JP3373609B2 - Ultrasonic material property value measuring device and its measuring method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to elastic modulus, Poisson's ratio, Lame parameter, sound velocity anisotropy of a sample made of metal, ceramics, amorphous (including glass), polymer material, etc. under a wide range of temperature conditions. The present invention relates to a measuring device for calculating a material characteristic value such as internal friction, which enables particularly highly accurate measurement.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for measuring material characteristic values of various solid materials such as metals, ceramics and polymer materials, for example, a tensile / compression tester is used for longitudinal elastic modulus and a resonance method is used for internal friction. The measuring machine used was.

[0003]

SUMMARY OF THE INVENTION The inventors have conducted research based on an idea completely different from the conventional technique, and have been able to obtain various characteristic values of various solid materials under a wide range of temperature conditions from low temperature to high temperature. We have already developed a device that can measure in an extremely short time using a single measuring device. This device applies an ultrasonic pulse to one end of a sample inserted in an atmosphere furnace via an ultrasonic wave guide, and measures the waveform, waveform position, and peak value of the pulse echo from the sample to determine the material characteristic value. The material characteristic values that can be calculated are longitudinal sound velocity, transverse sound velocity, Young's modulus, rigidity, bulk modulus, compressibility, Poisson's ratio, Lame parameter, sound velocity anisotropy coefficient,
There are 11 types of longitudinal wave internal friction and transverse wave internal friction.

By the way, although an analog type waveform recording device is used for this measuring device, for a material in which a liquid phase appears at a specific temperature, ultrasonic waves are remarkably attenuated in that temperature range, which makes measurement difficult. Becomes Further, it has been found that it is almost difficult to measure even a material such as a precipitated alloy or a cast alloy in which ultrasonic pulse echoes are significantly scattered.

Therefore, an attempt was made to set a threshold value and measure from an analog ultrasonic pulse echo signal.
The above-mentioned materials have large fluctuations in the threshold value due to overlapping pulse echoes, etc. Therefore, even if the applied voltage of the ultrasonic pulse is set to a high voltage, a defective focusing occurs or the detection becomes undetectable. It was impossible.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and as a means for solving the problem, a pulse is applied to a digital waveform storage device instead of an analog waveform recording device. The whole echo is focused, and the temperature measurement data of the sample is digitized and stored simultaneously. Then, by extracting the digital waveform stored by this device and performing a three-dimensional analysis with temperature and time as a function, even if the pulse echo to be detected changes due to various material phenomena of the sample, It becomes possible to correct as an abnormal value by comparison with the waveforms at temperatures before and after the sample temperature, and it becomes possible to determine the waveform of the pulse echo, the waveform position, and the peak value.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ultrasonic material characteristic value measuring apparatus and its measuring method of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram of a measuring device and a measuring system according to the present invention. In this figure, an ultrasonic waveguide 1 made of a rod-shaped body having screw-shaped irregularities formed on its outer peripheral surface is partially inserted into an atmosphere furnace 2 whose temperature can be adjusted, and a flange portion is provided at its insertion end. The provided rod-shaped sample 3 is attached. In this example, the sample 3 is fixed by the screw force of the cap nut 5 via the contact medium 4 made of metal, Teflon, vinyl or the like, but the contact medium 4 is not always necessary if the surface precision is improved.

The atmosphere furnace 2 uses liquid nitrogen, a cryostat, an infrared image furnace, a resistance heating furnace, etc., so that the temperature can be controlled from a minimum attainable temperature of about 4K to a maximum attainable temperature of about 2373K by a heating device. It is preferably a furnace. At the same time, in the atmosphere furnace 2, from 0.001 atm to 5 atm of air, oxygen,
Gas such as nitrogen, argon and helium or 10
^An atmosphere furnace capable of maintaining a vacuum up to ^-4 Torr is preferable.

The ultrasonic waveguide 1 has an end opposite to the insertion end which is outside the atmosphere furnace 2. At the opposite end, there are provided an ultrasonic pulse transmitter / receiver 6 and a temperature controller 7 for cooling or heating the transmitter / receiver 6 to keep it at room temperature. The ultrasonic waveguide 1 is preferably made of a material that has low ultrasonic propagation loss, cold resistance, and heat resistance. For example, the measurement temperature is 1073K.
Hereinafter stainless steel or Ti-6Al-4V alloy, high density graphite above 1373K, SiC, Si ₃ N ₄
Examples include sintered bodies.

In addition to the main body of the measuring apparatus as described above, this apparatus is composed of an ultrasonic pulse oscillator 8, a digital type waveform storage device 9, a digital thermometer 10 and a data processing device. A pulser receiver or a digital oscilloscope is used for the digital waveform storage device 9. The data processing device includes, for example, a computer such as a personal computer 11 and a storage device such as a disk 12, a printer 13 and a display 14.

The digital thermometer 10 is directly connected to the sample 3 by the thermocouple 15, and the temperature of the sample 3 can be successively observed. The thermocouple 15 normally uses platinum and a platinum-rhodium alloy pair, but uses copper and a copper-tantalum alloy pair at 300 K or less, and uses tungsten and a tungsten-rhenium alloy pair when measuring up to a temperature exceeding 1873 K. Good. The temperature measurement data is sent to the personal computer 11 via the RS-232C compliant serial interface 16.

Now, the ultrasonic pulse transmitted from the transmitter / receiver 6 through the delay circuit 17 / synchronous pulse oscillation 18 / ultrasonic pulse oscillation 19 which is a built-in function of the digital waveform storage device 9 is the ultrasonic waveguide 1. After traveling back and forth in the sample 3, it returns to the transmitter / receiver 6 again. This received analog signal is amplified to a proper voltage level by the amplifier 20,
It is sent to the A / D converter 22 in synchronization with the trigger 21. The gate / address counter 23 designates an address of the memory 24, and digital data is sequentially accumulated at the designated address.

This digital data is sent to the buses 25 and G.
It is transferred to the personal computer 11 through the P-IB cable.
The personal computer 11 displays the waveform data and the temperature of the sample 3 on the display 14, and writes both the data in a storage device such as the disk 12. The delay circuit 17 is effective in the measurement at a constant temperature, but is not always necessary in the measurement during the temperature increase or the temperature decrease.

The method of calculating the material characteristic value using this apparatus is as follows. FIG. 2 shows the path of the ultrasonic pulse in the sample 3.

The ultrasonic pulse incident from the ultrasonic waveguide 1 parallel to the central axis of the sample 3 becomes a longitudinal wave 26. On the other hand, an ultrasonic pulse incident at an angle on the central axis of the sample 3 hits the side surface of the sample 3 and is then divided into a reflected wave of the same angle and a reflected wave of the critical angle θ. θ
Since it disappears at, only the transverse wave 27 induced at the critical angle θ exists. Here, when the sound velocities of the longitudinal wave 26 and the transverse wave 27 are respectively set to V _L and V _S, Formula 1 is established.

[0017]

[Equation 1] Now, the ultrasonic pulse 26 incident on the sample 3 at time T ₁
Is reflected by the end face of the sample 3 and at the time T ₂ , the ultrasonic waveguide 1
Incident on. On the other hand, the ultrasonic pulse 27 is longitudinal wave → transverse wave →
While being converted into a longitudinal wave, the light is reflected by the end surface of the sample 3 and the time T ₃
Is incident on the ultrasonic waveguide 1. FIG. 3 shows the relationship between times T ₁ , T ₂ and T ₃ . If the length of the sample 3 is L and the diameter is D, the sound velocities of the longitudinal wave and the transverse wave can be obtained from the equations 2 and 3. However, L ≧ Dtan θ.

[0018]

[Equation 2]

[0019]

[Equation 3] On the other hand, if the density of the sample 3 is ρ, the solid elastic constants are given by the equations 4 to 10.

[0020]

[Equation 4]

[0021]

[Equation 5]

[0022]

[Equation 6]

[0023]

[Equation 7]

[0024]

[Equation 8]

[0025]

[Equation 9]

[0026]

[Equation 10] Next, as shown in FIG. 3, the peak values of the amplitude of the ultrasonic pulse incident on the ultrasonic waveguide 1 at times T ₁ , T ₂ and T ₃ are A ₁ , A ₂ and A ₃ , respectively. If the reflection at the interface is the total reflection, the internal friction of the sample 3 is given by Eq. However, f is the frequency of ultrasonic waves.

[0027]

[Equation 11] To proceed with the above calculation, the time T ₁ , T ₂ , T ₃
And it is necessary to find the peak values A ₁ , A ₂ , A ₃ of the amplitude of the ultrasonic pulse. As shown in FIG. 4, the present invention uses the temperature data transmitted from the digital thermometer and the waveform of the ultrasonic pulse echo transmitted from the sample 3 through the delay circuit / synchronous pulse oscillation / ultrasonic pulse oscillation to determine the sample temperature. The three-dimensional analysis with the function of time and time is performed in a personal computer, and the abnormal values and difficult-to-measure values are corrected and obtained by comparing the before and after data of each peak value.

[0028]

INDUSTRIAL APPLICABILITY As described above, by using the ultrasonic type material characteristic value measuring apparatus and its measuring method according to the present invention, it becomes possible to measure in a specific temperature range which is difficult to measure in the past. Continuous measurement is possible without interruption even with temperature fluctuations. Further, the present invention enables measurement of some materials that could not be measured conventionally.

[Brief description of drawings]

FIG. 1 is a conceptual measurement system diagram showing an embodiment of a measuring apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a progress state of an ultrasonic pulse transmitted in a sample.

FIG. 3 is a relationship diagram of a propagation time of an ultrasonic pulse and an amplitude peak value.

FIG. 4 is an analysis diagram when the waveform of a pulse echo is expressed as a function of sample temperature and time.

[Explanation of symbols]

1 Ultrasonic wave guide 2 atmosphere furnace 3 samples 6 transmitter and receiver 7 Temperature controller 26, 27 ultrasonic pulse

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 29/00-29/28 G01N 25/00-25/72

Claims (2)

(57) [Claims] 1. One end of a sample placed under arbitrary temperature conditions
The ultrasonic velocity of the sample is fixed by applying an ultrasonic pulse to the fixed end through the ultrasonic waveguide, and measuring the waveform of the pulse echo from the sample, the waveform position, and the peak value.
An ultrasonic material characteristic value measuring device capable of calculating material characteristic values such as elastic modulus, Poisson's ratio, Lame parameter, sonic anisotropy coefficient, and internal friction, in which a pulse echo from the sample is stored in a digital waveform storage device. The ultrasonic material characteristic value measuring device is characterized in that the temperature and time of the sample are simultaneously stored as digital data. 2. An abnormal value is obtained by continuously extracting pulse echoes stored in the digital waveform storage device according to claim 1 and performing three-dimensional analysis using the temperature and time of the sample simultaneously measured as a function. The measurement method using the measuring apparatus according to claim 1, wherein the material characteristic value is determined by correcting the value.