Blade vibration testing device coupled with composite material friction element and parameter optimization method of blade vibration testing device

Abstract

The invention discloses a blade vibration testing device coupled with a composite material friction element and a parameter optimization method of the blade vibration testing device. The blade vibration testing device comprises a basic platform, at least two simulation blade test pieces and a wedge-shaped friction element, each simulation blade test piece is fixed on the foundation platform, a damping structure is arranged on each simulation blade test piece, and a wedge-shaped contact surface is arranged at the end part of each damping structure; the wedge-shaped contact surfaces of two adjacent simulation blade test pieces are oppositely arranged; and the wedge-shaped friction element is arranged between the wedge-shaped contact surfaces of the two adjacent simulation blade test pieces. Applying harmonic excitation to the blade body surface of the simulation blade test piece; the instantaneous attenuation response of the simulation blade test piece is measured, the first-order bending vibration response is obtained through Fourier transform, and the first-order modal damping ratio of the simulation blade test piece is obtained through calculation. The influence of the friction damping effect at different positions on the vibration reduction effect can be explored, and the optimal geometric parameters of the wedge-shaped friction elements at all positions can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of gas turbine vibration reduction, and relates to a blade vibration testing device with coupled composite material friction elements and its parameter optimization method. Background Technology

[0002] As gas turbines and steam turbines develop towards higher power and higher efficiency, the aerodynamic and centrifugal loads on blades increase significantly, making them highly susceptible to resonance and high-cycle fatigue failure. Existing dry friction vibration reduction structures often incorporate metal friction pairs (such as wedge-shaped damping blocks or contact strips) at the blade root or shroud to dissipate vibration energy. To achieve optimal damping and vibration reduction, parameter optimization design of the friction structure is necessary.

[0003] However, metal friction pairs suffer severe wear under high temperature and high centrifugal force conditions, which leads to a decrease in damping performance and thus weakens the vibration suppression effect. Traditional optimization methods based on parameter simulation require finite element analysis of blade models with different shroud structures one by one. When studying the influence of single parameters, traversal calculations are required, which is time-consuming and extremely costly. Moreover, traditional optimization algorithms are prone to converge to local optima due to search space characteristics and algorithm parameter settings, which affects the optimization results. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a blade vibration testing device and its parameter optimization method for coupled composite material friction elements, which can explore the influence of friction damping at different locations on the vibration reduction effect and obtain the optimal geometric parameters of the wedge-shaped friction elements at each location.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A blade vibration testing device with coupled composite friction elements includes a base platform, at least two simulated blade test pieces, and a wedge-shaped friction element; Each simulated blade test piece is fixed on a base platform, and each simulated blade test piece is equipped with a damping structure, with a wedge-shaped contact surface at the end of the damping structure; the wedge-shaped contact surfaces of two adjacent simulated blade test pieces are positioned opposite each other; The wedge-shaped friction element is installed between the wedge-shaped contact surfaces of two adjacent simulated blade test pieces.

[0006] Preferably, the wedge-shaped friction element is made of aramid composite material.

[0007] Preferably, the damping structure is slidably connected to the simulated blade test specimen.

[0008] Preferably, it also includes a signal generator, a power amplifier, and an electromagnetic vibrator connected in sequence, with the push rod of the electromagnetic vibrator in contact with the blade surface of the simulated blade test specimen.

[0009] Preferably, it also includes an eddy current displacement sensor, which is mounted directly in front of the damping structure.

[0010] Preferably, it also includes a laser vibration meter, which includes an optical head and a laser controller. The optical head is mounted on a tripod and connected to the laser controller. The optical head uses a reflector to reflect light onto the measuring point on the blade surface.

[0011] Preferably, an optical reflective film is attached to the side of the simulated blade test piece facing the reflector.

[0012] Preferably, it also includes a wire rope, a pulley, and a mass weight, with one end of the wire rope connected to the top of the wedge-shaped friction element; the mass weight is connected to the other end of the wire rope, and the wire rope passes around the pulley.

[0013] A method for optimizing blade vibration parameters of a coupled composite friction element includes the following steps: Secure the roots of the first and second simulated blade test specimens to the base platform; Damping structures are installed on the first and second simulated blade test pieces, and a wedge-shaped friction element is installed between the two damping structures. A load is applied to the wedge-shaped friction element. Harmonic excitation is applied to the blade surface of the simulated blade test specimen; The instantaneous decay response of the simulated blade test specimen was measured, the first-order bending vibration response was obtained through Fourier transform, and the first-order modal damping ratio of the simulated blade test specimen was calculated.

[0014] Preferably, the following steps are also included: An analytical model for the blade modes and response characteristics was established and modified based on the current test conditions and the obtained first-order modal damping ratio. Global proxy optimization analysis is performed based on the analysis model to obtain the geometric parameters of the wedge-shaped friction element.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The testing device described in this invention uses aramid composite material as the friction element, significantly improving durability and damping performance throughout its life cycle. It also features an adjustable damping structure and a high-precision measurement system. Its optimization method combines experimental testing, numerical correction, and global proxy optimization based on the Kriging model, avoiding extensive repetitive finite element analysis. This allows for efficient and accurate acquisition of the optimal geometric parameters of the friction element, thereby maximally suppressing blade vibration and ensuring the safe and stable operation of high-end equipment such as gas turbines. This invention solves the technical problems of severe wear and damping performance degradation in traditional metal friction elements, as well as the inefficiency and susceptibility to local optima in optimization methods. Attached Figure Description

[0016] Figure 1 This is a front view of the blade vibration testing device for the coupled composite friction element of the present invention; Figure 2 This is a top view of the blade vibration testing device for the coupled composite friction element of the present invention; Figure 3 This is a schematic diagram of the geometric parameters of the wedge-shaped friction element of the present invention; Figure 4 This is a schematic diagram of the force balance analysis of the wedge-shaped friction element of the present invention.

[0017] Figure 5 This is a flowchart illustrating the parameter optimization of the blade vibration testing device for the coupled composite friction element of the present invention.

[0018] Figure 6 This is a flowchart of the global agent optimization strategy of the Kriging model based on the expected improvement point addition criterion of the present invention.

[0019] Figure 7 The results show the optimized geometry of the wedge-shaped friction element at different blade height positions according to the present invention.

[0020] The components are: 1-base platform, 2-fixing bolt, 3-simulated blade test piece, 4-damping structure, 5-wedge friction element, 6-electromagnetic exciter, 7-signal generator, 8-power amplifier, 9-electromagnetic exciter, 10-eddy current displacement sensor, 11-laser vibration meter, 111-optical head, 112-laser controller, 12-multi-channel data acquisition unit, 13-wire rope, 14-pulley, 15-mass weight, 16-top rod, 17-reflector. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terms “installation,” “connection,” and “linkage” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection, an electrical connection, or a connection that allows communication; a direct connection or an indirect connection via an intermediate medium; or a connection within two elements or an interaction between two elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0026] Please see Figure 1 and Figure 2 This invention provides an embodiment of a blade vibration testing device with coupled composite material friction elements, comprising a base platform 1, fixing bolts 2, simulated blade test piece 3, damping structure 4, wedge-shaped friction element 5, electromagnetic exciter 6, signal generator 7, power amplifier 8, electromagnetic exciter 9, eddy current displacement sensor 10, laser vibration meter 11, multi-channel data acquisition unit 12, wire rope 13, pulley 14, and mass weights 15.

[0027] The base platform 1 is used to install and fix the various test devices; the fixing bolts 2 are used to fasten the simulated blade test piece 3 to the base platform.

[0028] The first simulated blade test piece and the second simulated blade test piece 3 are fixed adjacently on the base platform 1 by fixing bolts 2. When fixed, the sides of the bottom ends of the two test blades overlap. Each blade is provided with a damping structure 4 that can be adjusted in height and angle. The damping structure 4 is slidably connected to the simulated blade test piece 3, and its end is set as a wedge-shaped contact surface to test the vibration reduction effect of friction damping at different positions.

[0029] The wedge-shaped friction element 5 is made of aramid composite material and is installed between the wedge-shaped contact surfaces of the adjacent simulated blade test pieces 3. The bottom wedge angle of the element corresponds to the angle of the damping structure, and the top is attached to a steel wire rope 13, which is connected to a mass weight 15 through a pulley 14.

[0030] A signal generator 7, a power amplifier 8, and an electromagnetic exciter 9 are connected in sequence. The signal generator 7 generates a sinusoidal electrical signal with a certain amplitude and frequency. The power amplifier 8 modulates the signal from the signal generator to drive the load. The electromagnetic exciter 9 is installed directly in front of the blades of the two simulated blade test specimens 3, with its push rod 16 in contact with the blade surface, used to apply an excitation load with a certain amplitude and frequency to the blades. An eddy current displacement sensor 10 is installed directly in front of the damping structure 4 of the two simulated blade test specimens, used to collect the forced vibration signal of the blades.

[0031] The laser vibration meter 11 consists of two parts: an optical head 111 and a laser controller 112. The optical head 111 is mounted on a tripod and connected to the laser controller 112. The measurement range and filter are set using the touchscreen of the laser controller 112. Then, the optical head 111 is aligned with the reflector 17. The laser beam is reflected and strikes the measurement point on the blade surface, then reflected back to the optical head 111. The relative position is adjusted to ensure the signal strength received by the laser, and the corresponding response data is obtained at the signal output terminal. An optical reflective film is attached to the side of the simulated blade test piece facing the laser to reduce laser signal loss. The laser spot diameter emitted by the optical head 111 is within the micrometer range, ensuring high-precision measurement of the response signal.

[0032] Please see Figure 3 A schematic diagram of the geometric parameters of the wedge-shaped friction element is given, including the axial contact length. Top edge length a Base length b Left wedge angle Right wedge angle ,high h wait.

[0033] Please see Figure 4 A schematic diagram of the force balance analysis of a wedge-shaped friction element. One of the important factors affecting the friction damping effect is the normal force at the contact surface. This invention uses weights to simulate centrifugal load, therefore the normal force at the contact surface is mainly provided by the centrifugal force of the friction element itself. Figure 4 The force state of a wedge-shaped friction element under static equilibrium, where For the centrifugal force it experiences, These are the normal pressures between the surface and the left and right sides of the surface. These represent the frictional forces on the left and right contact surfaces, respectively. These are the wedge angles on the left and right sides, respectively. Analysis reveals that the forces acting on the wedge-shaped friction element in the horizontal and vertical directions satisfy the following equilibrium relationship:

[0034] When both the left and right contact surfaces meet the conditions for sliding, that is... Then, the expression for the normal force load applied to the left and right contact surfaces of the wedge-shaped friction element can be obtained as follows:

[0035]

[0036] Currently, commonly used methods for calculating the normal force on the contact surface often neglect the influence of contact friction on both sides, resulting in the normal load being expressed as: This could lead to calculated values ​​being larger than the actual values. This invention considers the influence of contact friction on both sides when calculating the contact normal force, thereby improving the accuracy of the normal force calculation.

[0037] Please see Figure 5 A flowchart for parameter optimization of a blade vibration testing device with coupled composite friction elements is shown below, with specific steps as follows: Step S1: On the base platform, use fixing bolts 2 to tighten the roots of the first simulated blade test piece and the second simulated blade test piece 3, and make the natural frequency of the blade measured by the force hammer excitation method match the numerical calculation result, so as to achieve complete constraint of the blade root.

[0038] Step S2: Install the two damping structures 4 radially from the blade tip at the same scale position on the simulated blade test piece 3. Install the wedge-shaped friction element 5 between the two damping structures 4, keeping their wedge-shaped surfaces in contact. Tie a steel wire rope 13 to the top of the wedge-shaped friction element 5 and connect it to a weight 15 of a certain mass through a pulley 14 to simulate the application of centrifugal load.

[0039] Step S3: Apply instantaneous harmonic excitation to the surface of the simulated blade test piece 3 via signal generator 7, power amplifier 8, and electromagnetic vibrator 9. F 0sin ωt ,in F 0 represents the excitation amplitude. ω The first-order bending vibration frequency of the blade was obtained through numerical calculation and analysis.

[0040] Step S4: The instantaneous damping response of the blade is measured using an eddy current displacement sensor and a laser vibration meter. The first-order bending vibration response is obtained using Fourier transform. Based on the logarithmic damping method, Hilbert transform is used to select a specific part of the time-domain signal to calculate the first-order modal damping ratio of the blade. ζ 0.

[0041] Step S5: Establish an equivalent analysis model of blade modal and response characteristics based on the current test conditions, and use the test results to correct the numerical analysis model.

[0042] Step S6: Maximize the first-order modal damping ratio ζ With a target of 0, a global proxy optimization analysis of the Kriging model based on the expected improvement point addition criterion is carried out to obtain the optimal geometric parameters of the wedge friction element.

[0043] Step S7: Replace the damping structure with different geometric shapes and its corresponding wedge-shaped friction element, install it at different radial scales of the blade, and repeat steps S2 to S6 to investigate the effect of friction damping at different locations on the vibration reduction effect, and obtain the optimal geometric parameters of the wedge-shaped friction element at each location.

[0044] Please see Figure 6 This document presents a flowchart of a global proxy optimization strategy for the Kriging model based on the expected improvement point addition criterion in step S6 of this embodiment of the invention. For large-scale optimization tasks with numerous parameter decisions, the optimization process is typically very complex, and the optimization objective may be multimodal, non-convex, high-dimensional, and have high evaluation costs. Furthermore, many optimization decision models are black-box and have high evaluation costs, significantly reducing the applicability of traditional optimization methods. For the vibration reduction optimization problem of the turbine damping blade in this experiment, the maximum modal damping ratio is considered as the optimization objective. Vibration characteristic analysis is conducted by adjusting the geometric parameters of the trapezoidal friction element to maximize the objective. However, traditional parameter simulation-based optimization methods require finite element analysis of blade models with different shroud structures one by one. When studying the influence of single parameters, traversal calculations are required, which is time-consuming and extremely costly. Moreover, traditional optimization algorithms are prone to convergence to local optima due to search space characteristics and algorithm parameter settings, thus affecting the optimization results.

[0045] To avoid the aforementioned problems, this invention proposes a global proxy optimization strategy for the Kriging model based on the expected improvement point addition criterion. This type of analysis method is typically used for analytical solutions of variables and black-box optimization problems with unknown derivatives, and is suitable for vibration reduction optimization of damping blades. The basic idea of ​​this method is as follows: First, a certain number of initial points are selected within the design space of the optimization parameters, and the vibration characteristic parameterization analysis is performed on these sample points to obtain the modal damping ratio calculation results. The design points of the optimized geometric parameters are used as input parameters, and the modal damping ratio calculation results are used as output parameters to construct an initial Kriging proxy model, which is then used for subsequent modal damping ratio prediction. This avoids repeated finite element analysis and solves the problem of low optimization efficiency in parameter simulation methods. In the optimization process based on the proxy model, the expected improvement point addition criterion strategy is selected, and new design points are actively sampled in the design space. Based on the analysis results, an updated global proxy model is obtained, and the objective function is automatically evaluated. Iterative calculations are performed until the global optimum in the search space is gradually approached, obtaining the optimal geometric parameters of the wedge-shaped friction element. This overcomes the shortcomings of traditional optimization methods that are prone to getting trapped in local optima.

[0046] The Kriging method is used to construct the geometric design parameters of the wedge-shaped friction element. To the maximum modal damping ratio ζ The initial surrogate model is 0. Based on data near the design variable sample points, and utilizing a weighting strategy based on the proximity information of the design variable sample points, its mathematical model combines polynomial components to describe the basic trend and incorporates random terms to capture the nondeterminism and variability in the data, thereby achieving an accurate fit to information on other location variables.

[0047] in, It is a prediction function obtained from the Kriging model; For polynomial terms, Basic polynomial regression function, polynomial coefficients Represents the regression parameters. N The number of samples; For random terms, the mean is 0 and the variance is... The Gaussian function representation, used to provide an approximation for simulating local biases, satisfies the following statistical characteristics:

[0048] in, These are random sample points; It is a correlation function based on the hyperparameter Θ, used to describe the correlation between two sample points. The specific relationship between them, and related to the distance between the two sample points, can therefore be represented in the following form:

[0049] In the formula: They are The k One component; It is the first hyperparameter Θ k The term can be obtained using the maximum likelihood estimation method. Regression parameters It can be obtained by solving using the least squares method:

[0050] variance is It can be calculated using the following formula:

[0051] In the formula: This represents the covariance matrix.

[0052] For other unknown points x The predicted mean and predicted variance can be obtained from the following formulas:

[0053]

[0054] In the formula: Prediction variance The representative proxy model at the sample points x The prediction uncertainty at that point. Further, we need to find the maximum value of the objective function:

[0055] The improvement function obtained by maximizing the expected improvement value at the current maximum value is:

[0056] In the formula, To output the maximum modal damping ratio, .

[0057] Furthermore, by employing the expected improvement EI function, the distribution of sample points within the nonlinear region is effectively enhanced through the addition of points:

[0058] In the formula, The initial Kriging proxy model at the sample points are respectively The corresponding predicted value and prediction standard deviation, It is the standard normal distribution function. Let be the probability density function of the standard normal distribution. According to the above formula, when the predicted value increases... Significant or predictable uncertainty For larger locations, the predicted value is improved. Expectations The larger the space, the better. The largest point is the new training sample point.

[0059] The two terms in the above EI criterion expression reflect the local search capability and global search capability of the optimization method, respectively. Excessive global search will reduce the convergence speed of the optimization algorithm. By introducing a weighting factor into the EI function... ω This allows the optimization algorithm to balance global and local search capabilities by adjusting the degree of global exploration and local development.

[0060] By updating the sample set of design variables and setting the number of iteration steps, the above steps are repeated until the values ​​of newly added sampling points tend to stabilize, i.e., their variation range is limited to a small interval, or the preset number of iterations is reached. When this loop terminates, the final sample set and corresponding target values ​​are obtained, and a highly adaptable and accurate global proxy model is constructed based on these data.

[0061] Please see Figure 7 The results of the optimized geometry of the wedge friction element at different blade height positions are presented. By replacing the wedge blocks with different wedge angles and their corresponding wedge friction elements, installing them at different radial scales on the blade, and repeating steps S2 to S6 in the embodiments of the present invention, the optimal geometric parameters of the wedge blocks at each location are obtained. Figure 7 a- Figure 7 d presents the optimized geometry of the wedge-shaped friction element at 30%, 50%, 80%, and 100% blade height positions, respectively.

[0062] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0063] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0064] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0065] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0066] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0067] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A blade vibration testing device with coupled composite friction elements, characterized in that, It includes a base platform (1), at least two simulated blade test pieces (3) and a wedge-shaped friction element (5); Each simulated blade test piece (3) is fixed on the base platform (1), and each simulated blade test piece (3) is provided with a damping structure (4), and the end of the damping structure (4) is provided with a wedge-shaped contact surface; the wedge-shaped contact surfaces of two adjacent simulated blade test pieces (3) are arranged opposite to each other; The wedge-shaped friction element (5) is installed between the wedge-shaped contact surfaces of two adjacent simulated blade test pieces (3).

2. The blade vibration testing device for coupled composite material friction elements according to claim 1, characterized in that, The wedge-shaped friction element (5) is made of aramid composite material.

3. The blade vibration testing device for coupled composite material friction elements according to claim 1, characterized in that, The damping structure (4) is slidably connected to the simulated blade test piece (3).

4. The blade vibration testing device for coupled composite material friction elements according to claim 1, characterized in that, It also includes a signal generator (7), a power amplifier (8) and an electromagnetic vibrator (9) connected in sequence, with the top rod (16) of the electromagnetic vibrator (9) in contact with the blade surface of the simulated blade test piece (3).

5. The blade vibration testing device for coupled composite material friction elements according to claim 4, characterized in that, It also includes an eddy current displacement sensor (10), which is mounted in front of the damping structure (4).

6. The blade vibration testing device for coupled composite material friction elements according to claim 1, characterized in that, It also includes a laser vibration meter (11), which includes an optical head (111) and a laser controller (112). The optical head (111) is mounted on a tripod and connected to the laser controller (112). The optical head (111) uses a reflector (17) to reflect the light onto the measuring point on the blade surface.

7. The blade vibration testing device for coupled composite material friction elements according to claim 6, characterized in that, An optical reflective film is attached to the side of the simulated blade test piece (3) facing the reflector (17).

8. The blade vibration testing device for coupled composite material friction elements according to claim 1, characterized in that, It also includes a wire rope (13), a pulley (14) and a mass weight (15), one end of the wire rope (13) is connected to the top of the wedge-shaped friction element (5); the mass weight (15) is connected to the other end of the wire rope (13), and the wire rope (13) passes around the pulley (14).

9. A method for optimizing blade vibration parameters based on a coupled composite friction element using the testing apparatus described in any one of claims 1-8, characterized in that, Includes the following steps: Secure the roots of the first simulated blade test piece and the second simulated blade test piece (3) to the base platform (1); Damping structures (4) are installed on the first simulated blade test piece and the second simulated blade test piece (3), and wedge-shaped friction elements (5) are installed between the two damping structures (4) and a load is applied to the wedge-shaped friction elements (5); Harmonic excitation is applied to the blade surface of the simulated blade test piece (3); The instantaneous decay response of the simulated blade test piece (3) was measured, the first-order bending vibration response was obtained by Fourier transform, and the first-order modal damping ratio of the simulated blade test piece (3) was calculated.

10. The method for testing blade vibration parameters of a coupled composite friction element according to claim 1, characterized in that, It also includes the following steps: An analytical model for the blade modes and response characteristics was established and modified based on the current test conditions and the obtained first-order modal damping ratio. Global proxy optimization analysis was performed based on the analysis model to obtain the geometric parameters of the wedge friction element (5).

Images