Helicopter rotor shaft same cross section bending moment time domain correlation atlas analysis method

Abstract

The invention is applied to the field of helicopter model development fault diagnosis, and relates to a helicopter rotor shaft and cross section bending moment time domain correlation atlas analysis method. The method comprises the following steps: extracting actual measurement data of rotor shaft bending moment measurement strain gauges on all cross sections under a specific working condition, and constructing a bending moment data matrix Mm of each cross section according to geometric arrangement of the rotor shaft bending moment measurement strain gauges; data at the same moment in two groups of measured data of different direction channels of the same cross section form measuring point abscissas and ordinates of a Cartesian coordinate system; drawing positions of all measuring points on a time domain in a Cartesian coordinate system to obtain a time domain correlation graph; obtaining a time domain correlation graph normal form of the correct measurement data of the rotor shaft bending moment of the helicopter with the same number of rotor support arms under the same working condition; and comparing the time domain correlation graph with the time domain correlation graph normal form, and judging whether the actually measured data have faults or not.

Description

Technical Field

[0001] The present invention is used in the field of helicopter model development fault diagnosis and relates to a time-domain correlation spectrum analysis method for the same-cross-section bending moment of a helicopter rotor shaft. Background Art

[0002] The entire helicopter load measurement flight test system also tests the flapping / shimmying bending moments / torques of the main and tail rotor blades, the rotor shaft bending moments / torques / tensions, stresses in the hub centerpiece and pitch lever, stresses in the transmission case and horizontal drive shaft, and stresses and loads in key components such as the fuselage's center beam and tail beam. The number of load measurement channels can exceed 400. The attachment, connection, labeling, calibration, and inspection of these channels' load sensors and their cables are extremely complex, and the rotor shaft bending moment channel often suffers from hidden faults such as crosstalk, calibration coefficient errors, and data inversion.

[0003] Rotor shaft bending moment strain gauges, lead wires, and other high-precision measurement components are often damaged by the complex, variable, and high-gradient vibration and load environment of helicopters, as well as bumps and bruises during transportation, assembly, or scheduled inspections. This often results in damage to one or more strain gauges, invalidating the test data for a particular channel of the main shaft bending moment. Invalid data from any channel prevents complete real-time monitoring, safety assessment, and service life evaluation of the main shaft bending moment. Scientific research flight tests generally require interrupting the test equipment for repair, which inevitably prolongs the test cycle. This also makes it impossible to directly derive the yaw force, lateral force, pitch bending moment, and roll moment at the hub center, making it impossible to accurately obtain the hub center vibration load. Consequently, it is impossible to accurately estimate and determine the airframe structure vibration response, or conduct airframe structure vibration control design. Summary of the Invention

[0004] The purpose of the invention is to quickly verify the validity of the rotor shaft bending moment measurement data, accurately locate and process hidden faults, ensure the effectiveness of real-time monitoring of the main rotor shaft bending moment data and structural life assessment in helicopter development, ensure the safety of tests and test flights, as well as the development cycle, and save development costs.

[0005] Technical solution:

[0006] A method for analyzing the time-domain correlation graph of the bending moment of the same cross-section of a helicopter rotor shaft is provided, comprising:

[0007] Extract the measured data of the rotor shaft bending moment measurement strain gauges on all cross sections under specific working conditions, and construct the bending moment data matrix M of each cross section according to the geometric arrangement of the rotor shaft bending moment measurement strain gauges. m ; Each cross section has two channels of orthogonal measured data;

[0008] The data of two sets of measured data of channels in different directions of the same cross section at the same time are combined into the horizontal coordinates and vertical coordinates of the measuring points in the Cartesian coordinate system;

[0009] Plot the positions of all measurement points in the time domain in the Cartesian coordinate system to obtain the time domain correlation graph;

[0010] Obtain the time domain correlation graphical paradigm of the correct measurement data of the helicopter rotor shaft bending moment under the same working conditions and with the same number of rotor arms;

[0011] Compare the time domain correlation graph with the above time domain correlation graph paradigm to determine whether there is a fault in the measured data.

[0012] Furthermore, the method further comprises:

[0013] If the time domain correlation graph is the same as the above time domain correlation graph paradigm, then the measured data of the corresponding two channels are valid;

[0014] If the time domain correlation graph is different from the above time domain correlation graph paradigm, the measured data of the corresponding two channels are invalid and a fault exists.

[0015] Furthermore, after obtaining the time domain correlation graphical paradigm of the correct measurement data of the rotor shaft bending moment of helicopters under the same working condition and with the same number of rotor arms, the method further includes:

[0016] Calculate the correlation coefficient of two sets of measured data in different direction channels of the same cross section;

[0017] Compare the time domain correlation graph with the above time domain correlation graph paradigm, and compare the correlation coefficient of the measured data with the corresponding correct measured data time domain correlation coefficient paradigm to determine whether the measured data has a fault;

[0018] If the time domain correlation graph is consistent with the above time domain correlation graph paradigm, and the correlation coefficient of the measured data meets the requirements of the correct measurement data time domain correlation coefficient paradigm, then the measured data of the corresponding two channels are valid;

[0019] If the time domain correlation graph is different from the above time domain correlation graph paradigm, and the correlation coefficient of the measured data does not meet the requirements of the correct measurement data time domain correlation coefficient paradigm, the measured data of the corresponding two channels are invalid and a fault exists.

[0020] Furthermore, for the same cross-section, the time domain correlation diagram paradigm of the bending moment of the hub main shaft with the same cross-section and typical arm geometry includes the time domain correlation diagram paradigm of the correct measurement data of the bending moment of the helicopter rotor shaft with different numbers of rotor arms under different special working conditions.

[0021] Furthermore, the time domain correlation graph paradigm is shown in Table 1:

[0022] Table 1

[0023]

[0024] Furthermore, for different cross-sections, the time-domain correlation diagram paradigms of the bending moments of the hub main axis in the same cross-section orthogonal channel of the typical arm geometry configuration include:

[0025] The correlation coefficient of the two sets of measured data of the same direction channel is greater than or equal to 0.999, and / or the time domain correlation graph of the two sets of measured data of the same direction channel is a 45° oblique line;

[0026] The correlation coefficient of the two sets of measured data of the channels in different directions is less than 0.1, and\or, the time domain correlation graphs of the two sets of measured data of the channels in different directions conform to the time domain correlation graph paradigm of the bending moment of the orthogonal channel of the hub main axis with the same cross section of the typical support arm geometric configuration under the same cross section.

[0027] Furthermore, the method further comprises:

[0028] According to the characteristics of the helicopter rotor shaft bending moment, the time domain correlation diagram paradigm of the correct test data of the helicopter rotor shaft bending moment is determined.

[0029] Beneficial Effects: The data verification and analysis methods for helicopter rotor shaft bending moment measurement, as well as their engineering applications, primarily include analysis of digital signal consistency, zero drift, jitter, and signal fluctuation parameters (peak-to-peak, RMS, kurtosis, etc.). Engineering applications for rotor shaft bending moment primarily include the evaluation and optimization of rotor shaft static and dynamic strength, service life, reliability, and structural design, as well as real-time monitoring of rotor shaft health during flight testing and fault diagnosis of rotor shaft bending moment measurements.

[0030] Compared with the previous rotor shaft bending moment analysis method, the design method of the present invention has the following advantages or expanded applications:

[0031] 1) Graphical representation of digital information is intuitive, vivid, and quick, making it easier to understand;

[0032] 2) It can be used to verify the authenticity and validity of the bending moment measurement data of different cross sections of the rotor shaft;

[0033] 3) Can be used for rotor shaft bending moment measurement fault diagnosis and treatment;

[0034] 4) It can be used to understand and analyze the complexity and characteristics of blade loads in different flight conditions;

[0035] 5) It can be used to analyze and understand the problem of excessive vibration of helicopter body in working conditions such as transition speed forward flight, deceleration descent, deceleration forward flight, and high-speed forward flight. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the topological model diagram for the structural analysis of the five-arm ball flexible hub rotor system.

[0037] Figure 2 The diagram shows the arrangement of strain gauges for the main shaft structure and its bending moment measurement, as well as the channel identification diagram.

[0038] Figure 3(1) shows the arrangement of the bending moment strain gauges on the main shaft cross section 1. Figure 1 .

[0039] Figure 3(2) shows the arrangement of the bending moment strain gauges on the main shaft cross section 1. Figure 2 .

[0040] Figure 4 This is the main shaft bending moment mechanics analysis model and the geometric relationship diagram of the measuring points.

[0041] Figure 5 The time domain curve of typical data of main shaft bending moment.

[0042] Figure 6(1) is a time domain correlation diagram of two channel data in different orthogonal directions of the ground driving cross section of the five-arm hub main shaft.

[0043] Figure 6(2) is a time domain correlation diagram of two channel data in different orthogonal directions of the near-ground acceleration cross section of the five-arm hub main shaft.

[0044] Figure 6(3) is a time domain correlation diagram of two channel data in different orthogonal directions of the uniform climbing cross section of the five-arm hub main shaft.

[0045] Figure 6(4) is a time domain correlation diagram of two channel data in different orthogonal directions of the cross section of the five-arm propeller hub main shaft at low speed forward flight.

[0046] Figure 6(5) is a time domain correlation diagram of two channel data in different orthogonal directions of the five-arm hub main shaft mid-speed forward flight cross section.

[0047] Figure 6 (6) is a time domain correlation diagram of two channel data in different orthogonal directions of the cross section of the five-arm hub main shaft accelerated forward flight.

[0048] Figure 6 (7) is a time domain correlation diagram of two channel data in different orthogonal directions of the cross section of the five-arm hub main shaft deceleration forward flight.

[0049] Figure 6(8) is a time domain correlation diagram of two channel data in different orthogonal directions of the cross section of the five-arm hub main shaft at high speed forward flight.

[0050] Figure 6(9) is a time domain correlation diagram of two channel data in different orthogonal directions of the cross section of the five-arm propeller hub main shaft deceleration descent. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0052] In the description of the present invention, it should be understood that the terms "center", "axial", "vertical", "up", "down", "upper end", "bottom end", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0053] The layout and geometric relationship of the helicopter rotor shaft bending moment test channel (test station) are shown in Figure 1 and Figure 2 In fact, after many processes such as sensor calibration, installation, calibration, acquisition, and DSP processing, the bending moment data of each test channel is a set of digital signals sampled and arranged synchronously in time sequence, forming a one-dimensional digital array. The number of elements n in this array is determined by the sampling frequency f s and the length of the analyzed data period t c The typical time domain data of the bending moment of two orthogonal channels in a single cross section of the rotor shaft can be found in Figure 3(1)-Figure 3(2) .

[0054] The technical idea of ​​the present invention is: first, based on the geometric arrangement of the rotor shaft bending moment measurement strain gauge and the measured data, a bending moment data matrix M is constructed. m Secondly, the data from two bending moment channels in orthogonal directions on a single cross-section of the main shaft at the same time is used to construct a linear equation with unknown coefficients. Based on this linear equation, the data from any time period in the time domain is constructed into a linear matrix equation with two variables. Thirdly, computer software graphics tools (such as VC++, VB, or MATLAB) are used to plot the positions of all measurement points in the time domain of the two channel data in a Cartesian coordinate system to obtain their time domain correlation graph. Finally, a time domain correlation graph paradigm for the helicopter rotor shaft bending moment is established.

[0055] The present invention can be divided into the following 10 steps, which are detailed as follows.

[0056] The first step is to determine the geometric position relationship of the two cross sections of the rotor shaft and the identification of the two mutually orthogonal bending moment channels in a single cross section (taking cross section 1 as an example) according to the rotor shaft structure and the geometric arrangement of the bending moment test strain gauges, as shown in Figures 3(1), 3(2) and Figure 4 ,The two channels in cross section 1 are labeled BB1 NRL and BB1 PRL.

[0057] In the second step, the original measured data of the main shaft bending moment is a discrete digital signal collected synchronously and sequentially at equal time intervals. The data of each channel is arranged in order according to time to form a data sequence. is a data series of the main shaft bending moment channel with n elements, where b represents the main shaft bending moment; for the convenience of expression, p takes the natural numbers 1 and 2, where "1" represents "BB1NRL" and "2" represents "BB1PRL"; n is a natural number, which is determined by the sampling frequency f s and the length of the analyzed data period t c Sure.

[0058] The third step is to construct a time series digital signal main axis bending moment matrix M based on the measured data of the main axis bending moment and the two channels of the cross section under a typical flight condition. m , see formula (1).

[0059]

[0060] The fourth step is to construct a two-variable linear equation using the data of the main axis bending moment and the two orthogonal direction channels of the cross section at the same time, see formula (2).

[0061] y=k×x (2)

[0062] The fifth step is to construct a binary linear matrix equation for the data of any period in the time domain, see formula (3). The data signal series collected from the two main shaft bending moment channels, a single data is

[0063]

[0064] Step 6: Calculate the arithmetic mean of n sample signals of two channels and See equations (4) and (5).

[0065]

[0066] The seventh step is to use the Pearson product-moment correlation coefficient calculation model to obtain the correlation coefficient R of the two bending moment channel data in the time domain. 12 , see formula (6).

[0067]

[0068] The eighth step is to use computer software graphics tools (such as VC++, VB or MATLAB, etc.) to plot the positions of all measurement points in the time domain of the above two channel data in the Cartesian coordinate system, and obtain the time domain correlation graph of the channel bending moments in two orthogonal directions of the same cross-section of the main axis of a typical flight condition.

[0069] In the ninth step, repeat the first to eighth steps to obtain the time domain correlation diagram of the bending moment of the orthogonal channel of the hub main shaft with a support arm geometric configuration under multiple typical flight conditions.

[0070] In the tenth step, repeat steps one to nine to obtain the time-domain correlation maps of the bending moments of the orthogonal channels of the hub main shaft in the same cross section with different typical support arm geometric configurations, and establish the time-domain correlation map paradigm of the bending moments of the helicopter rotor shaft (four typical support arm geometric hub configurations), see Table 1.

[0071] Table 1 Time domain correlation diagram of bending moment of orthogonal channel in the same section of hub main axis in typical support arm geometry

[0072] Working condition name Three arms Four arms Five arms Six arms Ground driving Ring Ring Ring Ring Hover Ring Ring Ring Ring Near-ground acceleration Equilateral triangle ring Nearly square ring Regular pentagonal ring Regular hexagonal ring Fly forward at low speed Near-triangular ring Square ring Pentagonal Ring Hexagonal Ring Medium speed forward flight triangular cloud Nearly square ring Pentagonal Ring Hexagonal wreath Flying forward at high speed Equilateral triangle ring Square ring Pentagram Ring Hexagonal Ring Accelerate forward equilateral triangle cloud Square ring Pentagonal Ring Slow down and fly forward Near-triangular ring Pentagonal Cloud Decline in speed triangular cloud Four-cornered cloud Pentagonal Cloud Hexagonal Cloud

[0073] Now take the time domain correlation spectrum analysis of the bending moment of the main rotor shaft of the five-arm ball flexible hub as an example, as follows:

[0074] The first step is to determine the geometric position relationship of the two cross sections of the rotor shaft and the identification of the two mutually orthogonal bending moment channels in each cross section according to the rotor shaft structure and the geometric arrangement of the bending moment test strain gauges. Figure 1 and Figure 2 The two channels of cross section 1 are BB1 ​​NRL and BB1 PRL.

[0075] In the second step, the original measured data of the main shaft bending moment is a discrete digital signal collected synchronously and sequentially at equal time intervals. The data of each channel is arranged in order according to time to form a data sequence M. bpn is a data series of the main shaft bending moment channel with n elements, where b represents the main shaft bending moment; for the convenience of expression, p takes the natural numbers 1 and 2, where "1" represents "BB1NRL" and "2" represents "BB1PRL"; n is a natural number, which is determined by the sampling frequency f s and the length of the analyzed data period t c Sure.

[0076] The third step is to construct a time series digital signal spindle bending moment matrix M based on the measured data of the spindle bending moment under ground driving conditions. m , see formula (1).

[0077] The fourth step is to construct a two-variable linear equation with unknown coefficients using the data of the main axis bending moment and the two orthogonal direction channels of the cross section at the same time, see formula (2).

[0078] The fifth step is to construct a binary linear matrix equation for the data of any period in the time domain, see formula (3). The data signal series collected for the two main shaft bending moment channels are as follows: Figure 5 As shown, the single data is , q=1, 2, 3,…, n.

[0079] Step 6: Calculate the arithmetic mean of n sample signals of two channels and , see formulas (4) and (5).

[0080] The seventh step is to use the Pearson product-moment correlation coefficient method to calculate the correlation coefficient R of the two moment channel data in the time domain. 12 , see formula (6).

[0081] Step 8: Use computer software graphics tools (such as VC++, VB or MATLAB, etc.) to plot the positions of all measurement points in the time domain of the two channel data in the Cartesian coordinate system to obtain the time domain correlation graph of the channel bending moments in two orthogonal directions of the same cross section of the main axis under ground driving conditions (see Figure 6 (1)).

[0082] Step 9: Repeat steps 1 to 8 to obtain the time domain correlation graph of the bending moment of the orthogonal channel of the main axis of the five-arm geometric configuration under multiple typical flight conditions (see Figures 6(1) to 6(9) ), supplementing the time-domain correlation diagram paradigm of helicopter rotor shaft bending moment.

[0083] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

[0084] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A time domain correlation spectrum analysis method for the bending moment of the same cross section of a helicopter rotor shaft, characterized by: include: Extract the measured data of the rotor shaft bending moment measurement strain gauges on all cross sections under specific working conditions, and construct the bending moment data matrix M of each cross section according to the geometric arrangement of the rotor shaft bending moment measurement strain gauges. m ; Each cross section has two channels of orthogonal measured data; The data of two sets of measured data of channels in different directions of the same cross section at the same time are combined into the horizontal coordinates and vertical coordinates of the measuring points in the Cartesian coordinate system; Plot the positions of all measurement points in the time domain in the Cartesian coordinate system to obtain the time domain correlation graph; Obtain the time domain correlation graphical paradigm of the correct measurement data of the helicopter rotor shaft bending moment under the same working conditions and with the same number of rotor arms; Compare the time domain correlation graph with the above time domain correlation graph paradigm to determine whether there is a fault in the measured data.

2. The method according to claim 1, characterized in that The method further comprises: If the time domain correlation graph is the same as the above time domain correlation graph paradigm, then the measured data of the corresponding two channels are valid; If the time domain correlation graph is different from the above time domain correlation graph paradigm, the measured data of the corresponding two channels are invalid and a fault exists.

3. The method according to claim 2, characterized in that After obtaining the time-domain correlation graphical paradigm of the correct measurement data of the rotor shaft bending moment of the helicopter under the same working condition and with the same number of rotor arms, the method further includes: Calculate the correlation coefficient of two sets of measured data in different direction channels of the same cross section; Compare the time domain correlation graph with the above time domain correlation graph paradigm, and compare the correlation coefficient of the measured data with the corresponding correct measured data time domain correlation coefficient paradigm to determine whether the measured data has a fault; If the time domain correlation graph is consistent with the above time domain correlation graph paradigm, and the correlation coefficient of the measured data meets the requirements of the correct measurement data time domain correlation coefficient paradigm, then the measured data of the corresponding two channels are valid; If the time domain correlation graph is different from the above time domain correlation graph paradigm, and the correlation coefficient of the measured data does not meet the requirements of the correct measurement data time domain correlation coefficient paradigm, the measured data of the corresponding two channels are invalid and a fault exists.

4. The method according to claim 3, characterized in that For the same cross-section, the typical arm geometry configuration of the hub main shaft with the same cross-section orthogonal channel bending moment time domain correlation diagram paradigm includes the helicopter rotor shaft bending moment correct measurement data time domain correlation diagram paradigm for different numbers of rotor arms under different special working conditions.

5. The method according to claim 4, characterized in that The time domain correlation graph paradigm is shown in Table 1: Table 1 6. The method according to claim 5, characterized in that For different cross-sections, the time domain correlation diagram paradigms of the bending moment in the orthogonal channel of the hub main axis of the same cross-section of the typical arm geometry include: The correlation coefficient of the two sets of measured data of the same direction channel is greater than or equal to 0.999, and / or the time domain correlation graph of the two sets of measured data of the same direction channel is a 45° oblique line; The correlation coefficient of the two sets of measured data of the channels in different directions is less than 0.1, and\or, the time domain correlation graphs of the two sets of measured data of the channels in different directions conform to the time domain correlation graph paradigm of the bending moment of the orthogonal channel of the hub main axis with the same cross section of the typical support arm geometric configuration under the same cross section.

7. The method according to claim 1, characterized in that The method further comprises: According to the characteristics of the helicopter rotor shaft bending moment, the time domain correlation diagram paradigm of the correct test data of the helicopter rotor shaft bending moment is determined.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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