JPH05215728A - Device for measuring slid-state elastic modulus and internal friction in wide temperature range from low to high temperature - Google Patents

Abstract

PURPOSE:To measure horizontal length and vertical length, a volume elastic modulus, Poisson's ratio, and internal friction of a sample as a function of temperature simultaneously by applying a longitudinal wave ultrasonic wave pulse to one edge of the sample via an ultrasonic waveguide body and measuring a propagation time and an attenuation rate within the sample by using a measuring equipment with a multi-stage delay circuit and an automatic gate selection function. CONSTITUTION:An ultrasonic pulse which is discharged from a transmitter/receiver 1 is fed back to the transmitter/receiver 1 from a sample 3 the receiver 1 an AGC amplification 8 a zero-cross time detection 9 a multi-stage delay 10 a transmission circuit 11 through an ultrasonic waveguide body 2 and continues to oscillate within a same closed circuit. An average period of N singaround loops is measured, thus obtaining a highly accurate propagation time measurement value. In this case, an error due to deformation of a received waveform is reduced by the AGC amplification 8 and the zero-cross time detection 9 and interference in multiple echo within the sample is prevented by the multi-stage delay 10. Furthermore, sound velocities of a longitudinal wave and longitudinal wave transversal wave conversion wave are detected by a measuring equipment with an automatic gate selection function using only a longitudinal wave vibrator, thus measuring the longitudinal/transversal elastic modulus, Poisson's ratio, and internal friction simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to metals, ceramics,
The present invention relates to an apparatus for simultaneously measuring, as a function of temperature, a characteristic value relating to mechanical deformation among various basic properties of various solid materials such as a polymer over a wide range from liquid nitrogen temperature to 1700 ° C.

[0002]

2. Description of the Related Art Solid materials such as metals, ceramics, and polymers are basic materials that support the civilization of mankind, and when the same materials are used in parts subject to mechanical dynamic loads such as vibration, sliding, and rotation. , Longitudinal and transverse elastic moduli, Poisson's ratio and internal friction are
It is an extremely important physical property value in material design. Nevertheless, the present situation is that a simultaneous measurement device for the above-mentioned four physical property values in a wide temperature range has not been developed. Since the properties of materials are different from each other, it is necessary to measure properties of the same material at the same time. Among the above four physical property values, the lateral elastic modulus can be measured by a tensile and compression tester, but the longitudinal elastic modulus cannot be measured by the same method, and as a result, the Poisson's ratio cannot be calculated. On the other hand, regarding internal friction, although there are existing vibration methods based on vertical / horizontal and torsional vibration methods, the remaining three characteristic values cannot be measured by the same method. Further, there is a problem in the heat resistance of the vibration system in the measurement at high temperature.

[0003]

An object of the present invention is to apply an ultrasonic pulse to a sample, and determine the longitudinal and transverse elastic moduli, Poisson's ratio and internal friction at an arbitrary temperature from the propagation time and attenuation rate of the pulse. It is to develop a device that can measure simultaneously.

[0004]

As a result of repeated studies to achieve the above object, the present inventors have found that the acoustic impedance of a sample connected to one end of a sample kept at an arbitrary temperature is equal or close to that of the acoustic impedance. The present invention was made by discovering a method of transmitting longitudinal ultrasonic waves through the ultrasonic wave guide and measuring longitudinal-transverse elastic modulus, Poisson's ratio, and internal friction by using the longitudinal-> transverse wave conversion method. It was The form of sample holding is
Vertical shape is used to prevent deformation of the sample itself due to its own weight and the resulting scattering of ultrasonic echoes. For fixing the sample and the ultrasonic wave guide to each other, a heat- and cold-resistant metal spring or a holder containing a Si ₃ N ₄ or SiC ceramics spring is used. The sample is heated at a constant rate from liquid nitrogen temperature to 1700 ° C. in a heating furnace, and the sample atmosphere can be replaced by gas such as air, nitrogen, argon and helium at 1 to 5 atm up to 10 ⁻⁴ Torr. It can be maintained in vacuum. The ultrasonic wave guide is characterized by using the uneven skin surface as it is to scatter the reflected waves of the ultrasonic pulse on the side surface of the same, or by making it uneven with a screw cutting jig. ..

[0005]

[Operation] The ultrasonic pulse emitted from the transmitter / receiver is passed through the ultrasonic wave guide, sample → receiver → AGC amplification → zero crossing time detection → multistage delay → synchronous pulse oscillation → ultrasonic pulse oscillation, and the transmitter / receiver again. Return to and keep oscillating (singing around) the same closed circuit repeatedly. When the average value period of this sing-around loop is measured N times, the measurement precision of N times can be obtained by the principle of period measurement, and the propagation time can be measured with high precision. The present invention reduces errors due to changes in the received waveform by AGC amplification and zero-cross time detection, prevents errors due to interference of multiple echoes in a sample by a multistage delay circuit, and enables accurate sing-around measurement. Furthermore, using only the longitudinal wave oscillator, the sound velocity of each of longitudinal wave and longitudinal wave → transverse wave conversion wave is detected by the measuring instrument with automatic gate selection function, and the longitudinal and transverse elastic moduli are simultaneously measured.

The paths of the ultrasonic pulses in the sample are shown in FIGS. 3a and 3b. An ultrasonic pulse that is incident on the sample 3 from the ultrasonic waveguide 2 at time T ₀ includes a longitudinal wave 28 parallel to the sample central axis and a longitudinal wave 29 having a directivity angle with the central axis as shown in FIG. become. When the side surface of the sample is finished to be flat, the longitudinal wave 29 is reflected by the side surface 30 of the sample and is divided into a longitudinal wave l29 and a transverse wave S29. The longitudinal wave reflected wave l29 disappears at the critical angle, and only the induced transverse wave S29 exists at the critical angle. This state is shown in FIG. 3b. In the figure, θ represents the critical angle, and the sound velocities of the longitudinal and transverse waves in the sample are Vl and V, respectively.
If there is s, there is a relation of Equation 1.

[0007]

[Equation 1]

The ultrasonic pulse 28 of FIG. 3b is reflected by the end face of the sample and is incident on the ultrasonic waveguide 2 at time T ₁ . Similarly, the ultrasonic pulse 29 is reflected by the end face of the sample while being converted from longitudinal wave → transverse wave → longitudinal wave, and is incident on the ultrasonic waveguide at time T ₂ . The time relationship between T ₀ , T ₁ and T ₂ is shown in FIG. 3c. From the figure, the sound velocities of the longitudinal wave and the transverse wave are expressed by the formulas 2 and 3 with the length and diameter of the sample 3 being L and D, respectively.
Required by.

[0009]

[Equation 2]

[Equation 3]

However, L >> D tan θ. From the sound velocities Vl and Vs of longitudinal and transverse waves in the sample and the sample density ρ, the solid elastic constants are

[Equation 4] ~

It is given by

[0011]

[Equation 4]

[Equation 5]

[Equation 6]

[Equation 7]

In FIG. 3b, the ultrasonic pulse 28 enters the ultrasonic waveguide at time T ₁ , is reflected by the end face of the sample 3 and again becomes an ultrasonic pulse echo through the same path.
_{At 3} , the light enters the ultrasonic waveguide. T _0, between _{T 1} and _{T 3} a relationship of _{T 3 -T 1 = T 1 -T} 0. Figure 3c
Then, assuming that the peak values of the amplitudes of the ultrasonic pulses incident on the ultrasonic waveguide at times T ₁ and T ₃ are A ₁ and A ₂ , respectively, the internal friction Q ^{−1 of the} sample is that the reflection at the interface is total reflection. It is given by the number 8.

[0013]

[Equation 8]

[0014]

EXAMPLES The present invention will be described below with reference to examples. FIG. 1 is a measurement system diagram of one embodiment of the present invention, and FIG. 2 is a time chart of ultrasonic pulses for explanation of FIG. The ultrasonic pulse generated in the transmission circuit 11 in FIG.
Ultrasonic Waveguide 2 → Sample 3 → Ultrasonic Waveguide 2 → Transceiver 1
→ Amplifier 8 → Zero cross detector 9 → Multistage delay circuit 10 →
It circulates in the path of the transmission circuit 11, and this closed circuit constitutes a sing-around measurement system. The longitudinal ultrasonic wave pulse radiated from the transmitter / receiver propagates through the ultrasonic wave guide 2 and is reflected at the interface of the sample 3, and is reflected by the ultrasonic wave pulse 5 received by the transmitter / receiver 1 after T ₀ 'time and the sample. It is divided into incident ultrasonic pulses. The ultrasonic pulse incident on the sample is divided into a longitudinal wave → longitudinal wave mode ultrasonic pulse 6 and a longitudinal wave → transverse wave → longitudinal wave mode ultrasonic pulse 7 as shown in FIG. 3b. It re-enters the wave body and is received by transceiver 1 after T ₁ ′ and T ₂ ′ times, respectively. The peak detector 12 detects the peak value of the ultrasonic pulse, adjusts the peak voltage of the received pulse by the AGC amplifier so that the amplitude of the ultrasonic pulse is always a constant peak value, and the received pulse voltage is zero voltage. The time taken to cross the (zero point) is measured by the zero cross detector 9. The multi-stage delay circuit 10 is inserted in order to eliminate an error due to multiple echoes of ultrasonic pulses in a sample, is composed of an ultrasonic delay line and a feedback circuit, and is accurate to n times the delay time of the same delay line. Delay time.
In FIG. 2, reference numerals 23, 24, 25, 26, and 27 denote transmission pulses of the transmitter / receiver 1, reception signals thereof, and window gate 1 respectively.
4 shows the output signal, the output signal of the zero-cross detector 9 and the output signal of the multi-stage delay circuit 10. In the figure, a window gate 25 is set for measuring the ultrasonic pulse 5 that reciprocates in the ultrasonic waveguide. In this case, the time T ₀ 'is obtained from the sing-around cycle. Next is Windgate 2
5 is automatically set in sequence for measuring ultrasonic pulses 6 and 7, and times T ₁ ′ and T ₂ ′ are obtained, respectively. Time T
₀ ′, T ₁ ′ and T ₂ ′ are measured by the counter 15 in FIG. 1, pass through the I / O 17, and become the output of RS-232C18. From FIG. 2 and FIG. 3, there is a time relationship of the expression 9.

[0015]

[Equation 9]

The longitudinal / transverse wave sound velocities Vl and Vs are obtained from the equations 2, 3 and 9. If the peak values of the amplitudes of the received pulses 5 and 6 are set to A ₅ and A ₆ , respectively, the internal friction Q ⁻¹ is given by Eq.

[0017]

[Equation 10]

However, C is the correlation between the ultrasonic wave guide 2 and the sample 3, the effective area change rate S of both, and the contact medium 4 of both.
From the effective round-trip transmissivity of the ultrasonic pulse including C, C = S /
Since it is expressed as T, the value of C is set in the CPU 16 in advance. The round-trip effective sound pressure transmittance T is given by Equation 11 when the acoustic impedances of the ultrasonic wave guide and the sample are set to Z ₁ and Z _2, and the contact medium is ignored.
₆ / A ₆ is given by the equation 12.

[0019]

[Equation 11]

[Equation 12]

From Equation 12, in order to measure the internal friction with high sensitivity, the acoustic impedances of the ultrasonic waveguide and the sample are equal (Z ₁ = Z ₂ ) or close (Z ₁ ) over the measurement temperature range.
It is desirable to configure the material of the ultrasonic waveguide so that ₁ ≈Z ₂ ). In order to obtain more stable received pulses 5 and 6, it is essential that the propagation loss in the ultrasonic wave guide is small. Received pulse peak values A ₅ and A ₆
Is detected by the peak detector 12 and passed through I / O 17 to RS
It becomes the output of 232C18. The CPU 16 is a computer control unit of software of the automatic measurement system. The sample 3 is designed so that it can be replaced every time with an ultrasonic wave guide whose acoustic impedance is equal or close to each other. However, since there is a physical interface between the two, the reflection / absorption of the ultrasonic pulse is obtained. And the accurate information from the sample is lost. In particular, ultrasonic attenuation occurs as the temperature rises, so the contact medium 4 is interposed at the interface to prevent ultrasonic attenuation. As the contact medium, a metal foil that has ductility at low temperature, an organic material such as Teflon, a low melting point metal such as aluminum foil at around room temperature, and an emulsion solvent such as honey or platinum paste are used. A metal foil having a high melting point such as platinum or rhodium, which hardly causes oxidation, is used. For fixing the sample to the ultrasonic wave guide, the spring made of steel and phosphor bronze should be used in applications up to around 800 ° C.
1 and Si ₃ N ₄ or SiC at high temperatures up to 1700 ° C.
In principle, the cap 20 made of Inconel that has a built-in disc spring such as the above is attached to the ultrasonic wave guide and used. The temperature of the sample 3 is controlled by the low-temperature / high-temperature atmosphere furnace 19, and the ultrasonic waveguide on the transmitting / receiving side is cooled (or kept warm) by the water cooling jacket 22, whereby the transmitter / receiver 1 is kept at room temperature.

[0021]

[Examination of Another Embodiment] The mounting mechanism of the sample is not limited to the device with a built-in spring, and there is no problem even if a cylinder driven by hydraulic pressure, water pressure, air and voltage is used.
The heating furnace is not limited to the infrared image furnace and the resistance heating furnace, and other known heating furnaces may be used. As a cooling method, there is no problem whether it is a heating method from filling with liquid nitrogen or a cooling method using a cryostat. As the ultrasonic measurement method, either the pulse echo method or the sing-around method does not hinder the constitution of the present invention. Furthermore, the present invention relates to a device for simultaneously measuring longitudinal / lateral, bulk modulus, Poisson's ratio and internal friction, but even if only arbitrary characteristics are measured, it falls within the scope of the present invention. As described above, the configuration and shape of the device of the present invention can be appropriately changed according to the embodiment.

[0022]

As described above, according to the present invention, simultaneous measurement data of longitudinal / lateral, bulk modulus, Poisson's ratio and internal friction over a wide temperature range, which could not be obtained by the conventional method, was obtained. Be done. As a result, it becomes possible to obtain the development and design data of the structural material used in the part subjected to the mechanical load in a wide temperature range.

[Brief description of drawings]

FIG. 1 is a measurement system diagram showing an embodiment of the present invention.

FIG. 2 is a time chart of the ultrasonic pulse for explanation of FIG.

FIG. 3 is an explanatory diagram of a path and time of an ultrasonic pulse in a sample.

[Explanation of symbols]

1 ...... Ultrasonic transmitter / receiver 2 ......... Ultrasonic wave guide 3 ......... Sample 4 ......... Contact medium 5 ......... Longitudinal ultrasonic pulse reciprocating in the ultrasonic wave guide 6 ... Longitudinal wave ultrasonic pulse that reciprocates between the acoustic wave guide and the sample 7 .... Ultrasonic wave pulse that reciprocates between the ultrasonic wave guide and the sample through longitudinal → lateral → longitudinal wave mode conversion

Claims (6)

[Claims] 1. A longitudinal ultrasonic pulse is applied to one end of a sample held at an arbitrary temperature via an ultrasonic wave guide, and a propagation time and an attenuation rate of the pulse in the sample are calculated by a multistage delay circuit. By measuring with a measuring instrument with automatic gate selection function, it is possible to simultaneously measure the longitudinal and lateral directions of the sample, bulk modulus, Poisson's ratio and internal friction as a function of temperature.
Measuring device for solid elastic modulus and internal friction in high temperature and wide temperature range. 2. The ultrasonic wave guide is made of a material that has an acoustic impedance equal to or close to that of the sample, has little ultrasonic wave propagation loss and has cold and heat resistance within a target temperature range, and has an uneven side surface structure. The measuring device according to claim 1, wherein the measuring device is configured. 3. A longitudinal wave from a longitudinal ultrasonic wave propagating in a sample.
The longitudinal and transverse directions, bulk modulus, Poisson's ratio, and internal friction are measured using the transverse wave conversion method.
The measuring device described. 4. The measuring device according to claim 1, wherein the connection between the ultrasonic waveguide and the sample is fixed by a heat-resistant and cold-resistant metal spring or a ceramic spring. 5. The sample temperature ranges from liquid nitrogen temperature to 1700 ° C.
5. The measuring device according to claim 1, further comprising a cryostat and a heating device capable of controlling the temperature. 6. The atmosphere in the sample chamber is set to 1 to 5 atmospheres of air, a gas such as nitrogen, argon, or helium, and 10 atmospheres.
The measuring device according to any one of claims 1 to 5, wherein the measuring device is maintained in a vacuum up to ^-4 Torr.