JPH04244957A - Apparatus for measuring mechanical constant - Google Patents

Abstract

PURPOSE:To obtain the title apparatus capable of obtaining the accurate mechanical constant of a material by calculating the precise resonance frequency of the material by eliminating the effect on the inherent resonance frequency of the material due to the vibration of the material or the detection of the vibration of the material. CONSTITUTION:In a mechanical constant measuring apparatus, a sound generator 5 emits a sonic wave to a material through the sound transmission pipe 4 reaching the material 1 through the opening part 9 for the sound transmission pipe 4 to vibrate the material 1. Next, a laser Doppler vibrometer 7 irradiates the material 1 with laser beam through a laser opening part 10 to measure the reflected beam thereof to detect the vibration of the material 1 and the time response of the obtained detected vibration waveform is analyzed by a frequency analyser 12 to calculate resonance frequency. An electronic calculator 15 performs operation using the resonance frequency obtained by the analysis due to the frequency analyser 12 to calculate the mechanical constant of the material.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical constant measuring device for determining the mechanical constants of a material by vibrating the material, detecting the vibration, and calculating the resonant frequency of the material.

0002

BACKGROUND OF THE INVENTION Mechanical constants such as elastic modulus and rigidity of materials such as ceramics, metals, plastics, and wood can be determined with high precision from the resonant frequencies unique to the materials.

As an example of a conventional mechanical constant measuring device,
The material is suspended by two hanging strings such as platinum wire, the material is vibrated through these hanging strings, and the resonance frequency is calculated by detecting the vibration of the material while changing the excitation frequency. There are devices that can be used to determine the mechanical constants of materials. With this device, since the material and the hanging line are in contact, when detecting the vibration of the material, the resonant vibration of the hanging line itself is detected in addition to the resonant vibration of the material itself. There are drawbacks such as the hanging string absorbs the excitation vibration when doing so, making it impossible to excite the material efficiently.

[0004] As a conventional mechanical constant measuring device that solves the above-mentioned drawbacks, the resonant frequency of the material is calculated by exciting the material with an alternating voltage and detecting the vibration of the material while changing the excitation frequency. There are devices that can be used to determine the mechanical constants of materials.

[0005]

[Problem to be Solved by the Invention] In the latter conventional mechanical constant measuring device described above, when attempting to determine the mechanical constants of a non-conductive material, a conductive paste or the like is applied to the material. the electrode must be attached to the material. Therefore, there is a drawback that the mechanical constants of the non-conductive material determined by this mechanical constant measuring device are affected by the application of the paste. Further, there was a problem in that the work of applying the paste was time-consuming.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to accurately determine the mechanical constants of materials.
Another object of the present invention is to provide a mechanical constant measuring device that can be easily obtained.

[0007]

[Means for Solving the Problems] The present invention relates to a mechanical constant measuring device for determining the mechanical constants of a material by vibrating the material, detecting the vibration, and calculating the resonant frequency of the material. The above object of the present invention is achieved by causing the material to be vibrated by air vibration.

[0008]

[Operation] The present invention vibrates the material by projecting a sound wave to an arbitrary position of the material to excite the material, irradiating a laser beam to an arbitrary position of the excited material, and measuring the reflected light. can be detected, so the mechanical constants of the material can be determined without contacting the material.

[0009]

[Example] Fig. 1 is a configuration diagram showing an example of the mechanical constant measuring device of the present invention.
and a jig 3 can be stored therein, and the inside of the thermostatic container 6 can be heated or cooled to a desired temperature using the provided heating means and cooling means. The temperature inside the constant temperature container 6 is detected by the temperature detector 8, read by the temperature controller 13, compared with a temperature set value commanded in advance to the temperature controller 13 from the electronic computer 15, and adjusted by the temperature controller 13 according to the result. be done. Furthermore, by injecting an inert gas into the constant temperature container 6 through the inert gas injection opening 11, the inside of the constant temperature container 6 can be made into a non-oxidizing atmosphere.

On the other hand, the amplifier 14 drives the sonic wave generator 5 by passing a current through the sonic wave generator 5 according to the frequency instructed by the electronic computer 15. The sound wave generator 5 driven by the amplifier 14 excites the material 1 by projecting sound waves onto the material 1 via the speaking tube 4 which reaches the material 1 through the speaking tube opening 9 from the sound wave generator 5 .

The laser Doppler vibrometer 7 detects the vibration of the material 1 by irradiating the material 1 with a laser through the laser aperture 10 and measuring the reflected light, and calculates the time response of the detected vibration waveform. The frequency analyzer 12 performs analysis to determine the resonance frequency. The electronic computer 15 calculates the mechanical constants of the material by performing calculations using the resonance frequency obtained by analysis by the frequency analyzer 12.

Furthermore, the mechanical constant measuring device of the present invention can accurately measure mechanical constants such as the elastic modulus of a material by appropriately combining the positional relationship between the sound wave projection position (excitation position) and the vibration detection position. can be easily obtained. For example, FIG. 2 shows the positional relationship between the support position 18, the vibration position 16, and the vibration detection position 17 of the material 1 when measuring the elastic modulus.
Figure 3 shows the support position 18 and the excitation position 16 during rigidity measurement.
and the positional relationship with the vibration detection position 17. In this manner, the mechanical constant measuring device of the present invention can obtain accurate mechanical constants by moving the material position to the positional relationship shown in FIG. 2 or 3 each time the measurement mode changes. .

The mechanical constant measuring device of the present invention can adjust the excitation position 16 of the material 1 without moving the material position each time the measurement mode changes by using a plurality of speaking tubes or by using a flexible speaking tube. can be moved as shown in FIG. 2 or 3. A mechanical constant measuring device that has multiple speaking tubes has a valve attached to each speaking tube,
By controlling the opening and closing of each valve each time the measurement mode changes, the excitation position can be moved as shown in FIG. 2 or 3. The mechanical constant measuring device that has a flexible speaking tube moves the speaking tube opening 9 every time the measurement mode changes to change the excitation position as shown in Figure 2.
Or it can be moved as shown in Figure 3.

Furthermore, the mechanical constant measuring device of the present invention can change the vibration detection position 16 of the material 1 as shown in FIG. It can be moved as shown in Figure 3. In this case, the mechanical constant measuring device is installed at a plurality of locations in advance so that the position of the Doppler vibrometer and the corresponding position of the laser aperture 10 are aligned with the vibration detection position 16 shown in FIG. 2 or 3. By selecting the necessary detection signal from the Doppler vibrometer each time the measurement mode changes, vibration at a desired vibration detection position can be detected.

[0015]

[Effects of the Invention] As described above, according to the mechanical constant measuring device of the present invention, it is possible to excite and detect vibrations of a material without contacting the material, thereby eliminating fluctuations in the resonant frequency of the material caused by objects that come into contact with the material. It is possible to accurately calculate the resonant frequency of the material, and as a result, obtain accurate mechanical constants of the material.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a mechanical constant measuring device of the present invention.

FIG. 2 is a diagram showing the support position, vibration position, and vibration detection position of the material during elastic modulus measurement.

FIG. 3 is a diagram showing the supporting position, vibration position, and vibration detection position of the material during rigidity measurement.

[Explanation of symbols]

1 Material 2 Support part 3 Jig 4 Speaking tube 5. Sound wave generator 6　Thermostatic container 7 Laser Doppler vibration meter 8 Temperature detector 9 Opening for speaking tube 10 Laser opening 11 Inert gas injection opening 12 Frequency analyzer 13 Temperature controller 14 Amplifier 15 Electronic computer 16 Vibration position 17 Vibration detection position 18 Support position

Claims (5)

[Claims] 1. A mechanical constant measuring device for determining mechanical constants of a material by vibrating a material, detecting the vibration, and calculating a resonant frequency of the material, wherein the material is vibrated by air vibration. A mechanical constant measuring device characterized in that: 2. Claim 1, wherein the air vibration generating means for exciting the material is a sonic wave generator equipped with a speaking tube.
The mechanical constant measuring device described in . 3. The mechanical constant measuring device according to claim 1, wherein the means for detecting vibration when the material is excited is a laser Doppler vibrometer. 4. Calculating means for calculating the resonant frequency of the material,
The time response function of the vibration waveform when the material is excited is determined, and the frequency analysis of the determined time response function is performed to calculate acceleration, velocity,
2. The mechanical constant measuring device according to claim 1, wherein a displacement/force transfer function is determined, and a resonance frequency of the material is calculated from the determined transfer function. 5. The method according to claim 1, further comprising a container equipped with a heating means and a cooling means in which the material can be placed, and the mechanical constant of the material is determined by changing the temperature inside the container. Mechanical constant measuring device as described.