Method for analyzing time-domain correlation of different cross-section bending moments of helicopter rotor shaft

Abstract

The application belongs to the field of helicopter strength design, and relates to a rotor shaft cross section moment time domain correlation graph analysis method of a helicopter. The method comprises the following steps: extracting measured data of rotor shaft moment measuring strain gauges on all cross sections under a specific working condition, constructing a moment data matrix M of each cross section according to the geometric arrangement of the rotor shaft moment measuring strain gauges m ; wherein each cross section has two-channel orthogonal measured data; forming data of the same time in two groups of measured data of the same direction channels of different cross sections into a measuring point horizontal coordinate and a vertical coordinate of a Cartesian coordinate system, or forming data of the same time in two groups of measured data of different direction channels of different cross sections into a measuring point horizontal coordinate and a vertical coordinate of a Cartesian coordinate system; drawing positions of all measuring points in the time domain to obtain a time domain correlation graph; obtaining a rotor shaft moment correct measurement data time domain correlation graph paradigm of a helicopter with the same working condition and the same number of rotor arms; and comparing the time domain correlation graph with the time domain correlation graph paradigm.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of helicopter strength design, and relates to a helicopter rotor shaft different cross-section bending moment time domain correlation map analysis method. BACKGROUND

[0002] The rotor system is the core mechanical system for helicopters to perform various movement functions, the rotor shaft is the main path for the static and dynamic load of the blade to be transmitted to the body structure, the bending moment load borne by the structure is the manifestation of the hub center load, is the input and optimization object of the static strength, fatigue and vibration control design, and is the main basis for evaluating the static and dynamic strength, service life, reliability and structure design of the rotor shaft, and can also be used for real-time monitoring, analysis and evaluation of the static and dynamic load level and structure health state of the blade and the hub. Meanwhile, the bending moment can be inversely deduced to obtain four vibration loads at the hub center, which can be used for body structure vibration response prediction and verification, active / passive vibration control design, and mechanism analysis of the problem of excessive body structure vibration. The vibration load obtained through the technical route is directly derived from the flight test data, and is more accurate and more practical than the result obtained through rotor / airframe aerodynamic simulation calculation.

[0003] Meanwhile, the rotor shaft bending moment is also the most important transmission link of the blade aerodynamic load under different flight conditions and the most direct reflection of its characteristics, which provides a new perspective and scenario for understanding, recognizing, understanding and analyzing the complexity of the helicopter rotor system aerodynamic load (especially in the condition of speed reduction glide).

[0004] Rotor shaft bending moment measurement and its application have attracted more and more attention and emphasis in the helicopter industry, and in recent years, various data testing and analysis methods have been proposed to provide technical support for the model application of the main shaft bending moment. How to ensure the authenticity and effectiveness of the rotor shaft bending moment measurement data, and to research and find some more efficient and accurate data analysis methods, has become a new direction and hotspot for the research of rotor shaft bending moment. SUMMARY

[0005] The application aims to provide a new method for testing the authenticity and effectiveness of rotor shaft bending moment measurement data at different cross sections, which is intuitive, visual and fast; and to provide a new perspective and scenario for understanding, recognizing, understanding and analyzing the complexity of the helicopter rotor system aerodynamic load (especially in the condition of speed reduction glide).

[0006] TECHNICAL SCHEME

[0007] A helicopter rotor shaft different cross-section bending moment time domain correlation map analysis method is provided, which comprises the following steps:

[0008] Extracting the measured data of the rotor shaft bending moment measurement strain gauges at all cross sections under a specific condition, and constructing 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; wherein each cross section has two-channel orthogonal measured data;

[0009] composing the data of the same time in two groups of measured data of the same direction channel of different profiles into the horizontal and vertical coordinates of the measuring point of the Cartesian coordinate system, or composing the data of the same time in two groups of measured data of different direction channels of different cross sections into the horizontal and vertical coordinates of the measuring point of the Cartesian coordinate system;

[0010] drawing the positions of all measuring points on the time domain in the Cartesian coordinate system to obtain a time domain correlation graph;

[0011] obtaining a time domain correlation graph paradigm of correct measurement data of the rotor shaft bending moment of a helicopter with the same working condition and the same number of rotor support arms;

[0012] comparing the time domain correlation graph with the above-mentioned time domain correlation graph paradigm to determine whether the measured data has a fault.

[0013] Further, the method further comprises:

[0014] if the time domain correlation graph is the same as the above-mentioned time domain correlation graph paradigm, the measured data of the corresponding two channels is valid;

[0015] if the time domain correlation graph is different from the above-mentioned time domain correlation graph paradigm, the measured data of the corresponding two channels is invalid and has a fault.

[0016] Further, after obtaining the time domain correlation graph paradigm of correct measurement data of the rotor shaft bending moment of a helicopter with the same working condition and the same number of rotor support arms, the method further comprises:

[0017] calculating the correlation coefficient of two groups of measured data of the same direction channel of different profiles, or the correlation coefficient of two groups of measured data of different direction channels of different cross sections;

[0018] comparing the time domain correlation graph with the above-mentioned time domain correlation graph paradigm, comparing the correlation coefficient of the measured data with the time domain correlation coefficient paradigm of the correct measurement data, and determining whether the measured data has a fault;

[0019] if the time domain correlation graph is the same as the above-mentioned time domain correlation graph paradigm, and the correlation coefficient of the measured data meets the requirement of the time domain correlation coefficient paradigm of the correct measurement data, the measured data of the corresponding two channels is valid;

[0020] if the time domain correlation graph is different from the above-mentioned time domain correlation graph paradigm, and the correlation coefficient of the measured data does not meet the requirement of the time domain correlation coefficient paradigm of the correct measurement data, the measured data of the corresponding two channels is invalid and has a fault.

[0021] Further, the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment includes the time-domain correlation pattern of the helicopter rotor shaft bending moment correct measurement data of different numbers of rotor arms under different special working conditions.

[0022] Further, the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment includes the time-domain correlation pattern of the helicopter rotor shaft bending moment correct measurement data of different numbers of rotor arms under different special working conditions.

[0023] Table 1

[0024]

[0025] Further, the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment includes the time-domain correlation pattern of the helicopter rotor shaft bending moment correct measurement data of different numbers of rotor arms under different special working conditions.

[0026] 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 pattern of the two sets of measured data of the same direction channel is a 45° diagonal line.

[0027] The correlation coefficient of the two sets of measured data of the different direction channel is less than 0.1, and / or the time-domain correlation pattern of the two sets of measured data of the different direction channel is the same as the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment.

[0028] Further, the method further includes:

[0029] If the correlation coefficient of the two sets of measured data of the same channel on the different direction cross-section is less than 0.1, and / or the time-domain correlation pattern is the same as the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment, the channel identification string channel is determined.

[0030] If the time-domain correlation pattern of the two sets of measured data of the different direction channel on the different cross-section does not conform to any time-domain correlation pattern in the time-domain correlation pattern of the typical arm geometry hub main shaft cross-section orthogonal channel bending moment, the channel is determined to be in series with other structural member bending moment measurement channels.

[0031] Further, the method further includes:

[0032] According to the characteristics of the helicopter rotor shaft bending moment, the time-domain correlation pattern of the helicopter rotor shaft bending moment correct measurement data is determined.

[0033] Advantages:

[0034] 1) The graphical representation of digital information is intuitive, visual, and fast, and is convenient for cognition.

[0035] 2) It can be used to verify the authenticity and effectiveness of the rotor shaft bending moment measurement data of different cross-sections.

[0036] 3) can be used for rotor shaft bending moment measurement fault diagnosis and treatment;

[0037] 4) can be used for cognition and analysis of different flight conditions of blade load complexity and characteristics;

[0038] 5) can be used to analyze and understand the problem of large vibration of helicopter in working conditions such as transition speed forward flight, speed reduction glide, deceleration forward flight, high speed forward flight, etc. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a schematic diagram of main shaft structure and its bending moment measurement strain gauge arrangement and channel identification.

[0040] Figure 2(1) is a schematic diagram of main shaft cross section 1 bending moment strain gauge arrangement Figure 1 .

[0041] Figure 2(2) is a schematic diagram of main shaft cross section 1 bending moment strain gauge arrangement 2.

[0042] Figure 3 It is a typical data time domain curve of main shaft bending moment.

[0043] Figure 4 It is a five-armed hub main shaft different cross section same orthogonal direction two channel data time domain correlation graph.

[0044] Figure 5(1) is a five-armed hub main shaft ground running cross section different orthogonal direction two channel data time domain correlation graph.

[0045] Figure 5(2) is a five-armed hub main shaft near ground acceleration cross section different orthogonal direction two channel data time domain correlation graph.

[0046] Figure 5(3) is a five-armed hub main shaft uniform speed climbing cross section different orthogonal direction two channel data time domain correlation graph.

[0047] Figure 5(4) is a five-armed hub main shaft low speed forward flight cross section different orthogonal direction two channel data time domain correlation graph.

[0048] Figure 5(5) is a five-armed hub main shaft medium speed forward flight cross section different orthogonal direction two channel data time domain correlation graph.

[0049] Figure 5(6) is a five-armed hub main shaft acceleration forward flight cross section different orthogonal direction two channel data time domain correlation graph.

[0050] Figure 5(7) is a five-armed hub main shaft deceleration forward flight cross section different orthogonal direction two channel data time domain correlation graph.

[0051] Figure 5(8) is a five-armed hub main shaft high speed forward flight cross-section different orthogonal direction two-channel data time domain correlation diagram.

[0052] Figure 5(9) is a five-armed hub main shaft speed reduction glide cross-section different orthogonal direction two-channel data time domain correlation diagram. DETAILED DESCRIPTION

[0053] The helicopter rotor shaft bending moment test channel (test station) arrangement and geometric relationship are shown in Figure 1 Figures 2(1) and 2(2). In fact, after sensor calibration, installation, calibration, collection, DSP processing and many other work processes, the bending moment data of each test channel is a set of time-sequentially synchronized sampling, arranged digital signals, constituting a one-dimensional digital array. The element number n of the array is determined by the sampling frequency f s and the time length t c of the analyzed data period. The typical time domain data of the four-channel bending moment of the rotor shaft two cross-sections are shown in the accompanying Figure 3 .

[0054] The technical idea of the present application is: first, taking the geometric arrangement of the rotor shaft bending moment measurement strain gauge and the measured data as the object, a bending moment data matrix M m is constructed; second, the data of the same moment of the different direction channels of the main shaft bending moment constructs a binary first-order equation with unknown coefficients, and based on the second-order equation, the data of any period in the time domain constructs a binary first-order matrix equation; third, the position of all measurement points on the time domain of the above two-channel data is plotted in the Cartesian coordinate system using computer software graphics tools (such as VC++, VB or MATLAB, etc.), and the time domain correlation graph is obtained. Finally, the helicopter rotor shaft bending moment time domain correlation atlas paradigm is established.

[0055] The helicopter rotor shaft bending moment test channel (test station) arrangement and geometric relationship are shown in Figure 1 Figures 2(1) and 2(2). In fact, after sensor calibration, installation, calibration, collection, DSP processing and many other work processes, the bending moment data of each test channel is a set of time-sequentially synchronized sampling, arranged digital signals, constituting a one-dimensional digital array. The element number n of the array is determined by the sampling frequency f s and the time length t c of the analyzed data period. The typical time domain data of the four-channel bending moment of the rotor shaft two cross-sections are shown in the accompanying Figure 3 .

[0056] The technical idea of the present application is: first, taking the geometric arrangement of the rotor shaft bending moment measurement strain gauge and the measured data as the object, a bending moment data matrix M mSecondly, the data of the same time of the different directions of the shaft bending moment is used to build a binary first order equation of unknown coefficient, and the data of any time period in the time domain is used to build a binary first order matrix equation.

[0057] The application can be divided into the following 11 steps, which are as follows.

[0058] 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 orthogonal direction bending moment channels in each cross section according to the rotor shaft structure and the geometric arrangement of the bending moment test strain gauge, as shown in Figure 1 Fig. 2 (1) and Fig. 2 (2): the two channels of the cross section 1 are BB1 NRL and BB1 PRL, and the two channels of the cross section 2 are BB2 NRL and BB2 PRL.

[0059] The second step is to collect the discrete digital signals of the original measured data of the main shaft bending moment at equal time intervals, synchronously and sequentially, and arrange the data of each channel in order according to time to form a data sequence M bpn , which has n elements of the main shaft bending moment channel data sequence, wherein b represents the main shaft bending moment; for the convenience of description, p takes natural numbers 1, 2, 3 and 4, wherein “1” represents “BB1 NRL”, “2” represents “BB1 PRL”, “3” represents “BB2 NRL” and “4” represents “BB2 PRL”; n is a natural number determined by the sampling frequency f s and the time length t c of the analyzed data period.

[0060] The third step is to build a time sequence digital signal main shaft bending moment matrix M m by using the measured data of the four channels of the main shaft bending moment of a typical flight working condition of different cross sections, as shown in formula (1).

[0061]

[0062] The fourth step is to build a binary first order equation by using the data of the same time of the two channels (BB1 NRL and BB2 NRL) of the same orthogonal direction of the different cross sections of the main shaft bending moment, as shown in formula (2).

[0063] y=kx (2)

[0064] The fifth step is to build a binary first order matrix equation by using the data of any time period in the time domain, as shown in formula (3). The data signal series collected for two different cross-section principal axis bending moment channels, a single data is q = 1, 2, 3, …, n.

[0065]

[0066] The sixth step is to calculate the arithmetic mean of the n sample signals of the two channels And See formula (4) and (5).

[0067]

[0068] The seventh step is to calculate the correlation coefficient R of the two bending moment channel data in the time domain by using the Pearson product-moment correlation coefficient method ij , see formula (6).

[0069]

[0070] The eighth step is to use computer software graphics tools (such as VC++, VB or MATLAB, etc.) to draw the positions of all measurement points in the time domain of the above two channel data in the Cartesian coordinate system, and obtain their time domain correlation graphics.

[0071] The ninth step is to repeat the first step to the eighth step to obtain the time domain correlation graphics of the hub main shaft bending moment of the same orthogonal direction channel of different cross-sections of a variety of typical flight conditions and a branch arm geometric configuration.

[0072] The tenth step is to repeat the first step to the ninth step to obtain the time domain correlation graphics of the hub main shaft bending moment of the same orthogonal direction channel of different cross-sections of four typical branch arm geometric configurations, and establish the time domain correlation graphics paradigm of the hub main shaft bending moment of the same orthogonal direction channel of different cross-sections of a helicopter rotor, see Table 1.

[0073] The eleventh step is to construct a binary linear equation with the data of the same time of the two channels (BB1 NRL and BB2 PRL) of the different cross-section principal axis bending moment, repeat the fourth step to the tenth step, obtain the time domain correlation graphics of the hub main shaft bending moment of the same orthogonal direction channel of different cross-sections of four typical branch arm geometric configurations, and establish the time domain correlation graphics paradigm of the hub main shaft bending moment of the different orthogonal direction channel of different cross-sections of a helicopter rotor, see Table 2.

[0074] Table 1 Time domain correlation graphics of hub main shaft bending moment of the same orthogonal direction channel of different cross-sections of a typical branch arm geometric configuration

[0075]

[0076]

[0077] Table 2 Typical boom geometry hub main shaft different section different orthogonal direction channel bending moment time domain correlation atlas

[0078] Operating Condition Name Three-Prong Four-Prong Five-Prong Six-Prong Ground Level Taxi Circular Circular Circular Circular Near Ground Acceleration Equilateral Triangle Ring Near Square Ring Regular Pentagon Ring Regular Hexagon Ring Low Speed Forward Flight Near Equilateral Triangle Ring Square Ring Pentagon Ring Hexagon Ring Medium Speed Forward Flight Triangular Cloud Near Square Ring Pentagon Ring Hexagon Ring High Speed Forward Flight Equilateral Triangle Ring Regular Square Ring Pentagon Star Ring Hexagon Ring Accelerating Forward Flight Equilateral Triangle Cloud Square Ring Pentagon Ring Decelerating Forward Flight Near Equilateral Triangle Ring Pentagon Cloud Speed Bleeding Descent Triangular Cloud Square Cloud Pentagonal Cloud Hexagonal Cloud

[0079] Now take five boom ball flexible hub main rotor shaft bending moment time domain correlation atlas analysis as an example, as follows:

[0080] First, according to the rotor shaft structure and bending moment test strain gauge geometric arrangement, the geometric position relationship of two cross sections of rotor shaft and the identification of two mutually orthogonal direction bending moment channels in each cross section are determined, see Figure 1 , Figure 2(1) and Figure 2(2): the two channels of cross section 1 are BB1 NRL and BB1 PRL, and the two channels of cross section 2 are BB2 NRL and BB2 PRL.

[0081] Second, the main shaft bending moment original measured data is discrete digital signal collected at equal time interval, synchronously and sequentially, and the data of each channel is arranged in order according to time, forming a data sequence M bpn , which has n elements, where b represents the main shaft bending moment; for the convenience of expression, p takes natural numbers 1, 2, 3 and 4, where "1" represents "BB1 NRL", "2" represents "BB1 PRL", "3" represents "BB2 NRL" and "4" represents "BB2 PRL"; n is a natural number determined by sampling frequency f s and the time length t c of the analyzed data period.

[0082] Third, the main shaft bending moment matrix M m is constructed by the measured data of four channels of main shaft bending moment of a certain typical flight condition at different cross sections, see formula (1).

[0083] Fourth, a binary linear equation is constructed by the data of two channels (BB1 NRL and BB2 NRL) of the same orthogonal direction at different cross sections at the same time, see formula (2).

[0084] Fifth, the data of any period in time domain constitutes a binary linear matrix equation, see formula (3). The data signal sequence collected by the two main shaft bending moment channels of different cross sections is q = 1, 2, 3, …, n.

[0085] Sixth, the arithmetic mean values of n sample signals of two channels are calculated and see formulas (4) and (5).

[0086] Step 7, the Pearson correlation coefficient method is used to calculate the correlation coefficient R of the two bending moment channel data in time domain ij , see equation (6).

[0087] Step 8, use computer software graphics tools (such as VC++, VB or MATLAB, etc.) to draw the positions of all measuring points in time domain of the above two channel data in Cartesian coordinate system, and obtain their time domain correlation graphics, see Fig. 3. Figure 4 .

[0088] Step 9, repeat steps 1 to 8 to obtain the time domain correlation graphics of the bending moment channel in the same orthogonal direction of different cross sections of the hub main shaft of a typical flight condition and a typical arm geometry, see Fig. 4. Figure 5(1) - Figure 5(9) .

[0089] Step 10, repeat steps 1 to 9 to obtain the time domain correlation graphics of the bending moment channel in the same orthogonal direction of different cross sections of the hub main shaft of four typical arm geometries, and establish the time domain correlation graphics paradigm of the bending moment channel in the same orthogonal direction of different cross sections of the main shaft of the helicopter rotor, see Table 1.

[0090] Step 11, construct a binary linear equation with the data of the same time of the two channels (BB1 NRL and BB2 PRL) in different orthogonal directions of different cross sections of the main shaft, repeat steps 4 to 10 to obtain the time domain correlation graphics of the bending moment channel in the same orthogonal direction of different cross sections of the hub main shaft of four typical arm geometries, and establish the time domain correlation graphics paradigm of the bending moment channel in different orthogonal directions of different cross sections of the main shaft of the helicopter rotor, see Table 2.

Claims

1. A method for analyzing the time-domain correlation of different cross-section bending moments of a helicopter rotor shaft, characterized in that, Comprise: Extract the measured data of the rotor shaft bending moment measuring strain gauges on all cross sections under the specific working condition, and construct the bending moment data matrix M of each cross section according to the geometric arrangement of the rotor shaft bending moment measuring strain gauges m ; Wherein, each cross section has two-channel orthogonal measured data; The same time data of two groups of measured data of the same direction channel of different cross sections are composed into the horizontal and vertical coordinates of the measuring point of the Cartesian coordinate system, or the same time data of two groups of measured data of different direction channels of different cross sections are composed into the horizontal and vertical coordinates of the measuring point of the Cartesian coordinate system; The positions of all measuring points on the time domain are drawn in the Cartesian coordinate system to obtain a time domain correlation graph; Obtain the time domain correlation graph paradigm of the correct measurement data of the rotor shaft bending moment of the helicopter with the same working condition and the same number of rotor support arms; Compare the time domain correlation graph with the above-mentioned time domain correlation graph paradigm to determine whether the measured data has a fault.

2. The method of claim 1, wherein, The method further comprises: If the time domain correlation graph is the same as the above-mentioned time domain correlation graph paradigm, the measured data of the corresponding two channels is valid; If the time domain correlation graph is different from the above-mentioned time domain correlation graph paradigm, the measured data of the corresponding two channels is invalid and has a fault.

3. The method of claim 2, wherein, After obtaining the time domain correlation graph paradigm of the correct measurement data of the rotor shaft bending moment of the helicopter with the same working condition and the same number of rotor support arms, the method further comprises: Calculate the correlation coefficient of two groups of measured data of the same direction channel of different cross sections, or calculate the correlation coefficient of two groups of measured data of different direction channels of different cross sections; Compare the time domain correlation graph with the above-mentioned time domain correlation graph paradigm, compare the correlation coefficient of the measured data with the time domain correlation coefficient paradigm of the correct measurement data, and determine whether the measured data has a fault; If the time domain correlation graph is the same as the above-mentioned time domain correlation graph paradigm, and the correlation coefficient of the measured data meets the requirements of the time domain correlation coefficient paradigm of the correct measurement data, the measured data of the corresponding two channels is valid; If the time domain correlation graph is different from the above-mentioned time domain correlation graph paradigm, and the correlation coefficient of the measured data does not meet the requirements of the time domain correlation coefficient paradigm of the correct measurement data, the measured data of the corresponding two channels is invalid and has a fault.

4. The method of claim 3, wherein, For the same cross section, the time domain correlation graph paradigm of the same cross section orthogonal channel bending moment of the hub main shaft of the typical support arm geometric configuration includes the time domain correlation graph paradigm of the correct measurement data of the rotor shaft bending moment of the helicopter with different numbers of rotor support arms under different special working conditions.

5. The method of claim 4, wherein, The time domain correlation graph paradigm of different channels is as shown in Table 1: Table 1 。 6. The method of claim 5, wherein, For different cross sections, the time domain correlation graph paradigm of the same cross section orthogonal channel bending moment of the hub main shaft of the typical support arm geometric configuration includes: The correlation coefficient of two groups of measured data of the same direction channel is greater than or equal to 0.999, and / or the time domain correlation graph of two groups of measured data of the same direction channel is a 45° diagonal line; The correlation coefficient of two groups of measured data of different direction channels is less than 0.1, and / or the time domain correlation graph of two groups of measured data of different direction channels is the same as the time domain correlation graph paradigm of the same cross section orthogonal channel bending moment of the hub main shaft of the typical support arm geometric configuration under the same cross section.

7. The method of claim 1, wherein, The method further comprises: If the correlation coefficient of two groups of measured data of the same direction channel on different cross sections is less than 0.1, and / or the time domain correlation pattern of the same cross section is consistent with the time domain correlation pattern of the typical branch arm geometric configuration hub main shaft and the cross section orthogonal channel bending moment, the channel identification string channel is determined; If the time domain correlation pattern of two groups of measured data of different direction channels on different cross sections does not conform to any time domain correlation pattern in the typical branch arm geometric configuration hub main shaft and the cross section orthogonal channel bending moment time domain correlation pattern, the channel is determined to be combined with other structural member bending moment measurement channel string channel.

8. The method of claim 1, wherein, The method further comprises: According to the helicopter rotor shaft bending moment characteristics, the time domain correlation pattern of the correct test data of the helicopter rotor shaft bending moment is determined.

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