurement point location candidate set has a high signal-to-noise ratio; for the gearbox housing in this example, the measurement point location candidate set is shown in Figures 4(a) to 4(c) , where Fig. 4(a) is the X-axis acceleration sensor measurement point position candidate set, Fig. 4(b) is the Y-axis acceleration sensor measurement point position candidate set, and Fig. 4(c) is the Z-axis acceleration sensor measurement point position candidate set; extract the displacement modal vibration shape of each candidate measurement point in the measurement point candidate set, and construct the measurement point candidate matrix of the displacement modal vibration shape , size is n c ×n s , where φ i * is the i-th order main vibration displacement mode shape of the candidate measuring point in the measuring point candidate set, n c =11250 represents the number of candidate measuring points in the measuring point candidate set;

[0072] Determine the number and location of the acceleration sensors to be arranged. The number of acceleration sensors n at and the number of vibration multimodes n s The relationship is: n at ≥n s ; In engineering practice, the external excitation frequency is generally smaller than the natural frequency of the gearbox. Considering the complexity of the gearbox model, we focus on the first five vibration modes of the gearbox and take n s =5, the number of acceleration sensors is 6. From the measurement point candidate matrix Φ p Select n at = 6 measuring points, construct n at ×n s =6×5 measurement point displacement mode shape matrix Φ at , and calculate its matrix condition number w. This random process is repeated L times, and the acceleration sensor layout scheme with the smallest condition number w is selected as the best acceleration sensor layout scheme. The optimization layout result of the measuring points is shown in Figure 2(b). The X-axis acceleration sensors are selected to be installed at the positions of nodes 2280 and 3850, the Y-axis acceleration sensors are selected to be installed at the positions of node 5246, and the Z-axis acceleration sensors are selected to be installed at the positions of 2379, 2593 and 6410. The measured response of the acceleration sensor measuring points arranged at the nodes is simulated by the acceleration response of the corresponding direction of the nodes in the extracted numerical simulation.

[0073] 3. Construct the conversion matrix T for converting the acceleration responses of finite measurement points and the full-field acceleration responses A = Φ × Φ at -1 , with a size of 3n no × n at = 386097 × 6; where Φ at -1 is the inverse matrix of the measured point displacement modal vibration shape matrix.

[0074] 4. Use finite acceleration sensors to obtain the acceleration responses at finite positions on the gearbox housing. In this embodiment, a transient analysis is carried out by applying excitations F1: Fx1 = 40sin(60πt) N, F y1 = 30cos(60πt) N at node 4555 of the housing, simulating the state of the housing under normal excitations under normal working conditions. The excitation load frequency is 30 Hz. The schematic diagram of excitation F1 is shown in Fig. 2(b). Extract the acceleration responses of each node from 0.8125 s to 1 s in the simulation analysis as the reference for the reconstruction results.

[0075] Realize the reconstruction of the acceleration responses at any time, any position, and any direction of the gearbox housing: According to the acceleration conversion matrix T A = Φ × Φ at -1 , based on the acceleration responses A at of 6 optimized measurement points, calculate the acceleration response field A(t) in all directions at all nodes in the full field of the housing, where

[0076]

[0077] represents the acceleration responses in three directions at all nodes on the surface and inside of the gearbox housing;

[0078] Take node 2500 and node 25815 of the gearbox housing as typical representatives for high-precision reconstruction of the full-field acceleration responses. The results are shown in Figures 5(a) to 5(c) and Figures 6(a) to 6(c) . The conclusion also applies to other nodes. Among them, Figures 5(a) to 5(c) are respectively the comparison of the time-domain waveforms of the reconstructed X, Y, and Z acceleration responses at node 2500 of the gearbox housing in the embodiment and the X, Y, and Z acceleration response time-domain waveforms in the simulation analysis, Figures 6(a) to 6(c) are respectively the comparison of the time-domain waveforms of the reconstructed X, Y, and Z acceleration responses at node 25815 of the gearbox housing in the embodiment and the X, Y, and Z acceleration response time-domain waveforms in the simulation analysis. It can be seen that the coincidence degree of the reconstructed acceleration response and the simulation response time-domain waveforms is high and the consistency is good. Based on the method of this patent, accurate reconstruction of the structural full-field acceleration response can be achieved.

[0079] 5. Realize the visualization of the full-field acceleration response of the reconstructed gearbox housing: Divide the numerical range R of the acceleration response of each node of the housing at a certain moment \(t_0 = 0.898s\) into 9 equal-sized intervals \(R_i\) (\(1\leq i\leq9\)). Each interval corresponds to a color. Add the color corresponding to the interval to which the node acceleration response belongs to each node according to the magnitude of the node acceleration response value. Draw a scatter plot of the reconstructed acceleration response field based on the coordinates coor of each node extracted and the color of each node. At the same time, mark the node with the maximum acceleration response with MAX in the scatter plot. The acceleration response of node No. 41476 is the largest, which is \(2.1062mm / s^2\). i (1≤i≤9), each interval corresponds to a color. Add the color corresponding to the interval to which the node acceleration response belongs to each node according to the magnitude of the node acceleration response value. According to the coordinates coor no of each node extracted and the color of each node, draw a scatter plot of the reconstructed acceleration response field. At the same time, mark the node with the maximum acceleration response with MAX in the scatter plot. The acceleration response of node No. 41476 is the largest, which is \(2.1062mm / s^2\). 2 ;

[0080] Draw an indicator bar to clearly show the magnitude and distribution of the full-field acceleration response of the gearbox housing. Divide a line segment with a starting endpoint \(a_1\) min and an ending endpoint \(a_2\) max into 9 equal parts on average. Mark the numerical magnitudes \(a_1\) min , \(a_2\) max at the endpoints and each equal division point respectively, and add the color corresponding to this numerical interval to each small line segment. Among them, \(a_1\) min =0mm / s^2 2 represents the minimum value of the acceleration response of all nodes, \(a_2\) max =2.1062mm / s^2 2 represents the maximum value of the acceleration response of all nodes, \(|R| = 2.1062\) represents the magnitude of the numerical range R, and j represents the jth equal division point. The scatter plot and the indicator bar together constitute the full-field acceleration response cloud map K of the gearbox housing at \(t_0 = 0.898s\). The results are shown in Figure 7 .

[0081] 6. Based on the full-field reconstruction of the acceleration response and the visualization technology of the response field, reconstruct and monitor the full-field acceleration response of the structure of the gearbox housing in real time during operation. In this embodiment, by applying excitations \(F_1\) at node No. 4555 of the housing: \(F_1\) x1 =40sin(60πt)N, \(F_2\) y1 =30cos(60πt)N, and canceling the fixed constraint of one bolt hole surface to carry out transient analysis to simulate the vibration state of the housing when one bolt fails and the constraint is damaged during operation; when faults occur in internal gears, bearings, etc. of the gearbox, abnormal excitations will be applied to the housing. By applying excitations \(F_1\) at node No. 4555 of the housing: \(F_1\) x1 =40sin(60πt)N, \(F_2\) y1 =30cos(60πt)N and applying excitation \(F_2\) at node No. 4401 of the housing: \(F_2\) x2 =8sin(100πt)N, \(F_2\)y2 = 6cos(100πt) N to carry out transient analysis, simulating the vibration state of the box body under the abnormal excitation F2 during operation, where the frequency of the abnormal excitation is the typical fault characteristic frequency f o = 50 Hz; extract the acceleration responses A at (t) of each node from 0.8125 s to 1 s in the two simulation analyses; Figures 8(a) to 8(b) is a schematic diagram of a typical fault occurring in the gearbox in the embodiment. Among them, Fig. 8(a) is a schematic diagram of the state where a bolt of the gearbox box body fails and the constraint is damaged, and Fig. 8(b) is a schematic diagram of the gearbox box body under abnormal excitation;

[0082] Use step 4 to realize the reconstruction of the full-field acceleration response of the gearbox box body under the conditions of constraint damage and abnormal excitation; use step 5 to realize the visualization of the full-field acceleration response of the gearbox box body under the conditions of constraint damage and abnormal excitation; the results are shown in Figures 9(a) to 9(b) , where Fig. 9(a) is a cloud diagram of the full-field acceleration response of the gearbox box body when a bolt of the gearbox box body fails and the constraint is damaged at the moment t0 = 0.898 s, and Fig. 9(b) is a cloud diagram of the full-field acceleration response of the gearbox box body under the abnormal excitation state at the moment t0 = 0.898 s; compared with Figure 7 the cloud diagram K of the acceleration response of the gearbox box body under normal working conditions, the magnitude and distribution of the full-field acceleration response when the gearbox fails change significantly; at the moment t0 = 0.898 s, under normal working conditions, a max = 2.1062 mm / s 2 , na _max = 2585; under the state of constraint damage, a max = 1.8545 mm / s 2 , n a_max = 2495; under the abnormal excitation state, a max = 3.5451 mm / s 2 , n a_max = 41470; when the gearbox fails, the numerical value a max of the maximum acceleration response of the full field of the box body and the position of the node n a_max with the maximum acceleration response change significantly. Based on the full-field reconstruction of the structural acceleration response, by real-time monitoring of the acceleration response field of the gearbox box body, the working state monitoring and fault diagnosis of the gearbox can be realized.

[0083] 7. Reconstruct the full-field acceleration response of the typical fault characteristic frequency components of the gearbox, determine the typical fault sensitive measuring points. First, use a band-pass filter to retain the response A at of the gearbox typical fault characteristic frequency f0 component in the responses measured by the n at0 optimally arranged acceleration sensors, where n at= 6, f0 = 50Hz;

[0084] Based on the obtained response A after filtering at0 Reconstruct the full-field acceleration response A0(t) of the typical fault characteristic frequency f0 = 50Hz component of the gearbox, and find the candidate set Φ of measurement points p The measurement point with the maximum acceleration response in Φ, and the corresponding node number n a0_max = 63495, located in the candidate set of Z-direction measurement points. For details, see Fig. 10(a). Define this measurement point as the fault-sensitive measurement point d0 of the gearbox, and monitor the response of the fault-sensitive measurement point For the response of the sensitive measurement point Carry out FFT analysis. The result is shown in Fig. 10(b). Although there is a certain error, the information of the fault characteristic frequency component is significant. Under normal working conditions, there is no fault characteristic frequency f0 = 50Hz component in the response of the sensitive measurement point. Therefore, the fault characteristic frequency information in the response of the fault-sensitive measurement point has an obvious change in the frequency spectrum diagram, and it can be judged that the gearbox has a typical fault corresponding to the typical fault characteristic frequency f0 = 50Hz. In the simulation example of the abnormal excitation state, the magnitude of the applied abnormal excitation F2 is only 20% of the normal excitation F1, and in the response of the fault-sensitive measurement point determined by the method of this patent the amplitude of the response of the 50Hz component of the abnormal excitation frequency is 82.78% of the amplitude of the response of the 30Hz component of the normal excitation frequency. The typical fault characteristic information in the response of the fault-sensitive measurement point is significant. Therefore, the fault characteristic frequency information in the response of the sensitive measurement point is not easily submerged by other signals. It can be seen that the fault-sensitive measurement point determined by using this method has an important engineering application prospect in the field of health monitoring.

[0085] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present invention, and these all belong to the scope of protection of the present invention.

Claims

1. A gearbox fault detection method based on full-field reconstruction of structural acceleration response, characterized in that, It includes the following steps, In the first step, a three-dimensional finite element model of the gearbox housing is established, and the modal parameters and node coordinates of the three-dimensional finite element model are extracted. Among them, the first few modal parameters, modal frequencies and displacement modal vibration modes of size are extracted through modal analysis, and a full-field displacement modal vibration mode matrix of the gearbox housing is constructed, with a size of . Among them, represents the number of vibration multimodes, represents the modal order, represents the number of degrees of freedom of the three-dimensional finite element model, , represents the number of nodes of the three-dimensional finite element model; In the second step, an optimized layout scheme for the acceleration sensors is determined, including the number and installation positions of the acceleration sensors. Among them, the acceleration sensors are arranged in the candidate set of measurement points, the displacement mode shapes of each candidate measurement point in the candidate set of measurement points are extracted, and a candidate matrix of the displacement mode shapes of the measurement points is constructed , with a size of , where is the -th vibration displacement mode shape of the candidate measurement points in the candidate set of measurement points, represents the number of candidate measurement points in the candidate set of measurement points. Randomly select measurement points equipped with acceleration sensors from the candidate matrix to construct a measurement point displacement mode shape matrix with a size of , and calculate its matrix condition number . This random process is repeated L times, and the acceleration sensor layout scheme with the smallest condition number is selected as the optimized layout scheme for the acceleration sensors; In the third step, a conversion matrix between the acceleration responses at finite measurement points and the full-field acceleration responses of the gearbox housing is established. , with a size of ; where is the inverse matrix of the displacement modal shape matrix at the measurement points, with a size of ; In the fourth step, based on the optimized layout scheme of the acceleration sensors, the measured acceleration responses of the finite measuring points of the gearbox housing are obtained by the acceleration sensors, where represents the measured acceleration response of the th acceleration sensor of the system. According to the acceleration responses of the finite measuring points, all-node acceleration responses are obtained through the transformation matrix , where ； Among them, represents the acceleration response in the direction of the th node of the gearbox housing, represents the acceleration response in the direction of the th node of the gearbox housing, represents the acceleration response in the direction of the th node of the gearbox housing; In the fifth step, colors are assigned to the nodes according to the numerical magnitudes of the acceleration responses of the nodes, and a full-field acceleration response cloud diagram of the gearbox housing is drawn based on the node coordinates and the node colors to visually display the reconstructed full-field acceleration response of the gearbox housing; In the sixth step, based on the acceleration responses of limited measuring points obtained in real time through the conversion matrix obtain the real-time acceleration responses of all nodes of the gearbox housing , and generate a real-time full-field acceleration response contour map of the gearbox housing; In the seventh step, the full-field acceleration response cloud diagram of the gearbox housing under the real-time working state is compared with the full-field acceleration response cloud diagram of the gearbox housing under normal working conditions. Among them, the numerical distribution of the acceleration responses, the numerical value of the maximum full-field acceleration response, and the positions of the nodes with the maximum acceleration responses are compared to determine whether the gearbox has a fault.

2. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 1, wherein, In the first step, the node coordinates are , where represents the node number, represents the coordinate of the node, represents the coordinate of the node, represents the coordinate of the node.

3. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 1, wherein, In the second step, the number of acceleration sensors and the number of vibration multimodes are related as follows: .

4. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 1, wherein, In the fifth step, at the moment the numerical range of the acceleration responses of each node of the box body is divided into 9 equal-sized intervals R i , 1 ≤ i ≤ 9. Each interval corresponds to a color. According to the numerical magnitude of the acceleration responses of the nodes, the color corresponding to the interval to which the acceleration response of each node belongs is added to each node. According to the extracted coordinates of each node and the colors of each node, a scatter plot of the reconstructed acceleration response field is drawn to visually display the reconstructed full-field acceleration response.

5. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 4, wherein, In the scatter plot, the node with the maximum acceleration response is marked with MAX.

6. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 4, wherein, In the fifth step, draw an indicator bar to clearly show the magnitude and distribution of the full-field acceleration response. Divide the line segment with the starting endpoint and the ending endpoint into 9 equal parts on average. Mark the numerical magnitudes at the endpoints and each equal division point, and add colors corresponding to the numerical intervals to each small line segment. Among them, represents the minimum value of the acceleration responses of all nodes, represents the maximum value of the acceleration responses of all nodes, represents the magnitude of the numerical range , represents the th equal division point. The scatter plot and the indicator bar together constitute the full-field acceleration response nephogram of the gearbox housing at the moment.

7. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 1, wherein, It also includes, In the eighth step, a band-pass filter is used to retain the response components of the typical fault characteristic frequencies of the gearbox measured by the acceleration sensors . Based on the response , the typical fault characteristic frequencies of the gearbox housing are reconstructed for the full-field acceleration response components. The measurement point with the maximum acceleration response in the candidate measurement point set is found as the fault-sensitive measurement point of the gearbox. The measurement point response of the sensitive measurement point is monitored and analyzed, and compared with the response of this measurement point under normal conditions. According to whether there is an obvious change in the fault characteristic frequency information in the sensitive measurement point response, it is judged whether the gearbox has a typical fault characteristic frequency corresponding to the typical fault.

8. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 7, wherein, In the eighth step, a band-pass filter is used to retain the response of the typical fault characteristic frequencies of the gearbox measured by the components. Based on the response obtained after filtering , via the conversion matrix, the full-field acceleration response of the typical fault characteristic frequencies of the gearbox housing components is reconstructed .

9. The gearbox fault detection method based on full-field reconstruction of structural acceleration response according to claim 8, wherein, In the eighth step, for the typical fault characteristic frequency of the gearbox housing the full-field acceleration response of the component , find the measuring point with the largest acceleration response in the candidate set of measuring points, and the corresponding node number is , which is the fault-sensitive measuring point of the gearbox , monitor the response of the fault-sensitive measuring point of , for the response of the fault-sensitive measuring point carry out FFT analysis to generate the spectrum diagram of the response of the fault-sensitive measuring point , compare it with the spectrum diagram of the response of this measuring point under the normal working conditions of the gearbox. If the fault characteristic frequency information in the spectrum diagram of the response of the fault-sensitive measuring point changes significantly, it is judged that the gearbox has a typical fault corresponding to the typical fault characteristic frequency , otherwise, it is judged that the gearbox does not have a typical fault corresponding to the typical fault characteristic frequency .

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