JP2019196965A - Vibration tester and vibration testing method - Google Patents

Abstract

To test vibration properties of a plurality of blades in a shorter time.SOLUTION: A vibration tester which sweeps and excites an object to be tested, and thereby acquires vibration properties of the object to be tested, on the basis of an FRA (Frequency Response Analyzer) method, includes: an excitation signal generator which generates an excitation signal in which sweep sinusoidal signals of a plurality of frequency ranges are superposed; an excitation machine which sweeps and excites an object to be tested on the basis of the excitation signal; a vibration sensor which detects vibration of the object to be tested; and a frequency response analyzer which includes a plurality of analysis units corresponding to the sweep sinusoidal signal in order to analyze a frequency response of the object to be tested, by synchronizing an output signal of the vibration sensor with the sinusoidal signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vibration test apparatus and a vibration test method.

  Patent Document 1 listed below discloses a technique for performing a vibration test of a rotor system of a turbo machine (turbo compressor). This technology detects the vibration of the rotor system when the rotor system is swept and excited by a vibration exciter based on the FRA (Frequency Response Analyzer) method, and analyzes the output of the vibration sensor to analyze the rotor. A frequency response function of the system is obtained, and vibration characteristics (resonance frequency, damping ratio, vibration mode) are calculated from the frequency response function. Note that sweep excitation is an excitation method in which the excitation frequency is continuously changed within a predetermined range.

Japanese Patent Laying-Open No. 2015-108607

  By the way, as a method for obtaining a frequency response function based on sweep excitation, there are an FFT (Fast Fourier Transform) method using an FFT analyzer and an FRA (Frequency Response Analyzer) method using a frequency characteristic analyzer (Frequency Response Analyzer). is there. In the FFT method, it is necessary to switch the frequency range (frequency range) to several in order to ensure a desired resolution, so that there is a problem that the test time becomes long.

  On the other hand, in the FRA system, the frequency of the sine wave is continuously changed to sweep and vibrate the DUT, and when the frequency range to be measured is relatively wide, several frequency ranges (frequency Therefore, there is a problem that the time required for the vibration becomes long and the test time becomes long. In particular, in a turbo machine such as a gas turbine, the number of blades included in the device under test becomes enormous, so that the test time becomes long.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to test vibration characteristics of a device under test in a shorter time.

  In order to achieve the above object, in the present invention, as a first solving means related to the vibration test apparatus, the vibration of the test object is obtained by sweeping and vibrating the test object based on the FRA (Frequency Response Analyzer) method. A vibration test apparatus for acquiring characteristics, wherein an excitation signal generator that generates an excitation signal in which sweep sine wave signals in a plurality of frequency ranges are superimposed, and the device under test is swept based on the excitation signal A vibration exciter for vibration, a vibration sensor for detecting vibration of the device under test, and a plurality of analysis units corresponding to the sweep sine wave signal are provided, and the output signal of the vibration sensor is synchronized with the sweep sine wave signal. And a frequency response analyzing device for analyzing the frequency response of the device under test.

  In the present invention, as the second solving means relating to the vibration test apparatus, in the first solving means, the frequency response analyzing apparatus synthesizes and outputs the frequency response characteristics output by the analyzing unit on the frequency axis. , Is adopted.

  In the present invention, as a third solution means related to the vibration test apparatus, the first or second solution means further includes an FFT (Fast Fourier Transform) analyzer that performs frequency analysis of the output signal of the vibration sensor. Is adopted.

  In the present invention, as a fourth solving means related to the vibration test apparatus, in any one of the first to third solving means, the DUT is formed as a blisk in which a plurality of wings are integrated with a disk. The rotor of the gas turbine employs a means for vibrating the blades provided on the rotor.

  Further, in the present invention, as a means for solving the vibration test method, a vibration test method for acquiring the vibration characteristics of the DUT by sweeping and exciting the DUT based on the FRA (Frequency Response Analyzer) method. Then, the test object is temporarily swept with a temporary vibration signal in which a plurality of temporary sweep sine wave signals whose frequency ranges are temporarily set are superimposed, and obtained from the test object based on the temporary sweep vibration. A temporary measurement step for obtaining an outline of the resonance frequency of each vibration mode based on the provisional detection signal, and a formal addition in which a formal sweep sine wave signal in which the frequency range is formally set based on the outline of the resonance frequency is superimposed. A main measurement step of sweeping and vibrating the DUT with a vibration signal, and acquiring the resonance frequency of each vibration mode based on a formal detection signal obtained from the DUT based on the main sweep vibration. Yes That, to adopt the means of.

  According to the present invention, it is possible to test the vibration characteristics of a device under test in a shorter time.

1 is a block diagram illustrating an overall configuration of a vibration test apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the vibration signal in one Embodiment of this invention. It is a timing chart which shows the 1st-5th sine wave and the 1st-5th synchronous pulse signal in one Embodiment of this invention. It is a flowchart which shows the vibration test method which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the vibration test apparatus according to the present embodiment acquires vibration characteristics of a device under test X. The vibration signal generator 1, the vibrator 2, the vibration sensor 3, and the frequency response analysis. A device 4 and an FFT (Fast Fourier Transform) analyzer 5 are provided.

  The test object X is a rotor of a gas turbine formed as a blisk in which a plurality of blades x2 are integrated with a disk x1, for example. This blisk is a metal part such as a titanium alloy constituting a rotor of a gas turbine, and a plurality of blades x2 are provided radially on the outer peripheral surface of an annular disk x1. In FIG. 1, only a part of the blisk is shown due to space limitations.

  The vibration test apparatus according to the present embodiment measures the resonance frequency of each blade x2 in such a test object X as one of the vibration characteristics, and thus sequentially sweeps each blade x2 in a predetermined order. By doing so, the resonance frequency in each of several vibration modes of each blade x2 is measured. The vibration test apparatus according to the present embodiment measures the resonance frequency of the first to fifth vibration modes as an example of the vibration mode.

  The excitation signal generator 1 is an electronic circuit that generates an excitation signal K in which a plurality of sweep sine wave signals are superimposed, and includes a first oscillator 1a, a second oscillator 1b, a third oscillator 1c, a fourth oscillator 1d, A fifth oscillator 1e, a signal synthesizer 1f, an oscillation control unit 1g, and an operation unit 1h are provided. As schematically shown in FIG. 2, the first oscillator 1a generates a first sweep sine wave signal SW1 whose frequency continuously changes in the first frequency band F1 and outputs it to the signal synthesizer 1f.

Similarly, as shown in FIG. 2, the second oscillator 1b generates a second sweep sine wave signal SW2 whose frequency continuously changes in the second frequency band F2 and outputs it to the signal synthesizer 1f.
The third oscillator 1c generates a third sweep sine wave signal SW3 whose frequency continuously changes in the third frequency band F3 and outputs it to the signal synthesizer 1f.

  The fourth oscillator 1d generates a fourth sweep sine wave signal SW4 whose frequency continuously changes in the fourth frequency band F4 and outputs it to the signal synthesizer 1f. The fifth oscillator 1e generates a fifth sweep sine wave signal SW5 whose frequency continuously changes in the fifth frequency band F5 and outputs it to the signal synthesizer 1f.

  In the first to fifth frequency bands F1 to F5, the frequency increases in the order of the first frequency band F1, the second frequency band F2, the third frequency band F3, the fourth frequency band F4, and the fifth frequency band F5. As shown in FIG. 2, the frequency band is continuous in the excitation frequency band F0.

  Among the first to fifth frequency bands F1 to F5, the first frequency band F1 is for measuring the resonance frequency (first resonance frequency) of the vibration of the primary mode (fundamental mode) in the blade x2. It is. The second frequency band F2 is for measuring the resonance frequency (second resonance frequency) of the vibration in the secondary mode. The third frequency band F3 is for measuring the resonance frequency (third resonance frequency) of the vibration in the third-order mode. The fourth frequency band F4 is for measuring the resonance frequency (fourth resonance frequency) of the fourth-order mode vibration. Further, the fifth frequency band F5 is for measuring the resonance frequency (fifth resonance frequency) of the vibration in the fifth order mode.

  The first to fifth oscillators 1a to 1e start transmission at the same start timing (time t1) based on the reference timing signal input from the oscillation control unit 1g as shown in FIG. The transmission ends at the same end timing (time t2). That is, the timings of the minimum frequencies of the first to fifth sweep sine wave signals SW1 to SW5 on the time axis are all the same, and the timings of the maximum frequencies of the first to fifth sweep sine wave signals SW1 to SW5 are all the same. It is.

  The signal synthesizer 1f is an adder that synthesizes (multiplexes) by adding the first to fifth sweep sine wave signals SW1 to SW5, and an excitation signal K obtained by the combination (multiplexing). Is output to the vibrator 2. That is, the excitation signal K in the present embodiment is obtained by combining (multiplexing) the first to fifth sweep sine wave signals SW1 to SW5 at the same timing on the time axis. Such an excitation signal generator 1 outputs the excitation signal K to the shaker 2.

  The oscillation control unit 1g generates the reference timing signal and outputs the reference timing signal to the first to fifth oscillators 1a to 1e, and also synchronizes with the first to fifth sweep sine wave signals SW1 to SW5 as shown in FIG. First to fifth synchronization pulse signals D <b> 1 to D <b> 5 are generated and output to the frequency response analyzer 4.

  In FIG. 3, for convenience, the first to fifth sweep sine wave signals SW1 to SW5 and the first to fifth synchronization pulse signals D1 to D5 are easy to understand. The sine wave signals SW1 to SW5 are represented as single frequency sine waves that are not swept. Of the first to fifth synchronization pulse signals D1 to D5, the first synchronization pulse signal D1 is synchronized with the zero-crossing point of the first sweep sine wave signal SW1 as shown in FIG. The rising and falling edges of D2 are synchronized with the zero cross point of the second sweep sine wave signal SW2.

  As shown in FIG. 3, the rising and falling edges of the third synchronizing pulse signal D3 are synchronized with the zero cross point of the third sweep sine wave signal SW3, and the rising and falling edges of the third synchronizing pulse signal D4 are fourth. The fifth synchronization pulse signal D5 is synchronized with the zero cross point of the fifth sweep sine wave signal SW5 in synchronization with the zero cross point of the sweep sine wave signal SW4.

  The operation unit 1 h is an operation panel for manually setting various setting values of the vibration signal generator 1. For example, the operation unit 1h manually sets the first to fifth frequency bands F1 to F5 described above. That is, the test operator of the device under test X sets the first to fifth frequency bands F1 to F5, that is, the excitation frequency band F0, in the excitation signal generator 1 by operating the operation unit 1h. The following operations may be performed automatically.

  Subsequently, the vibrator 2 is a kind of signal converter that converts the vibration signal K input from the vibration signal generator 1 into a predetermined vibration medium and irradiates the blade x2. The vibration exciter 2 is a non-contact type that causes a vibration medium having an intensity change corresponding to the amplitude change of the excitation signal K, that is, the sinusoidal amplitude change in the first to fifth sweep sine wave signals SW1 to SW5, to the blade x2. This is an exciter. The blade x2 is swept and vibrated by the action of the vibration medium. The vibration medium is, for example, (ultra) sound waves.

  The vibration sensor 3 obtains a detection signal C (output signal) by detecting the vibration of the blade x2 caused by the sweep excitation by the shaker 2. The vibration sensor 3 is, for example, a non-contact vibration sensor that irradiates a blade x2 with a predetermined detection medium and converts reflected light from the blade x2 of the detection medium into a detection signal C (electric signal). Such a vibration sensor 3 outputs a detection signal C indicating the vibration of the blade x2 to the frequency response analyzer 4 and the FFT analyzer 5.

  The frequency response analysis device 4 is also called FRA (Frequency Response Analyzer), and the vibration exciter 2 is based on the detection signal C input from the vibration sensor 3 and the first to fifth synchronization pulse signals D1 to D5. The frequency response characteristics of each blade x2 with respect to the sweep excitation by the above is analyzed based on the well-known FRA method. As shown in FIG. 1, the frequency response analyzing apparatus 4 includes five analysis units corresponding to the first to fifth sweep sine wave signals SW1 to SW5, that is, first to fifth analysis units 4a to 4e, and a data synthesis unit 4f. And an output unit 4g.

  The first analysis unit 4a corresponds to the first sweep sine wave signal SW1, and the detection signal C is included in the detection signal C by detecting (synchronous detection) the detection signal C in synchronization with the first synchronization pulse signal D1. A vibration component in one frequency band F1 is extracted. That is, the first analysis unit 4a includes the first frequency band F1, which is the frequency band of the first sweep sine wave signal SW1, out of the frequency response of the blade x2 swept and excited according to the excitation signal K by the shaker 2. A frequency response characteristic (first frequency response characteristic) is calculated. The first frequency response characteristic includes the first resonance frequency of the blade x2.

  The second analysis unit 4b corresponds to the second sweep sine wave signal SW2, and detects the detection signal C in synchronization with the second synchronization pulse signal D2 (synchronous detection), and is included in the detection signal C. The vibration component of the two frequency bands F2 is extracted. That is, the second analysis unit 4b, among the frequency responses of the blade x2 swept and excited according to the excitation signal K, the frequency response characteristic (first frequency) of the second frequency band F2, which is the frequency band of the second sweep sine wave signal SW2. 2 frequency response characteristics) is calculated. The second frequency response characteristic includes the second resonance frequency of the blade x2.

  The third analysis unit 4c corresponds to the third sweep sine wave signal SW3, and detects the detection signal C in synchronization with the third synchronization pulse signal D3 (synchronous detection), and is included in the detection signal C. The vibration component of the three frequency bands F3 is extracted. That is, the third analysis unit 4c, among the frequency response of the blade x2 swept and excited according to the excitation signal K, the frequency response characteristic (first frequency) of the third frequency band F3 that is the frequency band of the third sweep sine wave signal SW3. 3 frequency response characteristics) is calculated. The third frequency response characteristic includes the third resonance frequency of the blade x2.

  The fourth analysis unit 4d corresponds to the fourth sweep sine wave signal SW4. The fourth analysis unit 4d detects the detection signal C in synchronization with the fourth synchronization pulse signal D4 (synchronous detection), and is included in the detection signal C. The vibration component of the 4 frequency band F4 is extracted. That is, the fourth analysis unit 4d has a frequency response characteristic (first frequency) of the fourth frequency band F4 that is the frequency band of the fourth sweep sine wave signal SW4 among the frequency responses of the blade x2 swept and excited according to the excitation signal K. 4 frequency response characteristics) is calculated. The fourth frequency response characteristic includes the fourth resonance frequency of the blade x2.

  The fifth analysis unit 4e corresponds to the fifth sweep sine wave signal SW5, and detects the detection signal C in synchronism with the fifth synchronization pulse signal D5 (synchronous detection), and is included in the detection signal C. The vibration component of the 5 frequency band F5 is extracted. That is, the fifth analysis unit 4e includes the frequency response characteristic (first frequency) of the fifth frequency band F5 that is the frequency band of the fifth sweep sine wave signal SW5 among the frequency responses of the blade x2 swept and excited according to the excitation signal K. 5 frequency response characteristics) is calculated. The fifth frequency response characteristic includes the fifth resonance frequency of the blade x2.

  The data synthesizing unit 4f synthesizes the first to fifth frequency response characteristics having different frequency bands on the frequency axis, so that the frequency of the blade x2 over the above-described excitation frequency band F0, that is, the frequency band of the excitation signal K is obtained. Get response characteristics. The data synthesizer 4f outputs the total frequency response characteristic over the excitation frequency band F0 to the output unit 4g as a measurement result.

  The output unit 4g includes at least a display unit that displays the total frequency response characteristic as an image. This display unit has a function of displaying a cursor on the measurement result, and additionally includes an operation unit for freely moving the cursor on the frequency axis. The test operator can read the resonance frequency of each vibration mode by aligning the cursor with the resonance peak of each vibration mode.

  The FFT analyzer 5 performs an FFT (Fast Fourier Transform) process on the detection signal C input from the vibration sensor 3, whereby the frequency component included in the vibration of the blade x 2 and the intensity of the frequency component, that is, the vibration of the blade x 2. It is a measuring instrument which acquires the frequency characteristic (vibration frequency characteristic). The FFT analyzer 5 displays the vibration frequency characteristic on the screen as an output form of the vibration frequency characteristic. The FFT analyzer 5 is used for grasping the outline of the resonance frequency of the blade x2 in each vibration mode in a preliminary test performed prior to the formal test of the blade x2.

  Next, a vibration test method using such a vibration test apparatus will be described in detail with reference to FIG.

  The vibration test method according to the present embodiment includes a temporary measurement process and a main measurement process as shown in FIG. The provisional measurement process includes two steps S1 and S2, and the main measurement process includes two steps S3 and S4. In step S1, the above-described first to fifth frequency bands F1 to F5, that is, the excitation frequency band F0 are temporarily set. That is, by operating the operation unit 1h, the test operator of the device under test X operates in the frequency range in which the resonance frequency of each vibration mode of the blade x2 is estimated to be included based on the past test results and the like. First to fifth frequency bands F1 to F5 are temporarily set.

  Then, the test operator instructs the vibration test apparatus to start the temporary test by operating the operation unit 1h in such a temporary setting state of the first to fifth frequency bands F1 to F5. As a result, the oscillation control unit 1g controls the first to fifth oscillators 1a to 1e to generate the first to fifth sweep sine wave signals SW1 to SW5 blisks (temporary sweep sine wave signals). These temporary sweep sine wave signals are combined (multiplexed) by the signal synthesizer 1 f to be output to the vibrator 2 as an excitation signal K (temporary excitation signal).

  Then, the blade x2 of the DUT (blisk) is temporarily swept by the shaker 2 based on the temporary vibration signal, and vibrates by the temporary sweep vibration. The vibration of the blade x2 based on the temporary sweep excitation is converted into a detection signal C (temporary detection signal) by the vibration sensor 3 and is taken into the FFT analyzer 5. Such a provisional detection signal is based on the excitation signal K (temporary excitation signal) generated by the first to fifth sweep sine wave signals SW1 to SW5 (temporary sweep sine wave signal). The frequency component corresponding to the vibration mode (first to fifth vibration modes) of x2 is included.

  The FFT analyzer 5 measures the vibration frequency characteristic of the blade x2 by performing FFT processing (frequency analysis processing) on the detection signal C indicating such vibration (step S2). The test operator grasps the outline of the resonance frequency of each vibration mode of the blade x2 by confirming this vibration frequency characteristic.

  Here, in the measurement of the vibration frequency characteristic in the FFT analyzer 5, the resonance frequency of each vibration mode included in the detection signal C is confirmed in the temporarily set frequency range of the first to fifth frequency bands F1 to F5. In the frequency range, the lower-order resonance frequency has a lower measurement accuracy than the higher-order resonance frequency. This is due to the principle of FFT processing, and is a well-known characteristic in the FFT analyzer 5.

  Then, the test operator uses the excitation frequency band F0, that is, the first frequency in order to measure the resonance frequency of each vibration mode, in particular, the lower-order resonance frequency with higher accuracy from the measurement result of the FFT analyzer 5. The first to fifth frequency bands F1 to F5 are formally set by finely adjusting the temporarily set values (step S3).

  Then, the test operator instructs the vibration test apparatus to start the main test by operating the operation unit 1h in such a formal setting state of the first to fifth frequency bands F1 to F5. As a result, the oscillation controller 1g controls the first to fifth oscillators 1a to 1e to generate first to fifth sweep sine wave signals SW1 to SW5 (formal sweep sine wave signals) for the main test. These formal sweep sine wave signals are combined (multiplexed) by the signal synthesizer 1f and output as the vibration signal K (formal vibration signal) to the vibrator 2.

  The wing x2 of the device under test X (blisk) is subjected to the main sweep vibration by the vibrator 2 based on the formal vibration signal, and vibrates by the main sweep vibration. The vibration of the blade x2 based on the main sweep excitation is converted into a detection signal C (formal detection signal) by the vibration sensor 3 and is taken into the frequency response analyzer 4. In addition, such a formal detection signal is an excitation signal K (formal excitation signal) generated by combining (multiplexing) the first to fifth sweep sine wave signals SW1 to SW5 (formal sweep sine wave signal). And includes frequency components corresponding to the vibration modes (first to fifth vibration modes) of the blade x2.

  The frequency response analyzer 4 measures the vibration frequency characteristics of the blade x2 by performing FFT processing (frequency analysis processing) on the detection signal C indicating such vibration (step S4). That is, the detection signal C which is a time signal is converted into the first frequency response characteristic corresponding to the first frequency band F1 by being synchronously detected by the first analysis unit 4a using the first synchronization pulse signal D1. . Further, this detection signal C is converted into a second frequency response characteristic corresponding to the second frequency band F2 by being synchronously detected by the second analysis unit 4b using the second synchronization pulse signal D2.

  The detection signal C is converted into a third frequency response characteristic corresponding to the third frequency band F3 by being synchronously detected by the third analysis unit 4c using the third synchronization pulse signal D3. Further, the detection signal C is converted into a fourth frequency response characteristic corresponding to the fourth frequency band F4 by being synchronously detected by the fourth analysis unit 4d using the fourth synchronization pulse signal D4. Furthermore, the detection signal C is converted into a fifth frequency response characteristic corresponding to the fifth frequency band F5 by being synchronously detected by the fifth analysis unit 4e using the fifth synchronization pulse signal D5.

  Then, such first to fifth frequency response characteristics are synthesized on the frequency axis in the data synthesis unit 4f, thereby becoming an overall frequency response characteristic over the excitation frequency band F0. The total frequency response characteristic is displayed as an image in the output unit 4g. That is, this total frequency response characteristic is composed of a horizontal axis indicating the excitation frequency band F0 and a vertical axis indicating the signal intensity, and the resonance frequency of each vibration mode is indicated as a signal intensity peak. The test operator acquires the resonance frequency of each vibration mode of the blade x2 based on such a total frequency response characteristic.

  In this way, the vibration test for the first blade x2 is completed, but the test is completed by obtaining the resonance frequencies of the respective vibration modes for all the blades x2 provided in the device under test X (blisk). Therefore, for the test object X (blisk) provided with a plurality of blades x2, it is determined whether or not this measurement process is completed for all blades x2 (step S5), and if this determination is "Yes" That is, when the resonance frequency of each vibration mode is acquired for all the blades x2, the vibration test of the device under test X (blisk) is completed.

  According to the present embodiment, the vibration test for the first to fifth frequency bands F1 to F5 is not sequentially performed in time series, but the vibration test for the first to fifth frequency bands F1 to F5 is performed in time series. Therefore, the resonance frequency (vibration characteristics) in each vibration mode of the device under test X (blisk) can be acquired in a shorter time.

  Further, according to the present embodiment, the main measurement process for the plurality of blades x2 is performed after the temporary measurement process for the one blade x2 among the plurality of blades x2 having a relatively close resonance frequency. In addition, the resonance frequency (vibration characteristics) in each vibration mode of the device under test X (blisk) can be acquired in a shorter time.

  Here, in the temporary measurement process using the FFT analyzer 5, as described above, the measurement accuracy can be ensured for the resonance frequency in the higher-order resonance mode. Therefore, the main measurement process for the higher-order resonance mode for one blade x2. It is possible to omit.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the excitation signal K uses the first to fifth sweep sine wave signals SW1 to SW5 having continuous frequencies as shown in FIG. 2, but the present invention is not limited to this. That is, the first to fifth frequency bands F1 to F5 may be discontinuous in frequency. For example, a discontinuous section over a predetermined frequency range may be set between the first to fifth frequency bands F1 to F5.

(2) In the above embodiment, as shown in FIG. 2, the start timings (time t1) of the first to fifth sweep sine wave signals SW1 to SW5 are set to the same timing, and the first to fifth sweep sine wave signals SW1. Although the end timing (time t2) of .about.SW5 is the same timing, the present invention is not limited to this. That is, the entire first to fifth sweep sine wave signals SW1 to SW5 do not need to overlap on the time axis. For example, the start timings (time t1) of the first to fifth sweep sine wave signals SW1 to SW5 are the same timing, but the end timings may be different timings.

(3) In the above embodiment, since the excitation signal K obtained by multiplexing the first to fifth sweep sine wave signals SW1 to SW5 is used, the first to fifth sweep sine wave signals SW1 to SW5 are distorted as signals. Alternatively, when the vibration medium is distorted with respect to the vibration signal K, the blade x2 has a first distortion frequency component in addition to the vibration medium based on the first to fifth sweep sine wave signals SW1 to SW5. The excitation medium based on the harmonics of the fifth sweep sine wave signals SW1 to SW5 acts.

  In such a case, the detection signal C includes a vibration component based on the excitation by the harmonics in addition to the vibration component based on the sweep excitation by the original first to fifth sweep sine wave signals SW1 to SW5. Become. For example, when the first sweep sine wave signal SW1 is distorted and a harmonic having a frequency included in the second frequency band F2 of the second sweep sine wave signal SW2 is generated, a vibration component based on the harmonic is converted into the second analysis unit 4b. Acts as a disturbance on the second frequency response characteristic (frequency response characteristic corresponding to the second frequency band F2) output by the.

  And this disturbance may reduce the measurement accuracy of the resonance frequency of the secondary vibration mode. In order to avoid or suppress such a decrease in measurement accuracy due to harmonics, the distortion of the first to fifth sweep sine wave signals SW1 to SW5 with respect to the sine wave and the distortion of the excitation medium with respect to the excitation signal K are reduced. It is necessary to suppress as much as possible. Further, it is necessary to set the first to fifth frequency bands F1 to F5 so that the harmonic frequency is not included in the first to fifth frequency bands F1 to F5 as much as possible.

(4) In the above embodiment, the case of measuring the resonance frequency of the first to fifth vibration modes has been described, but the present invention is not limited to this. That is, the order of the vibration mode measured in the present invention is not limited to the fifth order, and for example, only the first and second vibration modes may be measured.

(5) Although the provisional measurement step is provided in the above embodiment, the present invention is not limited to this. You may measure the resonant frequency of each vibration mode only by this measurement process. Further, the vibration characteristic to be measured is not limited to the resonance frequency. In addition to the resonance frequency or instead of the resonance frequency, the damping ratio or / and the vibration mode may be measured.

X DUT 1 Excitation signal generator 1a 1st oscillator 1b 2nd oscillator 1c 3rd oscillator 1d 4th oscillator 1e 5th oscillator 1f Signal synthesizer 1g Oscillation control unit 1h Operation unit 2 Exciter 3 Vibration sensor 4 Frequency Response analysis device 4a First analysis unit 4b Second analysis unit 4c Third analysis unit 4d Fourth analysis unit 4e Fifth analysis unit 4f Data synthesis unit 4g Output unit 5 FFT analyzer

Claims (5)

A vibration test apparatus for acquiring vibration characteristics of a test object by sweeping and exciting the test object based on a FRA (Frequency Response Analyzer) method,
An excitation signal generator for generating an excitation signal in which sweep sine wave signals in a plurality of frequency ranges are superimposed;
A vibration exciter that sweeps and vibrates the DUT based on the vibration signal;
A vibration sensor for detecting the vibration of the device under test;
A plurality of analysis units corresponding to the sweep sine wave signal, and a frequency response analysis device that analyzes the frequency response of the device under test by synchronizing the output signal of the vibration sensor with the sweep sine wave signal. Characteristic vibration test equipment.   The vibration test apparatus according to claim 1, wherein the frequency response analysis apparatus synthesizes and outputs the frequency response characteristics output from the analysis unit on a frequency axis.   The vibration test apparatus according to claim 1, further comprising an FFT (Fast Fourier Transform) analyzer that performs frequency analysis on an output signal of the vibration sensor. The test object is a rotor of a gas turbine formed as a blisk in which a plurality of blades are integrated with a disk,
The vibration test apparatus according to claim 1, wherein the vibration exciter vibrates a blade provided in the rotor. A vibration test method for acquiring vibration characteristics of a test object by sweeping and exciting the test object based on a FRA (Frequency Response Analyzer) method,
The test object is provisionally swept with a provisional excitation signal in which a plurality of provisional sweep sine wave signals with provisionally set frequency ranges are superimposed, and a provisional signal obtained from the object under test based on the provisional sweep excitation. A provisional measurement step for obtaining an outline of the resonance frequency of each vibration mode based on the detection signal;
The test object is swept and excited with a formal excitation signal superimposed with a formal sweep sine wave signal in which the frequency range is officially set based on the outline of the resonance frequency, and the object to be tested is based on the main sweep excitation. And a main measurement step of acquiring the resonance frequency of each vibration mode based on a formal detection signal obtained from a test body.

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