JPH058978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibrating device used for determining vibration characteristics of machines, structures, etc.

[Conventional technology]

There are several methods for measuring the frequency response function, but the method shown in Figure 3 is used because it does not require the installation of a vibrator like other excitation methods and can be easily carried out on site. As shown in the figure, the frequency response function can be obtained by simply striking an object 1 to be measured such as a machine or a structure with an impact hammer 5 equipped with a force detector 8a, and measuring the vibration response such as vibration acceleration with an accelerometer 8b or the like. The percussion excitation method is often used.

However, in this vibration method, the vibration energy is relatively small and the vibration condition is not stable because the impact is performed manually, and the vibration waveform is impulse-like as shown in Figure 4a. Since the excitation energy is concentrated in a very short period of time after impact and then becomes zero, the wave height factor becomes high and there are drawbacks such as being susceptible to the effects of noise and nonlinearity of the structure. In order to eliminate some of these drawbacks,
An irregular impact excitation method has also been implemented in which multiple impacts are performed within the time window of the FFT device 6, thereby reducing the crest factor of the excitation waveform and increasing the excitation energy. There is.

However, even in this excitation method, since one person swings the hammer 5, the period tends to be approximately periodic, and the spectrum of the excitation force becomes discontinuous or close to it, and the frequency response function There were drawbacks such as a decrease in measurement accuracy and the inability to maintain accuracy due to unstable vibration conditions. Therefore, in Japanese Patent Application No. 61-242882 (Japanese Unexamined Patent Publication No. 63-98526), the present applicant proposes to hit the object to be measured at the same time with multiple impact hammers (by two or more people), as well as to apply irregular input impact. We proposed a vibration method and attempted to improve the accuracy of frequency response function measurement by making the time intervals of impact irregular in the irregular impact vibration method.

On the other hand, using the vibrator 7 as shown in Fig. 5 a and b,
The method of excitation using a sine wave or irregular wave is superior to the three percussion excitation methods mentioned above in terms of accuracy and stability.

However, since the vibration exciter 7 must be fixed at the excitation point of the object to be measured 1, it takes time to prepare for measurement, and the excitation point of the object to be measured 1 requires processing such as drilling a screw hole. Therefore, there is a problem that the excitation point is restricted. Furthermore, in order to obtain higher accuracy, multiple vibrators 7 are used to simultaneously excite irregular waves with no correlation to each other (multi-point simultaneous excitation); When the vibrator 7 is fixed to the object to be measured 1 as shown in a and b, the vibrator 7 is affected by resonance points of the structure, and the excitation force is not uncorrelated. There is also the problem that the measurement accuracy deteriorates due to aging.

[Problem that the invention seeks to solve]

As detailed above, the percussion vibration method is inferior to the vibration method using a vibrator in terms of accuracy and stability, and the method using the vibrator requires time for measurement preparation and There are problems such as restrictions on the vibration point and simultaneous excitation at multiple points, where the excitation forces influence each other and measurement accuracy decreases. However, it was not possible to achieve both measurement accuracy and stability.

The present invention was devised in view of the current situation, and by providing an excitation device that can perform irregular percussion excitation, the present invention can be applied to the irregular percussion excitation method (in the case of multiple inputs) without relying on human power. The aim is to achieve both ease of measurement and measurement accuracy and stability.

[Means for solving problems]

Therefore, the present invention includes a signal generator that irregularly generates pulse-like signals, and a vibrator that is driven based on the signal generated by the signal generator to strike and vibrate the object to be measured. Its basic characteristics are:

In addition, the vibration response obtained by implementing the irregular impact vibration method using such a vibration device tends to be continuous and irregular waves, and there is a risk that the accuracy will decrease due to leakage errors. In order to prevent this, the second invention provides a signal interrupter that interrupts the signal generated by the signal generator, and drives the vibrator based on the interrupted signal to strike the object to be measured. It is designed to vibrate.

[Effect]

The irregular pulse-like signal generated by the signal generator is sent to a vibrator, and the vibrator further performs the following steps:
Since it is driven based on this signal, if the vibrator is placed close to the object to be measured, the vibrator can strike the object to be measured irregularly.

Further, in the second invention, in order to intermittent the signal generated by the signal generator with the signal interrupter and send it to the vibrator,
Irregular impact excitation to the object to be measured can be performed intermittently.

〔Example〕

Specific examples of the present invention will be described in detail below.

FIG. 1 shows the irregular percussion excitation method carried out using the excitation device according to an embodiment of the present invention, and 10 in the figure shows an attempt to obtain a frequency response function using the excitation method. The structure is the object to be measured.

In the device of this embodiment, the structure 1 is
Impact exciter 2 suspended at a position close to 0
and a signal generator 3 that sends an excitation signal to the vibrator 2.

Among these, the impact exciter 2 may be a general electromagnetic exciter or a hydraulic exciter, but it may also be a simple reciprocating device using an electromagnet, air pressure, etc., as long as it can strike a structure. Also, this vibration exciter 2
may be supported by a method other than the wire 20 as shown in the figure. In addition, the striking part of the vibrator 2 includes:
A force detector 8a is attached to the exciter 2, which is necessary when determining the frequency response function of the structure 10.
The device detects the force applied by the strike.

Further, the signal generator 3 generates an irregular pulse-like signal and sends it to the vibrator 2 as an excitation signal. In this embodiment, the excitation signal is obtained as follows. There is. That is, first, an irregular pulse signal as shown in FIG. 2b is prepared. This may be done by setting an appropriate threshold value for the irregular wave as shown in FIG. Next, this irregular pulse signal is passed through a filter, etc., and its pulse width is adjusted to a degree suitable for operating the vibrator 2, thereby obtaining a waveform as shown in FIG.

If this waveform signal is given as an excitation signal to the vibrator 2, the vibrator 2 will hit the structure 10 irregularly, so that the excitation force (detected by the force detector 8a) and The frequency response function can be calculated by measuring the vibration response (eg, vibration acceleration) of the structure 10.

Further, the measured vibration response of the structure 10 has a continuous irregular wave shape as shown in FIG. 2d, and when calculating the frequency response function, there is a possibility that the accuracy may be reduced due to leakage errors. Therefore, as shown by the imaginary line in FIG. 1, a signal interrupter 4 is provided between the vibrator 2 and the signal generator 3, and a gate waveform as shown in FIG. 2e is set. is used to intermittent the signal shown in c in the same figure to obtain an intermittent signal as shown in f in the same figure.

If such a signal is sent as an excitation signal to the exciter 2 and vibration excitation is performed, the vibration response at that time will be as shown in g in the same figure, and if the data in the dashed line is taken in and the frequency response function is calculated, Truncation errors can be prevented.

〔Effect of the invention〕

According to the vibrating device of the present invention described in detail above, the following excellent effects can be achieved.

Experiment preparation is easy because there is no need to attach a vibrator to the object.

Since there is no need to attach the vibration exciter to the target object, there are no restrictions on the target object or the point of vibration.

Even when multiple points are simultaneously excited, the vibrators do not affect each other, allowing completely uncorrelated excitation.

Irregular percussion excitation is ideally possible compared to when excitation is performed manually.

Stable vibration is possible compared to the case of manual vibration.

A larger excitation force can be obtained compared to when excitation is performed manually.

The vibration exciter may have a simple structure, and even one with a large excitation force can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the implementation of an irregular impact vibration method using a vibration device according to an embodiment of the present invention, and FIGS. Various signal waveforms are shown when the excitation method is implemented. Figure a is a signal waveform diagram of an irregular wave used to obtain an irregular pulse signal, and Figure b is a signal waveform diagram of an irregular wave used to obtain an irregular pulse signal, and Figure b is a waveform diagram of an irregular wave used to obtain an irregular pulse signal. A signal waveform diagram of an irregular pulse signal used to obtain an oscillation signal, c is a signal waveform diagram of an excitation signal generated by a signal generator, and d is a signal waveform diagram of an excitation signal generated by a signal generator. Figure e is a signal waveform diagram of the response signal obtained when percussion vibration is applied by the vibrator based on the above figure. Figure e is a signal waveform diagram showing the gate waveform used in the signal interrupter. Figure f is the signal waveform diagram showing the gate waveform used in the signal interrupter. Fig. 3 is a signal waveform diagram of a response signal obtained when a vibration exciter is used to perform impact vibration based on an intermittent excitation signal, and Fig. 3 is a signal waveform diagram of a conventional impact signal. An explanatory diagram showing the vibration excitation method, Fig. 4a is a waveform diagram showing the excitation force waveform by the percussion excitation method, Fig. 4b is a waveform diagram showing the excitation force waveform by the irregular percussion excitation method, Fig. 5 Figures a and b show the conventional vibration method in which a vibration exciter is connected to the object to be measured, and the frequency response function is determined.
Figure a is an explanatory diagram showing the sine wave excitation method, and Figure b is an explanatory diagram showing the random excitation method. In the figure, 1 is an object to be measured, 10 is a structure, 2 is an impact exciter, 3 is a signal generator, and 4 is a signal interrupter.

Claims (1)

[Claims] 1. Includes a signal generator that irregularly generates pulse-like signals, and a vibrator that is driven based on the signal generated by the signal generator and excites the object to be measured by impact. A percussion-type irregular vibration excitation device. 2. A signal generator that generates pulse-like signals irregularly, a signal interrupter that interrupts the signal generated by the signal generator, and a signal generator that drives and receives signals based on the signal interrupted by the signal interrupter. 1. A percussion-type irregular vibration excitation device, comprising: a vibrator for percussively vibrating an object to be measured.