Performance evaluation system for cable strand finished product

Abstract

The invention discloses a cable strand finished product performance evaluation system, and relates to the technical field of engineering structural member quality detection.According to the cable strand finished product performance evaluation system, an intelligent comparison chain of working condition modal fingerprints and reference modal fingerprints is constructed, test boundary condition interference is effectively stripped, evaluation indexes for purely representing cable strand structural characteristics are extracted, and the cable strand finished product performance is evaluated under a controllable free suspension boundary. Through standardized broadband excitation and global vision measurement, a working condition modal fingerprint of a measured cable strand is obtained, the fingerprint comprises the influence of a current suspension state, the fingerprint is intelligently compared with a same-model reference modal fingerprint which is pre-stored in a database and obtained in a calibration environment, and the relative frequency deviation and a modal confidence criterion value are calculated, so that the reliability of the cable strand is improved, and the reliability of the cable strand is improved. The difference between a current test state and an ideal reference state is quantified, and weighted fusion is utilized to filter and normalize difference components reflecting boundary interference to output a modal health index, so that the consistency degree of the cable strand in the aspects of quality, rigidity and damping distribution is quantified.

Description

Technical Field

[0001] This invention relates to the field of engineering structural component quality testing technology, specifically a performance evaluation system for finished cable strands. Background Technology

[0002] As a key load-bearing component of modern long-span suspension and cable-stayed bridges, the uniformity, consistency, and structural integrity of the finished product performance of the cable strand directly determine the overall load-bearing capacity and long-term service safety of the main cable or cable. Traditional factory performance evaluation relies heavily on destructive tests conducted through sampling, such as static load fracture tests and fatigue tests. These methods are not only costly and time-consuming, but can also only verify the single dimension of ultimate bearing capacity. They cannot comprehensively and non-destructively assess the structural dynamic characteristics that reflect the collaborative working state of the steel wires inside the cable strand, the uniformity of materials, and potential defects. This makes it difficult to meet the urgent needs of modern bridge engineering for full inspection, intelligent diagnosis, and full life-cycle quality traceability of core components.

[0003] Current attempts to evaluate the dynamic characteristics of cable strands mainly rely on modal testing technology. However, its direct application in factory-based quality control scenarios faces inherent bottlenecks: First, the low-order global modal parameters of cable strands are extremely sensitive to the boundary conditions of their end supports. The test suspension conditions on the production site are difficult to accurately reproduce with the actual installation state, resulting in significant fluctuations and dispersions in the measured modal parameters. This noise completely masks the subtle differences in the structural characteristics of the cable strands themselves, making the modal parameters unreliable signals for judging the consistency of product quality. Second, existing methods lack a standardized data processing mechanism to remove boundary effects. Even when using the same type of excitation and sensing equipment, slight differences in suspension tension and environmental disturbances caused by different batches, different times, and different operators will render the measurement results incomparable. Therefore, existing modal testing-based technologies have failed to develop into a stable, reliable, and standardized non-destructive performance evaluation method for finished cable strand products because they cannot solve the core interference of boundary condition sensitivity.

[0004] In summary, the current field of cable strand performance evaluation has a technological gap in its evolution from destructive to non-destructive and from single-dimensional strength to multi-dimensional characteristics. There is an urgent need for a method that can overcome the interference of boundary conditions on dynamic testing, achieve accurate extraction and standardized comparison of the structural dynamics of the cable strand itself, and thus establish a quantifiable and traceable non-destructive performance identity for each cable strand. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a performance evaluation system for cable strand products. This system effectively isolates test boundary condition interference by constructing an intelligent comparison chain between the working condition modal fingerprint and the baseline modal fingerprint, extracting evaluation indicators that purely characterize the structural properties of the cable strand itself. Under controllable free suspension boundaries, the system acquires the working condition modal fingerprint of the tested cable strand through standardized broadband excitation and full-domain visual measurement. This fingerprint includes the influence of the current suspension state. It is then intelligently compared with the baseline modal fingerprint of the same model obtained under ideal calibration conditions and pre-stored in a database. By calculating the relative frequency deviation and modal confidence criterion value, the system quantifies the difference between the current test state and the ideal baseline state. These differences mainly stem from fluctuations in boundary conditions. Through weighted fusion, the system filters out and normalizes the difference components reflecting boundary interference, ultimately outputting a modal health index. This highlights and quantifies the consistency of the cable strand's mass, stiffness, and damping distribution, achieving the extraction of pure features from mixed signals.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a performance evaluation system for finished products of stranded strands, which includes: a non-contact broadband excitation module, a full-domain visual vibration measurement module, a synchronous control and data acquisition module, a modal fingerprint extraction module, and a modal fingerprint comparison and evaluation module; The non-contact broadband excitation module is used to provide standardized free suspension boundary conditions for the tested cable strand, and applies a preset broadband excitation signal to the cable strand in a non-contact excitation manner. The full-field visual vibration measurement module is used to synchronously acquire the full-field vibration image sequence of the finished cable strand under the action of the broadband excitation signal; The synchronization control and data acquisition module is used to synchronously control the application of the broadband excitation signal and the acquisition of the full-field vibration image sequence, and synchronously acquire the excitation time history data corresponding to the broadband excitation signal and the image sequence data corresponding to the full-field vibration image sequence. The modal fingerprint extraction module is used to receive the excitation time history data and the image sequence data, calculate the working condition modal parameter set of the tested cable strand under the free suspension boundary condition, and package it to generate a working condition modal fingerprint package. The modal fingerprint comparison and evaluation module pre-stores a benchmark modal fingerprint package obtained by the same type of cable strand under standard boundary conditions. It is used to compare and analyze the working condition modal fingerprint package with the benchmark modal fingerprint package, calculate and output a modal health index that characterizes the consistency of the cable strand's own structural characteristics.

[0007] Furthermore, the non-contact broadband excitation module includes a signal generator, a power amplifier, and an electromagnetic exciter; The signal generator is used to generate the preset wideband excitation signal; The power amplifier is connected to the signal generator and is used to amplify the power of the wideband excitation signal. The electromagnetic exciter is connected to the power amplifier, and its working end is set in a non-contact manner with the finished strand product. It is used to convert the amplified broadband excitation signal into an alternating magnetic field force and apply it to the finished strand product.

[0008] Furthermore, the global visual vibration measurement module includes a speckle projection light source, a high-speed binocular stereo vision camera, and an image acquisition card; The speckle projection light source is used to project a speckle pattern onto the surface of the finished strand; The high-speed binocular stereo vision camera is used to simultaneously acquire the full-field vibration image sequence of the strand surface with the speckle pattern from different perspectives; The image acquisition card is connected to the high-speed binocular stereo vision camera and is used to receive and transmit the image sequence data.

[0009] Furthermore, the working principle of the synchronization control and data acquisition module is as follows: Send a first trigger signal to the non-contact broadband excitation module to start the output of the preset broadband excitation signal; Simultaneously, a second trigger signal synchronized with the first trigger signal is sent to the full-field visual vibration measurement module to initiate the acquisition of the full-field vibration image sequence; During the acquisition process, the excitation time history data is recorded in real time, and the image sequence data from the global visual vibration measurement module is received, so that the two sets of data have a unified time reference.

[0010] Furthermore, the modal fingerprint extraction module includes a visual displacement calculation unit and a modal parameter identification unit; The visual displacement calculation unit is used to process the full-field vibration sequence image and calculate the three-dimensional displacement time history data of multiple measuring points on the surface of the finished cable strand through stereo matching and three-dimensional reconstruction technology. The modal parameter identification unit receives the three-dimensional displacement time history data and the excitation time history data, and identifies the multi-order modal parameters of the tested cable strand under test conditions from the three-dimensional displacement time history data and the excitation time history data, including each natural frequency, damping ratio and mode shape. The multi-order modal parameters constitute the working condition modal fingerprint package.

[0011] Furthermore, the modal parameter identification unit extracts the multi-order modal parameters using the multi-reference point least squares complex frequency domain method. The specific steps are as follows: Using the excitation time history data and the three-dimensional displacement time history data, a complex frequency response function matrix and an output power spectrum matrix are constructed; The system matrix is ​​estimated by fitting the complex frequency response function matrix and the output power spectrum matrix using the least squares complex frequency domain method. By calculating and plotting the stability diagram, stable poles are identified on the frequency axis, wherein the frequency and damping ratio of the stable poles correspond to the natural frequency and the damping ratio, respectively. The mode shape vectors corresponding to the stable poles are calculated to complete the identification of the multi-order modal parameters.

[0012] Furthermore, the process of constructing the benchmark modal fingerprint database in the modal fingerprint comparison and evaluation module is as follows: Multiple modal tests were conducted on standard strand specimens of the same type to obtain multiple sets of initial modal parameters; Statistical analysis was performed on the multiple sets of initial modal parameters, the mean and variance of each modal parameter were calculated, and after removing outlier data, the mean of each modal parameter was used as a stable reference value. The stable reference values, including the reference natural frequency, reference damping ratio, and reference mode shape, are stored as the reference modal fingerprint.

[0013] Furthermore, the modal fingerprint comparison and evaluation module performs the following steps to compare and analyze the working condition modal fingerprint package with the benchmark modal fingerprint package: Read the measured natural frequencies and measured mode shapes of each order from the operating condition modal fingerprint package, and read the corresponding reference natural frequencies and reference mode shapes from the reference modal fingerprint; For each mode Calculate the relative frequency deviation respectively Modal confidence criterion value The ,in, To measure the natural frequency, For reference to the natural frequency; This is the measured mode shape vector. As the reference mode shape vector, This indicates the conjugate transpose.

[0014] Furthermore, the modal fingerprint comparison and evaluation module will compare and evaluate the fingerprints of each modality. and As a result, the modal health index HI was calculated through weighted fusion. ,in, For about The scoring function, when hour, ,when hour, , The first deviation threshold, This is the score decay coefficient. and The first The weighting factors for the first modal frequency score and the mode shape are related. The normalization coefficient is used to map the HI value to a preset score range. Based on the range of the calculated HI value, the corresponding performance consistency evaluation is output according to the preset standard.

[0015] Compared with existing technologies, this performance evaluation system for finished strand products has the following advantages: I. This invention effectively removes interference from test boundary conditions by constructing an intelligent comparison chain between working condition modal fingerprints and reference modal fingerprints, extracting evaluation indicators that purely characterize the structural properties of the cable strand itself. Under controllable free suspension boundaries, the working condition modal fingerprint of the tested cable strand is obtained through standardized broadband excitation and full-domain visual measurement. This fingerprint includes the influence of the current suspension state. It is intelligently compared with the reference modal fingerprint of the same model obtained under ideal calibration environment and pre-stored in the database. By calculating the relative frequency deviation and modal confidence criterion value, the difference between the current test state and the ideal reference state is quantified. These differences mainly originate from the fluctuation of boundary conditions. Through weighted fusion, the difference components reflecting boundary interference are filtered out and normalized, and finally a modal health index is output, thereby highlighting and quantifying the consistency of the cable strand itself in terms of mass, stiffness, and damping distribution, realizing the extraction from mixed signals to pure features.

[0016] Second, this invention transforms the modal parameter set into a concrete and traceable digital identity fingerprint, constructing a performance baseline file for cable strands throughout their entire lifecycle. The system extracts multiple natural frequencies, damping ratios, and complete three-dimensional spatial mode shapes from the vibration response of the cable strands through high-precision visual displacement calculation and modal parameter identification algorithms. This multi-dimensional parameter set is then structured and encapsulated to form a unique operating condition modal fingerprint package. This fingerprint is compared with a baseline fingerprint to determine the health status and can be permanently saved as the initial performance file of the cable strand. When the cable strands are operating in bridges, their vibration signals are acquired through online monitoring, and the modal fingerprints are extracted and compared to accurately diagnose the degree of performance degradation and the location of damage. This fundamentally changes the management model of cable strands, realizing full lifecycle quality control from factory testing to service traceability, and providing a standardized basis for batch quality judgment of cable strands.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 The flowchart for the operation of the performance evaluation system for finished products of the slub stock; Figure 2 This is a block diagram of the module composition of the performance evaluation system for finished products of the cable strand product. Figure 3 This is a schematic diagram of the working principle of the synchronous control and data acquisition module in the performance evaluation system for finished products. Detailed Implementation

[0020] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “solidated product performance evaluation system,” “described,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise; “plural” generally includes at least two.

[0022] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0023] To address the shortcomings of existing technologies, this invention first describes the performance evaluation scenario for cable strands involved in the present invention. This invention is primarily applied in bridge cable manufacturing plants and large structural component production sites to conduct non-destructive performance consistency testing and evaluation of main cable strands for suspension bridges or cable strands for cable-stayed bridges before they leave the factory. Traditional destructive sampling tests are costly, time-consuming, and cannot achieve full inspection; while direct modal testing is greatly affected by suspension boundary conditions, resulting in discrete and incomparable results. This invention, through standardized free suspension boundaries, non-contact excitation and visual measurement, and a mechanism for comparing working condition modal fingerprints with benchmark modal fingerprints, aims to eliminate boundary interference, extract and quantify the consistency of the structural dynamic characteristics of the cable strands themselves, and establish a traceable digital performance identity file for each cable strand.

[0024] The cable strand performance evaluation system provided by this invention constructs a complete technology chain integrating standardized excitation, high-precision visual measurement, synchronous control, intelligent identification, and comparative analysis. The system first applies a standard broadband excitation to the cable strand under controllable free suspension conditions and simultaneously collects its full-field vibration response. Then, it extracts the working condition modal fingerprint containing the influence of the current boundary from the response data. Finally, it performs intelligent comparison and fusion calculation with the benchmark modal fingerprint of the same model established in advance under standard ideal conditions, filters out the differences caused by boundary fluctuations, and outputs a modal health index that characterizes the consistency of the cable strand's own structural characteristics, thereby achieving non-destructive, rapid, and standardized evaluation of the performance of the cable strand.

[0025] The present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0026] This embodiment provides a performance evaluation system for finished strand products, such as... Figure 2 As shown, the system includes the following modules that are connected in sequence and work together: a non-contact broadband excitation module, a full-domain visual vibration measurement module, a synchronous control and data acquisition module, a modal fingerprint extraction module, and a modal fingerprint comparison and evaluation module. The non-contact broadband excitation module is used to provide standardized free suspension boundary conditions for the tested cable strand, and applies a preset broadband excitation signal to the cable strand in a non-contact excitation manner. The full-field visual vibration measurement module is used to synchronously acquire the full-field vibration image sequence of the finished cable strand under the action of the broadband excitation signal; The synchronization control and data acquisition module is used to synchronously control the application of the broadband excitation signal and the acquisition of the full-field vibration image sequence, and synchronously acquire the excitation time history data corresponding to the broadband excitation signal and the image sequence data corresponding to the full-field vibration image sequence. The modal fingerprint extraction module is used to receive the excitation time history data and the image sequence data, calculate the working condition modal parameter set of the tested cable strand under the free suspension boundary condition, and package it to generate a working condition modal fingerprint package. The modal fingerprint comparison and evaluation module pre-stores a benchmark modal fingerprint package obtained by the same type of cable strand under standard boundary conditions. It is used to compare and analyze the working condition modal fingerprint package with the benchmark modal fingerprint package, calculate and output a modal health index that characterizes the consistency of the cable strand's own structural characteristics.

[0027] In this embodiment, the finished cable strand to be tested is hoisted to a dedicated testing station and symmetrically suspended at both ends by elastic slings to form a free boundary condition at both ends. This free suspension state is a standardized test boundary condition, which aims to reduce the stiffness influence introduced by the fixed support, highlight the dynamic characteristics of the cable strand itself, and ensure that the boundary conditions for each test can be repeated.

[0028] In practical implementation, the non-contact broadband excitation module is used to provide standardized excitation input to the tested cable strand. Its core lies in applying a preset broadband excitation signal non-contactly to avoid the influence of the added mass or stiffness of the contact exciter on the cable strand modes. In practical implementation, this includes a signal generator, a power amplifier, and an electromagnetic exciter, wherein: The signal generator has a variety of standard excitation signal waveforms pre-stored. In this embodiment, a linear frequency modulated sinusoidal sweep signal of 0.1Hz to 200Hz is preferably used as the excitation signal. This frequency band can effectively cover the main low-order global modes of the cable strand.

[0029] The signal generator generates the preset wideband excitation signal, i.e., the analog voltage signal, and outputs it to the power amplifier.

[0030] The power amplifier amplifies the weak voltage signal and converts it into a high-current signal that can drive the electromagnetic exciter.

[0031] The electromagnetic vibrator is fixed on an independent rigid support, with its working end facing the lower middle part of the cable strand. When the amplified current signal is passed into the vibrator coil, an alternating magnetic field is generated. Since the cable strand is composed of high magnetic permeability steel wire, the alternating magnetic field will induce eddy currents inside the cable strand. The interaction between the eddy currents and the magnetic field will generate an alternating Lorentz force. This force is the non-contact excitation force applied to the cable strand. The magnitude of this force is proportional to the current amplitude, and the frequency component is consistent with the excitation signal, thereby converting the preset broadband excitation signal into a spatial force acting on the cable strand.

[0032] The aforementioned global vision vibration measurement module is used for non-contact, synchronous measurement of the three-dimensional vibration response of a cable strand over its entire length, acquiring full-field displacement data. This global vision vibration measurement module includes a speckle projection light source, a high-speed binocular stereo vision camera, and an image acquisition card, wherein: Before testing, a black and white matte paint was evenly sprayed onto the strand surface to create a natural texture contrast. A speckle projection light source was triggered, projecting a high-contrast random speckle pattern onto the strand surface, which served as feature points for visual tracking.

[0033] Two precisely calibrated high-speed binocular stereo vision cameras are positioned at a fixed angle on one side of the cable strand so that their common field of view covers the entire length of the cable strand. The cameras begin data acquisition after receiving the trigger signal synchronously.

[0034] Under the excitation, the strand vibrates, and the speckle pattern on its surface moves accordingly. Two high-speed cameras simultaneously capture a series of images of the strand surface with speckle patterns at a high frame rate, forming a full-field vibration image sequence.

[0035] The image acquisition card receives image data streams from two cameras, performs buffering and preliminary processing, and then uploads the synchronized image sequence data to the synchronization control and data acquisition module.

[0036] The aforementioned synchronization control and data acquisition module ensures strict synchronization between excitation application and response measurement, and assigns a uniform timestamp to all data. In this embodiment, the synchronization control and data acquisition module consists of a synchronization controller and a data acquisition unit, such as... Figure 3 As shown, the working principle of the synchronization control and data acquisition module is as follows: At the start of the test, the synchronous controller simultaneously sends a first trigger signal to the signal generator of the non-contact wideband excitation module, commanding it to immediately start outputting the preset wideband excitation signal. At the same time, it sends a synchronous second trigger signal to the high-speed binocular stereo vision camera of the full-domain visual vibration measurement module, commanding it to start acquiring image sequences. Simultaneously with the output of the excitation signal, the data acquisition unit records the time history signal of the current flowing through the electromagnetic exciter. This signal accurately reflects the time history of the actual excitation force applied to the strand and is recorded as the excitation time history data. During image acquisition, the data acquisition unit continuously receives image sequence data from the image acquisition card; The high-precision clock of the synchronization controller provides a unified reference for the first trigger signal, the second trigger signal, the sampling of excitation time history data, and the timestamp of each frame of the image sequence.

[0037] The modal fingerprint extraction module is responsible for extracting the working condition modal fingerprint package characterizing the dynamic characteristics of the cable strand under the current test state from the raw measurement data. This modal fingerprint extraction module includes a visual displacement calculation unit and a modal parameter identification unit, wherein: The visual displacement calculation unit receives synchronized image sequences from the left and right cameras from the synchronization control module. For each pair of left and right images at each time point, a stereo vision matching algorithm is used to find all corresponding pixels in the left and right images based on the characteristics of the speckle pattern. Combining the intrinsic parameters (focal length, principal point) and extrinsic parameters (calibrated relative position and attitude) of the binocular cameras, the coordinates (X, Y, Z) of each matching point in three-dimensional space are calculated using the principle of triangulation. This process is repeated for all frames in the image sequence to obtain a three-dimensional coordinate sequence of a large number of measuring points on the cable surface that changes over time. Subtracting the initial static position coordinates from the three-dimensional coordinate sequence of each measuring point yields the three-dimensional displacement time history data of each measuring point relative to its initial position.

[0038] The modal parameter identification unit receives three-dimensional displacement time history data from all measurement points, as well as synchronized excitation time history data. Parameter identification is performed using the multi-reference point least squares complex frequency domain method, with the following specific steps: Constructing the frequency response function matrix: Perform Fourier transform on the output signal and excitation input signal of each measurement point, calculate the cross power spectrum and self power spectrum between them, and then estimate the frequency response function of multiple output points relative to the excitation input point to form a complex frequency response function matrix; System matrix fitting: In the complex frequency domain, the least squares algorithm is used to simultaneously fit the frequency response function data of all measurement points and all frequency lines using a state-space model, in order to estimate the system matrix describing the dynamic characteristics of the system. Plotting and identifying stability plots: By repeatedly fitting different model orders and calculating poles, the poles calculated at different orders are arranged by frequency to plot stability plots. In the stability plots, stable poles that do not change drastically with the increase of model order are considered to be the true physical modes of the system. Modal parameters are extracted: the natural frequencies (imaginary parts of the poles) and damping ratios (calculated from the real and imaginary parts of the poles) of each mode are extracted from the stable poles. Based on information such as the modal participation vector in the system matrix, the mode shape vector corresponding to each stable pole is calculated. This mode shape vector describes the spatial deformation shape of the cable strand when it vibrates at that frequency. It is a multi-dimensional vector whose dimension is equal to the number of measurement points.

[0039] The natural frequencies, damping ratios, and complete mode shape vectors of the first N identified modes are structurally encapsulated to form a unique modal fingerprint package. This fingerprint package contains the complete modal characteristics of the currently tested cable strand under the specific suspension and excitation conditions, which includes both the structural information of the cable strand itself and the influence of the current test boundary.

[0040] The modal fingerprint comparison and evaluation module intelligently compares the operating condition fingerprint with the benchmark fingerprint, filters out boundary differences, and quantifies the consistency of the performance of the strand itself. This module includes a pre-stored benchmark modal fingerprint database and a comparison and evaluation algorithm. The benchmark fingerprint database construction process is as follows: Multiple standard cable strands of the same type, which have been rigorously inspected and confirmed to be qualified, were selected. In a highly controlled and ideal laboratory environment, this system is used to perform multiple repeated modal tests on each standard specimen. Statistical analysis is performed on the modal parameter set obtained from multiple tests of each specimen. For example, for the natural frequency of each mode, the average value and standard deviation of multiple measurements are calculated. After removing abnormal data that exceed ±3 times the standard deviation, the average value of each modal parameter is used as the reference value for the stability and reliability of the cable strand of this type. The reference value includes: reference natural frequency, reference damping ratio, and reference mode shape vector. All reference values ​​are structured and stored to form a baseline modal fingerprint package, which is then stored in the database. This fingerprint characterizes the pure modal features that a qualified strand of this model should have under standard ideal boundaries.

[0041] For the finished product to be evaluated, after obtaining its operating condition modal fingerprint package, the system retrieves the corresponding benchmark modal fingerprint package from the database and performs step-by-step modal comparison analysis. For each mode... Calculate the relative frequency deviation respectively Modal confidence criterion value The ,in, To measure the natural frequency, For reference to the natural frequency, This is the measured mode shape vector. As the reference mode shape vector, Representing the conjugate transpose, and in order to integrate frequency and mode shape information and reduce the impact of accidental fluctuations in boundary conditions on a single index, a weighted fusion method is used to calculate a comprehensive health index. ,in, For about The scoring function, when hour, ,when hour, , The first deviation threshold, This is the score decay coefficient. and The first The weighting factors for the first modal frequency score and the mode shape are related. The normalization coefficient is used to map the HI to a preset score range. Based on the range of the calculated HI value, the corresponding performance consistency evaluation is output according to the preset standard. The system finally outputs the modal health index and the corresponding performance consistency evaluation. At the same time, the working condition modal fingerprint package of this test can be stored in the archive as the digital fingerprint of the index for future status comparison and traceability during service.

[0042] Specifically, such as Figure 1 The flowchart shown below illustrates the performance evaluation system for finished strand products, detailing the specific steps involved in evaluating the performance of finished strand products. (1) System preparation and data acquisition Preparation: The cable strand to be tested is suspended on the test frame in a free-suspension state using flexible slings.

[0043] Surface treatment: Spray or paste random speckle patterns onto the surface of the strands to provide texture features for visual measurement.

[0044] Equipment positioning: Adjust the position of the non-contact electromagnetic vibrator so that its excitation head is aligned with the predetermined excitation point on the cable strand; adjust the angle and focal length of the two high-speed cameras to ensure that their common field of view covers the entire length of the cable strand.

[0045] Start the system and trigger synchronously: Start the test program in the control software, and the synchronous control module in the system sends trigger signals to the non-contact broadband excitation module and the full-domain visual vibration measurement module.

[0046] Excitation and image acquisition: After receiving the signal, the non-contact broadband excitation module immediately drives the electromagnetic vibrator to output the preset broadband sweep force. At the same time, the full-domain visual vibration measurement module receives the signal and drives the two high-speed cameras to start synchronously acquiring the vibration image sequence of the cable strand surface.

[0047] Data Synchronization Recording: Throughout the excitation and acquisition process, the system synchronously records the time-history waveform data of the excitation signal and the image sequence data acquired by the camera, ensuring that both have a unified time reference.

[0048] (2) Working condition modal fingerprint extraction Three-dimensional displacement field reconstruction: The vision processing unit processes the acquired binocular image sequence and calculates the spatial three-dimensional coordinates of each speckle on the cable strand surface at each time step through stereo vision matching and three-dimensional reconstruction algorithms, thereby obtaining the time history data of the three-dimensional displacement of each measuring point in the entire field as a function of time.

[0049] Modal parameter identification: The modal analysis unit receives three-dimensional displacement time history data and synchronously recorded excitation time history data. It uses a modal parameter identification algorithm to process the input and output data and identify the multi-order modal parameters exhibited by the cable strand in the current free suspension state, including the natural frequencies, damping ratios and corresponding three-dimensional spatial modes of each order.

[0050] Generate operating condition fingerprint package: All identified modal parameters are structured and packaged to form a unique data file representing the test results, namely the operating condition modal fingerprint package.

[0051] (3) Intelligent comparison and comprehensive evaluation Retrieve baseline fingerprint: Based on the model of the tested strand, the system retrieves the corresponding baseline modal fingerprint packet from the pre-stored baseline modal fingerprint database.

[0052] Parameter comparison calculation: The measured parameters in the working condition modal fingerprint package are compared with the reference parameters in the benchmark modal fingerprint package step by step and item by item. For each mode, the relative deviation between the measured frequency and the reference frequency, as well as the modal confidence index between the measured mode shape and the reference mode shape are calculated.

[0053] Calculate the modal health index: Based on the preset weighting rules, the frequency deviation scores and mode confidence scores of each mode are weighted and fused to calculate a comprehensive modal health index.

[0054] Output evaluation report: Based on the calculated modal health index value and the preset evaluation level standard, the system automatically generates the final performance evaluation conclusion and completes the evaluation.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A performance evaluation system for finished strand products, characterized in that, The system includes: a non-contact broadband excitation module, a full-domain visual vibration measurement module, a synchronous control and data acquisition module, a modal fingerprint extraction module, and a modal fingerprint comparison and evaluation module; The non-contact broadband excitation module is used to provide standardized free suspension boundary conditions for the tested cable strand, and applies a preset broadband excitation signal to the cable strand in a non-contact excitation manner. The full-field visual vibration measurement module is used to synchronously acquire the full-field vibration image sequence of the finished cable strand under the action of the broadband excitation signal; The synchronization control and data acquisition module is used to synchronously control the application of the broadband excitation signal and the acquisition of the full-field vibration image sequence, and synchronously acquire the excitation time history data corresponding to the broadband excitation signal and the image sequence data corresponding to the full-field vibration image sequence. The modal fingerprint extraction module is used to receive the excitation time history data and the image sequence data, calculate the working condition modal parameter set of the tested cable strand under the free suspension boundary condition, and package it to generate a working condition modal fingerprint package. The modal fingerprint comparison and evaluation module pre-stores a benchmark modal fingerprint package obtained by the same type of cable strand under standard boundary conditions. It is used to compare and analyze the working condition modal fingerprint package with the benchmark modal fingerprint package, calculate and output a modal health index that characterizes the consistency of the cable strand's own structural characteristics.

2. The performance evaluation system for finished strand products according to claim 1, characterized in that, The non-contact broadband excitation module includes a signal generator, a power amplifier, and an electromagnetic exciter. The signal generator is used to generate the preset wideband excitation signal; The power amplifier is connected to the signal generator and is used to amplify the power of the wideband excitation signal. The electromagnetic exciter is connected to the power amplifier, and its working end is set in a non-contact manner with the finished strand product. It is used to convert the amplified broadband excitation signal into an alternating magnetic field force and apply it to the finished strand product.

3. The performance evaluation system for finished strand products according to claim 1, characterized in that, The global visual vibration measurement module includes a speckle projection light source, a high-speed binocular stereo vision camera, and an image acquisition card. The speckle projection light source is used to project a speckle pattern onto the surface of the finished strand; The high-speed binocular stereo vision camera is used to simultaneously acquire the full-field vibration image sequence of the strand surface with the speckle pattern from different perspectives; The image acquisition card is connected to the high-speed binocular stereo vision camera and is used to receive and transmit the image sequence data.

4. The performance evaluation system for finished strand products according to claim 1, characterized in that, The working principle of the synchronization control and data acquisition module is as follows: Send a first trigger signal to the non-contact broadband excitation module to start the output of the preset broadband excitation signal; Simultaneously, a second trigger signal synchronized with the first trigger signal is sent to the global visual vibration measurement module to initiate the acquisition of the global vibration image sequence; During the acquisition process, the excitation time history data is recorded in real time, and the image sequence data from the global visual vibration measurement module is received, so that the two sets of data have a unified time reference.

5. The performance evaluation system for finished strand products according to claim 1, characterized in that, The modal fingerprint extraction module includes a visual displacement calculation unit and a modal parameter identification unit; The visual displacement calculation unit is used to process the full-field vibration sequence image and calculate the three-dimensional displacement time history data of multiple measuring points on the surface of the finished cable strand through stereo matching and three-dimensional reconstruction technology. The modal parameter identification unit receives the three-dimensional displacement time history data and the excitation time history data, and identifies the multi-order modal parameters of the tested cable strand under test conditions from the three-dimensional displacement time history data and the excitation time history data, including each natural frequency, damping ratio and mode shape. The multi-order modal parameters constitute the working condition modal fingerprint package.

6. The performance evaluation system for finished strand products according to claim 5, characterized in that, The modal parameter identification unit extracts the multi-order modal parameters using the multi-reference point least squares complex frequency domain method. The specific steps are as follows: Using the excitation time history data and the three-dimensional displacement time history data, a complex frequency response function matrix and an output power spectrum matrix are constructed; The system matrix is ​​estimated by fitting the complex frequency response function matrix and the output power spectrum matrix using the least squares complex frequency domain method. By calculating and plotting the stability diagram, stable poles are identified on the frequency axis, wherein the frequency and damping ratio of the stable poles correspond to the natural frequency and the damping ratio, respectively. The mode shape vectors corresponding to the stable poles are calculated to complete the identification of the multi-order modal parameters.

7. The performance evaluation system for finished strand products according to claim 1, characterized in that, The process of constructing the benchmark modal fingerprint database in the modal fingerprint comparison and evaluation module is as follows: Multiple modal tests were conducted on standard strand specimens of the same type to obtain multiple sets of initial modal parameters; Statistical analysis was performed on the multiple sets of initial modal parameters, the mean and variance of each modal parameter were calculated, and after removing outlier data, the mean of each modal parameter was used as a stable reference value. The stable reference values, including the reference natural frequency, reference damping ratio, and reference mode shape, are stored as the reference modal fingerprint.

8. The performance evaluation system for finished strand products according to claim 1, characterized in that, The modal fingerprint comparison and evaluation module performs the following steps to compare and analyze the working condition modal fingerprint package with the benchmark modal fingerprint package: Read the measured natural frequencies and measured mode shapes of each order from the operating condition modal fingerprint package, and read the corresponding reference natural frequencies and reference mode shapes from the reference modal fingerprint; For each mode Calculate the relative frequency deviation respectively Modal confidence criterion value The ,in, To measure the natural frequency, For reference to the natural frequency; This is the measured mode shape vector. As the reference mode shape vector, This indicates the conjugate transpose.

9. The performance evaluation system for finished strand products according to claim 8, characterized in that, The modal fingerprint comparison and evaluation module will compare and evaluate the modal fingerprints of each order. and As a result, the modal health index HI was calculated through weighted fusion. ,in, For about The scoring function, when hour, ,when hour, , The first deviation threshold, This is the score decay coefficient. and The first The weighting factors for the first modal frequency score and the mode shape are related. The normalization coefficient is used to map the HI value to a preset score range. Based on the range of the calculated HI value, the corresponding performance consistency evaluation is output according to the preset standard.

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