JPH0521174B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a multi-point excitation method for a structure, such as a turbine rotor blade or a pipe, in which vibration is simultaneously applied in a form having a phase difference, and an apparatus therefor. In particular, the present invention relates to a multi-point vibration device for a structure that maintains a constant phase difference between response signals and a constant response level.

[Background of the invention]

When a structure placed in a fluid vibrates, a fluid reaction force acts on the structure. The fluid reaction force acting on a structure in this way is an important problem in terms of the vibration characteristics of the structure. Furthermore, when there are structures in close proximity to each other in the fluid, the fluid reaction force is strongly influenced by the vibration phase difference between the structures. This fluid reaction force is deeply related to the vibration frequency in the form of added mass to the structure, or deeply related to the dissipation of vibration energy in the form of aerodynamic damping.

Conventionally, for example, multiple structures such as turbines,
In experiments to excite the rotor blades in fluid machines such as compressors, we conduct experiments such as excitation using magnets or water jets in order to simulate the circumferential excitation force distribution acting on the rotor blades. It was on. In this case, the spatial distribution of the excitation force should not change over time, so if the rotation speed of adjacent rotor blades is n and the number of blades is Z, then the rotation speed of adjacent rotor blades is 1/nZ.
It will be excited with a phase with a time difference of .
Therefore, when conducting a simulation excitation experiment of excitation force with the impeller stationary, it is necessary to perform phase difference excitation by operating a magnet etc. with an excitation signal having a phase difference corresponding to the excitation time difference. , it is possible to obtain the vibration characteristics of the rotor blade wheel as a structure.

However, in the case of self-excited vibration where the interaction between the fluid and the structure is important, multiple structures, such as a group of tubes in the fluid or a row of rotor blades attached to a blade wheel, vibrate with a certain phase difference. The fluid reaction force at the time of vibration becomes an important factor in vibration characteristics. Therefore, in order to eliminate the influence of such fluid reaction force, it is necessary to perform an excitation experiment in which adjacent tubes, blades, etc. vibrate with a certain phase difference. however,
It has been difficult to apply vibrations with a constant phase difference to multiple structures due to various factors. Let us consider this using the model of the degree-of-freedom vibration system shown in FIG. 1 as an example. In the vibration systems 1 and 2 shown in Fig. 1, if the masses are m ₁ and m ₂ , the spring constants are k ₁ and k ₂ , and the viscous damping coefficients are c ₁ and c ₂ , the natural angular frequencies of both P ₁ and _P2 is is given by Here, for simplicity, P ₁ = P ₂
Consider the case of . When applying an excitation force Fsinωt of the same phase and vibration to both vibration systems 1 and 2,
_{The vibration} responses x _{1 and x 2 are expressed as}
Figures ₂ and 2 show phase delays ₁ and ₂ of x2. In Figures 2 and 2, the vertical axis represents phase delays ₁ and ₂ , and the horizontal axis represents P ₁ /ω, P ₂ /ω.
are shown respectively. Here, as shown in Fig _. 2 _and , ω(=
P ₁ /f=P ₂ /f), even if the phase of the excitation force (Fsinωt) for both vibration systems 1 and 2 is in the same phase, the vibration responses x ₁ and x ₂ will be as follows. ｜ ₁₀ −
A phase difference of ₂₀ | will occur. The reason for this is that there is a difference between the viscous damping coefficients C ₁ and C ₂ .
Therefore, if you want to make the vibration responses x ₁ and x ₂ vibrate in the same phase, if ₁₀ > ₂₀ , the vibration system 2
The phase of the excitation force (Fsin ωt) is ( ₁₀ − ₂₀ )
It is necessary to advance Fsin {ωt + ( ₁₀ − ₂₀ )} by an amount.

In the case of the conventional arbitrary phase difference excitation method (for example, the one described in Japanese Patent Application Laid-Open No. 57-93227), the vibration of the elastic body structure excited by the vibrator is caused by the vibration of the elastic body Depending on the damping characteristics of the structure itself,
The phase of the vibration that appears in the actual vibration deviates from the phase set by the vibrator. As mentioned above, to modify the excitation force, first excite the structure, detect the response signal, grasp the amount of modification, and reset the phase of the excitation signal based on the modification. The need arose. However, in the case of the conventional method, such a correction operation was a very time-consuming operation, and therefore, there was an inconvenience that it took a long time to obtain the required vibration phase difference. In addition, especially when changing the excitation frequency ω, phase delays ₁ and ₂ change, and the difference between them | ₁
− ₂ | is not constant, and a method is adopted in which the excitation frequency ω is swept while giving a constant vibration phase difference (| ₁ − ₂ | is constant) to the vibration system to find its resonance response. It was extremely difficult to do so.

[Purpose of the invention]

The purpose of the present invention is to cancel the unique vibration response of each elastic body at multiple points of some elastic body structures, to excite them simultaneously in a form having a phase difference, and to adjust each response. An object of the present invention is to provide a multi-point vibration device for a structure that can keep the phase difference between signals and response level constant.

[Summary of the invention]

In order to achieve the above object, the multi-point vibration excitation device for a structure according to the present invention is an excitation device that vibrates several elastic structures at a plurality of points. , and reads the data previously stored in the memory by specifying an address in one or more memories according to the sequence of numbers, and when a modification command is given, generates a modified sequence of numbers, Therefore, there is an arbitrary phase multi-signal generating device that reads out data previously stored in a predetermined memory, and a D/A converter converts the data read out from this device into two or more analog signals each having a phase difference. a vibrator that vibrates a plurality of the elastic structures according to the analog signal; and a vibration response of the elastic structure from a detection element provided on each of the elastic structures subjected to the vibration. Capture the signal, measure the phase between the response signal at the reference excitation point and the other response signals among these signals, calculate the phase deviation from the initial setting phase, and based on the calculation result. a phase correction processing device that forms a correction command for causing the arbitrary phase multi-signal generation device to generate a corrected number sequence in which the phase shift is corrected, the phase correction processing device inputting to the arbitrary phase multi-signal generation device; In addition to forming the modification command to modify the level of the analog signal, a level adjustment device is provided to the D/A converter and the processor to form a level modification signal to modify the level of the analog signal, and to adjust the level of the analog signal using this level modification signal. and a vibrator, and adjusts the analog signal of the data read based on the correction command using the level correction signal, thereby adjusting the vibration response to a plurality of points of the elastic structure. It is characterized in that it has a form having a constant phase difference and response level, so that the vibration response inherent to the structure as an elastic body can be cancelled, and the structure can be vibrated.

Next, the effect of the above configuration will be explained.

When an elastic body is subjected to forced vibration, it vibrates with a certain amplitude and phase based on its own structure, mechanical properties, etc. This phase differs from the originally set phase between the vibrations of each structure. Furthermore, if the excitation force is constant, the amplitude will also differ.

According to the above configuration, it is possible to create an excitation signal that can cancel out the unique characteristics of a plurality of elastic body structures from the vibration response that appears as a result of including the unique characteristics of the structures. It is possible to change the excitation force and excitation phase for a plurality of arbitrary waveforms based on the difference between these set values and response values.

Therefore, it is possible to excite multiple points of several elastic structures with a constant phase difference and a constant response signal level, so it is possible to excite multiple points in a short time without complicated operations. A constant phase difference can be obtained and a resonance response can be determined. Moreover, its reliability can be improved.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram illustrating an example of an excitation device for realizing the multi-point excitation method for a structure according to the present invention, and is an example of an excitation device that excites three points on a structure. be.

The multi-point vibration excitation device for the structure shown in FIG. 3 is constructed as follows. In other words, the multi-point vibration device for a structure generates one or more number sequences at each time, specifies an address in one or more memories 3A to 3C using the number sequences, and writes the address in one or more memories 3A to 3C.
~Reads the data stored in advance in 3C, and when a modification command S ₁₀₀ is given, the modification command
A modified number sequence is generated by S ₁₀₀ , and an arbitrary phase multi-signal generator 4 reads out data previously stored in a predetermined memory 3 using the modified number sequence, and the data read out from this device 4 is D/A converters 5A to 5C that convert into analog quantities, and level adjustment that can adjust the levels of two or more analog signals having phase differences that have passed through the D/A converters 5A to 5C, according to a level correction signal. Devices 6A to 6
C, vibrators 7A to 7C that are excited in response to the analog signals passed through the level adjustment devices 6A to 6C and installed at multiple locations on the structure, and vibrators 7A to 7C that are installed in the structure 8 that receives the vibration. , a detection element and amplifiers 9A to 9C for detecting the response signal of the structure 8.
Then, the signals from each detection element and its amplifiers 9A to 9C are taken in, and the phase between the response signal at the reference excitation point and the other response signals is measured and calculated from the initial setting phase. a phase correction processing device 10 that calculates a phase shift of the phase shift and generates a correction command S ₁₀₀ for generating a correction sequence in which the phase deviation is corrected based on the calculation result, and also forms the level correction signal S ₂₀₀ ; and level correction signals S200A to _S200A from the phase correction processing device 10.
S ₂₀₀ C is input to the level adjustment devices 6A to 6C, and a correction command from the phase correction processing device 10 is input.
S ₁₀₀ B and S ₁₀₀ C are input to the arbitrary phase multi-signal generator 4 to read data from the memories 3A to 3C, which are again converted into analog quantities by the D/A converters 5A to 5C, and then to the level adjustment device. 6A to 6
The structure is configured such that the level is adjusted in step C so that vibration can be applied to a plurality of points of the structure 8 in a form having a constant phase difference and response level in the vibration response.

Here, the arbitrary phase multi-signal generator 4 in the above embodiment includes a clock pulse generator 41 that generates a clock pulse CP, and a clock pulse generator 41 that generates a clock pulse CP.
A reference counter 42A that performs a constant count using CP and generates a number sequence S ₃₀₀ A at each time.
and a predetermined number sequence by the clock pulse CP and modification commands S ₂₀₀ B and S ₂₀₀ C given from the outside.
It is configured to include dependent counters 42B and 42C that generate S ₃₀₀ B and S ₃₀₀ C.

The level adjustment devices 6A to 6C use amplifiers capable of variable amplification.

Furthermore, the vibrators 7A to 7C may be constructed of magnets, piezoelectric elements, or the like.

Regarding the detection elements and amplifiers 9A to 9C,
A strain gauge, an acceleration pickup, or the like may be used as the detection element, and any amplifier that can effectively amplify the signals from these detection elements may be used.

The phase correction processing device 10 in the above embodiment is as follows:
Reference response signal S ₄₀₀ A and other response signals
Phase meters 101B and 101C detect the phase difference between S ₄₀₀ B and S ₄₀₀ C;
The difference with the output phase value from 01C is calculated to form correction commands S ₁₀₀ B and S ₁₀₀ C, and this correction command S ₁₀₀ B
and S ₁₀₀ C to specify the initial values of the dependent counters 42B and 42C, and to compare the level of the response signal with the set response level to form level adjustment signals S ₂₀₀ A to S ₂₀₀ C for adjusting the levels of the amplifiers 6A to 6B. It is composed of arithmetic and control units 102A and 102B.

The operation of the apparatus configured as described above will be explained below.

The arbitrary phase multi-signal generator 4 generates signals at times t ₁ , t ₂ , t ₃ ,
..., t _i , t _i+1 , ... (however, t ₁ < t ₂ < t ₃ <...)
One or more sequences ({a _i },
{b _i }, {c _i }, ... (where a _i = a _i+L , b _i = b _i+M ,
c _i
=c _i+N , a _i , b _i , c _i , L, M, and N are integers. ))
Generate S ₃₀₀ A to S ₃₀₀ C. This sequence ({a _i },
{b _i }, {c _i }, . . . etc.) The addresses in the memories 3A to 3C are designated by S ₃₀₀ A to S ₃₀₀ C, and the data previously stored in the memories 3A to 3C are read out. Next, this data is converted into analog quantities by D/A converters 5A to 5C, and three analog exciters 7A to 7C are controlled by three analog signals having phase differences whose levels are adjusted by level adjustment devices 6A to 6C. It is activated to excite multiple points of the structure 8 simultaneously in a form having a phase difference. Furthermore, a response signal of the structure 8 subjected to vibration is detected via the detection element and its amplifiers 9A to 9C. In the phase correction processing device 10, the response signal of the reference excitation point is
The phase between S ₄₀₀ A and the other response signals S ₄₀₀ B and S ₄₀₀ C is measured with phase meters 101B and 101C to calculate the phase shift from the initial setting phase, and based on the calculation result, the corresponding Correction command that corrects phase shift
Generate S ₁₀₀ B to S ₁₀₀ C. Then, in the device 4, the generated number sequence is corrected by the correction commands S ₁₀₀ B and S ₁₀₀ C, and the corrected number sequence is used to specify an address in a memory other than the reference memory, and the data in the memory is read out. Next, the data and the data from the reference memory are transferred to the D/A converter 5 again.
Convert A to 5C into analog signals. The level of the analog signal is adjusted by level adjustment devices 6A to 6C so that the response signal level is maintained at the set value. This adjusted analog signal activates the plurality of exciters 7A to 7C with two or more analog signals having the modified phase difference. Therefore, a plurality of points on the structure 8 are simultaneously excited with a vibration response having a certain phase difference and response level.

Furthermore, the operation of the above embodiment will be explained in detail.

Let us now consider sine wave excitation with a phase difference as an example of excitation. The clock pulse CP generated by the pulse generator 41 is sent to the reference counter 4.
2A, dependent counters 42B and 42C, and the counters 42A to 42C output the count value of the clock as a count output. At this time, the reference counter 42A is an _n0- base counter that counts up to a prespecified value _n0 , then counts again from the initial value 1, and outputs the counted value. At this time, the reference counter 42A generates a synchronizing pulse TP when counting up to n ₀ , and the dependent counters 42B and 42C are activated by the synchronizing pulse TP to the calculation control unit 102B
Counting is performed by measuring the clock pulse CP of the pulse generator 41, using the numerical values n _b and n _c set by 102C as initial values, and outputs the counted value.
Here, 1≦n _b ≦n ₀ , 1≦n _c ≦n ₀ , and the dependent counters 42B and 42C count up to n ₀ , like the reference counter 42A, and then return to 1 and start counting.
n is a _0- base counter. Dependent counters 42B and 2
The count of C is set by a synchronization pulse generated when the dependent counters 4B and 42C count up to _n0 , and the dependent counter count initial value designation signal (correction command) _S100B and Initial value specified by S ₁₀₀ C
Counting will be restarted from n _b and n _c . The sequence of numbers {a _i }, {b _i }, {c _i } constructed from the counter count outputs as described above is shown in FIG. The count output of the reference counter 42A corresponds to the time sequence {t _i } and is expressed as a number sequence {a _i } (where a _i =a _i +n ₀ , a _i ,
_n0 is an integer, _n0 corresponds to the total number of memory data recording addresses), and the dependent counters 42B and 42C
The counting output corresponds to the time sequence {t _i }, and the number sequences {b _i }, {c _i }, respectively (where, b _i =b _i +n ₀ , c _i =c _i +n ₀ ,b _i ,
c _i
is an integer). Time t _j (j is the component of {i})
The components a _j , b _{j , c j of the sequence {a i }} , {b _{i }} , {c _{i }} in
designates the addresses of memories 3A to 3C, respectively. The memories 3A to 3C with designated addresses output pre-stored sine wave digital data at the designated addresses. The digital data is converted into sine wave analog signals S ₅₀₀ A to S ₅₀₀ C shown in FIG. 5 by D/A converters 5A to 5C, respectively. With respect to the analog signal S ₅₀₀ A, the analog signals S ₅₀₀ B and S ₅₀₀ C have a phase difference of α _b and α _c , a _i = a _i + n ₀ , b _i = b _i + n ₀ , c _i = Due to the periodicity of c _i +n ₀ , the analog signals S ₅₀₀ A to S ₅₀₀ C become continuous sine waves. As mentioned above, the phase differences α _b and α _c are
When the reference counter 42A counts n ₀ , it emits a synchronizing pulse, and the dependent counters 42B and 42C are controlled by the dependent counter count initial value designation signals S ₁₀₀ B and S ₁₀₀ C output from the calculation control units 102B and 102C. Addressing values for the memories 3A to 3C are set differently in order to start counting from the designated initial counting values n _b , n _c . α _b , α _c are n _b , n _c ,
There is a relationship of α _b =2π(n ₀ −n _b )/n ₀ , α _c =2π(n ₀ −n _c )/n ₀ , and the dependent counter initial value designation signal S ₁₀₀ B of the arithmetic control units 102B and 102C By changing b _b and n _c depending on S ₁₀₀ C, α _b and α _c can be set to any phase difference. The analog signal obtained as described above is amplified to a desired value by amplifiers 6A to 6C as level adjusters, and the piezoelectric element,
Alternatively, if vibration is performed using vibrators 7A to 7C operated by inputting an electric signal such as a magnet, three points of the structure 8 can be vibrated with a phase difference. Furthermore, as shown in FIG. 4, if the period of the clock pulse CP is _T0 , _the period T of the sine wave obtained by this method is T= _n0T0 . If the clock frequency is ₀ ( ₀ = 1/T ₀ ), the sine wave frequency is = ₀ / n ₀ , so by changing the clock frequency ₀ , the sine wave frequency can be set arbitrarily. It is possible. In addition, the digital data for one period of the sine wave can be stored in memories 3A to 3C.
In this case, the phase difference can be set with a resolution of 4α=2π/n ₀ since it is stored in each of n ₀ addresses. Even if the counted values of the counters 42A to 42C become incorrect due to noise etc.,
When the count value of the reference counter 42A reaches n ₀ every cycle, the initial count values of the dependent counters 42B and 42C are reset to n _b , n _c , so that a constant phase difference α _b , α _c is always maintained. Obtainable. Vibrator 7
The vibration response at each excitation point of the vibration system of the structure 8 that is excited by A to 7C is measured using vibration measurement detection elements such as strain gauges and acceleration pickups, and amplifiers 9A to 9C, and the vibration response is measured. The signal is input to phase meters 101B and 101C. Vibrator 7A
The points subjected to vibration by 7C are A, B, respectively.
C, point A receives vibration from a reference signal, point B receives vibration with a phase difference of α _b from point A, and
The point is subjected to an excitation having a phase difference of α _a from point A. In order to see the phase difference between the response signals, the output signals of the detection elements 9A and 9B are input to the phase meter 101B, and the output signals of the detection elements 9A and 9C are input to the phase meter 101C. As a result, the vibration response phase differences β _b and β _c between points A and B and between points A and C are determined. As mentioned above, as the vibration system of the structure 8, a row of rotor blades and a base material 81 of a fluid machine as shown in FIG.
A plurality of protrusions 82, 82, 8 protruding from
2, etc., the damping coefficient of each blade or protrusion is different, and the response phase difference and response level to the excitation force are also not constant. The phase difference of the excitation force between points A and B, α _b , and the phase difference of the excitation force between A and C, α _c , are similar to the response phase difference when sinusoidal vibration is applied to the vibration system, β _b , β _c . FIG. 7 shows the signal. Phase meters 101B and 101C
The outputs are β _b and β _c , and the outputs of the phase meters 101B and 101C are sent to the calculation control units 102B and 102.
Input to C. Arithmetic control units 102B and 102C
is preset in the dependent counters 42B and 4.
Data n _b and n _c specifying the initial count value of 2C are held. When the response phase differences β _b and β _c from the phase meters 101B and 101C are input, they are measured with a phase setting resolution of 4α (=2π/n ₀ ), and n' _b = [β _b /4α] n' _c = [β _c /4α] …(3) However, n′ _b and n′ _c shall take the integer values closest to β _b /4α and β _c /4α. In order to make the response phase differences β _b and β _c equal to the preset phase differences α _b and α _c , it is necessary to modify the phase difference of the excitation signals. To avoid confusion, let _b , _c (where _b = α _b ,
_c = α _c ), and the initial values of the counter counts to obtain the phase difference using the excitation force are N _b , N _c (however, N _b = n _b , N _c
= n _c ). The difference between the response signal and the desired phase is _b − β _b and _c − β _c between A and B and between A and C, respectively.
, and the dependent counter count values specifying the memory address are N _b −n _b ′ and N _c −n _c ′. In order to obtain a desired response phase difference for the vibration system of the structure 8 having such a phase lag, the phase difference α _b and α _c of the excitation signals is expressed as α _b = _b + ( _b + β _b ) = 2 _b - β _b α _c = _c + ( _c - β _c ) = 2 _c - β _c ... (4) At the initial counting values of dependent counters 42B and 42C, n _b = 2N _b - β _b n _c = 2N _c −β _c …(5).

However, when 2N _b −β _b <1, n _b = (2N _b − β _b ) + n ₀ 2N _c − β _c <1, n _c = (2N _c − β _c ) + n ₀ 2N _b When −β _b >n ₀ , n _b =(2N _b +β _b )−n ₀ When 2N _c −β _c >n ₀ , n _c =(2N _c +β _c )=n ₀ .

The above-mentioned calculations and logical judgments are performed by the calculation control unit 102B.
and 102C, and dependent counters 42B and 4
When new counting initial values n _b , n _c are specified for 2C, the dependent counters 42B, 42C create new numerical sequences {b _i ′}, { corresponding to the numerical sequence {a _i } constituted by the reference counter 42A. c _i ′}, detect the response position at any time,
Then, by correcting the phase shift, A, B
The response phase difference between A and C can be maintained at the desired values _b and _c . Further, the vibration response signals measured by the sensors and amplifiers 9A to 9C are directly sent to the calculation control units 10A to 10C, and compared with a prespecified response level, so that the actual vibration response level is determined from the specified response level. The gains of the amplifiers 6A to 6C are automatically adjusted to operate the vibrators 7A to 7C so as to be equal to the response level. In this way, the vibration response level of each excitation point A, B, and C can be kept constant.

As an example, the same clock pulse PC generated from a pulse generator is transmitted to three counters 42.
A to 42C are counted and the count output of the reference counter 42A forms a sequence {a _i }, and the count from the initial count value designated by the arithmetic control units 102B and 102C is transferred to the dependent counter by the synchronization pulse of the reference counter 42A. 42B and 42C, n ₀ and n _b ,
{b _i } with the same period as {a _i } so that n _c corresponds to
Generate {c _i }. The addresses of each of the memories 3A to 3C are designated by the number sequence S ₃₀₀ A to S ₃₀₀ C, and the corresponding data is read out. D/ the data
After converting the signals into analog signals using A converters 5A to 5C, the signals are amplified and actuated by vibrators 7A to 7C.
As a result, three points on the structure 8 are vibrated. The detection element detects the vibration response, and the phase meters 101B and 101C detect the vibration response due to the excitation signal formed by {a _i } and the phase of other vibration responses, and the vibration response having the initial set phase difference is detected. In order to obtain this, the arithmetic and control units 102A and 102C calculate correction values for the phase shift and the dependent counter count initial value, and output these as correction commands S ₂₀₀ B and S ₂₀₀ C.

The above modified commands S ₂₀₀ B and S ₂₀₀ C are sent to subordinate counter 4.
2B and 42C, thereby constructing a new sequence {b _i ′}, {c _i ′}, and specifying the addresses of memories 3B to 3C by {b _i ′}, {c _i ′}. Thus, the response phase difference is held at a constant value.

The arithmetic control units 102A to 102C also detect the response level, and apply level adjustment signals S ₂₀₀ A to S ₂₀₀ C to the exciter operating amplifiers 6A to 6C so that the response level is maintained at a specified response level. , make adjustments to their gains. As a result, three points on the structure are simultaneously excited with a phase difference, and the phase difference between the response signals and the response level are kept constant.

In addition, in Fig. 3, a method was described in which phase difference excitation is performed simultaneously on three points on a structure, but a method of creating a signal having a phase difference with respect to a reference signal is as follows.
Since the number of signals is the same regardless of the number of signals, and it is easy to create multiple channels, it is possible to excite the structure at any number of points.

Furthermore, the memories 3A to 3C in Fig. 3 store digitized data for one period of a sine wave, and a sine wave as shown in Fig. 5 is obtained as an excitation waveform, but of course this In order to digitally form an excitation waveform having an arbitrary phase difference, the waveform can be any arbitrary waveform such as a rectangular wave or a triangular wave. Of course, different waveforms may be stored in the memory of each channel. Furthermore,
The memory 3 can store waveforms for arbitrary periods. For example, if M periods of waveforms are stored in n ₀ memory addresses, the dependent counter can be stored in the range of 1 to n ₀ /M. By specifying the initial count value of , it is possible to obtain the same vibration excitation method according to the present invention as explained using FIG.

In addition, although the clock pulse CP is a rectangular wave in FIG. 4, the clock is for operating a counter, and it is of course possible to use a waveform other than a rectangular wave, such as a sine wave or a triangular wave. Furthermore, by sweeping and changing the frequency of the clock, it is possible to change the data reading speed from each memory and sweep the excitation frequency. Thereby, the resonance response can be determined by sweeping the excitation frequency around the natural frequency of the structure while keeping the vibration response phase difference between the plurality of excitation points of the structure constant. At this time, it is necessary to keep the excitation force constant, but in this case, automatic control of the vibration response level may be canceled and the gain of the amplifier that operates the exciter may be kept constant. Furthermore, when it is desired to perform excitation while keeping the phase between the excitation forces constant, it is sufficient to cancel the subsequent feedback control from the detection of the phase between the response signals.

〔Effect of the invention〕

As described above, according to the present invention, multiple points on a structure are simultaneously excited in a form having a phase difference, and the phase difference between response signals and the response level are kept constant at multiple points on the structure. A vibration device can be provided.

Further, according to the present invention, as an experimental method for elucidating fluid vibrations of various fluid machines, it is possible to greatly contribute to improving reliability in terms of vibration strength.

In other words, vibration responses based on the unique shapes and mechanical properties of multiple elastic structures can be canceled out.
By using controlled and defined vibrations of multiple structures, we can clarify the interactions between physical phenomena in fluids and vibrations. Therefore, it is possible to set the actual vibration phase difference and amplitude between the elastic structures to intended values, and thereby, for example, the disturbance given to the fluid flowing between the blade rows vibrating with a certain phase difference. It becomes possible to provide the information in an ideal form.
This is completely different from conventional vibration experiments in which vibration responses are observed, and enables vibration experiments with controlled responses.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram explaining the excitation force and response of the vibration system including damping, Fig. 2 is a characteristic diagram showing the phase change between excitation force and response signal with respect to excitation frequency, and Fig. 3
The figure is a block diagram showing an example of the device used in the multi-point vibration method for a structure according to the present invention, which vibrates three points, and Figure 4 shows a clock and a sequence of numbers obtained by counting the clock. An explanatory diagram, FIG. 5 is a waveform diagram showing three sine waves having a phase difference obtained by D/A conversion in an embodiment of the present invention, and FIG. 6 is a waveform diagram showing three sine waves having a phase difference obtained by D/A conversion. FIG. 7 is a perspective view showing a wing that has been rotated, and FIG. 7 is a waveform diagram showing an excitation signal, a response signal, and a phase relationship. 41...Pulse generator, 42A...Reference counter,
42B and 42C...dependent counters, 3A to 3C
...Memory, 4...Arbitrary phase multi-signal generator, 5A to 5C...D/A converter, 6A to 6C...Level adjuster, 7A to 7C...Exciter, 8...Structural vibration system, 9A to 9C...Detection element and its amplifier, 1
0... Phase correction processing device, 101A and 101C...
Phase meter, 102A to 102C... Arithmetic control unit,
CP…Clock pulse, TP…Synchronization pulse, S ₁₀₀ B
and S ₁₀₀ C...counting initial value designation signal (correction command signal), S ₅₀₀ A to S ₅₀₀ C...excitation signal.

Claims (1)

[Claims] 1. In a vibration device that vibrates several elastic structures at a plurality of points, one or more number sequences are generated at each time, and one or more number sequences are generated by the number sequence. Specify an address in the memory to read out the data pre-stored in the memory, and when a modification command is given, generate a modified number sequence, and use the modified number sequence to read the data pre-stored in the predetermined memory. an arbitrary phase multi-signal generating device that reads out the data; and a D/A converter converts the data read out from this device into two or more analog signals each having a phase difference, and converts the elastic body structure according to the analog signal into two or more analog signals each having a phase difference. A vibration exciter that excites multiple parts of an object and a detection element provided on each of the elastic structures subjected to vibration capture vibration response signals of the elastic structure, and among these signals, an excitation signal that serves as a reference is captured. The phase between the response signal of the point and the other response signals is measured to calculate the phase shift from the initial setting phase, and based on the calculation result, a modified sequence in which the phase shift is corrected is applied to the arbitrary phase multiplier. a phase correction processing device that forms a correction command to be generated by the signal generation device, the phase correction processing device not only forms the correction command to be input to the arbitrary phase multi-signal generation device, but also processes the analog signal. A level adjustment device is provided between the D/A converter and the vibrator to form a level correction signal for correcting the level and adjust the level of the analog signal using the level correction signal, based on the correction command. By adjusting the analog signal of the data read out by the level correction signal, the vibration response has a constant phase difference and response level with respect to a plurality of points of the elastic body structure. A multi-point vibration excitation device for a structure, characterized in that the vibration response inherent to the structure as an elastic body is cancelled.