JP2554996B2 - Non-destructive inspection of mechanical behavior of a loaded object, its determination method and its apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for inspecting materials and structures and an apparatus therefor, and more particularly to a nondestructive inspection method for mechanical behavior of an object under load, a determination method therefor, and Regarding the device.

(Background Art) Conventionally, a loaded object is irradiated with a coherent laser beam before and after a load is applied to obtain a pair of superimposed speckle patterns, and the loaded object is then applied. There are known methods for determining the stress and strain of. In this method, the speckle pattern obtained by the above method is converted into a diffraction pattern and subjected to mathematical processing. From the amplitudes obtained by this mathematical process, the stress and strain values at each point of the elastically deformed body are calculated (see, for example, PCT 87/07365).

However, since the above method is not set for the purpose of obtaining a three-dimensional plastic deformation wave, it cannot be applied to the analysis of the plastic deformation process. That is, although it is possible to calculate the stress and strain fields in the elastic region from the displacement obtained during inspection,
Analysis of plastic flow due to plastic deformation cannot be performed. Therefore, the above method is merely applied to the evaluation of elastic deformation, and is not substantially suitable for analyzing the region of plastic deformation.

On the other hand, the dynamics of deformation are extremely important especially in various application fields centering on nondestructive inspection of mechanical behavior of objects. This is because in all cases, local plastic deformation occurs in the material prior to the fracture of the externally loaded material. Therefore, it has long been a problem that there is no appropriate approach to the problem of plastic deformation dynamics.

Another conventional method other than the above is to clarify the actual process of plastic flow in various plastically deformed materials and the contribution to fracture. ("Handbook of Experimental Mechanics", edited by A.S. Kobayashi, Prentice Hall, 1987
Year (Handbook on Experimental mechanics, Ed.by AS
Kobayashi Prentice-Hall Inc. 1987)). These methods are based on microscopic observation of the defective structure of the deformed material and are generally carried out after unloading. These methods include optical microscopy,
Many techniques such as electron microscopy, X-ray structural analysis, and various micromechanical methods are used.

However, these methods have drawbacks such as a large amount of labor, a complicated device, and a high resolution method that requires extremely localized inspection regions.
And the biggest drawback is that these methods can be applied only to defects remaining in the material, and the generation and movement of defects cannot be analyzed.

The most widely used method for obtaining data on indicators of material reliability (eg, Structural Integrity Monitoring by R. A. Coracott, Chapman & Hall, London, 1985 (Collacott RA " Struct
ual lntegrity Monitoring ", London, Chapman and Hall,
1985)) for various loading conditions (tensile,
It consists of mechanical tests such as compression, bending, twisting, crack sample tests, etc.), and has properties such as ultimate elasticity, yield limit, ultimate strength, stress strength coefficient, fracture toughness, ultimate fatigue and long-term strength.

These tests are generally performed on specially prepared and preconditioned samples of shape and size. The strength and plasticity data thus obtained are used for strength calculation of mechanical parts and structures, and calculation of reliability characteristics.

This type of method has a problem in that it is necessary to use a combination of special mechanical properties and judgment criteria for destruction for each inspection item. That is, these characteristics for different test items are not related to each other, and their physical interpretation is based on a number of mutually inconsistent and often mutually exclusive models.

Another drawback of this type of method is related to the problem of applying mechanical property data obtained in laboratory conditions to mechanical parts actually used in the field. That is, a mechanical part or an actual machine operating in the field is usually in a more complicated stress state than in the inspection stage. further,
The mechanical property data of actual materials are greatly affected by the surface condition and environment. Considering this, even if an attempt is made to take into consideration the influence of the actual machine at the inspection stage, only the inspection device and the inspection process become very complicated, and appropriate data cannot be obtained under such conditions.

Finally, the mechanical properties obtained by the above test are essentially averaged values over the test sample. this is,
This is a problem when trying to describe the properties of polycrystalline materials with special interfaces or composite materials with different elastic and strength properties.

One of the problems common to all of these existing plastic material test methods is that these test methods cannot adequately record the progress of plastic deformation, and therefore cannot predict the location of future fractures. Is.

In order to solve the above problems, it is necessary to locally analyze the dynamics of deformation, and in particular, establish a fundamentally new plastic deformation analysis method that can predict the behavior of the actual machine under various load conditions. is necessary.

The Applicant has established a theoretical system which is the basis of such a new analytical method (eg, “Structural Level of Plastic Deformation Failure”, Vi Y Panin et al., Novosibirsk, Nauka, 1990 (“ Structual levels of plastic
deformation failure ", VEPaninn et al, Novosibirsk,
Nauka, 1990)). The essence of this method of analyzing the mechanical behavior of objects is based on the wave theory of plastic deformation. According to this wave theory, the plastic flow due to plastic deformation and the resulting fracture have wave nature, and the parameters of the wave (wavelength, amplitude, propagation velocity)
However, it has become clear that it depends on the material properties and load conditions at that time. Therefore, changes in these wave parameters indicate that structural changes have occurred in the material. However, at the time the book was written, their quantitative criteria had not yet been established.

Also, “Structural Level of Plastic Deformation Failure”, Vi Y Panin et al., Novosibirsk, Nauka, 1990 (“St
ructual levels of plastic deformation failure ", V.
E. Panin et al, Novosibirsk, Nauka, 1990) ”, the inventors found the wave nature of plastic deformation, systematized it theoretically, and experimentally tested it for simple loading. I am also considering.

According to this method, an object to be analyzed is irradiated with a coherent laser beam and imaged on a photographic plate. Then, after the deformation of the object, the second irradiation is performed on the photographic plate without moving the plate. The photographic plate is then chemically processed and the plastic displacement information described in the same photograph is decoded by speckle photographic point scanning using a narrow laser beam. Then, measure the parameters of the Young band diffraction pattern at each point,
The absolute value of the displacement vector between the two irradiations is determined from the band interval.

Furthermore, by taking the spatial differentiation with respect to the coordinate axes, the components of the strain tensor, for example, the shear component, εxy = 1/2 (Δu / Δy + Δv / Δx) and the rotational displacement ωz = 1/2 (Δv / Δx-Δu / Δy) Is obtained.

The consistent distribution of the plastic strain tensors εxy, ωz in the body becomes the relaxation wave of plastic deformation.

The idea of predicting the failure of an object by analyzing the wave parameters obtained in this way is based on the above-mentioned “structural level of plastic deformation damage”, Vi Y Panin et al., Novosibirsk, Nauka, 1990 (“ Structual le
vels of plastic deformation failure ", VEPanin et
al, Novosibirsk, Nauka, 1990) ”. See the same book for details.

However, at the time of writing the book, there was no research on the law of the relaxation wave of plastic deformation as it progresses with the degree of deformation, and the relationship between deformation and the resulting fracture. In addition, the quantification of fracture judgment conditions by wave parameters under various loading conditions has not been established. Therefore, at that time, it was impossible to nondestructively inspect the behavior of the loaded object by analyzing the wave pattern.

Therefore, as an object of the present invention, in view of the problems of the above-mentioned conventional technique, a three-dimensional wave pattern of a relaxation wave of plastic deformation is obtained, and the rate of change of the plastic strain tensor is tested, either during the test or during the operation. The object is to provide a new and improved method and apparatus for a nondestructive inspection method of a mechanical behavior of an object and a determination method thereof, which can be evaluated even in.

DISCLOSURE OF THE INVENTION The problem is solved according to an embodiment of the method and the device according to the invention by obtaining a time-varying optical pattern of the surface of the object to be inspected. These patterns are superimposed and converted into a diffraction pattern consisting of parameters characterizing the deformation of the target object. According to the invention, the optical pattern is obtained in the form of a hologram of the images collected at regular time intervals. The diffraction patterns of these superimposed images are transformed into spatially and temporally wave patterns of velocity distributions of deformation and rotational displacement that are correlated on-axis, and by observing the temporal variation of the velocity distribution, the object The mechanical behavior of is evaluated.

That is, as a result of paying attention to the wave nature of plastic deformation of an object to which a load is applied, the inventors of the present application have found that the characteristics of the wave pattern characteristically change in a state close to fracture. That is, the wavelength becomes almost the same as the size of the sample, the velocity becomes zero, and the waves are concentrated into two local vortices having opposite angular velocities. As a result, the wave pattern of plastic deformation at various stages of deformation has much information, and the yield limit, ultimate strength, work hardening coefficient, etc. regarding plasticity, strength, reliability, and fracture of materials and structures. Different from the mechanical properties used conventionally,
Give a new judgment condition. At that time, it is extremely important that the judgment conditions of plasticity, strength, and reliability can be handled in a unified manner, not the kind of plastic material or the condition of load. By such a method, it becomes possible to treat the plastic deformation and the resulting fracture as different stages of the same process. The present invention
From this point of view, it is intended to provide some new and improved methods and apparatuses for a nondestructive inspection method of a mechanical behavior of an object and a determination method thereof.

Therefore, according to a first aspect of the present invention, a first step of obtaining an optical pattern of the inspection object; and the first step, which is a predetermined time period, over a time period when a load is externally applied to the inspection object. And a second step of: repeating the plurality of optical patterns obtained in the second step over a period in which a load is externally applied to the inspection target; a third step; the superposition obtained in the third step. A fourth step of obtaining from the optical pattern a diffraction pattern including a parameter characterizing the plastic deformation of the inspection object; the inspection object externally loaded from the diffraction pattern obtained in the fourth step A fifth step of obtaining a parameter that characterizes the plastic deformation that has occurred in the object; and the object to be inspected by processing the parameter obtained in the fifth step. A sixth step of obtaining a wave pattern including a wave parameter that characterizes a relaxation wave of plastic deformation, which is a temporal and spatial distribution of velocities of deformation and rotational displacement due to the generated plastic deformation; And a seventh step of determining a mechanical behavior of the inspection object to which a load is applied from the outside based on a predetermined change appearing in the wave pattern.
A non-destructive test method for the mechanical behavior of a loaded object is provided.

In the above method, the optical pattern obtained in the first step is configured as a holographic image of a focused image of the inspection object, whereby the analysis can be optically performed easily.

In addition, mathematical processing can be facilitated by setting the time period repeated in the second step to a constant time interval selected within a range in which the deformation and rotational displacement of the inspection object can be differentiated. Can be done.

Furthermore, in the fourth step, as a parameter that characterizes the plastic deformation that occurs in the inspection target included in the diffraction pattern, for example, the period (d) of the interference fringes that is generated by the interference between the diffracted lights from the superimposed pattern, The angle (θ) formed by the stripe and the direction of load can be used.

Regarding the fifth step, as a parameter that characterizes the plastic flow, for example, a displacement velocity vector at each point on the surface of the inspection object, a time derivative of a strain tensor component such as deformation and rotational displacement, its spatial distribution, and distribution. Can be used. Further, as the wave parameters included in the wave pattern, for example, the wavelength, amplitude, and propagation velocity of the plastic deformation relaxation wave distributed in the inspection object can be used.

Regarding the seventh step, the criterion of the mechanical behavior of the inspection object that appears as a predetermined change in the wave pattern is determined by whether or not the propagation velocity of the relaxation wave of the plastic deformation is zero, that is, the wave is a standing wave. Or not. Alternatively, the determination criterion can be calculated such that the waveform of the relaxation wave of the plastic deformation as a standing wave becomes approximately the same as the size of the inspection object. Furthermore, it is also possible to determine that the criterion is that local vortices having opposite angular velocities occur in the displacement velocity vector pattern. Which of these criteria should be adopted?
It can be arbitrarily determined according to the inspection object and the inspection method.

According to a second aspect of the present invention, a first step of obtaining a parameter characterizing a plastic deformation that has occurred in an inspection object externally loaded; processing the parameter obtained in the first step. A second step of obtaining a wave pattern including a wave parameter that characterizes a relaxation wave of the plastic deformation, which is a temporal and spatial distribution of the velocity of the deformation and the rotational displacement due to the plastic deformation of the inspection object. And; a third step of determining a mechanical behavior of the inspection target subject to an external load, based on a predetermined change appearing in the wave pattern obtained in the second step. A method for determining the mechanical behavior of a loaded object is provided.

Also in the method for determining the mechanical behavior of an object based on the present invention, as a parameter characterizing the plastic flow, for example, a displacement velocity vector at each point on the surface of the inspection object, and a strain tensor component such as deformation and rotational displacement The time derivative of, its spatial distribution, as well as the temporal change of the distribution can be used. Further, as the wave parameters included in the wave pattern, for example, the wavelength, amplitude, and propagation velocity of the plastic deformation relaxation wave distributed in the inspection object can be used.

Similarly, the criterion of the mechanical behavior of the inspection object that appears as a predetermined change in the wave pattern, whether the propagation velocity of the relaxation wave of the plastic deformation is zero, that is, the wave is a standing wave. Or not. Alternatively,
It is also possible to determine that the criterion is that the wavelength of the relaxation wave of the plastic deformation as a standing wave is approximately the same as the size of the inspection object. Furthermore, it is also possible to determine that the criterion is that local vortices having opposite angular velocities occur in the displacement velocity vector pattern. Which of these determination criteria is to be adopted can be arbitrarily determined according to the inspection object and the inspection method.

Further, according to a third aspect of the present invention, an optical means for repeatedly obtaining an optical pattern of the inspection object over a period of time when stress is applied to the inspection object from outside by a predetermined time cycle; An optical pattern superposing means for superposing a plurality of optical patterns obtained by the optical means;
Diffractive pattern forming means for obtaining a diffractive pattern including a parameter characterizing plastic deformation of the inspection object from the superimposed optical pattern obtained by the optical pattern superimposing means; diffractive pattern obtained by the diffractive pattern forming means A wave pattern forming means for obtaining a wave parameter including a wave parameter that characterizes a relaxation wave of plastic deformation distributed in the inspection object due to the plastic deformation of the inspection object; and obtained by the wave pattern forming means. Determination means for determining the mechanical behavior of the inspection object based on a predetermined change appearing in the wave pattern;
A non-destructive test device for an inspection object is provided.

As described above, the present invention is constructed based on a new system established theoretically and experimentally by the present inventors. According to it, the plastic deformation and the resulting fracture are described by the deformation of the plastic deformation wave and the change of the velocity field of the rotational displacement. A plastic deformation wave is characterized as a process in which a plastic elemental event self-focuses into a single wave, referred to herein as the "plastic deformation relaxation wave."

When the group velocity of the relaxation wave of plastic deformation decreases and becomes zero,
The resulting standing wave degenerates into a pair of localized displacement vortices. At this time, the angular velocities of the vortices are opposite to each other, and the amplitude of rotation continuously increases. As a result, a discontinuity occurs at the boundary of the vortex, and this discontinuity grows and the material is destroyed. This fact defines a new criterion for fracture based on the evolution of group velocity of relaxation waves of plastic deformation. This new decision condition can be applied to the non-destructive inspection method for a loaded material / object according to the present invention.

That is, since the plastic deformation wave always appears as a three-dimensional wave on the surface of a loaded object, in order to properly apply the above-mentioned fracture judgment condition based on the group velocity of the relaxation wave of plastic deformation being zero. , It is essential to measure the wave parameters in a three-dimensional space. Wave parameter 3
The measurement in the dimensional space is realized according to the invention by superimposing the collecting holograms and processing the superimposed images.

According to one embodiment of the present invention, the above-mentioned method is a method for forming an optical image of the surface of the inspection object, a means for converting the obtained optical image of the surface into a diffraction pattern, and a parameter of the pattern mathematically. It is realized by a non-destructive inspection device including a means for processing. According to the invention, the means for obtaining an optical image are designed to obtain a hologram of the focused image and the mathematical processing means are provided with a temporal distribution of the deformation and rotational displacement from the parameters of the diffraction pattern. A unit to calculate is provided. The output of this device is connected to a visualization device for the purpose of obtaining a wave pattern.

(Brief Description of Drawings) FIG. 1 is a conceptual diagram of an apparatus for nondestructively inspecting the mechanical behavior of an object based on the wave theory of plastic deformation.

FIG. 2 is a relaxation wave diagram of plastic deformation of the Fe + 3% Si alloy obtained by the apparatus of FIG.

FIG. 3 is a diagram of a relaxation wave of plastic deformation obtained by a theoretical technique using a wave model of plastic deformation.

FIG. 4 is a diagram of relaxation waves of plastic deformation of steel obtained by the apparatus of FIG.

FIG. 5 is a relaxation wave diagram of plastic deformation of the same sample as in FIG. 4 at the moment of initiation of fracture, and the fractured sample is also shown.

FIG. 6 is a diagram of the relaxation wave of the deformation of the sample having the welded portion, and the welded portion observed metallurgically is also shown.

FIG. 7 is a diagram of a relaxation wave of plastic deformation of an aluminum sample, and a diagram of a vortex pattern of the deformation rate calculated at the fracture initiation site.

FIG. 8 is a diagram of relaxation waves of plastic deformation in an amorphous material.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the examples described below.

Before discussing the method of nondestructively inspecting the mechanical behavior of an object according to the present invention, a specific example will be described for the purpose of helping understanding of the essence of the present invention.

The non-destructive inspection device is an arbitrary laser device 1 (eg He / Ne laser) that can irradiate the hologram medium within 1 second.
Consists of.

The optical system of this device has two optical paths. The first optical path is designed to form a collimated object beam and consists of a reflector 2, a semitransparent mirror 3, a reflector 4, a beam expander 5 and a collimation lens 6. The second optical path is designed to produce a reference beam and consists of mirrors 2, 3 and mirrors 7, 8 and a beam expander 9. Further, the optical system has an objective lens 10 for forming an object pattern on a carrier 11 (for example, a photo plate) set in a holder (not shown). The holder is movable in two mutually orthogonal directions for the purposes described below. As described above, the hologram of the condensed image can be obtained by irradiating the carrier with light.

In addition, the system uses a hologram to screen
It has an optical decoder consisting of reflectors 12 and 13 which form a 0.8 mm diameter beam on 14 which forms a diffraction pattern. The mathematical processing of the hologram obtained on the carrier 11 is carried out in a computing unit consisting of an input and an analog / digital signal conversion system 15.

Input and analog / digital signal conversion system 15
As, a digital output video camera can be used.
The output of system 15 is connected to monitor 16 and computer 17. The computer program calculates the information from the output of the system 15, namely the value of the velocity of deformation and rotational displacement, which is determined by the diffraction pattern on the screen 14, and its velocity on the axis in the preset direction. It is configured to display the distribution of values. Therefore, the output of the computer is the wave pattern of plastic deformation, and the deformation of the object can be predicted by observing its behavior. The same wave pattern is reproduced by the plotter 18.

This device operates on the following principle. The output of the laser 1 is split into two beams by the optical system. The first beam is the object beam, which, after being collimated, serves to illuminate the image of the object 19 with a plane wave. The second beam illuminates the photographic plate 11 as reference light. The intensity ratio of the two beams is empirically selected by the semi-transparent mirror 3 acting as a beam splitter.

The objective lens system 10 forms an image of an object 19 illuminated by coherent light on the surface of the photographic plate 11.
Thus, the first exposure is performed on the photographic plate 11. The exposure time is empirically determined. And a certain time Δ
After t (for example, 40 to 80 seconds) elapses and the object 19 is deformed (deformation is a load application, a change in temperature or surrounding conditions,
The exposure is done again on the same photo plate, depending on other factors). Thus, two superimposed holograms of condensed images having the properties of speckle photography are recorded on the photographic material.

This series of processes is repeated at a new time interval or the same time interval Δt. The resulting double-exposure hologram of the series of focused images records the entire course of the deformation that occurred during that time. In the embodiment where a video camera is used to record the hologram, the image obtained by the digital computer can be directly recorded.

In this way, the data of velocity values of the displacement vector at all points on the surface of the target object can be recorded in the double exposure holographic image. This data can be reconstructed by optically processing the resulting image. If the image is recorded on a photographic plate, the photographic latent image is first developed and fixed to give a negative film. Then, the hologram is housed in a holder and irradiated with the same reference beam as that used for recording. Along the axis perpendicular to the surface of the object, an object image formed by superposition of equal displacement lines is input to the computer 17 by the system 15, and the displacement velocity component (δw / δt) (z-axis direction) is calculated. The observed image is monitored on display 16.

The displacement velocity on the surface of the object (in the x and y directions) is determined by processing the speckle pattern of the object image. For this purpose, the double exposure image is line-scanned every 1 mm by the narrow beam formed by the reflecting mirrors 12 and 13. At this time, a so-called Young band diffraction pattern is formed at each point. This pattern is recorded by system 15, digitized and input to a computer. The computer estimates the band step d and the tilt x angle θ with respect to the axis x.

Further, the value of the displacement velocity vector on the xy plane is formed by the following equation, and r ∼ = 1 / Δt · λs / d Furthermore, the tensor component of the plastic deformation velocity of the object is calculated by the following equation.

In the present specification, δA / δt and A
Will be written as.

δu / δt = r to cos θ, δ / δt = r to sin θ δ (εxx) / δt = δ (δu / δt) / δx, δ (εyy) / δt = δ (δv / δt) / δy, δ (εxy ) / Δt = 1/2 {δ (δu / δt) / δy + δ
(Δv / δt) / δx}, δ (ωz) / δt = 1/2 {δ (δv / δt) / δx-δ
(Δu / δt) / δy} obtained by the above equation, δ (εxx) / δt, δ (εyy)
/ Δt, δ (εxy) / δt, δ (ωz) / δt are continuously evaluated along a selected axis (for example, the pulling direction) and plotted on a plotter. Then, the mechanical behavior of the object material is judged from the dynamic characteristics of the change. At that time, the analysis of the behavior of the material before the failure is performed based on the new theoretical and experimental judgment conditions regarding the strength and the failure established by the present inventors.

FIG. 2 shows, as an example of the plastic wave obtained by the above method, the case of tensile strain for an Fe + 3% Si alloy. For comparison, theoretical calculation values of the wave pattern for the same example are shown in FIG. The good agreement between the experiments and the theory found in these is also a factor that proves the validity of the wave theory of plastic deformation, which is the basis of the present invention, and the validity of describing the criteria for judging the strength and fracture of an object by the wave parameter. Is one of.

For the purpose of better understanding of the essence of the present invention, specific examples in the case of targeting a specific sample will be shown below.

(Example 1) First, plastic deformation due to tensile of steel will be discussed. The image formation and the processing method thereof are as described above.

The size of the test sample is substantially 3 x 10 x 60 mm. The sample was subjected to a tensile load at 2 × 10 ⁻⁵ S ⁻¹ by the test apparatus “lnstron”. Deformation display diagrams were recorded during the test. The entire tensile test process was divided into 0.2% steps in the following order. 0-0.2-0.4-0.6-0.
8-1.0-1.2-1.4-1.6-1.8-2.0-2.2% ... However,
The numbers on the left represent the ratio to the total deformation. A focused image hologram was recorded at each of these points.

Here we discuss the deformation stages of 0.4-0.6%. At the moment when the total elongation of the sample reaches 0.4%, the focused image hologram is recorded on the photographic plate by the apparatus shown in FIG. Then, 100 seconds later, when the strain reaches 0.6%, a second hologram is recorded on the same photo plate.
However, the photo plate is not moved during the production of the first and second holograms. This creates a double-exposed hologram. The hologram is developed and processed by a usual chemical method. This recorded all the data about the distribution of sample deformation at this stage 1:
A 1-scale sample image photograph (negative) is created.

Next, the data obtained by the above method is decoded. The double exposure hologram described above is scanned by a thin laser beam (diameter 0.8 mm) formed by the reflecting mirrors 12 and 13. The scan is performed with a step width of 1 mm and covers the entire image. The same scanning is performed by a hologram holder (see above) with a step motor. Each time the laser light is transmitted, a diffraction band having a tilt angle θ with respect to the pulling direction is formed at step d. These values are sent to the computer 17 by the system 15 and automatically measured, whereby the displacement velocity (time derivative) of each point is calculated using the following equation.

r ˜ = 1 / Δt · λs / d where λ = 0.63 × 10 ⁻⁶ m is the wavelength of the laser, d is the distance between diffraction bands (m), s is the distance from the hologram to the screen (m), Δt = 10 ² s strain is step
It is the time between double exposures (time from the first exposure to the second exposure) at 0.4-0.6%.

Further, the time derivative of the shear deformation εxy and the rotational displacement ωz is calculated by the computer 17. Here, x is an axis in the tensile load direction, and y is an axis on the observation surface (x and y are perpendicular to each other). The calculation is performed by the following formula.

δ (εxy) / δt = 1/2 {δ (δu / δt) / δy + δ
(Δv / δt) / δx} δ (ωz) / δt = 1/2 {δ (δv / δt) / δx−δ
(Δu / δt) / δy} where δu / δt = r to cosθ, δv / δt = r to sinθ δ (εxy) / δt and δ (ωz) / δt are mathematically processed to obtain plasticity. The waves can be observed experimentally on a display or plotter (see Figure 4). The above measurement and processing procedure is 0.6-0.8,
By applying to each stage of 0.8-1.0 and 1.0-1.2%, the distributions of δ (εxy) / δt and δ (ωz) / δt in the tensile direction can be obtained in the same manner. By following the movement of one of the axial peaks of δ (εxy) / δt or δ (ωz) / δt, the propagation velocity of the relaxation wave of plastic deformation can be obtained.

Vrv = Δ1 / Δt = ˜10 ⁻⁵ m / s where Δ1 is the peak offset of εxy during the time Δt (Δ1 = 10 ⁻³ m). Thus, the distribution of the plastic deformation wave at this deformation stage is known.

Performing the same procedure for stages 1.6-1.8% gives
A completely different distribution pattern of δ (εxy (x)) / δt is obtained. By repeating all the above steps, the pattern shown in FIG. 5 was obtained.

FIG. 5 is characterized by two regions. 0 <x
At <37 mm, the rates of shear and rotational displacement are almost zero (δ (εxy) / δt ~ 0, δ (ωz) / δt ~
0). At x> 37 mm, these velocities are large and tend to increase. When this measurement was continued further, the propagation of the plastic deformation relaxation wave in the tensile direction x-axis direction stopped (Vr
v = 0). The observations above at x = 37 mm show that there is a concentration of deformation at this point and failure begins at this point. After that, when the observation was continued while applying the load at the same rate of 2 × 10 ^-5 S _-1 , the sample broke at the point of x = 37 mm when the total deformation reached 2.67% (No. (Fig. 5).

Thus, changes in the plastic wave pattern suggest the onset of fracture. That is, it can be seen that the phenomenon that the propagation of the wave stops and the standing wave whose wavelength is about the same as that of the sample stands up can be used as a criterion for the start of the destruction of the object.

(Example 2) For the purpose of demonstrating that the nondestructive inspection method according to the present invention is also applied to the inspection of a welded portion, a plastic deformation pattern was analyzed for a portion including a welded region. The sample is an effective size of two steel strips connected by electric welding.
It is 20 x 30 x 120 mm. The welded part could not be visually confirmed in advance, and therefore it was not possible to determine which part in the sample was the welded part. The speed of this sample is 10 ^-5 S _-1
I pulled it at. When the deformation reached 0.6%, the first photograph was taken to create a hologram of the condensed image 11. Then, when the total amount of deformation reached 0.66% after Δt = 1 min, a second hologram was formed on the same photo plate. The photo was then developed and visualized by conventional chemical methods.

The information on the displacement point recorded at the site where the plastic deformation of the sample surface occurred was decoded by the optical method using the diffraction image described above. Ie double exposure pattern diameter
Line scanning was performed with a 0.8 mm narrow laser beam. The resulting diffraction pattern consisting of the Young band was input to the computer 17 by the system 15. Than this,
The band interval d and the tilt angle θ with respect to the pulling direction were obtained by the method described above. Then, the displacement velocity vector on the surface of the object was calculated by the following formula.

r˜ = 1 / Δt · λs / d where λ = 0.63 × 10 ⁻⁶ m is the wavelength of the laser beam, and s is the distance from the hologram to the screen during the coating. As the description parameter, the tensile plastic deformation rate δ (εxx) δt is adopted. However, δ (εxx)
δt is determined by the computer 17 by the following equation.

δ (εxx) / δt = δ (δu / δt) / δx Here, δu / δt = r to cosθ data. FIG. 6 shows data obtained in the form of δ (εxx) / δt so that the location of future fracture can be predicted.

It is well known that welds always break in the heat affected zone. In FIG. 6, two points of x = 20 mm and x = 32 mm are characterized as heat affected zones. That is, the plastic deformation rate is low in the welded portion 20 <x <30 mm, but is rapidly increased in the heat affected zone. This indicates that the relaxation wave of plastic deformation does not propagate to the weld, and the plastic deformation is concentrated in the heat affected zone. After that, when the application of load was continued, x = 32
A fracture occurred in the heat affected zone of mm. From this, it is understood that the fracture point of the welded portion can be predicted under the determination condition that the group velocity of the relaxation wave of plastic deformation becomes zero.

(Example 3) The plastic strain of pure aluminum was also inspected. The sample is 8 × 70 × 1.5mm and the speed is 5 × by the inspection device “lnstron”.
It was pulled with 10 ^-5 S ^-1 . From the particle size of 10-15 mm, it can be seen that the same sample contained only 6 crystals. The wave pattern shown in FIG. 7 was obtained by the above apparatus and procedure when the deformation was 0.5-0.6% of the stage. Further, the obtained data was extrapolated to a large strain region (5%) by the wave theory to obtain a displacement velocity field (Fig. 7). As a result, it was found that at this stage, two vortices with two opposite velocities shown in Fig. 7 were formed in the material. The boundary of these two vortices, which corresponds to x = 20 mm, indicates the starting point of failure. When the sample was pulled further, a constriction occurred in the same area, resulting in a total deformation of 30
When the percentage was reached, the sample viscously fractured at the same site.
Therefore, the obtained wave pattern predicts the site of destruction.

(Example 4) The deformation of the amorphous alloy Fe ₄₀ Ni ₄₀ B ₂₀ was also inspected. The sample is a small piece with a length of 50 mm, a width of 15 mm and a thickness of 22 mm.
It was pulled by ron at a speed of 10s ^-1 . The inspection procedure and the data analysis method are all the same as in the above example. However, in the case of the present embodiment, the total deformation amount is small, 0.1-0.2%
Was in the range. According to the velocity distribution of shear deformation and rotational displacement shown in FIG. 8, in the case of amorphous metal,
Even at this stage, a relaxation wave of plastic deformation is formed, and it can be understood from the characteristics of its distribution that breakage occurs if load application is continued. This means that x <27 mm and x>
It is judged from the fact that the rates of shear deformation and rotational displacement are different in amplitude and sign in the two regions of 27 mm, that is, two uncompensated vortices develop in this region. x =
The boundary of these two vortices at 27 mm is the potential starting point for failure. When the same sample was pulled further, x = 27 mm
Destroyed at. This shows that the prediction according to the invention also applies to future destruction.

(Industrial Applicability) As described above, according to the present invention, a converging hologram is superimposed, and the superimposed image is processed to appear as a three-dimensional wave on the surface of a loaded object. It is possible to describe the plastic deformation of the inspected object and predict the resulting failure by applying the conditions for determining the failure based on the fact that the relaxation wave of the plastic deformation can be obtained and the group velocity becomes zero. It becomes possible and is suitable for easily performing non-destructive inspection of the mechanical behavior of an object and its determination.

The method and apparatus of the present invention also provides a loaded operating machine such as a pressure vessel, pipeline, load structure, power plant, power plant equipment, chemical reactor, steam boiler, turbine and engine housing. It can be applied to the analysis of stress / strain state of various structures and devices. Further, the method and apparatus of the present invention are useful for research on analysis of machines for plastic deformation and fracture, evaluation of reliability of new materials, evaluation of maximum allowable load, and the like.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G01N 3/32 G01N 3/32 Z (72) Inventor Zevrev Borisovic Russian Federation, 634048 Tomsk Prospekt Academi Cesky 2/1 Eremtze (72) Inventor Makarov Pavel Basilievich Russian Federation, 634048 Tomsk Prospekt Academia Chesky 2/1 Eremtze (72) Inventor Yegorshkin Valery Efimovic Russian Federation, 634048 Tomsk Prospektje Academichek (72) Inventor Gorbatenko Badim Vladimirovich Russian Federation, 634048 Tomsk Prospekt Academi Cesky 2/1 Eremtze (72) Inventor Danilov Vladimir Ivanovich Russian Federation, 634048 Tomsk Prospekt Akademie Chesky 2/1 Eremtse (56) References JP 617442 (JP, A)

Claims (16)

(57) [Claims] 1. A first step of obtaining an optical pattern of an object to be inspected; a second step of repeating the first step at a predetermined time period over a time when a load is externally applied to the object to be inspected; A third step of superimposing the plurality of optical patterns obtained in the second step over a time when a load is externally applied to the inspection object; and the inspection object from the superimposed optical pattern obtained in the third step. A fourth step of obtaining a diffraction pattern including a parameter that characterizes the plastic deformation of; and a plastic flow due to the plastic deformation generated in the inspection object externally loaded from the diffraction pattern obtained in the fourth step. A fifth step of obtaining parameters for characterizing; a plastic generated in the inspection object by processing the parameters obtained in the fifth step. A sixth step of obtaining a wave pattern including wave parameters that characterize a relaxation wave of plastic deformation, which is a temporal and spatial distribution of the speed of deformation and rotational displacement due to deformation; and the wave pattern obtained in the sixth step. A seventh step of determining the mechanical behavior of the inspection object externally loaded based on a predetermined change appearing in the mechanical behavior of the loaded object. Nondestructive testing method. 2. The nondestructive testing method according to claim 1, wherein the optical pattern obtained in the first step is a hologram of a focused image of an inspection object. 3. The time period repeated in the second step is a constant time interval selected within a range in which deformation and rotational displacement of an inspection object can be differentiated. The nondestructive test method according to claim 1. 4. The period (d) of interference fringes generated by interference between diffracted light from the superimposed pattern is a parameter that characterizes plastic deformation occurring in the inspection object included in the diffraction pattern obtained in the fourth step. And the angle (θ) formed by the interference fringe and the direction of the load. 4. The nondestructive test method according to claim 1, 2, or 3. 5. A parameter that characterizes the plastic flow obtained in the fifth step includes a displacement velocity vector at each point on the surface of the inspection object, a time derivative of a strain tensor component such as deformation and rotational displacement, and its space. 2. The distribution and the time change of the distribution.
The nondestructive test method according to any one of 2, 3 and 4. 6. The wave parameter included in the wave pattern obtained in the fifth step is the wavelength, amplitude, and propagation velocity of a relaxation wave of plastic deformation distributed in an inspection object. The nondestructive test method according to claim 1, 2, 3, 4, or 5. 7. The determination criterion of the mechanical behavior of the inspection object, which appears as a predetermined change in the wave pattern in the seventh step, is whether or not the propagation velocity of the relaxation wave of the plastic deformation is zero, that is, The nondestructive test method according to any one of claims 1, 2, 3, 4, 5, or 6, characterized by whether the wave is a standing wave or not. 8. The criterion of the mechanical behavior of the inspection object that appears as a predetermined change in the wave pattern in the seventh step is that the wavelength of the relaxation wave of the plastic deformation as a standing wave is the size of the inspection object. The nondestructive test method according to any one of claims 1, 2, 3, 4, 5 or 6, characterized in that 9. The determination criterion of the mechanical behavior of the inspection object that appears as a predetermined change in the wave pattern in the seventh step is that local vortices having mutually opposite angular velocities are generated in the displacement velocity vector pattern. Non-destructive testing method according to any of claims 1, 2, 3, 4, 5 or 6, characterized by 10. A first step of obtaining a parameter that characterizes a plastic flow due to a plastic deformation generated in an inspection object externally loaded; and by processing the parameter obtained in the first step, A second step of obtaining a wave pattern including a wave parameter that characterizes a relaxation wave of the plastic deformation, which is a temporal and spatial distribution of the velocity of the deformation and the rotational displacement due to the plastic deformation of the inspection object; and the second step. A third step of judging a mechanical behavior of the inspection object externally applied on the basis of a predetermined change appearing in the wave pattern obtained in the step; Method for determining the mechanical behavior of a stored object. 11. A parameter that characterizes the plastic flow obtained in the first step is a displacement velocity vector at each point on the surface of the inspection object, a time derivative of a strain tensor component such as deformation and rotational displacement, and its space. 11. The distribution and the temporal change of the distribution, as claimed in claim 10.
The method for determining the mechanical behavior of the object according to. 12. The wave parameter included in the wave pattern obtained in the second step is the wavelength, amplitude, and propagation velocity of a relaxation wave of plastic deformation distributed in an inspection object. 12. The method for determining the mechanical behavior of the object according to claim 10 or 11. 13. The determination criterion of the mechanical behavior of the inspection object, which appears as a predetermined change in the wave pattern in the third step, is whether or not the propagation velocity of the relaxation wave of the plastic deformation is zero, that is, 13. The method for determining the mechanical behavior of an object according to claim 10, 11 or 12, characterized by whether or not the wave is a standing wave. 14. The determination criterion of the mechanical behavior of an inspection target appearing as a predetermined change of the wave pattern in the third step is that the wavelength of the relaxation wave of the plastic deformation as a standing wave is the size of the inspection target. 13. The method for determining the mechanical behavior of an object according to claim 10, 11 or 12, characterized in that the mechanical behavior of the object is substantially the same. 15. The determination criterion of the mechanical behavior of the inspection object that appears as a predetermined change of the wave pattern in the third step is that local vortices having mutually opposite angular velocities are generated in the displacement velocity vector pattern. Characterized by: 13. A method for determining the mechanical behavior of an object according to claim 10, 11 or 12. 16. Optical means for repeatedly obtaining an optical pattern of the inspection object over a period of time when an external load is applied to the inspection object, at a predetermined time cycle; and a plurality of optical means obtained by the optical means. An optical pattern superimposing means for superimposing the optical pattern of the above; and a diffraction pattern forming for obtaining a diffraction pattern including a parameter characterizing the plastic deformation of the inspection object from the superposed optical pattern obtained by the optical pattern superimposing means. A wave for obtaining a wave pattern including a wave parameter that characterizes a relaxation wave of plastic deformation distributed in the inspection object by plastic deformation of the inspection object from the diffraction pattern obtained by the diffraction pattern forming means. Pattern forming means; based on a predetermined change appearing in the wave pattern obtained by the wave pattern forming means And a determination means for determining the mechanical behavior of the inspection object.