JPH0257930A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To enable execution of quick and precise measurement by disposing in the same case a pair of transversal-wave vibrators which are made adjacent on the same plane, made to intersect each other perpendicularly in the direction of vibration and employed for both transmission and reception. CONSTITUTION:When a substance 10 to be inspected is measured by a probe, the probe is brought into contact with the substance through the intermediary of a contact medium so that the probe is across a line y-y of the substance 10 whereon a round hole 10a is provided therein. When a stress sigma1 acts on the substance 10 in the direction X herein, stress concentration occurs at the edge of the round hole 10a and the stress on the line y-y is not fixed. When a transversal wave is made incident in the direction of the plate thickness of the substance 10 from each transversal-wave vibrator at each measuring position, a reflected wave from the base of the substance 10 is received and sonic speeds in the respective directions of vibration in the directions X and Y are measured simultaneously. The measured sonic speeds are compared with a known reference sonic speed on the basis of the principle of a double refraction effect of a transversal ultrasonic wave that a sonic speed difference between two transversal waves is proportional to a stress difference, and a stress at the given measuring position is determined from the stress difference.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic probe using a transverse wave transducer, and in particular, an ultrasonic probe that acts on a plane in two directions, X and Y, of a plate-like member in a structure. This is an ultrasonic probe suitable for measuring stress.

[Conventional technology]

Ultrasonic measurements of stress when a load is applied to a structural member, its distribution state, and residual stress existing in the member are important for evaluating the safety and lifespan of structures, and have traditionally been carried out in various technical fields. However, as a highly accurate measurement method, a method that utilizes the birefringence effect of a transverse ultrasonic pulse incident on a subject has been developed and has been put into practical use to a certain extent. The birefringence effect is based on the principle that when a plate-like member is in a plane stress state, the speed difference between two transverse waves that vibrate in the principal stress direction and propagate in the thickness direction of the plate-like member is proportional to the principal stress difference. Y
Measurement is performed using a transverse wave resonator such as a cut crystal resonator or a resonator made of lead zirconate titanate ceramic with a high electromechanical coupling coefficient. A conventional measuring method will be explained with reference to FIG. In the figure, 1 is a plate-shaped test object with stress σl+ in the X direction.
A stress σ2 is acting in the Y direction. Thickness (Z direction) is t
It is. Reference numeral 2 denotes a transverse wave vibrator, which is housed in a case (not shown) with its back surface held by a damper, and has a vibration direction in the X direction indicated by the arrow. When the transverse wave transducer 2 receives an electric pulse, a transverse wave S)+1 propagating in the direction of the plate thickness is incident on the object 1, and a reflected wave reflected from the bottom surface thereof is received.

The transverse wave transducer 2 is brought into contact with the well-polished surface 1a of the subject 1 via a couplant. In this state, the transverse wave 5) I
After measuring the sound speed of I, change the direction of the transverse wave oscillator 2 by 90 degrees as shown by the one-dot line so that the vibration direction is in the X direction shown by the arrow.

Similarly to the above, the transverse wave SH2 propagating in the direction of the plate thickness t is incident on the object 1, and the reflected wave reflected from the bottom surface is received, and the sound speed of the transverse wave SH2 is measured. In this case as well, the transverse wave transducer 2 is brought into close contact with the surface 1a of the subject 1 via the couplant. Within the elastic limit of the object 1, the sound velocity of the measured transverse wave SHI is proportional to the stress σi, and the sound velocity of the transverse wave S)+2 is proportional to the stress σ2, so the transverse wave 5)ll*s
Each sound velocity difference of H2 is a stress σ1. Proportional to each stress difference of σ2,
For example, when the stress σ weight and the corresponding sound velocity are known, by measuring the sound speed, it is possible to easily and accurately know the unknown stress σ weight with respect to the measured sound speed.

However, in the above-mentioned measurement, it is a prerequisite to maintain reliable acoustic coupling between the transverse wave vibrator 2 and the subject 1, and if this cannot be achieved, not only the measurement accuracy but also the success or failure of the measurement become a problem. For this reason, measurements must be made with the shear wave transducer 2 in close contact with the surface 1a of the test object, but as mentioned above, the state of close contact is different when measuring the sound speed of the shear wave SHI in the X direction and when measuring the sound speed of the shear wave SH2 in the X direction. It is difficult to measure under the same conditions, and the stress σ1. If σ2 changes due to differences in shape, measurements will be taken at multiple positions at appropriate pitches depending on the change. It takes a long time to measure because the orientation has to be changed and the state of contact needs to be checked each time, and the changes in the state of contact also lead to poor reproducibility of measurements and large variations in measured values, resulting in poor accuracy. The problem was that good measurements could not be made.

[Problem to be solved by the invention]

As mentioned above, in the conventional measurement of plane stress acting on a plate-shaped member, the state of contact of the shear wave vibrator with the surface of the specimen differs each time the measurement is performed, so it is difficult to perform measurements under the same conditions. In cases where the shape of the specimen changes or the measurement site is long, the shear wave transducer must be attached to and removed from the specimen surface each time the position is changed, which not only takes a long time but also There was a problem that the reproducibility was poor and accurate measurements could not be made.

The present invention solves the problems of the prior art as described above, and it is not necessary to measure the plane stress acting on a plate-like member by changing the direction of the transverse wave vibrator in the X or X direction. It is an object of the present invention to provide an ultrasonic probe that can perform measurements quickly and accurately in a good acoustic coupling state by reducing the number of times a transverse wave transducer is attached to and detached from a subject.

[Means to solve the problem]

The present invention can act on a plate-shaped member by using an ultrasonic probe in which a pair of transverse wave transducers for transmitting and receiving, which are adjacent to each other on the same plane and whose vibration directions are orthogonal, are arranged in the same case. By improving the acoustic coupling of the transverse wave vibrator to the surface of the specimen in the X and X directions, the plane stress can be measured quickly and accurately.

[For production]

A pair of transverse wave transducers, one for each vibration direction in the When the transverse wave transducers are brought into close contact with each other through the transducer and transmit electric pulses, each transverse wave transducer injects a transverse wave into the object and receives a reflected wave reflected from the bottom surface of the object. In this case, since transmission and reception in each shear wave transducer are performed simultaneously, the sound speed measured by each transverse wave transducer is also measured simultaneously, and from the sound speed difference between the known sound speed of each reference and the known sound speed of each reference, the sound speed of each reference in the By knowing the stress difference from the known stress, it is possible to measure each stress in the plate thickness direction. Since the transverse wave transducers are arranged adjacent to each other in the same case, the ultrasonic probe is in close contact with the subject, so that the pressing force is applied to each transverse transducer at the same time, so that the state of contact of the ultrasonic probe with the subject can be made uniform. Furthermore, if the number of pairs of transverse wave oscillators is increased in the same case, the same effect as described above will be performed on the test object in a range corresponding to the increased number, and the average stress in the plate thickness direction in the range of the test object will be and the stress distribution in the plate width direction are measured simultaneously.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 to 3. Figure 1 is a partially sectional side view, Figure 2 is the same as Figure 1.
-■ sectional view and FIG. 3 are explanatory diagrams of measurement examples for a test object having a circular hole and on which stress concentration acts. In the figure, the same reference numerals as in FIG. 4 indicate the same parts. Reference numeral 3 denotes a case, which has an open surface on which the transverse wave vibrator 2 is arranged adjacently on the same plane. 4 is a damper attached to the back of the transverse wave transducer 2, which also serves as a holder; 5 is a protective film for preventing wear attached to the outer end surface of the transverse wave transducer 2; and 6 is a contact attached to the case 3. It's a stopper. In the present embodiment, the transverse wave vibrator 2 includes four pairs of transverse wave vibrators 2 whose vibration directions are perpendicular to each other, which are arranged in a case 3 in alignment.

The flat object 1 shown in FIG. 3 is detected using the probe configured as described above.
When measuring 0, first insert the probe into the circular hole 10 of the object 10.
A is brought into contact via the couplant so as to straddle the y-y line provided with a. In this case, the contact state of the probe is such that the four shear wave transducers 2 are arranged on the same plane and adjacent to each other in the case 3, so that the pressing force applied to the probe is applied to each shear wave transducer. 2, and each transverse wave vibrator 2 is brought into the same close contact state, resulting in good acoustic coupling. When a stress σ is applied to the test object 10 in the X direction in the figure, stress is concentrated on the edge of the circular hole 10a, and the stress on the y-y line is not constant as shown in the figure. Since the size of the probe is generally smaller than the width of the subject 10, the probe is moved along the y-y line for measurement. When a transverse wave is incident in the thickness direction of the object 10 from each shear wave vibrator 2 at each measurement position, the reflected waves reflected from the bottom surface of the object 10 are received, and the sound velocity in each vibration direction of the X direction and the Y direction is are measured simultaneously. The measured sound speed is compared with a reference known sound speed based on the principle of the birefringence effect of the transverse ultrasound pulse, in which the sound speed difference between two shear waves is proportional to the stress difference, and the stress at the measurement position is determined from the stress difference. It will be done.

However, in this example, no stress is acting in the Y direction, so although the sound speed is measured, there is no sound speed difference, and therefore there is no stress difference, so it can be said that no stress is acting in the Y direction. You can know. When the measurement of the y-y line is completed, a stress distribution including stress concentration as shown in FIG. 3 is obtained.

The probe in the above embodiment has four probes whose vibration directions are orthogonal to each other.
Two pairs of shear wave transducers 2 are arranged in the same case 3, but this can also be used as a probe in which the number of pairs of shear wave transducers 2 is increased and they are arranged in the same case 3. good. In this case, the sound velocity in each of a large number of pairs of transverse wave transducers 2 can be measured simultaneously. For example, if a probe is used in which the transverse wave transducer 2 is arranged along the entire length of the y-y line in FIG. 3, the measurement can be carried out in a short time simply by touching the y-y line without moving the probe. In addition, the direction of vibration is such that all adjacent shear wave oscillators 2 are orthogonal to each other, as shown in FIG.
The arrangement is not limited to pairwise arrangement, but may be arranged such that one side is all oriented in the same direction, for example, in the X direction, and all the other sides are arranged in a perpendicular direction, for example, in the Y direction. Furthermore, in the case of a probe in which many pairs of transverse wave transducers 2 are arranged in both the vertical and horizontal directions in a grid pattern, the stress within the area of the probe is applied simultaneously in the X direction and the Y direction. It has the effect of being able to perform measurements over a wide range in a shorter time.

〔Effect of the invention〕

As explained above, the ultrasonic probe according to the present invention has one or more pairs of transverse wave transducers for transmitting and receiving functions arranged adjacent to each other on the same plane and with their vibration directions perpendicular to each other in the same case. Because I did it like that.

It has a remarkable practical effect of being able to quickly and accurately measure the plane stress acting on a plate-shaped member by improving the acoustic coupling of the transverse wave vibrator to the surface of the specimen in the X and Y directions. .

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view of an embodiment of the ultrasonic probe according to the present invention, Fig. 2 is a sectional view taken along the line ■-■ of Fig. 1, and Fig. 3 is an explanatory diagram of an example of measurement of a subject. It is. FIG. 4 is an explanatory diagram of an example of a conventional measuring method. Patent Applicant Hitachi Construction Machinery Co., Ltd. Representative Patent Attorney Masami Akimoto (1 other person)

Claims (1)

[Claims] 1. An ultrasonic probe characterized in that a pair of transverse wave transducers for transmitting and receiving, which are adjacent to each other on the same plane and whose vibration directions are orthogonal, are arranged in the same case. 2. The ultrasonic probe according to claim 1, wherein a plurality of pairs of transverse wave transducers are arranged in the same case.