JPH0394155A - Measuring method for vibration damping ratio of metallic member - Google Patents

Abstract

PURPOSE:To measure a vibration damping ratio by measuring a natural frequency by a simple method by deriving in advance a correlation of the natural frequency and the vibration damping ratio of a metallic member made of cast iron. CONSTITUTION:The responsiveness of input acceleration (a) to force F (voltage) inputted by an exciter 4 to the exciting surface 1a of a disk plate 1 of a brake device is inputted as a vibration transfer function a/F to a frequency analyzing device 6. By analyzing a frequency of the plate 1 from the function a/F, a natural frequency (fn) is measured. In this case, within a range of object frequencies 1 - 10kHz, a correlation exists between a ratio fn'/fn(MP)' of a natural frequency fn' obtained by a model analyzing device and a natural frequency fn(MP)' of the plate 1 which becomes a reference, and an average value (1/n).SIGMA.1/deltai of an inverse number 1/delta of a vibration damping ratio delta of each resonance of the plate 1. Based on this correlation, an average vibration damping ratio delta of the plate 1 is measured from the frequency (fn) obtained by the device 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a measurement method for measuring the vibration damping ratio of a metal member made of cast iron.

(Prior Art) In general, this type of cast iron metal member is sometimes used for disc plates of brake equipment, etc., and the brake noise generated when the brake equipment is operated is affected by the vibration damping ratio of the disc plate itself. A causal relationship exists. That is, the higher the vibration damping ratio of the disc plate, the more advantageous it becomes to brake noise, and therefore, the vibration damping ratio of the disc plate has been actively measured in recent years.

One way to measure the vibration damping ratio of such a cast iron metal member (disc plate) is to first conduct a vibration test on the metal member, and then use a modal analysis device to measure the vibration damping ratio obtained from the vibration test. A collection of data,
After converting the digitally processable frequency axis into a digital value, that is, a collection of points, we curve-fed these discrete points into a continuous collection of points. A vibration equation is created from the waveform.This vibration equation is then solved to calculate (measure) the vibration damping ratio.In this case, the "force-one fit" check, which is the bottleneck of modal analysis equipment, is artificially performed. As a result, a highly accurate vibration damping ratio of the metal member can be obtained.

Another method is to make the vibration damping ratio of the metal member by vibrating the metal member by an excitation test and then making the time when the vibration waveform obtained by the excitation test settles correspond to a predetermined sampling time. There are also some that measure . In this case, the vibration damping ratio of the metal member can be obtained by a method that requires less measurement steps.

(Problem to be solved by the invention) However, in the method of measuring vibration damping ratio using a modal analysis device, in addition to the complicated measurement process such as data processing and calculation performed by the modal analysis device, it requires “curve fitting”. This requires an artificial measurement process to check the waveform, and there is a problem in that the number of measurement steps required to measure the vibration damping ratio of the metal member increases. Furthermore, since a modal analysis device that performs complicated measurement processes such as data processing and calculation is required, there is also the problem that the equipment cost increases when providing a modal analysis device.

On the other hand, in the method of measuring the vibration damping ratio using a vibration waveform, there is a risk of "leakage" in which the vibration waveform does not settle within a predetermined sampling time. This allows “
There is a problem in that the vibration waveform is determined to have subsided even though "leakage" has occurred, resulting in variations in the measurement accuracy of the vibration damping ratio of the metal member.

The present invention was made based on the fact that in the case of cast iron metal members, there is a close correlation between the natural frequency and the vibration damping ratio, and vibration damping is performed based on the measured value of the natural frequency. The purpose is to measure the ratio with high precision and with a small number of man-hours.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the present invention is a method for measuring the vibration damping ratio of a cast iron metal member, in which the cast iron metal member is vibrated and its natural frequency is measured. After obtaining the natural frequency, the vibration damping ratio is measured based on the correlation between the natural frequency and the vibration damping ratio.

(Function) With the above structure, in the present invention, when measuring the vibration damping ratio, as long as the correlation between the natural frequency of the cast iron metal department and the vibration damping ratio is prepared, simple vibration tests etc. can be performed. Since the vibration damping ratio can be obtained by measuring the natural frequency using this method, the vibration damping ratio can be measured with less measurement man-hours without using complicated methods such as the measurement method using a modal analysis device or the measurement method using vibration waveforms. be done. Furthermore, as described above, complicated measurement processes such as data processing and calculation by the modal analysis device are no longer necessary, and equipment costs can be reduced as the modal analysis device is discontinued.

In addition, since there is a close correlation between the natural frequency and vibration damping ratio of cast iron metal members as mentioned above,
The vibration damping ratio can be obtained with high accuracy. Moreover, unlike the conventional method of measuring the vibration damping ratio using vibration waveforms mentioned above, "leakage" in which the vibration waveform does not settle within a predetermined sampling time does not occur, so the measurement accuracy of the vibration damping ratio of metal members is accurate. It is possible to obtain a highly accurate vibration damping ratio without causing any variation.

(Tip example) Embodiments of the present invention will be described below based on the drawings.

5. FIGS. 1 and 2 show a measurement process for a cast iron metal member using a vibration damping ratio measuring method according to an embodiment of the present invention.

As shown in these figures, when measuring the vibration damping ratio of the disc plate 1 of a brake device used as a cast iron metal member, first, the excitation surface 1 of the disc plate 1 is measured.
Attach acceleration pickup 2 to a and force gauge 3
A vibration test is performed by applying an input to the vibration surface 1a of the disk plate 1 using the impact hammer 4 (vibrator) to which the impact hammer 4 is attached (S1).

Then, when the human force is applied to the excitation surface 1a of the disc plate 1, the force F(
voltage) and the impact hammer 4 generated from the acceleration pickup 2 against the excitation surface 1a of the disk plate 1.
After the output (voltage) proportional to the human acceleration a is amplified by the amplifiers 5 and 5, the response of the input acceleration a to the force F is expressed as the vibration transfer function a/F.
Determine.

Then, this vibration transfer function a/F is measured by a frequency analyzer 66. (S2).

Next, the vibration transfer function a/F is input into the frequency analyzer 6, and the frequency analyzer 6 calculates the vibration transfer function a.
By analyzing the frequency of the disk plate 1 from /F, the natural frequency fn that is the peak of that frequency is measured (S3).

At this time, as shown in FIG. 3, target frequencies 1 to 1. 0
Within the range of kHz, the natural frequency fn' obtained by the conventional modal analysis device described above and the natural frequency fn (MP) of the reference disc plate 1.
The horizontal axis is the ratio f n' / f n (MP)', and the average value (1/n) of the reciprocal 1/ζ of the vibration damping ratio ζ of each resonance of the disk plate 1 (1/n) ・Σ・1/ζi is the vertical axis The ratio of the natural frequencies of the disc plate with good precision obtained by the above modal analysis device fn"/fn(M
P) Average value of the reciprocal of the vibration damping ratio for '(1/n)
・If the characteristic of Σ・1/ζ1 is shown by a broken line, the ratio of this natural frequency f n'/ f 1 (Hp) ' and the average value of the reciprocal of the vibration damping ratio (1/n) ・Σ・1/ There is a close correlation between ζi and ζi.

Then, the natural frequency ratio f n of this disk plate 1
Based on the careful correlation between '/f n (MP) ' and the average value of the reciprocal of the vibration damping ratio (1/n) ・Σ・1/ζi, the eigenvalue obtained by the frequency analyzer 6 is From the frequency fn, the average vibration damping ratio ζ of the disk plate 1
is measured (S4).

In this case, the vibration damping ratio of the cast iron metal member is determined in advance by its size, weight, etc., and is based on the data characteristic of one good degree obtained by a modal analysis device etc. {Ratio of natural frequencies f n Average value of the reciprocal of the vibration damping ratio for '/fn(MP}' (1/n) ・Σ・1/ζ
i}, the vibration damping ratio of other cast iron metal members is measured from the natural frequency.

In this way, when measuring the vibration damping ratio, the ratio of natural frequencies f n'/f of a cast iron metal member as shown in Fig. 3 is used.
n(MP)' and the average value of the reciprocal of the vibration damping ratio {1/
n) ・Σ・1/ζ1}, the natural frequency f can be determined by a simple method such as an excitation test.
Since the vibration damping ratio ζ can be obtained by measuring n, the vibration damping ratio ζ can be measured without using complicated methods such as the measurement method using a modal analysis device or the measurement method using vibration waveforms, thereby reducing the number of measurement man-hours. It is possible to reduce the amount. Furthermore, as mentioned above, the complicated measurement process such as data processing and calculation using the modal analysis device is no longer necessary.
With the abolition of modal analysis equipment, it is possible to reduce the equipment cost (σ).

In addition, as mentioned above, between the natural frequency ratio f n' / f n (MP) ' of the disc plate 1.1 and the average value of the reciprocal of the vibration damping ratio (1/n) ・Σ・1/ζ Since there is a close correlation, the vibration damping ratio ζ can be obtained with high accuracy. Moreover, unlike the conventional method of measuring the vibration damping ratio using the vibration waveform described above, "leakage" in which the vibration waveform does not settle within a predetermined sampling time does not occur, so the disk plate
There is no variation in the measurement accuracy of the vibration damping ratio, and a highly accurate vibration damping ratio ζ can be obtained.

(Effects of the Invention) 9 As described above, according to the method for measuring the vibration damping ratio of a cast iron metal member according to the present invention, the vibration damping ratio of the cast iron metal member can be determined by an excitation test of the cast iron metal member. Since it is easily measured by talking about the solid H frequency, which has a close correlation with the vibration damping ratio, the vibration damping ratio can be easily measured while eliminating the need for complicated or artificial measurement processes. It is possible to reduce the total number of man-hours by +1111 compared to the previous model that required a total of δIIIL, and the modal analysis equipment that requires complex measurement processes such as data processing and calculations is abolished, resulting in a reduction in equipment costs. can be achieved. Moreover, since there is a close correlation between the vibration damping ratio and the vibration damping ratio of cast iron metal parts, there is no variation in the measurement accuracy of the vibration damping ratio of metal parts, resulting in highly accurate vibration damping. You can get the ratio.

[Brief explanation of drawings]

The drawings show examples of the present invention; Fig. 1 is a process diagram of a method for measuring the vibration damping ratio of a disc plate, Fig. 2 is an explanatory diagram for measuring the natural frequency of a disc plate, and Fig. 3 is an explanatory diagram for measuring the natural frequency of a disc plate. FIG. 2 is a characteristic diagram showing the characteristics of the average ffi'i of the reciprocal of the vibration damping ratio to the ratio of the solid vibration frequency of the disk plate. 1... Disc plate (cast iron metal part shrine) fn...
Natural frequency ζ...Vibration damping ratio patent Applicant: Mazda Motor Corporation
Hiroshi Maeda and two others11 Figure 3

Claims (1)

[Claims] (1) A method of measuring the vibration damping ratio of a cast iron metal member, in which the cast iron metal member is vibrated, its natural frequency is determined, and then the natural frequency is determined based on this natural frequency. A method for measuring a vibration damping ratio of a metal member, the method comprising measuring the vibration damping ratio from a correlation with the vibration damping ratio.