Disclosure of Invention
In order to solve the existing problems, the invention provides a real-time monitoring method for the health of a fan blade based on resonance response.
The invention is realized by the following technical scheme:
a real-time fan blade health monitoring method based on resonance response comprises a resonance mode detection test bed, a wind driven generator blade, an excitation source, an environmental vibration analyzer, a filter and an upper computer. And carrying out experimental detection on modes exciting resonance at different stages in the whole life cycle of the wind driven generator blade by using the resonance mode detection test bed.
The well recorded data obtained were subjected to the following statistical analysis:
taking the run-in period detection data as an example, the damping ratio and the natural frequency in the run-in period detection data are respectively subjected to interval estimation. Data population X obeys normal distribution N (mu, sigma)2) And carrying out interval estimation on the normal population mean value mu. Confidence intervals with 95% confidence of damping ratio and natural frequency are respectively calculated:
deriving from the sample values
n、σ
The confidence 1- α is 0.95, α is 0.05,
looking up the normal distribution numerical table to obtain mu
0.025=1.96
and (5) solving a confidence interval of the damping ratio, and calculating the confidence interval of the natural frequency in the same way.
And solving the normal working resonance mode confidence interval, the severe abrasion resonance mode confidence interval and the failure fracture stage resonance mode confidence interval in the same way.
And establishing a running-in period resonance modal interval, a normal working resonance modal interval, a severe abrasion resonance modal interval and a failure fracture stage resonance modal interval. And carrying out interval division on the obtained data by utilizing mathematical statistics to obtain modal intervals of exciting resonance of the fan blade at different stages, obtaining the remaining life intervals of each state through experiments, and establishing a database. In the real-time monitoring stage, the resonance mode of the blade is measured by the excitation source, the environmental vibration analyzer and the filter, and the real-time detection data is compared and divided with each mode interval obtained by the experiment by adopting a dividing method in a clustering algorithm.
And obtaining the real-time state of the fan blade and the residual service life of the fan blade.
As a further optimization scheme of the invention, the resonance response-based real-time monitoring method for the health of the fan blade utilizes the characteristic that resonance modes excited at different stages in the life cycle of the blade are different, and carries out real-time monitoring and residual life assessment.
As a further optimization scheme of the invention, the main component of the fan blade is a composite material, the fan blade belongs to a nonlinear system, the amplitude jump phenomenon occurs in a resonance region, a resonance peak is obviously deformed, and super-harmonic resonance and sub-harmonic resonance can occur. The excitation source is used for inducing the fan blade to resonate, the environment vibration analyzer is used for detecting the mode of a resonance area, and the filter is used for eliminating super-harmonic resonance and sub-harmonic resonance and simplifying the obvious deformation of a resonance peak.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and drawings, but the present invention is not limited to these embodiments.
The invention realizes real-time monitoring by utilizing resonance response and is applied to the detection of the wind driven generator blade. As shown in fig. 1: a real-time monitoring method for fan blade health based on resonance response is divided into two parts, including a database establishing stage, a real-time detection stage and an intelligent decision stage. Firstly, a database is established, in order to accurately collect data, the resonance mode detection test bed is adopted to carry out staged detection on the fan blades, a plurality of groups of blades detected by the same model at different stages are synchronously detected, and the obtained data are separately recorded.
The well recorded data obtained were subjected to the following statistical analysis:
taking the run-in period detection data as an example, the damping ratio and the natural frequency in the run-in period detection data are respectively subjected to interval estimation. Data population X obeys normal distribution N (mu, sigma)2) And carrying out interval estimation on the normal population mean value mu. Confidence intervals with 95% confidence of damping ratio and natural frequency are respectively calculated:
deriving from the sample values
n、σ
The confidence 1- α is 0.95,α=0.05,
Looking up the normal distribution numerical table to obtain mu
0.025=1.96
and (5) solving a confidence interval of the damping ratio, and calculating the confidence interval of the natural frequency in the same way.
And solving the normal working resonance mode confidence interval, the severe abrasion resonance mode confidence interval and the failure fracture stage resonance mode confidence interval in the same way.
Establishing a modal interval of the fan blade: a running-in period resonance mode interval, a normal working resonance mode interval, a severe abrasion resonance mode interval and a failure fracture stage resonance mode interval. For ease of programming, a function pointer name is set for each interval: the index name of the resonant mode interval in the running-in period is Runnng-in; the pointer name of the normal working resonance mode interval is Regular-work; the pointer name of the violent abrasion resonance mode interval is Abrasive; the index of the resonant mode interval at the failure fracture stage is named Falife. In addition, the remaining life intervals corresponding to the various state intervals are obtained through experiments.
Subsequently, real-time detection is performed: under natural conditions, even if the fan is suspended, the detection accuracy of the fan blade cannot reach the experimental level, the main component of the fan blade is made of a composite material and belongs to a nonlinear system, the amplitude jump phenomenon occurs in a resonance area, a resonance peak is obviously deformed, and super-harmonic resonance and sub-harmonic resonance may occur, so that the actual detection is more difficult. Therefore, the resonance mode of the blade is measured by adopting the excitation source, the environmental vibration analyzer and the filter, so that the detection steps are simplified, and the measured result has enough reliability. The specific functions of the excitation source, the environment vibration analyzer and the filter are as follows: the excitation source is used for inducing the fan blade to resonate, the environment vibration analyzer is used for detecting the mode of a resonance area, and the filter is used for eliminating super-harmonic resonance and sub-harmonic resonance and simplifying the obvious deformation of a resonance peak. The obtained data is the mode of the blade of the wind driven generator measured in real time. Namely the damping ratio and the natural frequency.
And finally, carrying out comparison analysis and life prediction, and comparing and dividing the real-time detection data with each modal interval obtained by the experiment by using a dividing method in a clustering algorithm.
The algorithm idea is as follows: inputting: real-time detection data A [ p
The subscript q (p < ═ q < ═ r) is present, wherein the elements in a [ p.. q ] do not exceed a [ r ], and the elements in a [ q +1.. r ] are each greater than a [ r ].
The two indices i, j are initially set to p-1 and p, respectively, let j scan in [ p.. r ], if aj < ═ ar ], then a j is exchanged for a [ i +1], then i is increased by 1, as j increases, a [ p.. i ] and a [ i +1.. j ] also increase, and finally j reaches r, exchanging a [ i +1] for a [ r ].
C + + Source program
The program is a partial program, and the complete program compares the real-time detection data with the established database and analyzes the health stage of the detected fan blade and the residual service life of the fan blade.
As shown in fig. 2, the excitation source is disposed on one side of the fan blade, the input probe of the environmental vibration analyzer is disposed on the surface of the fan blade, the output probe is connected to the filter, and the filter is connected to the upper computer.
As shown in fig. 3, the resonance mode detection test bed measures multiple groups of experimental data, divides the obtained data into intervals by using mathematical statistics, divides a running-in period resonance mode interval, a normal working resonance mode interval, a severe wear resonance mode interval and a failure fracture stage resonance mode interval, controls a single time variable, estimates the remaining life of the fan blade corresponding to each interval, and makes analysis decisions.