Load testing machine

Abstract

The present invention provides a load-load testing machine that can acquire deformation amounts with high accuracy in dynamic testing and effectively suppress unintended behavior in the load-generating section. [Solution] The load testing machine 1 is characterized by comprising: a first sensor 14 installed on the surface of any of the movable part 131 of the load generating unit 13, the load-side holding unit 121, the load-side jig J111, and the test specimen M11, which measures the amount of deformation in the vibration direction D12 generated in the test specimen M11 by the excitation operation and acceleration that can be used for feedback control of the operation of the load generating unit 13; and a second sensor 15 installed inside the movable part 131 or the load-side holding unit 121, which monitors the behavior of the movable part 131 or the load-side holding unit 121.

Description

Technical Field

[0001] The present invention relates to a load testing machine that applies a load to a specimen to examine its characteristics.

Background Art

[0002] Conventionally, a load testing machine that applies a load to a specimen to examine its characteristics has been known (see, for example, Patent Document 1). The testing machine described in this Patent Document 1 is used for a dynamic test in which a compressive or tensile load is applied to a specimen as a load to examine its dynamic characteristics. In such a load testing machine for performing a dynamic test, a vibration load is applied to the specimen, and the amount of deformation or the like generated in the specimen at that time is obtained based on the measurement results of an acceleration sensor installed at the following positions. That is, the acceleration sensor may be installed on the surface of a movable part near the specimen in the load testing machine, on the surface of a mounting jig that is moved together with the specimen, or on the surface of the specimen itself. By being installed at these positions, the amount of deformation or the like of the specimen when a vibration load is applied can be obtained with high accuracy. Further, an acceleration sensor for obtaining such an amount of deformation or the like with high accuracy may be used for feedback control of the operation of a load generating unit that applies a desired vibration load to the specimen in the load testing machine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of acceleration sensors, the installation of acceleration sensors at the various installation locations described above is often done manually by workers during the test preparation stage, for example, by using adhesive or screws. In such cases, insufficient adhesion or insufficient tightening of screws can result in unstable installation of the acceleration sensor, which may fall off due to vibrations or external shocks during testing. Furthermore, even if the acceleration sensor itself is installed stably, if it is installed in an incorrect orientation that does not correspond to the direction of vibration, it may become difficult to measure acceleration correctly. If the measurement results become unreliable due to the detachment or incorrect installation of the acceleration sensor, it may interfere with the feedback control of the operation of the load generating unit, potentially causing the load generating unit to behave unintended.

[0005] The objective of the present invention is to provide a load testing machine that can acquire deformation amounts with high accuracy in dynamic testing and effectively suppress unintended behavior in the load generation section. [Means for solving the problem]

[0006] To solve the above problems, the load-load testing machine is characterized by comprising: a pair of specimen holding parts that directly clamp and hold a specimen in a predetermined clamping direction, or clamp and hold a specimen with a mounting jig interposed therebetween; a load generating unit that performs an excitation operation to apply a vibration load to the specimen by vibrating one of the pair of specimen holding parts as a load-side holding part in a vibration direction along the clamping direction; a first sensor installed on the surface of any of the following: a movable part in the load generating unit that is provided with the load-side holding part and moves together with the load-side holding part; the load-side holding part; a load-side jig interposed between the load-side holding part and the specimen in the mounting jig; and the specimen, and measuring the acceleration in the vibration direction; and a second sensor installed inside the movable part or the load-side holding part, and monitoring the behavior of the movable part or the load-side holding part.

[0007] According to the load-bearing tester described above, a first sensor for measuring acceleration is provided on the surface of either the movable part of the load-generating section, the load-applying holding section, the load-applying jig, or the test specimen. Since the installation locations of these first sensors are all near the test specimen or on the test specimen itself, the deformation amount of the test specimen in dynamic testing can be obtained with high accuracy by utilizing the acceleration measurement results from this first sensor. In addition, the acceleration measurement results from this first sensor can be used for feedback control of the operation of the load-generating section. Separately from this first sensor, a second sensor is provided to monitor the behavior of the movable part of the load-generating section or the load-applying holding section. Since the installation location of this second sensor is inside the movable part of the load-generating section or the load-applying holding section, there is a low possibility of it falling off due to vibrations during testing or external shocks. Furthermore, since its installation is pre-built during the manufacturing of the load-bearing tester, there is a low possibility of incorrect installation occurring during the test preparation stage. Therefore, when performing feedback control based on the measurement results of the first sensor, by referring to the monitoring results of the second sensor, even if there is some malfunction in the installation of the first sensor, unintended behavior in the load generation area can be effectively detected and suppressed. In this way, the above-described load testing machine can acquire deformation amounts with high accuracy in dynamic tests and effectively suppress unintended behavior in the load generation area.

[0008] In this case, it is preferable that the second sensor is a sensor that measures acceleration to monitor the behavior of the movable part or the load-bearing holding part.

[0009] With this configuration, the acceleration measured by the second sensor can be used as an acceleration limiter, which is effective in minimizing damage to the test specimen and load testing machine by reducing the vibration amplitude during dynamic testing. Furthermore, since the acceleration measured by the second sensor can also be used to obtain the amount of deformation in the direction of vibration, the deformation amount of the test specimen can be obtained using the measurement result of the second sensor instead of the measurement result of the first sensor.

[0010] Furthermore, it is preferable that the load generating unit vibrates the load-bearing side holding unit along a predetermined axis in the vibration direction, and that the second sensor is installed at an installation location on the axis of the load-bearing side holding unit to measure acceleration.

[0011] This configuration improves the accuracy of monitoring the behavior by the second sensor compared to the case where the second sensor is positioned off-center from the vibration axis. It also improves the accuracy of acquiring the deformation amount of the test specimen when the measurement results from the second sensor are used.

[0012] Furthermore, it is preferable to further include a load sensor provided on the receiving-side holding part of the pair of specimen holding parts, which receives the specimen separately from the loading-side holding part, for measuring the load applied from the specimen; a displacement sensor for measuring the displacement of the loading-side holding part; a deformation amount acquisition unit for acquiring the amount of deformation in the vibration direction generated in the specimen by the excitation operation based on the acceleration measurement result from at least one of the first sensor and the second sensor, or the displacement measurement result from the displacement sensor; and a characteristic acquisition unit for acquiring the excitation load generated in the specimen against the excitation operation from the measurement result of the load sensor, and for acquiring the spring constant in the specimen with respect to the excitation operation based on the excitation load and the deformation amount acquired by the deformation amount acquisition unit.

[0013] This configuration allows for the automatic execution of a series of processes, from acquiring the deformation and excitation load of the specimen during dynamic testing to obtaining the spring constant based on those results. Furthermore, by automating all of these processes, it becomes possible to, for example, display the change in the spring constant in response to changes in the excitation frequency during dynamic testing in real time during the test.

[0014] Furthermore, it is preferable to further include a load control unit that controls the operation of the load generating unit so that a predetermined vibration load is applied to the test specimen based on the measurement results of the first sensor, and stops the operation of the load generating unit if the behavior of the movable part or the load-applying holding part monitored by the second sensor exceeds a predetermined limit.

[0015] With this configuration, even if a malfunction occurs in the installation of the first sensor, damage to the test specimen and the load testing machine can be effectively suppressed by stopping the operation of the load generation unit, which is performed by the load control unit based on the monitoring results of the second sensor. [Effects of the Invention]

[0016] According to the load testing machine described above, deformation can be obtained with high accuracy in dynamic testing, and unintended behavior in the load-generating section can be effectively suppressed. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram showing a load testing machine according to one embodiment. [Figure 2] This is a magnified view of region A11 in Figure 1. [Figure 3] This is a view of the enlarged view shown in Figure 2, with the test specimen and mounting fixture removed. [Figure 4] This is a magnified view of region A12 in Figure 1. [Figure 5] Figure 1 is a schematic graph showing how the resonance point in the load-load testing machine shifts outside the measurement frequency range due to the weight. [Figure 6] Figure 1 shows how the deformation amount acquisition unit processes the measurement results from the first sensor to remove noise. [Modes for carrying out the invention]

[0018] Hereinafter, a load testing machine according to an embodiment of the present invention will be described.

[0019] FIG. 1 is a schematic diagram showing a load testing machine according to an embodiment. FIG. 2 is an enlarged view of region A11 in FIG. 1, and FIG. 3 is a view obtained by removing the test specimen and the mounting jig from the enlarged view shown in FIG. 2. Further, FIG. 4 is an enlarged view of region A12 in FIG. 1.

[0020] The load testing machine 1 of the present embodiment is a device used for a load testing that applies a compressive or tensile load to a test specimen M11 to obtain the dynamic and static characteristics of the test specimen M11. Here, the test specimen M11 is a rubber product such as an engine mount rubber, which is one of the automotive parts. Also, one of the characteristics to be obtained is the spring constant of such a rubber product. In the dynamic test for obtaining dynamic characteristics, a vibration load is applied to the test specimen M11 to obtain the dynamic spring constant, and in the static test for obtaining static characteristics, a constant load is applied to the test specimen M11 to obtain the static spring constant. Further, in the present embodiment, in the dynamic test, as a characteristic representing the remarkable viscosity of the rubber product, when a vibration load is applied to the test specimen M11 as an input, the phase difference representing the delay with respect to the input of the excitation load as the output generated in the test specimen M11 against the vibration load is also obtained.

[0021] The load testing machine 1 shown in FIG. 1 includes an equipment frame 11, a pair of test specimen holding portions 12, a load generating portion 13, a first sensor 14, a second sensor 15, a load sensor 16, a displacement sensor 17, a weight 18, and a control portion 19.

[0022] The equipment frame 11 is a frame structure installed at a predetermined installation location and supporting the load generating portion 13 and the weight 18. This equipment frame 11 includes a lower support column 111, a lower air spring 112, an intermediate frame 113, an upper support column 114, an upper surface plate 115, and an upper air spring 116.

[0023] The lower support columns 111 are arranged in multiples so as to form a forest at the installation site. One lower air spring 112 is placed on the upper end surface of each lower support column 111, and elastically supports the intermediate frame 113 above each. These lower air springs 112 are elastic parts installed between each lower support column 111 and the intermediate frame 113, suppressing vibration transmission between them. The intermediate frame 113 is the frame part that supports the load generating section 13. Multiple upper support columns 114 are erected on the upper end surface of the intermediate frame 113, and the upper end surfaces of the multiple upper support columns 114 support a single upper base plate 115. The upper base plate 115 is a single metal plate, and supports a weight 18 on its upper surface via multiple upper air springs 116. Multiple upper air springs 116 are installed between the upper base plate 115 and the weight 18, supporting the weight 18. Furthermore, in this embodiment, each upper air spring 116 is switchable between a floating mass state in which the weight 18 is supported while suspended above the upper base plate 115, and a rigid state in which the weight 18 is connected to the upper base plate 115. The floating mass / rigid switching function of this upper air spring 116 will be described later with reference to Figure 5.

[0024] The pair of specimen holders 12 are parts that hold the specimen M11 by clamping it in a clamping direction D11 along gravity, with one being the load-adding holder 121 and the other being the receiving holder 122. The load-adding holder 121 is held by the load-generating unit 13 and driven by this load-generating unit 13. The receiving holder 122 is a separate part from the load-adding holder 121 and is the part that receives the specimen M11 while fixed to the bottom surface of the weight 18 that passes through a through hole 115a provided in the upper base plate 115. With respect to the specimen M11, the pair of specimen holders 12 can be held by directly clamping the specimen M11 or by clamping and holding it with the mounting jig J11 interposed therebetween. These two types of holding are used depending on the shape and size of the specimen M11 to be tested.

[0025] Furthermore, two types of mounting fixtures J11 can be installed: a load-side fixture J111 interposed between the load-side holding part 121 and the test specimen M11, and a receiving-side fixture J112 interposed between the receiving-side holding part 122 and the test specimen M11. When a mounting fixture J11 is used, either one or both mounting fixtures J11 are used depending on the shape and size of the test specimen M11, and are used to hold the test specimen M11 with a pair of test specimen holding parts 12.

[0026] The load generating unit 13 is a mechanism that holds the load-adding holding unit 121 and applies dynamic vibration loads and static loads to the test specimen M11 by moving the load-adding holding unit 121 along the clamping direction D11. The load generating unit 13 is an electric mechanism comprising a movable part 131 that holds the load-adding holding unit 121 and is slidable in the clamping direction D11, and a fixed part 132 that is fixedly positioned adjacent to the movable part 131 and includes a drive mechanism that moves the movable part 131 by supplying power to a drive coil (not shown). The movable part 131 is also installed so as to be movable or vibrable along a predetermined axis X11. The load generating unit 13 moves or vibrates the load-adding holding unit 121 by moving the movable part 131 along this axis X11 by the drive mechanism of the fixed part 132.

[0027] The dynamic load is applied by an excitation operation in which the load generation unit 13 vibrates the load-applying holding unit 121 in the vibration direction D12 along the clamping direction D11 with an amplitude corresponding to the load to be applied. This excitation operation applies a vibration load to the test specimen M11 as a dynamic load, consisting of repeated compressive and tensile loads corresponding to the amplitude. Furthermore, the load generation unit 13 is capable of excitation operation over a predetermined excitation frequency range. In the dynamic test, the vibration load is applied while changing the excitation frequency within this excitation frequency range, thereby obtaining a dynamic spring constant that changes with frequency.

[0028] Static loading is performed by the load generating unit 13 moving the load-applying side holding unit 121 closer to or further away from it along the clamping direction D11 by a distance corresponding to the desired load, and then maintaining that close or separated state. By moving closer and then maintaining that state, a compressive load corresponding to the amount of approach is applied to the test specimen M11 as a static load, or by moving further away and then maintaining that state, a tensile load corresponding to the amount of separation is applied to the test specimen M11 as a static load. In a static test, by applying such a static load, the static spring constant for a given load is obtained.

[0029] The first sensor 14 is a sensor that measures acceleration. This first sensor 14 is installed on the surface of either the movable part 131 of the load generation part 13, the load-side holding part 121, or the load-side jig J111 of the mounting jig J11. The installation location is determined by the shape and size of the test specimen M11, but basically, a nearby position as close as possible to the test specimen M11 is selected. In the example in Figures 1 and 2, the test specimen M11 is held between a pair of test specimen holding parts 12 with two types of mounting jigs J11 interposed between them: the load-side jig J111 and the receiving jig J112. The first sensor 14 is installed on the mounting surface J111a of the load-side jig J111, adjacent to the test specimen M11. Furthermore, the orientation of the first sensor 14 at this time is such that it can detect the acceleration of the installation location due to the vibration load from the load generation unit 13. The first sensor 14 is attached by manually fixing it to the installation location with adhesive during the test preparation stage. The acceleration measured by this first sensor 14 can be used to acquire the amount of deformation in the vibration direction D12 generated in the test specimen M11 by the excitation operation, and for feedback control of the operation of the load generation unit 13, and is used for these purposes in the control unit 19.

[0030] The second sensor 15 is installed inside the movable part 131 of the load generation unit 13 or the load-side holding unit 121, and is a sensor that monitors the behavior of the movable part 131 or the load-side holding unit 121. In this embodiment, the second sensor 15 is installed inside the load-side holding unit 121 and monitors the behavior of the load-side holding unit 121. In addition, as part of monitoring the behavior of the load-side holding unit 121, the second sensor 15 is a sensor that measures acceleration, which can also be used to obtain the amount of deformation of the test specimen M11 in the vibration direction D12. The second sensor 15 is installed at an installation location on the vibration axis X11 of the load-side holding unit 121 and measures acceleration.

[0031] The load sensor 16 is installed on the receiving side holding part 122 of the pair of specimen holding parts 12 and measures the load applied from the specimen M11. In static tests, the load sensor 16 measures the static load generated on the specimen M11 along the axis X11 due to compressive loads and tensile loads. In dynamic tests, the load sensor 16 measures the dynamic load generated on the specimen M11 along the axis X11 due to vibration loads.

[0032] The displacement sensor 17 is a sensor that measures the displacement of the load-bearing side holding part 121, and is installed on the side surface of the movable part 131 of the load-generating part 13 to which the load-bearing side holding part 121 is provided. As an example of its installation configuration, the load-bearing side holding part 121 is connected to the upper surface of the movable part 131. In this embodiment, a linear encoder is used as the displacement sensor 17. The measurement results of this displacement sensor 17 are used to obtain the amount of static deformation that occurs in the test specimen M11 during a static test, that is, to obtain the static spring constant. Alternatively, they may be used to measure the amount of displacement during a dynamic test.

[0033] As described above, weight 18 is a weight supported by an upper air spring 116 so as to be switchable between a floating mass state and a rigid state. Its purpose is to move the resonance point in the load testing machine 1 outside the measurement frequency range during testing, especially during dynamic testing.

[0034] Figure 5 is a schematic graph showing how the resonance point in the load-load testing machine shown in Figure 1 moves outside the measurement frequency range due to the weight. In graph G11 of Figure 5, the horizontal axis shows frequency f, and the vertical axis shows the spring constant k obtained in the dynamic test. In graph G11, the graph curve L11 representing the frequency characteristics of the spring constant k is shown as a solid line, and the peak curve L11a superimposed on this graph curve L11 due to the resonance effect occurring in the load-load testing machine 1 is shown as a dashed line.

[0035] Generally, the spring constant k of any material is given by the amount of deformation x of the material and the load F applied to the test specimen M11 against the deformation. k = F / x ·····(1) It is expressed by the following equation. In the above-described load-load testing machine 1, the deformation amount x in the dynamic test is the magnitude of the deformation that occurs in the test specimen M11 due to the excitation load from the load generation unit 13. The acquisition of this deformation amount x is mainly based on the measurement results of the first sensor 14, as will be described in detail later. On the other hand, the acquisition of the load F in the dynamic test is performed by the load sensor 16. If a resonance point of the equipment frame 11 in the load-load testing machine 1 exists within the measurement frequency range of the dynamic test, and the load sensor 16 is affected by such resonance in the dynamic test, then a peak unrelated to the excitation load applied to the test specimen M11 will appear in the measurement result at the resonance point of the load-load testing machine 1. As a result, a peak P11 unrelated to the excitation load will also appear at the resonance point of the load-load testing machine 1 in the frequency characteristics of the spring constant k expressed by the above-described equation (1), and a peak curve L11a having such a peak P11 will be superimposed on the graph curve L11 representing the frequency characteristics of the spring constant k.

[0036] In dynamic testing, the weight 18 eliminates the peak P11 unrelated to the excitation load by moving the resonance point of the load-load testing machine 1 outside the measurement frequency range of the spring constant k. Generally, the resonance point of a structure appears on the lower frequency side as the mass of the floating mass in the structure increases, and on the higher frequency side as the entire structure is rigid. In the load-load testing machine 1 of this embodiment, by making the weight 18 a floating mass state with the upper air spring 116, the peak P11 originating from resonance can be moved to the lower frequency side. Alternatively, by turning off the floating function of the upper air spring 116 and rigidly connecting the weight 18 to the upper base plate 115, the peak P11 originating from resonance can be moved to the higher frequency side. By performing such a shift of peak P11 according to the target measurement frequency range in dynamic testing, the peak P11 originating from the resonance of the load-load testing machine 1 can be excluded from the test results.

[0037] Next, the control unit 19 shown in Figure 1 performs overall operational control of the load testing machine 1, including the floating mass / rigid switching of the weight 18 and the operation of the load generation unit 13 as described above. The control unit 19 also performs the process of acquiring spring constants based on the measurement results of the first sensor 14, the second sensor 15, the load sensor 16, and the displacement sensor 17. The control unit 19 includes a deformation amount acquisition unit 191 and a characteristic acquisition unit 192 as control parts related to the spring constant acquisition process, and a load control unit 193 as a control part related to the operational control of the load generation unit 13.

[0038] The deformation acquisition unit 191 acquires the amount of deformation generated in the test specimen M11 due to a dynamic load based on the measurement results of the first sensor 14, and also acquires the amount of deformation generated in the test specimen M11 due to a static load based on the measurement results of the displacement sensor 17. In dynamic tests, the deformation acquisition unit 191 acquires the amount of deformation in the vibration direction D12 generated by the excitation operation.

[0039] In the dynamic test, the deformation amount acquisition unit 191 does not use the measurement result of the first sensor 14 as is, but rather performs the following noise reduction processing on the measurement result before acquiring the deformation amount.

[0040] Figure 6 shows how the deformation amount acquisition unit shown in Figure 1 processes the measurement results of the first sensor to remove noise. In Figure 6, the three stages of processing the measurement results s of the first sensor 14 are shown by graphs G121, G122, and G123 corresponding to each stage. First, in graph G121 of the first stage (S11), time t is shown on the horizontal axis and the measurement result s is shown on the vertical axis. Then, graph G121 shows a graph curve L121 that represents the time change of the noisy measurement result s received by the deformation amount acquisition unit 191. In this example, the graph curve L121 is a curve in which random noise is superimposed on a sine wave corresponding to the vibration load of one excitation frequency applied in the dynamic test.

[0041] In the graph G122 of the second stage (S12), the horizontal axis shows frequency f, and the vertical axis shows the sensor measurement result s. The graph curve L122 shown in this graph G122 is a curve obtained by the Fourier transform of the graph curve L121 of the first stage (S11), which contains various frequency components. In this graph curve L122 of the second stage (S12), a peak P12 appears at the excitation frequency f0 in the dynamic test that is inherent to the measurement result s. The deformation amount acquisition unit 191 applies such a Fourier transform to the sensor measurement result s to identify the excitation frequency f0 component in the noisy measurement result s. Then, noise is removed by extracting the excitation frequency f0 component from the measurement result s after the Fourier transform.

[0042] In the graph G123 of the third stage (S13), time t is again shown on the horizontal axis and the sensor measurement result s is shown on the vertical axis. The graph curve L123 shown in this graph G123 is a sinusoidal curve representing the component of the excitation frequency f0 extracted from the noisy measurement result s represented by the graph curve L121 of the first stage (S11). The extraction result for the component of the excitation frequency f0 represented by this graph curve L123 is obtained by the inverse Fourier transform of the component of the excitation frequency f0 extracted from the measurement result s after the Fourier transform. The deformation amount acquisition unit 191 acquires the deformation amount using the component of the excitation frequency f0, which is represented as a sinusoidal wave and obtained by this inverse Fourier transform. That is, since the first sensor 14 is an acceleration sensor, the deformation amount acquisition unit 191 acquires the deformation amount of the test specimen M11 by double integration of the component of the excitation frequency f0 (acceleration) after the inverse Fourier transform.

[0043] Up to this point, as an example of noise reduction for the measurement results of the first sensor 14, a series of processes including Fourier transform → extraction of the excitation frequency f0 component → inverse Fourier transform on the extracted result has been illustrated. However, as outlined below, this noise reduction may also be performed by determining the excitation frequency f0 component from the waveform of the measurement results of the first sensor 14 using Fourier series expansion. First, the measurement result of the first sensor 14 is a periodic waveform in which the waveform of the excitation frequency f0 is superimposed with the waveforms of various other frequency components as noise components. Such a periodic waveform can be expanded into multiple waveforms with discretely different frequencies, that is, into multiple waveforms using a known Fourier series expansion. Each waveform is a function of time using trigonometric functions of each frequency. The Fourier transform described above is a process that applies to any waveform, including non-periodic waveforms, but in this embodiment, since the waveform to be processed is a periodic waveform that includes the excitation frequency f0 component, it is possible to determine the excitation frequency f0 component using Fourier series expansion instead of Fourier transform. In this method, the waveform of excitation frequency f0 is selected from among several waveforms obtained by Fourier series expansion of the measurement results of the first sensor 14. This selection separates the waveform of excitation frequency f0, i.e., the component of excitation frequency f0, from the waveforms of other frequency components that constitute noise, i.e., the noise component, thus removing the noise component from the measurement results of the first sensor 14. Furthermore, as mentioned above, the waveform obtained by Fourier series expansion is originally a function of time. Therefore, the component of excitation frequency f0 (acceleration) after noise removal can be directly subjected to a double integral over time without the need for processing such as an inverse Fourier transform, and the deformation amount of the test specimen M11 can be obtained from this double integral.

[0044] On the other hand, in static testing, the deformation amount acquisition unit 191 acquires the measurement result (displacement) from the displacement sensor 17 as a direct representation of the static deformation amount of the test specimen M11.

[0045] Next, the characteristic acquisition unit 192 in the control unit 19 shown in Figure 1 acquires the load generated on the test specimen M11 against the load from the measurement results of the load sensor 16. In dynamic testing, the excitation load generated on the test specimen M11 against the excitation motion is acquired from the dynamic measurement results of the load sensor 16. The acquisition of the excitation load at this time is also performed through a series of processes, such as Fourier transform → extraction of the excitation frequency f0 component → inverse Fourier transform on the extracted result, and noise reduction using the Fourier series expansion described above, similar to the acquisition of the deformation amount by the deformation amount acquisition unit 191. That is, the characteristic acquisition unit 192 applies this noise reduction processing to the measurement results of the load sensor 16 and acquires the result of this processing as the excitation load. Furthermore, the characteristic acquisition unit 192 acquires the spring constant by substituting the excitation load obtained in this way and the deformation amount acquired as described above by the deformation amount acquisition unit 191 into equation (1) above. By obtaining the spring constant in this way while changing the excitation frequency within the range of measurement frequencies, a dynamic spring constant that changes in accordance with the change in excitation frequency is obtained. On the other hand, in static testing, the characteristic acquisition unit 192 obtains the static spring constant by substituting the static measurement results of the load sensor 16 and the static deformation amount obtained by the deformation amount acquisition unit 191 into equation (1) above.

[0046] Furthermore, in this embodiment, the characteristic acquisition unit 192 acquires the phase difference as a characteristic representing the significant viscosity of the rubber product during dynamic testing. This phase difference represents the delay between the input of the excitation load, which is the output generated on the test specimen M11 in opposition to the vibration load when the vibration load is applied to the test specimen M11 as input. The larger the phase difference, the greater the viscosity of the test specimen M11, and conversely, the smaller the phase difference, the smaller the viscosity of the test specimen M11. The characteristic acquisition unit 192 acquires such a phase difference based on the extraction results for noise reduction described above. That is, the characteristic acquisition unit 192 can acquire the phase difference between the extraction result of the excitation frequency f0 component from the measurement result of the first sensor 14 and the extraction result of the excitation frequency f0 component from the measurement result of the load sensor 16 as a characteristic value corresponding to the viscosity described above.

[0047] Next, the load control unit 193 in the control unit 19 shown in Figure 1 controls the operation of the load generation unit 13 as described above. First, based on the measurement results of the first sensor 14, the load control unit 193 provides feedback control to the operation of the load generation unit 13 so that a vibration load of a predetermined magnitude is applied to the test specimen M11. Furthermore, if the behavior of the load-side holding unit 121, which is monitored by the second sensor 15, which is another acceleration sensor, exceeds a predetermined limit, the operation of the load generation unit 13 is stopped.

[0048] In the load-load testing machine 1 of the embodiment described above, a first sensor 14 for measuring acceleration is provided on the surface of the load-applying jig J111. Since the installation location of the first sensor 14 is near the test specimen M11, the amount of deformation of the test specimen M11 in dynamic testing can be obtained with high accuracy by utilizing the acceleration measurement result from this first sensor 14. Furthermore, the acceleration measurement result from this first sensor 14 can also be used for feedback control of the operation of the load generation unit 13. In this embodiment, however, a second sensor 15 is provided separately from the first sensor 14 to monitor the behavior of the load-applying holding unit 121. Since the installation location of this second sensor 15 is inside the load-applying holding unit 121, there is a low possibility of it falling off due to vibrations during testing or external impacts. In addition, since its installation is pre-built during the manufacturing of the load-load testing machine 1, there is a low possibility of incorrect installation occurring during the test preparation stage. Therefore, by referring to the monitoring results of the second sensor 15 in the feedback control based on the measurement results of the first sensor 14, even if a malfunction such as detachment occurs in the mounting of the first sensor 14, unintended behavior in the load generation unit 13 can be effectively detected, and the load generation unit 13 can be stopped or its operation suppressed. In this way, the load testing machine 1 of this embodiment can acquire the amount of deformation with high accuracy in dynamic testing and effectively suppress unintended behavior in the load generation unit 13.

[0049] In this embodiment, the second sensor 15 is a sensor that measures acceleration. With this configuration, the acceleration measured by the second sensor 15 can be used as an acceleration limiter that is effective in reducing the vibration amplitude in dynamic testing to minimize damage to the test specimen M11 and the load testing machine 1. Furthermore, since the acceleration measured by the second sensor 15 can also be used to obtain the amount of deformation in the vibration direction D12, the amount of deformation of the test specimen M11 can be obtained using the measurement result of the second sensor 15 instead of the measurement result of the first sensor 14. For example, if any malfunction occurs in the first sensor 14, the measurement result of the second sensor 15 may be used to obtain the amount of deformation and the spring constant of the test specimen M11.

[0050] Furthermore, in this embodiment, the second sensor 15, which functions as an acceleration sensor, is installed at a location on the vibration axis X11 in the load-side holding section 121. This configuration improves the accuracy of monitoring the behavior by the second sensor 15 compared to the case where the second sensor 15 is positioned at a location offset from the vibration axis X11. It also improves the accuracy of acquiring the deformation amount of the test specimen M11 when the measurement results of the second sensor 15 are used.

[0051] In this embodiment, a load sensor 16 is provided on the receiving side holding part 122, and a displacement sensor 17 is provided on the movable part 131 of the load generating part 13. In dynamic testing, the deformation amount acquisition unit 191 acquires the deformation amount of the test specimen M11 based on the acceleration measurement result from at least one of the first sensor 14 and the second sensor 15 (normally the first sensor 14, and the second sensor 15 when a malfunction occurs). On the other hand, in static testing, the deformation amount acquisition unit 191 acquires the deformation amount of the test specimen M11 based on the displacement measurement result from the displacement sensor 17. Then, the characteristic acquisition unit 192 acquires the dynamic and static spring constants of the test specimen M11 based on the dynamic and static deformation amounts acquired in this way and the excitation load of the test specimen M11 acquired from the measurement result of the load sensor 16. With this configuration, a series of processes from acquiring the deformation amount and excitation load of the test specimen M11 in dynamic and static testing to acquiring the spring constant based on the acquired results can be performed automatically. Furthermore, automating all of these processes makes it possible, for example, to display in real time during dynamic testing how the spring constant changes in response to changes in excitation frequency.

[0052] Furthermore, in this embodiment, during dynamic testing, the load control unit 193 provides feedback control to the operation of the load generation unit 13 based on the measurement results of the first sensor 14. In addition, the load control unit 193 stops the operation of the load generation unit 13 if the behavior monitored by the second sensor 15 exceeds a predetermined limit. With this configuration, even if some malfunction occurs in the mounting of the first sensor 14, the operation of the load generation unit 13, which is performed by the load control unit 193 based on the monitoring results of the second sensor 15, can be stopped. This operation stop process effectively reduces damage to the test specimen M11 and the load testing machine 1.

[0053] The embodiments described above are merely representative examples of the present invention, and the present invention is not limited thereto. That is, the present invention can be implemented with various modifications without departing from the core principles. As long as such modifications still possess the configuration of the load-bearing testing machine of the present invention, they are of course included within the scope of the present invention.

[0054] For example, in the embodiment described above, a load-load testing machine 1 is exemplified using a rubber product such as an engine mount rubber, which is a type of automobile part, as the test specimen M11. However, load-load testing machines are not limited to this, and can be used to test specimens of any material, not just such rubber products.

[0055] Furthermore, in the embodiments described above, a load-load testing machine 1 that performs both static and dynamic tests is exemplified as an example of a load-load testing machine. However, the load-load testing machine is not limited to this, and may perform only dynamic tests.

[0056] Furthermore, in the embodiments described above, a load generating unit 13 is exemplified as an example of a load generating unit, in which an electric mechanism moves the load-bearing side holding unit 121. However, the load generating unit is not limited to this, and the load-bearing side holding unit may be moved by a mechanism other than electric, such as a hydraulic mechanism.

[0057] Furthermore, in the embodiments described above, an example of a load-bearing holding part is shown as a load-bearing holding part 121 connected to the movable part 131 of the load-generating part 13. However, the load-bearing holding part is not limited to this, and any part provided on the movable part is acceptable. For example, the upper surface of the movable part may be used as the load-bearing holding part.

[0058] Furthermore, in the above-described embodiment, as an example of the first sensor, a first sensor 14 is provided which is installed adjacent to the test specimen M11 on the mounting surface J111a of the load-side jig J111. However, the first sensor is not limited to this, and the specific installation location can be set as appropriate, as long as it is installed on any surface of the movable part of the load-generating part, the load-side holding part, the load-side jig, or the test specimen.

[0059] Furthermore, in the embodiments described above, a first sensor 14 is exemplified as an example of a first sensor, which is manually fixed to the installation location by an operator during the test preparation stage. However, the first sensor is not limited to this, and any installation method, including screw fastening, can be adopted for its specific installation.

[0060] Furthermore, in the embodiments described above, a second sensor 15 is provided as an example of a second sensor, which is installed inside the load-side holding part 121 and monitors the behavior of the load-side holding part 121. However, the second sensor is not limited to this, and may also be a sensor installed inside the movable part 131 of the load-generating part 13 and monitors the behavior of this movable part 131.

[0061] Furthermore, in the embodiments described above, a second sensor 15 that measures acceleration, which can also be used to obtain the deformation amount of the test specimen M11, is exemplified as an example of a second sensor. However, the second sensor is not limited to this, and may be a sensor that measures velocity or displacement. However, as described above, if the second sensor 15 measures acceleration, its measurement results can be used in the acceleration limiter. Also, as described above, the deformation amount of the test specimen M11 can be obtained using the measurement results of the second sensor 15 instead of the measurement results of the first sensor 14.

[0062] Furthermore, in the embodiments described above, a second sensor 15 installed at an installation location on the vibration axis X11 is given as an example of a second sensor as an acceleration sensor. However, the second sensor is not limited to this, and the specific installation location is not restricted as long as it is installed inside the movable part or the load-side holding part. However, as mentioned above, by installing the second sensor 15 at an installation location on the axis X11, the accuracy of monitoring the behavior by the second sensor 15 and the accuracy of obtaining the deformation amount of the test specimen M11 when using the measurement results of the second sensor 15 can be improved.

[0063] Furthermore, in the embodiments described above, a load-load testing machine 1 is exemplified as an example of a load-load testing machine, equipped with a load sensor 16, a displacement sensor 17, a deformation amount acquisition unit 191, and a characteristic acquisition unit 192. However, the load-load testing machine is not limited to this, and these configurations may not be provided. However, as mentioned above, by providing these configurations, it is possible to automatically acquire the deformation amount and excitation load of the test specimen M11 in dynamic and static tests, as well as the spring constant, and it is also possible to display the change in the spring constant in real time during the test.

[0064] Furthermore, in the above-described embodiment, as an example of a deformation amount acquisition unit, a deformation amount acquisition unit 191 is provided that acquires the deformation amount, excitation load, and spring constant using the excitation frequency component extracted from the measurement results of the first sensor 14 and the load sensor 16 in a dynamic test. However, the deformation amount acquisition unit is not limited to this, and the deformation amount, excitation load, and spring constant may be acquired by directly using the measurement results of the first sensor and the load sensor. However, as mentioned above, by going through the extraction process described above, noise included in the measurement results can be removed, thereby improving the accuracy of acquiring the deformation amount in a dynamic test. In the above-described embodiment, as an example of the extraction process here, an extraction process that follows the procedure of Fourier transform → component extraction → inverse Fourier transform, or a process using Fourier series expansion is provided. However, the extraction process is not limited to this, and any method can be adopted, such as a process using a bandpass filter that allows the excitation frequency component to pass through.

[0065] Furthermore, in the above-described embodiment, a load-load testing machine 1 equipped with a load control unit 193 is exemplified as an example of a load-load testing machine. The load control unit 193 provides feedback control to the operation of the load generation unit 13 based on the measurement results of the first sensor 14, and stops the operation of the load generation unit 13 if the behavior monitored by the second sensor 15 exceeds a predetermined limit. However, the load-load testing machine is not limited to this, and the load control unit described above may not be provided. However, as mentioned above, by providing the load control unit 193, damage to the test specimen M11 and the load-load testing machine 1 can be effectively suppressed by stopping the operation of the load generation unit 13 when a malfunction occurs in the first sensor 14. [Explanation of symbols]

[0066] 1. Load-bearing testing machine 11. Equipment Frame 12 Specimen holding part 13 Load generation section 14. First Sensor 15. Second Sensor 16. Load sensor 17 Displacement Sensor 18 weights 19 Control Unit 111 Lower support column 112 Lower air spring 113 Intermediate Frames 114 Upper support column 115 Upper surface plate 115a Through hole 116 Upper air spring 121 Load side holding part 122 Receiving side holding part 131 Moving parts 132 Fixed part 191 Deformation amount acquisition unit 192 Characterization Unit 193 Load Control Unit f frequency f0 is the excitation frequency. s Measurement results t time D11 Clamping direction D12 Vibration direction G11, G121, G122, G123 graphs J11 Mounting jig J111 Load-side jig J111a Mounting surface J112 Receiving jig L11, L121, L122, L123 graph curves L11a Peak Curve P11, P12 peaks M11 specimen S11 Stage 1 S12 Stage 2 S13 Stage 3 X11 axis center

Claims

1. A pair of specimen holding parts that directly clamp and hold the specimen in a predetermined clamping direction, or clamp and hold it with a mounting jig interposed between them, A load generating unit performs an excitation operation that applies a vibration load to the test specimen by vibrating one of the pair of test specimen holding parts in the vibration direction along the clamping direction, with the load-applying holding part being the load-applying holding part. The load generation unit includes a movable part that moves together with the load-side holding part, the load-side holding part, a load-side jig interposed between the load-side holding part and the test specimen among the mounting jigs, and a first sensor installed on any surface of the test specimen to measure the acceleration in the vibration direction. A second sensor is installed inside the movable part or the load-side holding part to monitor the behavior of the movable part or the load-side holding part, A load-load testing machine characterized by being equipped with the following features.

2. The load-bearing testing machine according to claim 1, characterized in that the second sensor is a sensor that measures acceleration as a means of monitoring the behavior of the movable part or the load-bearing holding part.

3. The load generating unit causes the load-bearing holding unit to vibrate in the vibration direction along a predetermined axis, The load-bearing testing machine according to claim 2, characterized in that the second sensor is installed at the installation location on the axis of the load-bearing holding portion to measure acceleration.

4. A load sensor is provided on the receiving-side holding part of the pair of specimen holding parts, which is separate from the load-applying-side holding part and receives the specimen, and measures the load applied from the specimen. A displacement sensor for measuring the displacement of the load-side holding part, A deformation amount acquisition unit acquires the amount of deformation in the vibration direction generated in the test specimen by the excitation operation based on the acceleration measurement result from at least one of the first sensor and the second sensor, or the displacement measurement result from the displacement sensor. A characteristic acquisition unit obtains the excitation load generated on the test specimen against the excitation motion from the measurement results of the load sensor, and obtains the spring constant in the test specimen for the excitation motion based on the excitation load and the deformation amount obtained by the deformation amount acquisition unit, The load testing machine according to claim 2, further comprising the above.

5. The load testing machine according to claim 1, further comprising a load control unit that controls the operation of the load generating unit so that a vibration load of a predetermined size is applied to the test specimen based on the measurement results of the first sensor, and stops the operation of the load generating unit when the behavior of the movable part or the load-applying holding part monitored by the second sensor exceeds a predetermined limit.

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