Test equipment and test method

Abstract

To accurately grasp a relation between test measurement results and captured images.SOLUTION: A testing apparatus 1 includes: a testing machine 20 which performs a test for measuring a load and displacement applied to a test piece 10 by alternately repeating a dynamic load in which a periodically changing load is applied to the test piece, and a static load in which a load is applied to the test piece 10 under conditions of substantially constant load or substantially constant displacement; an imaging device 22 which images the test piece under the static load; and a data processing device 28 which synchronizes a measurement result of the test with the captured image of the test piece output from the imaging device 22 and records them in a storage device 82.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a test apparatus and a test method for testing a test specimen.

Background Art

[0002] For example, Patent Document 1 discloses imaging images of a test specimen before and after deformation in a small punch test. In such Patent Document 1, the strain distribution of the test specimen is measured by a digital image correlation method (DIC: Digital Image Correlation) based on the captured images.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a fatigue test, which is an example of a test of the strength of a test specimen, a dynamic load or a static load is repeatedly applied to the test specimen by a testing machine, and the load and displacement acting on the test specimen are measured multiple times. Further, when the digital image correlation method is applied to the fatigue test, a plurality of images of the test specimen are captured during loading in order to analyze the displacement behavior.

[0005] However, since the measurement of the load and displacement is performed by a testing machine and the imaging of the images is performed by an imaging device, the measurement results of the load and displacement and the captured images may be recorded separately. Then, for example, the correspondence between a plurality of captured images and a plurality of measurement results may become unclear or inaccurate. As a result, for example, the reliability of image analysis or verification of test accuracy may decrease.

[0006] This disclosure aims to provide a test apparatus and test method that can accurately determine the relationship between test measurement results and captured images. [Means for solving the problem]

[0007] To solve the above problems, a test apparatus according to one aspect of this disclosure includes dynamic loading that applies a periodically changing load to a test specimen, The load applied to the test specimen is a constant value, or the displacement applied to the test specimen is a constant value. The system comprises a testing machine that performs a test by repeatedly alternating between static loading, which applies a load to a test specimen under certain conditions, and dynamic loading, and measuring the load and displacement applied to the test specimen; an imaging device that images the test specimen during static loading; a data processing device that synchronously records the test measurement results and the images of the test specimen output from the imaging device into a storage device; and a control device provided separately from the data processing device that controls the dynamic loading and static loading by the testing machine. The control device transmits a predetermined trigger signal to the data processing device multiple times during the execution of static loading, and the data processing device acquires and synchronously records the test measurement results and the images of the test specimen in response to the receipt of the trigger signal.

[0008] Furthermore, the test results may include measurement data output from the testing machine during static loading, and the measurement data may include the load and displacement applied to the test specimen by the testing machine.

[0009] Furthermore, the testing machine may be equipped with a separate sensor that measures at least the displacement of the test specimen, and the test results may include measurement data output from the sensor during static loading.

[0011] Furthermore, the control device outputs a periodically changing signal to the testing machine, causing the machine to perform dynamic loading. The value does not change regardless of the passage of time. Alternatively, a specific signal can be output to the testing machine to cause it to perform static loading.

[0013] Furthermore, the data processing device may derive the displacement distribution or strain distribution of the test specimen using a digital image correlation method based on multiple captured images of the test specimen.

[0014] To solve the above problems, a test method according to one aspect of this disclosure includes dynamic loading, which applies a periodically changing load to a test specimen, The load applied to the test specimen is a constant value, or the displacement applied to the test specimen is a constant value. The system controls the dynamic and static loading processes while performing a test that alternately applies a load to the test specimen under specified conditions, measuring the load and displacement applied to the specimen. During the execution of the static loading, a predetermined trigger signal is transmitted multiple times. When static loading occurs, the test specimen is imaged. In response to the receipt of the trigger signal, the test measurement results and the imaged specimen are acquired and recorded synchronously in a storage device. [Effects of the Invention]

[0015] According to this disclosure, it becomes possible to accurately understand the relationship between the test measurement results and the captured images. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a schematic diagram illustrating the outline of the test apparatus according to this embodiment. [Figure 2] Figure 2 illustrates the operation of the load control unit and trigger signal control unit according to this embodiment. [Figure 3] Figure 3 shows an example of an image captured according to this embodiment. [Figure 4] Figure 4 is a flowchart illustrating the flow of the test method according to this embodiment. [Modes for carrying out the invention]

[0017] Embodiments of this disclosure will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely illustrative for ease of understanding and do not limit this disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to this disclosure are omitted from the illustrations.

[0018] FIG. 1 is a schematic diagram for explaining the outline of a test apparatus 1 according to the present embodiment. The test apparatus 1 is an apparatus for performing a test for measuring the strength of a test piece 10, such as a fatigue test. In the present embodiment, as an example of the strength test, a fatigue test in which a tensile load and a compressive load are repeatedly applied to the test piece 10 will be described. However, the test of the present disclosure is not limited to such an example, and is applicable to tests for measuring various strengths of the test piece 10, such as compressive strength, tensile strength, bending strength, torsional strength, and the like. Also, the direction in which a load is applied to the test piece 10 in the test may be a uniaxial direction or a multiaxial direction.

[0019] The test piece 10 is, for example, a composite material such as metal, plastic, or fiber reinforced plastic. The test piece 10 is, for example, in a flat plate shape. Note that the shape of the test piece 10 is not limited to the flat plate shape, and may be an arbitrary shape depending on the purpose of the test, such as a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, a curved plate shape, or a tubular shape.

[0020] The test apparatus 1 includes a testing machine 20, an imaging device 22, a sensor 24, a control device 26, and a data processing device 28.

[0021] The testing machine 20 applies a load to the test piece 10 to deform the test piece 10, and measures the load and displacement applied to the test piece 10.

[0022] In addition, in the test using the test apparatus 1, the digital image correlation method (DIC: Digital Image Correlation) can be applied. In the digital image correlation method, first, a random pattern (random pattern) is formed on the surface of the test specimen 10. Then, before the deformation of the test specimen 10 is performed, a digital image of the random pattern of the test specimen 10 is captured by the imaging device 22. After that, the test specimen 10 is deformed, and again, a digital image of the random pattern is captured by the imaging device 22. Then, a plurality of subsets are set in the digital image before deformation. Note that the subset is a region of a predetermined size set on the digital image and is used to analyze the displacement of each position of the test specimen 10. Subsequently, a plurality of subsets corresponding to the plurality of subsets set in the digital image before deformation are specified in the digital image after deformation. Then, by calculating the displacement of the representative points (for example, the center points) of the subsets before and after deformation, the displacement behavior of the test specimen 10 is analyzed. Hereinafter, the captured digital image may sometimes be referred to as a captured image.

[0023] As described above, the measurement of the load and displacement applied to the test specimen 10 is performed by the testing machine 20, and the imaging of the image of the test specimen 10 is performed by the imaging device 22. If the measurement results of the test and the captured images are recorded separately, it may be unclear which of the plurality of measurement results each of the plurality of captured images corresponds to. As a result, for example, the reliability of image analysis or verification of test accuracy may decrease.

[0024] Therefore, in the test apparatus 1 of the present embodiment, the measurement results of the fatigue test and the captured images are recorded synchronously. Hereinafter, the configuration and operation of the test apparatus 1 will be described in detail.

[0025] The testing machine 20 includes a frame body 30, a movable part 32, a first chuck 34, a second chuck 36, a load cell 38, and a control panel 40.

[0026] The frame 30 consists of a base 30a, two side column sections 30b, and a ceiling section 30c. The base 30a is formed, for example, in a flat plate shape and is placed on the floor. The two side column sections 30b are spaced apart from each other and rise upward from the edge of the base 30a. The ceiling section 30c connects the two side column sections 30b at the ends of the two side column sections 30b opposite to the base 30a.

[0027] The movable part 32 is formed, for example, in the shape of a rod. The first of the two ends of the movable part 32 is supported by the first of the two side column parts 30b. The second of the two ends of the movable part 32 is supported by the second of the two side column parts 30b. The movable part 32 is slidable in the direction of extension of the side column parts 30b, that is, in the vertical direction in Figure 1.

[0028] The first chuck 34 is connected to the bottom 30a of the frame 30. The second chuck 36 is connected to the movable part 32 via a load cell 38. The first chuck 34 and the second chuck 36 are positioned opposite each other. The test specimen 10 is placed between the first chuck 34 and the second chuck 36. The first chuck 34 grips the first end of the test specimen 10, i.e., the lower end in Figure 1. The second chuck 36 grips the second end of the test specimen 10, opposite to the first end, i.e., the upper end in Figure 1. Hereafter, the act of gripping the test specimen 10 with the first chuck 34 and the second chuck 36 may be referred to as "setting the test specimen 10 in the testing machine 20."

[0029] The load cell 38 is provided between the second chuck 36 and the movable part 32. The lower end of the load cell 38 is connected to the second chuck 36, and the upper end of the load cell 38 is connected to the movable part 32. When the movable part 32 slides with the test specimen 10 set in the testing machine 20, a load is applied to the test specimen 10, causing it to deform. The load cell 38 transmits the load received from the movable part 32 to the test specimen 10 via the second chuck 36 and measures the load applied to the test specimen 10.

[0030] The control panel 40 has a user interface that accepts input operations from operators and displays the status of the testing machine 20 to the operators. The control panel 40 is connected to an actuator (not shown) that moves the movable part 32, and the movable part 32 can be moved using this actuator. The control panel 40 can measure the distance the movable part 32 is moved by the actuator. The distance the movable part 32 is moved roughly corresponds to the displacement of the test specimen 10. In this way, the control panel 40 can indirectly measure the displacement applied to the test specimen 10 using the distance the movable part 32 is moved. The control panel 40 is also connected to a load cell 38, and can acquire the load measured by the load cell 38.

[0031] The control panel 40 has external input terminals and external output terminals that can be electrically connected to external devices of the testing machine 20. Control signals are input to the control panel 40 from the outside via the external input terminals. As will be described later, the test operation of the testing machine 20 is automatically controlled based on the control signals input to the testing machine 20 from the outside. The control panel 40 can also output measurement data to the outside via the external output terminals. The measurement data output from the testing machine 20 includes the load and displacement applied to the test specimen 10 by the testing machine 20.

[0032] The imaging device 22 is installed in front of the test specimen 10 set in the testing machine 20 and can image the test specimen 10. As will be described later, the imaging device 22 performs imaging when it receives an imaging command from the data processing device 28 and generates an image, which is a still image.

[0033] Sensor 24 is, for example, a displacement meter and is provided separately from the testing machine 20. Sensor 24 is directly attached to the test specimen 10. Sensor 24 measures at least the displacement of the test specimen 10 to which it is attached. Sensor 24 outputs measurement data including the displacement measured by the sensor 24. Sensor 24 is connected to a data processing device 28, for example, through a predetermined cable. The measurement data from sensor 24 is input to the data processing device 28.

[0034] More specifically, the sensor 24 is attached to the surface of the test specimen 10 opposite to the surface imaged by the imaging device 22. If the test specimen 10 is tubular in shape, the sensor 24 may be attached to the inner surface of the tubular test specimen 10. By attaching the sensor 24 to the surface opposite to the surface imaged by the imaging device 22, it is possible to obtain displacement in areas where an image cannot be obtained. Furthermore, it is possible to prevent the sensor 24 from interfering with imaging by the imaging device 22.

[0035] The control device 26 is composed of, for example, a personal computer. The control device 26 has a communication unit 50 and a control unit 52. The communication unit 50 is connected to the external input terminal of the control panel 40 of the test machine 20 via a predetermined cable. The control device 26 is not limited to being connected to the test machine 20 by wire, but may also be connected to the test machine 20 wirelessly. The communication unit 50 can also communicate with the data processing device 28 by wire or wireless.

[0036] The control unit 52 comprises one or more processors 60 and one or more memories 62 connected to the processors 60. The memories 62 include ROM for storing programs and RAM as a work area. The processors 60 cooperate with the programs contained in the memories 62 to control the entire control device 26. The control unit 52 also functions as a load control unit 70 and a trigger signal control unit 72 by executing programs.

[0037] Figure 2 illustrates the operation of the load control unit 70 and the trigger signal control unit 72 according to this embodiment. The load control unit 70 performs control to transmit a control signal to the test machine 20 through the communication unit 50 and the external input terminal of the test machine 20. The control signal is represented, for example, by the time change of an analog voltage.

[0038] When the fatigue test begins, the load control unit 70 generates a control signal (e.g., voltage) as illustrated in the upper waveform of Figure 2, and outputs the generated control signal to the test machine 20. The test machine 20 moves the movable part 32 according to the control signal input from the control device 26.

[0039] More specifically, when the test is started, the load control unit 70 outputs a periodically changing control signal to the test machine 20. The periodically changing control signal may be, for example, a sine wave signal, a triangular wave signal, a trapezoidal wave signal, or a square wave signal. Hereafter, for the sake of explanation, the periodically changing control signal may be referred to as a dynamic signal.

[0040] The testing machine 20 applies a tensile load to the test specimen 10 when the input control signal is positive, and moves the movable part 32 so that the tensile load increases as the value of the control signal increases. The testing machine 20 applies a compressive load to the test specimen 10 when the input control signal is negative, and moves the movable part 32 so that the compressive load increases as the value of the control signal decreases.

[0041] As illustrated by the upper waveform in Figure 2, when a dynamic signal is input to the testing machine 20, the testing machine 20 moves the movable part 32 so as to alternately repeat tensile and compressive loads. Hereafter, the operation of applying such periodically changing loads to the test specimen 10 may be referred to as dynamic loading. Note that although an example of alternating tensile and compressive loads is given here, dynamic loading is not limited to the example of alternating tensile and compressive loads. For example, dynamic loading may involve applying only a tensile load, with the magnitude of the tensile load changing periodically, or applying only a compressive load, with the magnitude of the compressive load changing periodically.

[0042] The load control unit 70 stops outputting the dynamic signal after it has been continuously outputting for a predetermined period of time. In other words, dynamic loading is performed for a predetermined period of time. This predetermined period can be arbitrarily set depending on the purpose of the fatigue test, for example, the time it takes to vary the load 10,000 times.

[0043] After the dynamic signal is stopped, the load control unit 70 outputs a constant control signal to the testing machine 20. This constant control signal is actually a substantially constant control signal, that is, a substantially constant control signal whose value does not change substantially regardless of the passage of time. A constant or substantially constant control signal allows for slight fluctuations, such as noise. For example, the constant control signal is the control signal corresponding to the maximum load applied to the test specimen 10 in the fatigue test. However, the constant control signal is not limited to the control signal corresponding to the maximum load; for example, it can be set arbitrarily depending on the purpose of the fatigue test, such as a control signal corresponding to half the maximum load. Hereafter, for the sake of convenience in explanation, the constant control signal may be referred to as a static signal.

[0044] As illustrated by the upper waveform in Figure 2, when a static signal is input to the testing machine 20, the testing machine 20 restricts the movement of the movable part 32 to apply a constant load corresponding to the static signal to the test specimen 10. The constant load is actually a substantially constant load, that is, a load whose value does not substantially change regardless of the passage of time. A constant load or a substantially constant load allows for load fluctuations within a predetermined range caused by slight fluctuations in the substantially constant control signal. For example, a load 2.5% higher than a predetermined value indicating a constant load is set as the upper limit, and a load 2.5% lower than that predetermined value is set as the lower limit, allowing load fluctuations within a predetermined range. Hereafter, the operation of applying a constant load to the test specimen 10 in this manner may be referred to as static loading.

[0045] The load control unit 70 stops outputting the static signal after it has been continuously outputting for a predetermined period of time. In other words, static loading is performed for a predetermined period of time. This predetermined period can be arbitrarily set depending on the purpose of the fatigue test, for example, several tens of minutes.

[0046] After the static signal stops, the load control unit 70 outputs a dynamic signal to the testing machine 20 again, and after continuing to output the dynamic signal for a predetermined time, it outputs a static signal to the testing machine 20 again.

[0047] In this manner, the loading control unit 70 causes the testing machine 20 to perform dynamic loading by outputting a periodically changing control signal to the testing machine 20, and causes the testing machine 20 to perform static loading by outputting a constant control signal to the testing machine 20. The loading control unit 70 then repeatedly performs dynamic loading and static loading alternately.

[0048] The trigger signal control unit 72 performs control to transmit a predetermined trigger signal to the data processing unit 28 via the communication unit 50 during static loading (i.e., the period during which the loading control unit 70 outputs a static signal to the test machine 20). The trigger signal is, for example, a voltage pulse signal.

[0049] The trigger signal control unit 72 generates a trigger signal (e.g., voltage) as illustrated in the lower waveform of Figure 2 when static loading is applied, and transmits the generated trigger signal to the data processing unit 28. The trigger signal is a signal that instructs the data processing unit 28 to record the fatigue test measurement results and the captured image of the test specimen 10 in a synchronized manner. In response to receiving the trigger signal transmitted from the control unit 26, the data processing unit 28 records the fatigue test measurement results and the captured image of the test specimen 10 in a synchronized manner.

[0050] The trigger signal control unit 72 may transmit multiple trigger signals (see Figure 2) to the data processing unit 28 during a single static load. This causes the data processing unit 28 to perform multiple imaging processes consecutively during a single static load, and to continuously record multiple images obtained through these imaging processes. The number of times trigger signals are transmitted can be arbitrarily set by the operator depending on the number of images to be recorded. For example, if only one image is recorded during a single static load, and that single image is unclear, it may not be possible to perform image analysis properly. However, by supplementarily capturing and recording multiple images during a single static load, the likelihood of recording clear images increases, and as a result, image analysis can be performed properly.

[0051] Furthermore, the trigger signal control unit 72 is not limited to transmitting multiple trigger signals during a single static load; it may also transmit at least one trigger signal during a single static load. In this configuration, one image can be recorded during a single static load, and image analysis can be performed using this single image.

[0052] Returning to Figure 1, let's continue the explanation. The data processing device 28 is composed of, for example, a high-spec personal computer with image analysis capabilities. In this embodiment, the data processing device 28 is provided separately from the control device 26, which has relatively low specifications. The data processing device 28 has a communication unit 80, a storage device 82, and a control unit 84. The communication unit 80 is connected to the external output terminal of the control panel 40 of the test machine 20 via a predetermined cable. Note that the data processing device 28 is not limited to being connected to the test machine 20 by wire, but may also be connected to the test machine 20 wirelessly. Furthermore, the communication unit 80 can communicate with the control device 26 by wire or wirelessly.

[0053] The storage device 82 is composed of a non-volatile storage element, such as a hard disk or flash memory. The storage device 82 stores the measurement results and captured images of the fatigue test. Note that the storage device 82 is not limited to being included in the data processing device 28, but may also be attached externally to the data processing device 28.

[0054] The control unit 84 comprises one or more processors 90 and one or more memories 92 connected to the processors 90. The memories 92 include ROM for storing programs and RAM as a work area. The processors 90 cooperate with the programs contained in the memories 92 to control the entire data processing unit 28. The control unit 84 also functions as a recording execution unit 100 and an image analysis unit 102 by executing programs.

[0055] The recording execution unit 100 records the fatigue test measurement results and captured images in synchronization with the storage device 82 in response to receiving a trigger signal transmitted from the control device 26.

[0056] More specifically, when the recording execution unit 100 receives a trigger signal, it transmits an imaging command to the imaging device 22. When the imaging device 22 receives the imaging command, it performs still image capture at that time. The imaging device 22 then transmits the captured image to the data processing device 28. In this way, the recording execution unit 100 acquires an image at the time it receives a trigger signal during static loading.

[0057] Furthermore, during the fatigue test, the testing machine 20 outputs measurement data from the testing machine 20 to the data processing device 28 in real time via an external output terminal. The data processing device 28 receives the measurement data from the testing machine 20 in real time via the communication unit 80. When the recording execution unit 100 receives a trigger signal, it latches and acquires the measurement data from the testing machine 20 at that time. In this way, the recording execution unit 100 acquires measurement data, including load and displacement, from the testing machine 20 at the time it receives a trigger signal during static loading.

[0058] Furthermore, during the fatigue test, the sensor 24 outputs its measurement data to the data processing unit 28 in real time. The data processing unit 28 receives the measurement data from the sensor 24 in real time via the communication unit 80. When the recording execution unit 100 receives a trigger signal, it latches and acquires the measurement data from the sensor 24 at that time. In this way, the recording execution unit 100 acquires measurement data, including displacement from the sensor 24, at the time it receives a trigger signal during static loading.

[0059] The recording execution unit 100 simultaneously performs the acquisition of captured images, the acquisition of measurement data from the test machine 20, and the acquisition of measurement data from the sensor 24, in accordance with the trigger signal.

[0060] When the recording execution unit 100 acquires the captured image, the measurement data from the test machine 20, and the measurement data from the sensor 24, it records the acquired captured image, the measurement data from the test machine 20, and the measurement data from the sensor 24 in the storage device 82 in a synchronized manner. More specifically, the recording execution unit 100 records the captured image, the measurement data from the test machine 20, and the measurement data from the sensor 24 in the storage device 82 in association with a common recording time. As a result, the captured image, the measurement data from the test machine 20, and the measurement data from the sensor 24, acquired in response to a single trigger signal, are recorded in association with each other, that is, in a synchronized manner.

[0061] Here, the measurement data from the test machine 20 and the measurement data from the sensor 24 are sometimes collectively referred to as the measurement results of the fatigue test. That is, the recording execution unit 100 records the measurement results of the fatigue test and the captured image of the test specimen 10 output from the imaging device in synchronization with the storage device 82.

[0062] The recording execution unit 100 is not limited to recording all of the captured images, the measurement data from the test machine 20, and the measurement data from the sensor 24 in a synchronized manner. For example, the recording execution unit 100 may omit the synchronization of the measurement data from the sensor 24 and record the measurement data from the test machine 20 and the captured images in a synchronized manner.

[0063] The image analysis unit 102 performs image analysis using the digital image correlation method based on the captured images recorded during the fatigue test.

[0064] Figure 3 shows an example of an image captured according to this embodiment. In Figure 3, subset 112 is shown relatively large for ease of understanding. In Figure 3, the random pattern 114 is shown using cross-hatching.

[0065] Here, the image of the test specimen 10 before deformation may be referred to as the first image, and the image of the test specimen 10 after deformation may be referred to as the second image. Note that "before deformation" is not limited to before the start of the fatigue test, but can be any time before the "deformation" that specifies "after deformation," or any time before dynamic loading. For example, if the second dynamic loading corresponds to a specific "deformation," the static loading before the second dynamic loading, i.e., the static loading after the first dynamic loading, may be considered "before deformation," and the static loading after the second dynamic loading may be considered "after deformation."

[0066] The image analysis unit 102 sets a subset 112 in the first captured image. The subset 112 in the first captured image is a region of a predetermined size set on the first captured image. The subset 112 in the first captured image is, for example, a 21-pixel x 21-pixel square region, but it can be set to any size.

[0067] The image analysis unit 102 identifies a subset 112 in the second captured image that corresponds to a subset 112 in the first captured image. The subset 112 in the second captured image is a region of a predetermined size identified on the second captured image. The subset 112 in the second captured image is set to the same size as the subset 112 in the first captured image.

[0068] More specifically, the image analysis unit 102 identifies the subset 112 on the second image that has the highest correlation with the random pattern 114 of the subset 112 in the first image. Various existing techniques can be applied to identify the subset 112 on the second image.

[0069] The image analysis unit 102 derives the displacement of the representative point P of the subset 112 of the second captured image relative to the representative point P of the subset 112 of the first captured image. The representative point P is set to, for example, the center or centroid of the subset 112, but can be set to any point in the subset 112.

[0070] The image analysis unit 102 then sets subsets 112 in the first captured image at various positions in the first captured image, and for each subset 112 in the first captured image, it repeatedly identifies the subset 112 in the second captured image and derives its displacement. In this way, the image analysis unit 102 can obtain the displacement behavior of the entire test specimen 10. Furthermore, by converting the displacement into strain, the image analysis unit 102 can obtain the strain behavior of the entire test specimen 10.

[0071] Figure 4 is a flowchart illustrating the flow of the test method according to this embodiment. First, the operator prepares to start the fatigue test (S10). More specifically, the operator forms a random pattern on the surface of the test specimen 10 to be imaged. The operator sets the test specimen 10, on which the random pattern has been formed, into the testing machine 20. The operator sets up the imaging device 22 so that its optical axis is perpendicular to the surface of the test specimen 10 on which the random pattern has been formed. The operator focuses the imaging device 22 on the test specimen 10. The operator also attaches the sensor 24 to the surface of the test specimen 10 opposite to the surface on which the random pattern has been formed.

[0072] Once preparations are complete, the operator records initial images before deforming the test specimen 10 (S11). More specifically, before the operator causes the control device 26 to start the fatigue test, the operator causes the control device 26 to send an initial trigger signal to the data processing device 28. Upon receiving this initial trigger signal, the data processing device 28 sends an imaging command to the imaging device 22. The imaging device 22 generates an image in response to the imaging command and transmits the generated image to the data processing device 28. This allows the data processing device 28 to acquire the initial images. The data processing device 28 also latches the initial load and displacement output from the testing machine 20 and the initial displacement output from the sensor 24. The data processing device 28 then synchronously records the initial load and displacement from the testing machine 20, the initial displacement from the sensor 24, and the initial images in the storage device 82.

[0073] After recording the initial images, the operator instructs the control device 26 to start the fatigue test. The load control unit 70 of the control device 26 then transmits a periodically changing voltage to the test machine 20, causing the test machine 20 to perform dynamic loading (S12).

[0074] When a predetermined time has elapsed in the state of dynamic loading, the loading control unit 70 stops transmitting the periodically changing voltage and stops the dynamic loading. Subsequently, the loading control unit 70 transmits a constant voltage corresponding to a predetermined constant load to the testing machine 20, causing the testing machine 20 to perform static loading (S13). The loading control unit 70 then maintains the state of static loading until a predetermined time has elapsed.

[0075] During static loading, the trigger signal control unit 72 of the control device 26 transmits a predetermined trigger signal to the data processing device 28 (S14). The trigger signal control unit 72 may transmit the trigger signal multiple times during the current static loading.

[0076] When the recording execution unit 100 of the data processing device 28 receives a trigger signal, it performs the acquisition of measurement results and captured images (S15). More specifically, the recording execution unit 100 transmits an imaging command to the imaging device 22. The imaging device 22 performs imaging in response to the imaging command and transmits the generated captured image to the data processing device 28. The recording execution unit 100 acquires the captured image transmitted from the imaging device 22. In parallel, the recording execution unit 100 latches and acquires the load and displacement measurement data of the testing machine 20 and latches and acquires the displacement measurement data of the sensor 24.

[0077] Next, the recording execution unit 100 records the acquired measurement results and captured images in the storage device 82 in a synchronized manner (S16). That is, the recording execution unit 100 stores the acquired measurement data from the test machine 20, the measurement data from the sensor 24, and the captured images, associating them with a common recording time.

[0078] After the recording execution unit 100 completes the recording process in step S16, the image analysis unit 102 performs image analysis using the image recorded during the current static loading as the second image after deformation, and the image recorded during the previous static loading as the first image before deformation (S17). This provides a displacement distribution based on two images taken before and after the dynamic loading immediately preceding the current static loading. The image analysis unit 102 records the obtained displacement distribution in the storage device 82 in association with the image recorded this time. Alternatively, the image analysis unit 102 may convert the displacement into strain to derive a strain distribution and record the derived strain distribution in the storage device 82 in association with the image recorded this time.

[0079] After image analysis, the loading control unit 70 determines whether the fatigue test termination conditions have been met (S18). For example, the data processing unit 28 determines that the termination conditions have been met if the number of repetitions of dynamic loading and static loading exceeds a predetermined number. The predetermined number can be arbitrarily set depending on the material of the test specimen 10. The loading control unit 70 also determines that the termination conditions have been met if the test specimen 10 is destroyed and the fatigue test can no longer be continued.

[0080] If the fatigue test termination conditions are not met (NO in S18), the loading control unit 70 maintains the static loading state until a predetermined time has elapsed, and returns to the process in step S12 when that predetermined time has elapsed. That is, the loading control unit 70 stops transmitting a constant voltage to stop static loading, and transmits a periodically changing voltage to the testing machine 20 to perform dynamic loading (S12). On the other hand, if the fatigue test termination conditions are met (YES in S18), the loading control unit 70 terminates the fatigue test.

[0081] As described above, in the test apparatus 1 of this embodiment, a fatigue test is performed in which dynamic loading and static loading are repeatedly applied alternately to measure the load and displacement applied to the test specimen 10. In the test apparatus 1 of this embodiment, the measurement results of the test and the captured images output from the imaging device 22 that captures images of the test specimen 10 are recorded in synchronization.

[0082] Therefore, according to the test apparatus 1 of this embodiment, the measurement results of the test and the captured images can be recorded in a clear and accurate correspondence, so that the operator can accurately grasp the correspondence.

[0083] For example, in the test apparatus 1 of this embodiment, when performing image analysis, it is easy to understand the correspondence between each of the multiple captured images and the state of the measurement data in which the image was captured. As a result, the reliability of the displacement distribution or strain distribution derived by the image analysis can be improved in the test apparatus 1 of this embodiment.

[0084] Furthermore, the accuracy of the test may be verified by comparing the displacement distribution derived from image analysis with the displacement distribution obtained from the test measurement results. In the test apparatus 1 of this embodiment, the relationship between the test measurement results and the captured images can be accurately understood, so the accuracy of the test can be accurately verified, and the reliability of the test accuracy verification can be improved.

[0085] Furthermore, in the test apparatus 1 of this embodiment, dynamic and static loading by the testing machine 20 are automatically controlled, and the measurement results and captured images of the test are automatically recorded in sync. As a result, in the test apparatus 1 of this embodiment, there is no need for the operator to manually interrupt dynamic loading, apply load during static loading, or capture and record images of the test specimen 10. Therefore, the test apparatus 1 of this embodiment can reduce the workload and burden on the operator. In addition, the test apparatus 1 of this embodiment can perform fatigue tests not only during the hours when the operator is available, but also, for example, at night.

[0086] Furthermore, processing related to captured images tends to have a higher processing load compared to load control for dynamic and static loading. In the test apparatus 1 of this embodiment, the control device 26 performs the load control, while a separate data processing device 28 performs the processing related to captured images. This allows the data processing device 28 to concentrate on processing related to captured images, which has a relatively high processing load. Also, since the control device 26 performs load control, which has a relatively low processing load, it can use a computer with lower specifications than the data processing device 28.

[0087] While embodiments have been described above with reference to the attached drawings, it goes without saying that this disclosure is not limited to the embodiments described above. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure.

[0088] For example, in the static loading of the above embodiment, the load applied to the test specimen 10 was constant under test conditions (i.e., constant load conditions). However, the invention is not limited to this example, and in static loading, the load may be applied to the test specimen 10 under test conditions (i.e., constant displacement conditions) where the displacement applied to the test specimen 10 is constant. More specifically, the loading control unit 70 acquires the displacement of the test specimen 10 from the testing machine 20 during static loading. The loading control unit 70 controls the control signal by feedback control so that the acquired displacement becomes constant, and outputs the control signal to the testing machine 20. A constant displacement is actually a substantially constant displacement, that is, a substantially constant displacement, and is a displacement whose value does not substantially change regardless of the passage of time. A constant or substantially constant displacement allows for fluctuations in displacement within a predetermined range due to control errors or control delays in the feedback control. For example, a displacement fluctuation within a predetermined range is permitted, with an upper limit of +2.5% higher than a predetermined value representing a constant displacement, and a lower limit of -2.5% lower than that predetermined value. In this embodiment as well, the test specimen 10 can be imaged when statically loaded.

[0089] Furthermore, the sensor 24 in the above embodiment was a displacement meter. However, the sensor 24 may be a strain gauge, and the strain may be output as measurement data.

[0090] Furthermore, in the above embodiment, the control device 26 and the data processing device 28 were provided separately. However, the functions of the control device 26 may be included in the data processing device 28, or the functions of the data processing device 28 may be included in the control device 26.

[0091] Furthermore, in the above embodiment, image analysis was performed during the fatigue test. However, the image analysis unit 102 may perform image analysis after the fatigue test is completed.

[0092] Furthermore, in the above embodiment, the imaging device 22 may have a wide field of view capable of imaging the entire test specimen 10, or it may be combined with a microscope to magnify and image a portion of the test specimen 10 that is of interest.

[0093] Furthermore, in the above embodiment, tests applying tensile and compressive loads were used as examples for explanation. However, the tests performed by the test apparatus 1 are not limited to tests applying tensile and compressive loads. For example, the test apparatus 1 may perform tests applying bending loads or tests applying torsional loads.

[0094] Furthermore, in addition to the test apparatus 1 of the above embodiment, a test method for performing the test described in the above embodiment is also provided. [Explanation of symbols]

[0095] 1. Test apparatus 10 test specimens 20 Testing Machines 22 Imaging device 24 sensors 26 Control device 28 Data Processing Devices 82 Storage device

Claims

1. A testing machine that performs a test by repeatedly alternating between dynamic loading, which applies a periodically changing load to a test specimen, and static loading, which applies a load to the test specimen under the condition that the load applied to the test specimen is a constant value or the displacement applied to the test specimen is a constant value, and measuring the load and displacement applied to the test specimen. An imaging device for imaging the test specimen during the static loading described above, A data processing device that synchronously records the measurement results of the aforementioned test and the image of the test specimen output from the imaging device into a storage device, A control device is provided separately from the data processing device, which controls the dynamic loading and static loading by the testing machine, Equipped with, The control device transmits a predetermined trigger signal to the data processing device multiple times during the execution of the static loading. The data processing device, upon receiving the trigger signal, acquires and synchronously records the measurement results of the test and the captured image of the test specimen. Testing equipment.

2. The measurement results of the aforementioned test include measurement data output from the testing machine during static loading. The test apparatus according to claim 1, wherein the measurement data includes the load and displacement applied to the test specimen by the testing machine.

3. Separately from the aforementioned testing machine, the machine further includes a sensor that measures at least the displacement of the test specimen, The test apparatus according to claim 1 or 2, wherein the measurement results of the test include measurement data output from the sensor during static loading.

4. The test apparatus according to any one of claims 1 to 3, wherein the control device causes the test machine to perform the dynamic loading by outputting a periodically changing signal to the test machine, and causes the test machine to perform the static loading by outputting a constant signal whose value does not change regardless of the passage of time to the test machine.

5. The test apparatus according to any one of claims 1 to 4, wherein the data processing device derives the displacement distribution or strain distribution of the test specimen by digital image correlation based on a plurality of captured images of the test specimen.

6. While performing a test in which a dynamic loading, in which a periodically changing load is applied to the test specimen, and a static loading, in which a load is applied to the test specimen under the condition that the load applied to the test specimen is a constant value or the displacement applied to the test specimen is a constant value, are repeated alternately, the load and displacement applied to the test specimen are measured, Controlling the dynamic loading and the static loading, During the execution of the static loading described above, a predetermined trigger signal is transmitted multiple times. During the static loading described above, the test specimen is imaged, A test method comprising acquiring the measurement results of the test and an image of the test object in response to the reception of the trigger signal, and recording them synchronously in a storage device.

Images