Method for measuring the fatigue life of a diaphragm of a diaphragm coupling

Abstract

This invention relates to a measurement method for dynamically evaluating the fatigue life of diaphragm couplings. The method includes: S1, defining a coordinate system; establishing a measurement coordinate system with the center of the light source as the origin: Z-axis, along the axial direction; X-axis, horizontal radial direction; Y-axis, vertical radial direction; normal operating alignment, defined as the standard, where the center O of the photosensitive surface coincides with the center M of the light source, and the light spot uniformly covers the annular area; S2, measuring axial displacement; S3, measuring radial displacement; S4, measuring angular displacement; S5, synthesizing the three-dimensional displacement using a formula. This invention is rationally designed, compact in structure, and easy to use.

Description

Technical Field

[0001] This invention relates to a measurement method for dynamically evaluating the fatigue life of diaphragm couplings. Background Technology

[0002] Currently, there are four main technical approaches for dynamic life assessment of diaphragm couplings for wind turbines: Direct strain gauge measurement involves attaching strain gauges to the high-stress area of ​​the diaphragm, acquiring strain signals in real time, establishing a load spectrum using the rainflow counting method, and calculating lifespan consumption according to Miner's cumulative damage rule. This method offers the highest accuracy but involves complex handling of rotating leads.

[0003] Indirect calculation using vibration spectrum involves extracting characteristic components such as the second harmonic from the vibration signal using an accelerometer, and then indirectly inferring the bending stress state of the diaphragm. This method is the most convenient to install but has limited quantitative accuracy.

[0004] Acoustic emission crack early warning involves placing an AE sensor on the coupling's protective cover to capture high-frequency stress wave signals when cracks initiate, providing early warning before final fracture. It is simple to install but can only qualitatively determine "whether there is a crack" and cannot provide a value for the remaining life.

[0005] Centering deviation monitoring + finite element stress mapping: The three-dimensional centering deviation is acquired in real time using eddy current or MEMS sensors. Combined with the torque data of the SCADA system, the equivalent stress of the diaphragm is calculated in real time through an offline pre-calibrated finite element stress mapping model, and then the life is assessed by accumulating damage.

[0006] Currently, all technical approaches for dynamic life assessment of diaphragm couplings have significant limitations: While direct strain gauge measurement is the most accurate, the diaphragm is rotating at high speed, making lead wire arrangement extremely difficult. It requires slip rings or wireless strain gauges, resulting in complex protection design and high engineering implementation costs.

[0007] The vibration spectrum indirect calculation scheme is easy to install, but it requires an accurate transfer function model to infer the diaphragm stress from the vibration signal. It is affected by many factors (imbalance, resonance, environmental noise, etc.), has limited quantitative accuracy, and is prone to misjudgment.

[0008] Acoustic emission crack early warning schemes can only respond after cracks have already formed, which is essentially a "post-event warning" rather than a "lifetime prediction", and cannot provide a quantitative estimate of the remaining life.

[0009] While the center-monitoring + finite element mapping scheme is most suitable for engineering implementation, the establishment of a high-precision finite element stress mapping model requires a lot of offline calibration work, and the applicability of the model to actual working conditions (changes in boundary conditions such as temperature, wear, and bolt loosening) is difficult to guarantee continuously. Once the boundary conditions deviate from the calibration state, the life assessment error will be significantly amplified.

[0010] Overall, all the proposed solutions share common shortcomings: the load spectrum of wind turbines is highly random (random wind speed, turbulence, variable pitch speed), the dispersion of the SN curve of the diaphragm material, and the fact that Miner's rule itself ignores the load sequence effect, resulting in a large degree of uncertainty between theoretical life prediction and actual life. Summary of the Invention

[0011] In general, the technical problem to be solved by this invention is to provide a measurement method for dynamically evaluating the fatigue life of diaphragm couplings.

[0012] This invention achieves non-contact synchronous direct measurement of three misalignment quantities: axial displacement, radial displacement, and angular deviation by arranging a grating emitting light source on one end face and a circumferential photosensitive element array on the opposite end face. Using an algorithm, the calculated axial, radial, and angular displacements are input into the control unit. The diaphragm fatigue life is calculated using the diaphragm SN curve, which predicts the risk of diaphragm breakage in advance and avoids problems such as the coupling flying through the wind turbine nacelle and falling and injuring people after the diaphragm breaks.

[0013] To solve the above problems, the technical solution adopted by the present invention is as follows: A measurement method for dynamically evaluating the fatigue life of diaphragm couplings, based on diaphragm couplings; Diaphragm couplings have a driven side shaft end and a driving side shaft end; The diaphragm coupling has a brake disc end face and a flange end face that rotate synchronously; The brake disc end face has a driven side shaft end; The flange end face has a drive-side shaft end; A light source and a grating are provided on the end face of the brake disc; The light source section has several light sources arranged in a circumferential array with the center of the brake disc end face as the origin; A photosensitive surface is provided on the flange end face; Each photosensitive face has a corresponding photosensitive surface; A photosensitive surface is provided on the flange end face; The light source transmits light through the grating section to the photosensitive surface; The measurement method includes the following steps; S1, Coordinate system definition; Establish the measurement coordinate system with the center of the light source as the origin: Z-axis, along the axial direction; X-axis, horizontal radial direction; Y-axis, perpendicular to the radial direction; In normal operation, as defined by the standard, the center O of the photosensitive surface coincides with the center M of the light source, and the light spot evenly covers the annular area. S2, Axial displacement measurement; S3, Radial displacement measurement; S4, angular displacement measurement; S5, the formula for synthesizing the three-dimensional displacement.

[0014] As a further improvement to the above technical solution: The light source section has several light sources arranged in a circumferential array with the center of the brake disc end face as the origin; The photosensitive face is an array of photoelectric sensors; The driven side shaft end corresponds to the gearbox shaft. The light source unit has a circumferential photosensitive array and is mounted on the driven side shaft end; The drive-side shaft end corresponds to the generator shaft, and the photosensitive surface is mounted on the drive-side shaft end.

[0015] The advantages of this invention are: First, it truly achieves simultaneous direct measurement of three-dimensional deviations. The circumferential photosensitive array naturally possesses 360° spatial resolution, and a single sampling can decouple radial offset, angular deviation, and axial distance. Unlike eddy current schemes, it does not require indirect synthesis using multiple probes, nor does it rely on transfer function assumptions like vibration schemes, fundamentally reducing error accumulation in the measurement process. Second, it does not interfere with rotating components at all. Both the light source and the photosensitive receiver are fixedly installed on the non-rotating side, eliminating the need to attach strain gauges, install sensors, or handle lead wire transmission issues on the high-speed rotating coupling diaphragm. This reduces installation complexity and eliminates the reliability risks associated with modifying rotating components. Third, it has an extremely high sampling rate. The photoelectric detection response speed can reach the microsecond level, which can accurately capture transient overload conditions such as pitch operation and sudden gusts. It is more sensitive to the identification of extreme load cycles, making fatigue life prediction based on Miner's cumulative damage law more conservative and reliable. Fourth, it has rich data dimensions. The circumferential photosensitive array outputs complete spatial distribution information of light spots, which can intuitively restore the real-time deformation state of the diaphragm. It is also naturally suitable for integration with deep learning models. In the future, a more accurate data-driven life prediction system can be established without relying on traditional finite element pre-calibration methods. Fifth, the hardware structure is simple. Only one light source and one photosensitive array are needed to replace the combination of 5 to 6 sensors in the traditional solution, reducing system complexity and maintenance costs.

[0016] This invention optimizes measurement dimensions, response speed, and engineering convenience, and enables intelligent expansion, solving technical problems in existing solutions such as being able to measure accurately but not being able to install the device, or being able to install the device but not being able to measure accurately. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the brake disc end face structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the light source unit of the present invention.

[0019] Figure 3This is a schematic diagram of an embodiment of the light source unit of the present invention.

[0020] The components are: 1. Brake disc end face; 2. Light source section; 3. Gearbox shaft; 4. Generator shaft; 5. Photosensitive surface; 6. Flange end face; 7. Grating section; 8. Diaphragm assembly. Detailed Implementation

[0021] like Figure 1-3 The measurement method for dynamically evaluating the diaphragm fatigue life of diaphragm couplings in various embodiments is based on diaphragm couplings. The diaphragm coupling has a brake disc end face 1 and a flange end face 6 that rotate synchronously; The brake disc end face 1 has a gearbox shaft 3. The flange end face 6 has a generator shaft 4. A light source 2 and a grating 7 are provided on the end face 1 of the brake disc; that is, a circumferential photosensitive array is installed on the driven side shaft end. The light source section 2 has a plurality of light sources arranged in a circumferential array with the center of the brake disc end face 1 as the origin; A photosensitive surface 5 is provided on the flange end face 6, that is, the photosensitive surface 5 is installed on the drive side shaft end; The photosensitive face 5 has a photosensitive surface; The light source 2 transmits light through the grating 7 to the photosensitive surface 5; The calculation of the three-dimensional displacement of the grating-circular photosensitive array is as follows; S1, coordinate system definition; Establish a measurement coordinate system with the center of light source unit 2 as the origin: Z-axis, along the axial direction; X-axis, horizontal radial direction; Y-axis, perpendicular to the radial direction; In normal operation, as defined in the standard, the center O of the photosensitive surface 5 coincides with the center M of the light source 2, and the light spot evenly covers the annular area.

[0022] S2.1, Axial distance MO is adjusted and changed; S2.2, the distance from the grating section 7 to the photosensitive surface changes, thereby obtaining changes in the spot size and light intensity distribution on the photosensitive surface; Formula (1); in: —Axial displacement deviation of axial distance MO; —The measured spot diameter on the current photosensitive surface is calculated using the edge response position of the circumferential photosensitive array; — Reference spot diameter under the set standard alignment condition; — The set standard installation distance; Spot size includes diameter; S2.3, For formula (1), add the grating diffraction divergence angle. θ : Formula (2); in: — Initial calibration distance; — The effective divergence half-angle of the grating is determined by the parameters of the photosensitive surface 5; S2.4, Photosensitive array output characteristics: Formula (3); The equivalent radius of the edge of the light spot on the circumferential photosensitive array can be extracted using methods such as thresholding or gradient methods.

[0023] S3.1, Radial deviation of the X-axis; S3.2, The center of the light spot is translated within the photosensitive array plane of the photosensitive surface; S3.3, Calculation of the centroid of the light spot; Formula (4); in: — The spatial coordinates of the i-th photosensitive pixel; — The light intensity response value of the i-th photosensitive pixel; — Coordinates of the centroid of the light spot; N — Total number of pixels in the circumferential photosensitive array; S3.4, Calculation of radial displacement along the X-axis; ; ; ; Formula (5); in: — Reference centroid coordinates under standard alignment conditions; — Radial composite offset; — Radial offset direction angle;

[0024] S4.1, angular deviation around the Z-axis; S4.2, the grating surface of the grating section 7 changes from parallel to oblique to the photosensitive surface; S4.3, the light spot undergoes asymmetrical deformation on the photosensitive array of the photosensitive surface, that is, it is compressed on one side and widened on the other side; S4.4, Angular displacement measurement, including spot ellipticity analysis and / or second-order moment tensor method; In the method of analyzing the ellipticity of light spots; When there is an angular deviation α, the light spot changes from a circle to an ellipse: ; ; ; ;Formula (6); in: , , , — The equivalent diameter of the light spot in each of the four quadrants of the photosensitive array; , ; — The distance from the grating to the photosensitive surface is obtained synchronously by axial measurement; — Angular deviation resultant angle, rad; — The direction angle of angular deviation; The second-order moment tensor method is more accurate. Treating the light intensity distribution of the circumferential photosensitive array on the photosensitive surface as a two-dimensional probability distribution, the second-order central moment tensor is calculated: ; ;Formula (7); Equivalent Ellipse Major and Minor Axis Through eigenvalue decomposition: Formula (8); Angular deviation: Formula (9); Angular deviation direction: Formula (10); S5, Comprehensive three-dimensional displacement synthesis formula; The final output is the complete misalignment state vector of the diaphragm coupling: Formula (11); S6, Associated Lifetime Prediction; Based on formula (11), the triaxial deviation is mapped to the equivalent stress of the membrane, and the lifetime consumption is calculated using the SN curve and Miner's rule: S6.1, Membrane equivalent stress, simplified linear superposition model: Formula (12); in: , , — The stress influence coefficients for radial, axial, and angular deviations are obtained from finite element calibration; — The reference stress generated by the current torque is calculated from the torque data of the SCADA system; , , — Real-time measured triaxial deviation;

[0025] The relationship between SN curves, in power function form: Formula (13); Miner cumulative damage: Formula (14); Remaining lifespan, number of cycles: Formula (15); when When this occurs, a diaphragm replacement warning is triggered.

[0026] The preferred parameters are as follows:

[0027] Recommended value / range: 5°~15°; Choose the appropriate angle based on the specific sensor installation distance and photosensitive surface size.

[0028] Recommended value / range: ≥ 360 pixels / ring This resolution is to ensure that the system's angular resolution meets the requirement of ≤ 1°.

[0029] Recommended value / range: ≥ 1 kHz A higher sampling frequency is used to ensure that transient impact signals can be effectively captured.

[0030] Fatigue index m, for stainless steel diaphragm materials; Recommended value / range: 3~6; The specific value of this index needs to be determined based on the results of fatigue tests on the material.

[0031] Recommended value / range: 0.7 ~ 0.8; This range represents a relatively conservative warning setting, designed to provide early warnings and leave a safety margin.

[0032] This invention provides online real-time prediction of diaphragm fatigue life, dynamic monitoring of operating status, and integration with an AI-powered large-scale fan model to display the fatigue life of the coupling and diaphragm damage values. This reduces the frequency of routine maintenance and lowers operating costs.

[0033] The present invention has been described in detail for the purpose of making the disclosure clearer, and the prior art will not be listed in detail.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. It is obvious to those skilled in the art that multiple technical solutions of the present invention can be combined. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. All technical contents not described in detail in the present invention are well-known technologies.

Claims

1. A method for dynamically evaluating the fatigue life of a diaphragm coupling, characterized in that: Based on diaphragm couplings; Diaphragm couplings have a driven side shaft end and a driving side shaft end; The diaphragm coupling has a brake disc end face (1) and a flange end face (6) that rotate synchronously. The brake disc end face (1) has a driven side shaft end; The flange end face (6) has a drive-side shaft end; A light source part (2) and a grating part (7) are provided on the end face (1) of the brake disc. A photosensitive surface (5) is provided on the flange end face (6); The light source (2) transmits light through the grating (7) to the photosensitive surface (5); The measurement method includes the following steps; S1, Coordinate system definition; Establish a measurement coordinate system with the center of the light source (2) as the origin: Z-axis, along the axial direction; X-axis, horizontal radial direction; Y-axis, perpendicular to the radial direction; In normal operation, as defined by the standard, the center O of the photosensitive surface (5) coincides with the center M of the light source part (2), and the light spot evenly covers the annular area; S2, Axial displacement measurement; S3, Radial displacement measurement; S4, angular displacement measurement; S5, the formula for synthesizing the three-dimensional displacement.

2. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: The light source section (2) has several light sources arranged in a ring around the center of the brake disc end face (1); The photosensitive face (5) is a photoelectric sensor array; A diaphragm group (8) is provided on one side of the grating section (7); the receiving surface of the diaphragm group (8) is concave and the transmitting surface is convex. The driven side shaft end corresponds to the gearbox shaft (3). The light source unit (2) has a circumferential photosensitive array and is mounted on the driven side shaft end; The drive-side shaft end corresponds to the generator shaft (4), and the photosensitive surface (5) is installed on the drive-side shaft end.

3. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: In S2; S2.1, Axial distance MO is adjusted and changed; S2.2, the distance from the light source (2) to the photosensitive surface (5) is changed, and the changes in the size of the light spot and the light intensity distribution on the photosensitive surface (5) are obtained; Official (1); in: —Axial displacement deviation of axial distance MO; —The measured diameter of the light spot on the current photosensitive face (5); — Reference spot diameter under the set standard alignment condition; — The set standard installation distance; Spot size includes diameter; S2.3, For formula (1), add the grating diffraction divergence angle. θ : Official (2); in: — Initial calibration distance; — The effective divergence half-angle of the grating is determined by the parameters of the photosensitive surface (5); S2.4, Photosensitive array output characteristics: Official (3); —The equivalent radius of the edge of the spot on the circumferential photosensitive array is extracted by the threshold method or the gradient method.

4. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: In S3, S3.1, Radial deviation of the X-axis; S3.2, The center of the light spot is translated within the photosensitive array plane of the photosensitive surface (5); S3.3, Calculation of the centroid of the light spot; Official (4); in: — The spatial coordinates of the i-th photosensitive pixel; — The light intensity response value of the i-th photosensitive pixel; — Coordinates of the centroid of the light spot; N — Total number of pixels in the circumferential photosensitive array; S3.4, Calculation of radial displacement along the X-axis; ； ； Official (5); in: — Reference centroid coordinates under standard alignment conditions; — Radial composite offset; — Radial offset direction angle.

5. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: In S4, S4.1, angular deviation around the Z-axis; S4.2, the grating surface of the grating section (7) and the photosensitive surface of the photosensitive section (5) change from parallel to oblique; S4.3, the light spot undergoes asymmetrical deformation on the photosensitive array of the photosensitive surface; S4.4, Angular displacement measurement, including spot ellipticity analysis and / or second-order moment tensor method.

6. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 5, characterized in that: In the method of analyzing the ellipticity of light spots; In S4.4, when there is an angular deviation α, the light spot changes from a circle to an ellipse: ； ； ； Official (6); in: , , , — The equivalent diameter of the light spot in each of the four quadrants of the photosensitive array; ， ； — The distance from the grating to the photosensitive surface is obtained synchronously by axial measurement; — Angular deviation resultant angle, rad; — The direction angle of angular deviation.

7. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 5, characterized in that: In S4.4, the second-order moment tensor method is more accurate. Treating the light intensity distribution of the circumferential photosensitive array on the photosensitive surface as a two-dimensional probability distribution, the second-order central moment tensor is calculated: ； Official (7); Equivalent ellipse major and minor axis λ 1，2 Through eigenvalue decomposition: Official (8); Angular deviation: Official (9); Angular deviation direction: Official (10).

8. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: In S5, The final output is the complete misalignment state vector of the diaphragm coupling: Official (11).

9. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 1, characterized in that: S6, Associated Lifetime Prediction; Based on formula (11), the triaxial deviation is mapped to the equivalent stress of the membrane, and the lifetime consumption is calculated using the SN curve and Miner's rule: S6.1, Membrane equivalent stress, simplified linear superposition model: Official (12); in: , , — The stress influence coefficients for radial, axial, and angular deviations are obtained from finite element calibration; — The reference stress generated by the current torque is calculated from the torque data of the SCADA system; , , — Real-time measured triaxial deviation; in, The relationship between SN curves, in power function form: Official (13); Miner cumulative damage: Official (14); Remaining lifespan, number of cycles: Official (15); when When this occurs, a diaphragm replacement warning is triggered.

10. The method for measuring the fatigue life of a diaphragm coupling dynamically according to claim 8, characterized in that: For the grating section (7). Grating divergence half-angle θ range: 5° to 15°; Photosensitive array resolution range: ≥ 360 pixels / ring; Sampling frequency range: ≥ 1 kHz; Fatigue index m, for stainless steel diaphragm materials; Range: 3 to 6; Warning threshold D, range: 0.7 to 0.8.

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