Load testing machine

Abstract

The present invention provides a load-load testing machine capable of obtaining highly accurate deformation measurements over a wide range of excitation frequencies during dynamic testing. [Solution] The load testing machine 1 is characterized by comprising: a pair of specimen holding parts 12; a load generating part 13 capable of performing vibration operation on a specimen M11 over a predetermined vibration frequency range, with one of the holding parts 121 being the load-side holding part 121; a first sensor 14 capable of measuring the acceleration of the load-side holding part 121 in a first frequency range that occupies the high-frequency side of the vibration frequency range; a second sensor 15 capable of measuring the velocity or displacement of the load-side holding part 121 in a second frequency range that occupies the lower frequency side of the first frequency range while allowing partial overlap with the first frequency range in the vibration frequency range; and a deformation amount acquisition part 181 that acquires the deformation amount of the specimen M11 based on the measurement results of the first sensor 14 or the second sensor 15.

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 load testing in which a compressive or tensile load is applied to a specimen to examine dynamic and static characteristics. One of the characteristics to be targeted is the spring constant of the specimen. In a dynamic test, a vibration load is applied to the specimen to obtain a dynamic spring constant, and in a static test, a constant load is applied to the specimen to obtain a static spring constant. In obtaining such a spring constant, it is necessary to obtain the amount of deformation generated in the specimen by a dynamic or static load, and the load testing machine is equipped with a sensor for obtaining such an amount of deformation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the load-load testing machines described above are used to test various types of specimens. In particular, in dynamic tests to obtain the dynamic spring constant, it is desirable to be able to obtain the deformation of the specimen under a wide range of vibration loads, from low frequencies of a few Hz to high frequencies of a few kHz, so that tests can be conducted on various specimens. Furthermore, since such deformation is directly related to obtaining the spring constant, high accuracy is required in obtaining it. However, in reality, it is difficult for many load-load testing machines to obtain deformation with high accuracy over such a wide range of vibration frequencies.

[0005] The objective of the present invention is to provide a load-load testing machine that can obtain deformation amounts with high accuracy over a wide excitation frequency range in dynamic testing. [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 clamp and hold a specimen in a predetermined clamping direction; a load generating part that can perform an excitation operation over a predetermined excitation frequency range, in which one of the pair of specimen holding parts is used as the load-side holding part and vibrates in a vibration direction along the clamping direction to apply a vibration load to the specimen; a sensor for measuring the acceleration of the load-side holding part, which is a first sensor capable of measuring in a first frequency range that occupies the high-frequency side of the excitation frequency range; a sensor for measuring the velocity or displacement of the load-side holding part, which is a second frequency range that occupies a lower frequency side than the first frequency range while allowing partial overlap with the first frequency range of the excitation frequency range; and a deformation amount acquisition part that acquires the amount of deformation in the vibration direction generated in the excitation operation of the specimen based on the measurement results of the first sensor or the second sensor.

[0007] According to the load testing machine described above, the amount of deformation due to vibration load in the first frequency range on the high-frequency side can be obtained using the measurement results of a first sensor suitable for high-frequency measurement, which measures the acceleration of the load-bearing part. Furthermore, the amount of deformation due to vibration load in the second frequency range on the low-frequency side can be obtained using the measurement results of a second sensor suitable for low-frequency measurement, which measures the velocity or displacement of the load-bearing part. Thus, by providing two sensors suitable for measurement at high and low frequencies respectively, the load testing machine described above can acquire deformation amounts with high accuracy over a wide excitation frequency range in dynamic testing.

[0008] Here, it is preferable that the deformation amount acquisition unit acquires the deformation amount by double integration with respect to the measurement result of the first sensor when the excitation operation is an operation that applies a vibration load in the first frequency range, acquires the deformation amount by single integration with respect to the measurement result of the second sensor when the excitation operation is an operation that applies a vibration load in the second frequency range and the second sensor is a sensor that measures velocity, and acquires the deformation amount from the measurement result of the second sensor when the excitation operation is an operation that applies a vibration load in the second frequency range and the second sensor is a sensor that measures displacement.

[0009] With this configuration, the deformation amount acquisition unit acquires the deformation amount through optimal processing based on the frequency of the vibration load and the type of sensor in the dynamic test, thereby further improving the accuracy of the deformation amount acquisition.

[0010] Furthermore, it is preferable that the deformation amount acquisition unit extracts the excitation frequency component in the excitation operation from the measurement results of the first sensor or the second sensor, and acquires the deformation amount using the extracted result.

[0011] With this configuration, even if the measurement results from the first and second sensors include noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount can be obtained from the extracted excitation frequency with the noise removed. By going through this extraction process, the accuracy of acquiring the deformation amount in dynamic testing can be further improved.

[0012] Furthermore, it is preferable to further include a load sensor, which is provided on the receiving-side holding part of the pair of specimen holding parts that receive the specimen and is separate from the loading-side holding part, for measuring the load applied from the specimen, and which is capable of measuring over the entire range of the excitation frequency; and a characteristic acquisition part, which, from the measurement results of the load sensor, acquires the excitation load generated on the specimen against the excitation motion, and acquires the spring constant in the specimen for the excitation motion based on the excitation load and the deformation amount acquired by the deformation amount acquisition part.

[0013] With this configuration, by providing a load sensor and a characteristic acquisition unit, it is possible to automatically acquire not only the amount of deformation due to the excitation motion, but also the dynamic spring constant using this data.

[0014] Furthermore, it is even more preferable that the deformation amount acquisition unit extracts the excitation frequency component in the excitation operation from the measurement results of the first sensor or the second sensor and acquires the deformation amount using the extracted result, and that the characteristic acquisition unit extracts the excitation frequency component from the measurement results of the load sensor and acquires the excitation load using the extracted result.

[0015] With this configuration, even if the measurement results from the first sensor, second sensor, and load sensor contain noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount and excitation load can be obtained from the extracted excitation frequency results after the noise has been removed. Through this extraction process, the accuracy of obtaining the deformation amount and excitation load in dynamic tests can be further improved, and as a result, the accuracy of obtaining the dynamic spring constant can also be further improved.

[0016] Furthermore, it is preferable that the load generating unit comprises a movable part that is provided with the load-bearing side holding part and is movable in the direction of vibration, and a fixed part that is fixedly adjacent to the movable part and includes a drive mechanism that moves the movable part in the direction of vibration to cause vibration, and that the second sensor comprises a movable part fixed to the movable part and a measuring part that is fixed to the fixed part and has an output cable that measures the amount of movement of the movable part and outputs the measurement result.

[0017] In this configuration, the movable part of the second sensor, which is easier to reduce in mass compared to the measurement part, is fixed to the movable part of the load generating unit, thus making it easier to suppress an increase in the mass of the movable part of the load generating unit. This makes it possible to suppress a decrease in the responsiveness of the load generating unit. Furthermore, in the above configuration, since the output cable is provided to the measurement part which is fixed to the immovable part, it is possible to suppress the complexity of cable routing caused by the movement of the output cable when the load generating unit is operating, and simplify the wiring.

[0018] Furthermore, the second sensor is a velocity sensor that measures the displacement of the load-side holding part, and the third sensor is capable of measuring displacement in a third frequency range that occupies an even lower frequency range than the second frequency range, while allowing partial overlap with the second frequency range that can be measured by the velocity sensor in the excitation frequency range, and the deformation amount acquisition unit preferably acquires the deformation amount from the measurement result of the third sensor when the excitation operation is an operation that applies a vibration load in the third frequency range.

[0019] With this configuration, when a velocity sensor is used as the second sensor, the deformation caused by vibration loads in the third frequency range, which are even lower in frequency and where measurement by the second sensor becomes difficult, is obtained using the measurement results of the third sensor, which is capable of measuring displacement at even lower frequencies. In other words, with the above configuration, deformation can be obtained with high accuracy even for vibration loads in a wide range of excitation frequencies, including extremely low frequencies that are difficult to measure with a velocity sensor.

[0020] Furthermore, it is preferable that the load generating unit comprises a movable part that holds the load-adding holding unit and is movable in the direction of vibration, and a fixed part that is fixedly adjacent to the movable part and includes a drive mechanism that moves the movable part in the direction of vibration to cause vibration, and that at least the third sensor of the second and third sensors comprises a movable part fixed to the movable part and a measuring part fixed to the fixed part and provided with an output cable that measures the amount of movement of the movable part and outputs the measurement result.

[0021] In this configuration, at least the third sensor, of the two sensors, has a movable part that is easier to reduce in mass compared to the measurement part, and this movable part is fixed to the movable part of the load generating unit. This makes it easier to suppress an increase in the mass of the movable part of the load generating unit. As a result, a decrease in the responsiveness of the load generating unit can be suppressed. Furthermore, in the above configuration, at least the third sensor has an output cable provided on the measurement part that is fixed to the immovable part. Therefore, at least for the third sensor, it is possible to suppress the complexity of cable routing caused by the movement of the output cable when the load generating unit is operating, and simplify the wiring.

[0022] Furthermore, it is even more preferable that the deformation amount acquisition unit extracts the excitation frequency component in the excitation operation from the measurement results of the first sensor, the second sensor, or the third sensor, and acquires the deformation amount using the extracted result.

[0023] With this configuration, even if the measurement results from the first, second, and third sensors include noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount can be obtained from the extracted excitation frequency with the noise removed. By going through this extraction process, the accuracy of acquiring the deformation amount can be further improved for dynamic tests with a wide frequency range, including the measurement range of the third sensor.

[0024] Further, it is preferable that the load generating unit vibrates the load-applying side holding unit in the vibration direction along a predetermined axis, and the first sensor is disposed on the axis in the load-applying side holding unit.

[0025] According to this configuration, the acquisition accuracy of the amount of deformation based on the measurement result of the first sensor can be further improved as compared with the case where the first sensor is disposed at a position deviated from the axis of vibration in the load-applying side holding unit.

Advantages of the Invention

[0026] According to the above-described load loading testing machine, it is possible to acquire the amount of deformation with high accuracy over a wide range of vibration frequencies in a dynamic test.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram showing a load loading testing machine according to the first embodiment. [Figure 2] It is an enlarged view of the region A11 in FIG. 1. [Figure 3] It is an enlarged view of the region A12 in FIG. 1. [Figure 4] It is a schematic diagram showing an example of an installation mode of a linear encoder as the second sensor shown in FIGS. 1 and 2. [Figure 5] It is a schematic diagram showing a frequency range measurable by the first sensor and the second sensor shown in FIGS. 1 to 4. [Figure 6] It is a schematic graph showing a state in which a resonance point in the load loading testing machine shown in FIG. 1 moves outside the measurement frequency range due to a weight. [Figure 7] It is a schematic diagram showing a state in which processing for noise removal is performed on the measurement results of the first sensor and the second sensor by the deformation amount acquisition unit shown in FIG. 1. [Figure 8] It is a diagram showing the types of sensors included in the load loading testing machine of the second embodiment using a schematic diagram equivalent to FIG. 5. [Figure 9]Figure 8 is a schematic diagram showing an example of an installation configuration for the speed sensor, which is the second sensor. [Figure 10] This figure shows the types of sensors included in the load testing machine of the third embodiment, using a schematic diagram similar to that of Figure 8. [Figure 11] Figure 10 is a schematic diagram showing an example of an installation configuration when a differential transformer is used as the third sensor. [Modes for carrying out the invention]

[0028] The following describes a load-load testing machine according to one embodiment of the present invention. First, the first embodiment will be described.

[0029] Figure 1 is a schematic diagram showing a load-load testing machine according to the first embodiment. Figure 2 is an enlarged view of region A11 in Figure 1, and Figure 3 is an enlarged view of region A12 in Figure 1.

[0030] The load testing machine 1 of this embodiment is a device used for load testing to obtain the dynamic and static characteristics of a test specimen M11 by applying compressive and tensile loads to the specimen M11. Here, the test specimen M11 is a rubber product such as an engine mount rubber, which is a type of automobile part. One of the characteristics obtained is the spring constant of such a rubber product. In a dynamic test to obtain dynamic characteristics, a vibration load is applied to the test specimen M11 to obtain the dynamic spring constant, and in a static test to obtain static characteristics, a constant load is applied to the test specimen M11 to obtain the static spring constant. In addition, in this embodiment, in a dynamic test, when a vibration load is applied to the test specimen M11 as input, a phase difference representing the lag between the input and the excitation load, which is the output generated in opposition to the vibration load, is also obtained as a characteristic representing the significant viscosity of the rubber product.

[0031] The load testing machine 1 shown in Figure 1 comprises an equipment frame 11, a pair of test specimen holders 12, a load generating unit 13, a first sensor 14, a second sensor 15, a load sensor 16, a weight 17, and a control unit 18.

[0032] The equipment frame 11 is a frame structure that is installed in a predetermined location and supports the load generating section 13 and the weight 17. This equipment frame 11 comprises a lower support column 111, a lower air spring 112, an intermediate frame 113, an upper support column 114, an upper base plate 115, and an upper air spring 116.

[0033] 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 17 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 17, supporting the weight 17. Furthermore, in this embodiment, each upper air spring 116 is switchable between a floating mass state in which the weight 17 is supported while suspended above the upper base plate 115, and a rigid state in which the weight 17 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 6.

[0034] The pair of specimen holding parts 12 are the parts that hold the specimen M11 by clamping it in a clamping direction D11 along gravity, with one being the load-adding holding part 121 and the other being the receiving holding part 122. The load-adding holding part 121 is held by the load-generating part 13 and driven by this load-generating part 13. The receiving holding part 122 is a separate part from the load-adding holding part 121 and is the part that receives the specimen M11 while being fixed to the bottom surface of the weight 17 that passes through a through hole 115a provided in the upper base plate 115.

[0035] 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 to which the load-adding holding unit 121 is provided and which is slidable in the clamping direction D11, and a fixed part 132 which includes a drive mechanism that moves the movable part 131 by supplying power to a drive coil (not shown). As an example of its installation configuration, the load-adding holding unit 121 is connected to the upper surface of the movable part 131. The movable part 131 is installed so as to be movable or vibrable along a predetermined axis X11, and the fixed part 132 is positioned adjacent to the movable part 131 in a fixed state. The load generating unit 13 moves or vibrates the load-adding holding unit 121 by moving the movable part 131 along the axis X11 using the fixed part 132.

[0036] 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.

[0037] 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. The approach and subsequent maintenance of the state apply a compressive load to the specimen M11 as a static load, corresponding to the amount of approach. Alternatively, the separation and subsequent maintenance of the state apply a tensile load to the specimen M11 as a static load, corresponding to the amount of separation. In a static test, the static spring constant for a given load is obtained by applying such static loads.

[0038] The first sensor 14 is a sensor that measures the acceleration of the load-side holding part 121, and the second sensor 15 is a sensor that measures the displacement of the load-side holding part 121. In this embodiment, a linear encoder is used as the second sensor 15. The first sensor 14, which is an acceleration sensor, is positioned on the axis X11 of the load-side holding part 121. The second sensor 15, which is a linear encoder, is installed, for example, as shown below, in the load-generating part 13 and the immobile part 132 which is positioned adjacent to it in an immobile state.

[0039] Figure 4 is a schematic diagram showing an example of the installation configuration of the linear encoder as the second sensor shown in Figures 1 and 2. Note that in Figure 4, the left-right positional relationship in the diagram is reversed compared to Figures 1 and 2.

[0040] In the example shown in Figure 4, the second sensor 15, which is a linear encoder, comprises a movable part 151 fixed to the side of the movable part 131 of the load generating unit 13, and a measuring part 152 fixed to the stationary part 132 at a position opposite the movable part 151. The movable part 151 is a linear scale, and the measuring part 152 is an encoder head. The measuring part 152 measures the amount of movement of the movable part 151, which moves in the vibration direction D12 together with the movable part 131 when the load generating unit 13 is operating, by optically or magnetically reading the scale at the point on the linear scale that faces the encoder head. An output cable 152a is also provided on the measuring part 152, and the measurement result is output from this output cable 152a.

[0041] Furthermore, the first sensor 14 and the second sensor 15 described above differ in the following excitation frequency ranges that can be measured by each sensor in dynamic testing.

[0042] Figure 5 is a schematic diagram showing the frequency ranges that can be measured by the first and second sensors shown in Figures 1 to 4.

[0043] In Figure 5, the excitation frequency range F11 in which the load generation unit 13 can operate during dynamic testing is shown as fa to fd. The first sensor 14, which is an acceleration sensor, is capable of measuring the first frequency range F12, which occupies the high-frequency side of the excitation frequency range F11. The second sensor 15, which is a linear encoder, is capable of measuring the second frequency range F13, which occupies a lower frequency side than the first frequency range F12, while allowing partial overlap with the first frequency range F12 within the excitation frequency range F11. Generally, in the field of vibration measurement, the amplitude of vibration decreases as the frequency increases, making measurement difficult with displacement sensors such as linear encoders. On the other hand, acceleration sensors can obtain good sensitivity at high frequencies. Conversely, the acceleration decreases as the frequency decreases, making measurement difficult with acceleration sensors, but displacement sensors can obtain good sensitivity. From the above, the first sensor 14, which is an acceleration sensor, is capable of accurate measurement in the first frequency range F12 on the high frequency side, and the second sensor 15, which is a linear encoder, is capable of accurate measurement in the second frequency range F13 on the low frequency side. In Figure 5, the first frequency range F12 is represented in the range of fb to fd, and the second frequency range F13 is represented in the range of fa to fc. The range of fb to fc is an intermediate region F14 where the first frequency range F12 and the second frequency range F13 overlap. This intermediate region F14 is a range that can be measured by either the first sensor 14 or the second sensor 15. In this embodiment, the second sensor 15, which is a linear encoder, is responsible for measuring the displacement of the load-side holding part 121 in static tests that do not involve vibration. Here, fa, fb, fc, and fd, which represent the start and end points of each frequency range, have the following frequencies. That is, fa is a few Hz, and specific numerical examples include frequencies of 2 to 7 Hz. fb is in the range of tens of Hz, with specific examples being frequencies of 30-60 Hz. fc is in the range of several hundred Hz, with specific examples being frequencies of 200-500 Hz. And fd is in the range of several kHz, with specific examples being frequencies of 2-4 kHz.

[0044] Next, the load sensor 16 shown in Figures 1 and 3 is a sensor installed on the receiving side holding part 122 of the pair of specimen holding parts 12, which 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. Furthermore, in dynamic tests, this load sensor 16 is a sensor capable of measuring across the entire excitation frequency range F11 from fa to fd, during which the load generation part 13 is operational.

[0045] As described above, weight 17 is a weight supported by the 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.

[0046] Figure 6 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 6, 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.

[0047] 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. This deformation amount x is obtained based on the measurement results of the first sensor 14 and the second sensor 15, as will be described in detail later. On the other hand, the load F in the dynamic test is obtained 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.

[0048] In dynamic testing, the weight 17 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 17 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 17 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.

[0049] Next, the control unit 18 shown in Figure 1 performs overall operational control of the load testing machine 1, including the floating mass / rigid switching of the weight 17 and the operation of the load generation unit 13 as described above. The control unit 18 also performs the process of acquiring the spring constant based on the measurement results of the first sensor 14, the second sensor 15, and the load sensor 16. The control unit 18 includes a deformation amount acquisition unit 181 and a characteristic acquisition unit 182 as control parts related to the spring constant acquisition process.

[0050] The deformation acquisition unit 181 acquires the amount of deformation generated in the test specimen M11 due to dynamic or static loads, based on the measurement results of the first sensor 14 and the second sensor 15. In dynamic tests, the deformation acquisition unit 181 acquires the amount of deformation in the vibration direction D12 generated by the excitation operation. At this time, the deformation acquisition unit 181 switches between the first sensor 14 and the second sensor 15 depending on the measurement frequency range to be measured in the dynamic test.

[0051] First, if the excitation operation is an operation that applies a vibration load in the first frequency range F12, that is, if the measurement frequency range is within the first frequency range F12 on the high frequency side, the deformation amount acquisition unit 181 uses the first sensor 14, which is an acceleration sensor, as the sensor used to acquire the deformation amount. The deformation amount acquisition unit 181 then acquires the deformation amount of the test specimen M11 by the measurement result of this first sensor 14, i.e., by double integration with respect to acceleration. Furthermore, if the excitation operation is an operation that applies a vibration load in the second frequency range F13, that is, if the measurement frequency range is within the second frequency range F13 on the low frequency side, the deformation amount acquisition unit 181 uses the second sensor 15 as the sensor used to acquire the deformation amount. In this case, the deformation amount acquisition unit 181 acquires the deformation amount with processing content according to the type of sensor of the second sensor 15. In this embodiment, the second sensor 15 is a linear encoder that measures the displacement of the load-side holding part 121, which is directly related to the amount of deformation of the test specimen M11. Therefore, the deformation amount acquisition unit 181 acquires the deformation amount from the measurement result of the second sensor 15.

[0052] In this embodiment, the deformation amount acquisition unit 181 does not use the measurement results of the first sensor 14 and the second sensor 15 as they are, but rather performs the following noise reduction processing on the measurement results before acquiring the deformation amount.

[0053] Figure 6 is a schematic diagram showing how the deformation amount acquisition unit shown in Figure 1 processes the measurement results of the first and second sensors to remove noise. Figure 6 shows three stages of processing for abstract measurement results s, which disregard the distinction between sensors, with 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 of the sensor is shown on the vertical axis. This graph G121 also contains a graph curve L121 that represents the time change of the noisy measurement result s received by the deformation amount acquisition unit 181. In this example, the graph curve L121 is a curve in which random noise is superimposed on a sine wave corresponding to a vibration load of one excitation frequency applied in the dynamic test.

[0054] 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 181 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, it removes noise by extracting the excitation frequency f0 component from the measurement result s after the Fourier transform.

[0055] 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 excitation frequency f0 component represented by this graph curve L123 is obtained by an inverse Fourier transform on the excitation frequency f0 component extracted from the measurement result s after the Fourier transform. The deformation amount acquisition unit 181 acquires the deformation amount using the excitation frequency f0 component, which is obtained by this inverse Fourier transform and represented as a sinusoidal wave. That is, when using the measurement result of the first sensor 14, which is an acceleration sensor, the deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 by double integration on the excitation frequency f0 component after the inverse Fourier transform. Furthermore, when using the measurement results of the second sensor 15, which is a displacement sensor, the deformation amount acquisition unit 181 acquires the component of the excitation frequency f0 after the inverse Fourier transform directly as the deformation amount of the test specimen M11.

[0056] Up to this point, as an example of noise reduction for the measurement results of the first sensor 14 and the second sensor 15, a series of processes including Fourier transform → extraction of the excitation frequency f0 component → inverse Fourier transform of the extracted result has been illustrated. However, this noise reduction may also be performed by determining the excitation frequency f0 component from the waveforms of the measurement results of the first sensor 14 and the second sensor 15 using Fourier series expansion, as outlined below. First, the measurement results of both the first sensor 14 and the second sensor 15 are periodic waveforms in which the waveform of the excitation frequency f0 is superimposed with the waveforms of various other frequency components as noise components. Such periodic waveforms 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 the trigonometric functions of each frequency. The Fourier transform described above is a process that applies to any waveform, including non-periodic waveforms. However, in this embodiment, the waveform to be processed is a periodic waveform that includes a component of the excitation frequency f0. Therefore, instead of the Fourier transform, it is possible to obtain the component of the excitation frequency f0 using a Fourier series expansion. In this method, the waveform of the excitation frequency f0 is selected from among several waveforms obtained by the Fourier series expansion of the measurement results of the first sensor 14 and the second sensor 15. This selection separates the waveform of the excitation frequency f0, i.e., the component of the excitation frequency f0, from the waveforms of other frequency components that constitute noise, i.e., the noise components. Thus, the noise components are removed from the measurement results of the first sensor 14 and the second sensor 15. Furthermore, as described above, the waveform obtained by the Fourier series expansion is originally a function of time. Therefore, the component of the 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 by this double integral.

[0057] Next, the characteristic acquisition unit 182 in the control unit 18 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 excitation frequency components → inverse Fourier transform on the extracted results, and noise reduction using the Fourier series expansion described above, similar to the acquisition of deformation amount by the deformation amount acquisition unit 181. That is, the characteristic acquisition unit 182 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 182 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 181 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 182 obtains the static spring constant by substituting the static measurement result of the load sensor 16 and the static deformation amount obtained by the deformation amount acquisition unit 181 into equation (1) above.

[0058] Furthermore, in this embodiment, the characteristic acquisition unit 182 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. For example, the closer the phase difference in a sine wave is to 90°, the greater the viscosity of the test specimen M11; conversely, the closer the phase difference is to 0°, the smaller the viscosity of the test specimen M11. The characteristic acquisition unit 182 acquires such a phase difference based on the extraction results for noise reduction described above. That is, the characteristic acquisition unit 182 can acquire the phase difference between the extraction result of the excitation frequency component from the measurement results of the first sensor 14 or the second sensor 15 and the extraction result of the excitation frequency component from the measurement results of the load sensor 16 as a characteristic value corresponding to the viscosity described above.

[0059] According to the load-load testing machine 1 of the first embodiment described above, the amount of deformation due to vibration load in the first frequency range F12 on the high frequency side can be obtained using the measurement results of the first sensor 14, which is suitable for high-frequency measurement and measures the acceleration of the load-loading holding part 121. Furthermore, the amount of deformation due to vibration load in the second frequency range F13 on the low frequency side can be obtained using the measurement results of the second sensor 15, which is suitable for low-frequency measurement and measures the displacement of the load-loading holding part 121. Thus, with the load-load testing machine 1 described above, by providing two sensors suitable for high-frequency and low-frequency measurement respectively, the amount of deformation can be obtained with high accuracy over a wide excitation frequency range in dynamic testing.

[0060] In this embodiment, the deformation amount acquisition unit 181 acquires the deformation amount by processing in the following cases depending on the frequency of the vibration load and the type of sensor in the dynamic test. First, if the excitation operation is an operation that applies a vibration load in the first frequency range F12, the deformation amount acquisition unit 181 acquires the deformation amount by double integration of the measurement result of the first sensor 14. If the excitation operation is an operation that applies a vibration load in the second frequency range F13 and the second sensor 15 is a sensor that measures velocity, the deformation amount is acquired by single integration of the measurement result of the second sensor 15. Furthermore, if the excitation operation is an operation that applies a vibration load in the second frequency range F13 and the second sensor 15 is a sensor that measures displacement, the deformation amount is acquired from the measurement result of the second sensor 15. With this configuration, the deformation amount acquisition unit 181 acquires the deformation amount by processing that is optimal for the frequency of the vibration load and the type of sensor in the dynamic test, so that the accuracy of acquiring the deformation amount can be further improved.

[0061] Furthermore, in this embodiment, the deformation amount acquisition unit 181 extracts the excitation frequency component from the measurement results of the first sensor 14 or the second sensor 15, and acquires the deformation amount using the extracted result. With this configuration, even if the measurement results of the first sensor 14 or the second sensor 15 contain noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount can be acquired using the extracted excitation frequency result from which the noise has been removed. By going through such an extraction process, the accuracy of acquiring the deformation amount in dynamic testing can be further improved.

[0062] Furthermore, in this embodiment, the second sensor 15, which is a linear encoder, comprises, for example, a movable part 151 fixed to the movable part 131, and a measuring part 152 fixed to the immovable part 132, which measures the amount of movement and is provided with an output cable 152a that outputs the measurement result. With this configuration, the movable part 151 of the second sensor 15, which is easier to reduce in mass compared to the measuring part 152, is fixed to the movable part 131 of the load generating unit 13, making it easier to suppress an increase in the mass of the movable part 131 of the load generating unit 13. This makes it possible to suppress a decrease in the responsiveness of the load generating unit 13. In addition, with the above configuration, the output cable 152a is provided on the measuring part 152 which is fixed to the immovable part 132. Therefore, it is possible to suppress the complexity of cable routing caused by the movement of the output cable 152a when the load generating unit 13 is operating, and simplify the wiring state.

[0063] Furthermore, in this embodiment, a load sensor 16 is provided on the receiving-side holding part 122 of the pair of test specimen holding parts 12, and the characteristic acquisition unit 182 acquires the excitation load of the test specimen M11 obtained from the measurement results and the spring constant based on the deformation amount of the test specimen M11. This configuration is preferable because it allows a series of processes from acquiring the deformation amount and excitation load of the test specimen M11 to acquiring the spring constant to be performed automatically.

[0064] Furthermore, in this embodiment, the deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 after extracting the excitation frequency component from the measurement results of the first sensor 14 or the second sensor 15. In addition, the characteristic acquisition unit 182 acquires the excitation load of the test specimen M11 after extracting the excitation frequency component from the measurement results of the load sensor 16. With this configuration, even if the measurement results of the first sensor 14, the second sensor 15, and the load sensor 16 contain noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount and excitation load can be acquired from the extraction results of the excitation frequency from which the noise has been removed. By going through such extraction processing, the accuracy of acquiring the deformation amount and excitation load in dynamic testing can be further improved, and as a result, the accuracy of acquiring the dynamic spring constant can also be further improved.

[0065] Furthermore, in this embodiment, the characteristic acquisition unit 182 acquires the phase difference between the result extracted from the measurement results of the first sensor 14 or the second sensor 15 and the result extracted from the measurement results of the load sensor 16 as a characteristic value representing the viscosity response of the test specimen M11 to the excitation frequency. With this configuration, not only the amount of deformation of the test specimen M11 necessary for acquiring the spring constant can be obtained, but when the test specimen M11 is made of a material with significant viscosity, such as a rubber product, the phase difference as a characteristic value representing the viscosity response of the test specimen M11 can be obtained with high accuracy.

[0066] Furthermore, in this embodiment, the first sensor 14 is positioned on the vibration axis X11 of the load-side holding portion 121. With this configuration, the accuracy of acquiring the deformation amount based on the measurement results of the first sensor 14 can be further improved compared to the case where the first sensor 14 is positioned at a location offset from the vibration axis X11.

[0067] This concludes the description of the first embodiment, and now we will describe the second embodiment. In this second embodiment, the type of second sensor used to measure displacement on the low-frequency side in the dynamic test differs from that of the first embodiment. On the other hand, the overall equipment configuration is the same as that of the first embodiment. In the following description, we will focus on the differences between the second embodiment and the first embodiment, and will omit illustrations and explanations of the overall configuration that is the same as that of the first embodiment. In addition, the elements shown in Figure 1 will be referred to as appropriate in the following description.

[0068] Figure 8 shows the types of sensors included in the load testing machine of the second embodiment, using a schematic diagram equivalent to that of Figure 5. In Figure 8, elements equivalent to those shown in Figure 5 are denoted by the same reference numerals as in Figure 5, and redundant explanations will be omitted below.

[0069] In this embodiment, the excitation frequency range F11 in the dynamic test is the same range as in the first embodiment, from fa to fd. Also, the first frequency range F12 on the high-frequency side that the first sensor 14 can measure in the dynamic test is the same range as in the first embodiment, from fb to fd, and the second frequency range F13 on the low-frequency side that the second sensor 25 can measure is the same range as in the first embodiment, from fa to fc. Furthermore, the intermediate region F14 where both ranges overlap is also the same range as in the first embodiment, from fb to fc. Here, in this embodiment, the sensor type of the first sensor 14 is an acceleration sensor, the same as in the first embodiment, while the sensor type of the second sensor 25 is a velocity sensor, and for example, it is installed as follows.

[0070] Figure 9 is a schematic diagram showing an example of an installation configuration for the speed sensor, which is the second sensor shown in Figure 8. In Figure 9, elements equivalent to those shown in Figure 1 are denoted by the same reference numerals as in Figure 1, and redundant explanations will be omitted below.

[0071] In the example shown in Figure 9, the second sensor 25, which is a speed sensor, also comprises a movable part 251 and a measuring part 252, similar to the first embodiment described above. However, in this embodiment, the movable part 251 is a rod-shaped permanent magnet connected and fixed to the movable part 131 of the load generating unit 13 shown in Figures 1 and 2, so as to extend in the vibration direction D12. The measuring part 252 has a pair of coils 252a fixedly installed on the immovable part 132, arranged in the vibration direction D12 so as to surround the movable part 251. The coils 252a are fixed to the immovable part 132 while covered with molded resin 252b. When the load generating unit 13 is in operation, the movable part 251 moves inside the coils 252a in the vibration direction D12 together with the movable part 131, inducing an induced voltage in the coils 252a. Since this induced voltage is proportional to the moving speed of the movable part 251, this induced voltage becomes the speed measurement result. The output cable 252c is connected to the coil 252a, and the induced voltage described above is output from the output cable 252c as the speed measurement result. Furthermore, since the speed in vibration is greater at lower frequencies than acceleration, the second sensor 15, which is a speed sensor, is capable of measuring in the second frequency range F13 on the low-frequency side.

[0072] In this example, a second sensor 25 is provided, which is a speed sensor, in which a pair of coils 252a are covered with molded resin 252b and fixed to the immovable part 132. However, the second sensor, which is a speed sensor, is not limited to this, and the number of coils may be one or more than one pair, and the fixing method may also be to fix it directly without covering it with molded resin.

[0073] In this embodiment, during dynamic testing, the deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 by single integration of the measurement result (velocity) of the second sensor 25. In acquiring this deformation amount, the deformation amount acquisition unit 181 performs a series of processes including Fourier transform of the measurement result of the second sensor 25 → extraction of the excitation frequency component → inverse Fourier transform, as well as noise reduction using Fourier series expansion. The deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 by single integration of the excitation frequency component after these processes. Subsequently, the same processing as in the first embodiment is performed in the characteristic acquisition unit 182 to acquire the dynamic spring constant.

[0074] It goes without saying that, as with the first embodiment described above, the load-load testing machine of the second embodiment can also acquire deformation amounts with high accuracy over a wide excitation frequency range in dynamic testing.

[0075] Furthermore, in this embodiment, a speed sensor is used as the second sensor 25. This second sensor 25 also comprises a movable part 251 fixed to the movable part 131 and a measuring part 252 fixed to the immovable part 132 and provided with an output cable 252a. With this configuration, similar to the first embodiment described above which is equipped with a linear encoder second sensor 15, a decrease in the responsiveness of the load generation unit 13 can be suppressed, and the structure of the load testing machine can be simplified.

[0076] Next, the third embodiment will be described. This third embodiment is a modification of the second embodiment, and a sensor that measures at an even lower frequency than the second frequency range F13 described above has been added. In the following description, the third embodiment will be described focusing on the differences from the second embodiment, and the overall configuration and other details will be omitted from the illustrations and explanations, as with the second embodiment. Also, the elements shown in Figure 1 will be referred to as appropriate in the following description.

[0077] Figure 10 shows the types of sensors included in the load testing machine of the third embodiment, using a schematic diagram equivalent to that of Figure 8. In Figure 10, elements equivalent to those of the second embodiment shown in Figure 8 are denoted by the same reference numerals as in Figure 8, and redundant explanations will be omitted below.

[0078] In this embodiment, the excitation frequency range F31 in the dynamic test differs from the first and second embodiments in that it ranges from a frequency even lower than fa (not shown) to fd. The first frequency range F12 measured by the first sensor 14 (accelerometer) is the same range from fb to fd as in the first and second embodiments, and the second frequency range F13 measured by the second sensor 25 (velocity sensor) is the same range from fa to fc as in the first and second embodiments. The intermediate region F14 where both ranges overlap is also the same range from fb to fc as in the first embodiment. In this embodiment, a third sensor 36 is provided that allows for the measurement of displacement in the third frequency range F34, which occupies an extremely low frequency range even lower than the second frequency range F13, while allowing for partial overlap with the second frequency range F13. The third frequency range F34 is the extremely low frequency range (not shown) to fa. As this third sensor 36, the linear encoder described above, which is an example of a displacement sensor, is used, but a differential transformer, which is another example of a displacement sensor, may also be used.

[0079] If a linear encoder is used as the third sensor 36, it will be installed in the same manner as the second sensor 15 shown in Figure 4. If a differential transformer is used as the third sensor 36, it will be installed as shown below, for example.

[0080] Figure 11 is a schematic diagram showing an example of an installation configuration when a differential transformer is used as the third sensor shown in Figure 10. In Figure 11, elements equivalent to those shown in Figure 1 are denoted by the same reference numerals as in Figure 1, and redundant explanations will be omitted below.

[0081] In the example shown in Figure 11, the third sensor 36, when using a differential transformer, comprises a movable part 361 and a measuring part 362, similar to the second sensor 25 (speed sensor). The movable part 361 is a magnetic material such as a rod-shaped iron core, which is connected and fixed to the movable part 131 of the load generating unit 13 shown in Figures 1 and 2 so as to extend in the vibration direction D12. The measuring part 362 has a primary coil 362a and a pair of secondary coils 362b, which are provided on the immovable part 132 so as to surround the movable part 361. The pair of secondary coils 362b are arranged so as to sandwich the primary coil 362a in the vibration direction D12. The primary coil 362a and the pair of secondary coils 362b are fixed to the immovable part 132 while covered with molded resin 362c. When an AC voltage is applied to the primary coil 362a, an induced voltage is induced in the pair of secondary coils 362b. At this time, as the load generation unit 13 operates, the movable part 361, which is a magnetic material, moves inside the primary coil 362a and the pair of secondary coils 362b, and the differential voltage between the pair of secondary coils 362b changes according to the amount of movement. In the third sensor 36, which is a differential transformer, this differential voltage becomes the measurement result for the amount of movement. The measurement unit 362 is provided with an output cable 362d connected to the pair of secondary coils 362b, and the measurement result is output from this output cable 362d.

[0082] In this example, a third sensor 36 is provided in which a differential transformer is used as the third sensor, and the primary coil 362a and a pair of secondary coils 362b are covered with molded resin 362c and fixed to the immovable part 132. However, the third sensor when using a differential transformer is not limited to this, and the primary and secondary coils may be fixed directly without being covered with molded resin.

[0083] The deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 from the measurement results of the third sensor 36 when the excitation operation is an operation that applies a vibration load in the third frequency range F34. In acquiring this deformation amount, the deformation amount acquisition unit 181 performs a series of processes on the measurement results of the third sensor 36, such as Fourier transform → extraction of excitation frequency components → inverse Fourier transform, and noise reduction by processing using Fourier series expansion. The deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 using the excitation frequency components after these processes as they are. After that, the characteristic acquisition unit 182 performs the same processing as in the first embodiment to acquire the dynamic spring constant.

[0084] Furthermore, in this embodiment, the displacement in the static test is acquired based on the measurement results of the third sensor 36, which is a displacement sensor. That is, in this static test, the deformation amount acquisition unit 181 uses the measurement results of the third sensor 36 directly to acquire the deformation amount of the test specimen M11, and the characteristic acquisition unit 182 uses the acquired results to acquire the static spring constant.

[0085] It goes without saying that, as with the first embodiment described above, the load-load testing machine of the third embodiment can also acquire deformation amounts with high accuracy over a wide excitation frequency range in dynamic testing.

[0086] Furthermore, in this embodiment, a third sensor 36 is provided, which is a displacement sensor capable of measuring displacement in a third frequency range F34 that occupies an even lower frequency range than the second frequency range F13, while allowing partial overlap with the second frequency range F13. For example, the linear encoder or differential transformer described above may be used as the third sensor 36. The deformation amount acquisition unit 181 acquires the deformation amount of the test specimen M11 from the measurement results of the third sensor 36 when the excitation operation is an operation that applies a vibration load in the third frequency range F34. With this configuration, the deformation amount due to the vibration load in the third frequency range F34, which is on the lower frequency side, is acquired using the measurement results of the differential transformer, which is the third sensor 36 and is suitable for measurement at even lower frequencies. In other words, with the above configuration, the deformation amount can be acquired with high accuracy for excitation loads in a wide excitation frequency range F34, including extremely low frequencies, which tend to have reduced accuracy with the second sensor 25, which is a velocity sensor.

[0087] Furthermore, in this embodiment, even when a differential transformer is used as the third sensor 36, the third sensor 36 is equipped with a movable part 361 and a measuring part 362, similar to the second sensor 25 (speed sensor) also provided in the second embodiment described above. The movable part 361 is a part fixed to the movable part 131, and the measuring part 362 is a part fixed to the immovable part 132 and to which an output cable 362d for measurement results is provided. With this configuration, since the movable parts 251 and 361 of the second sensor 25 and the third sensor 36, respectively, which are easy to reduce in mass, are fixed to the movable part 131 of the load generation unit 13, it is easy to suppress an increase in the mass of the movable part 131 of the load generation unit 13. This makes it possible to suppress a decrease in the responsiveness of the load generation unit 13. Also, with the above configuration, output cables 252c and 362d are provided to the measuring parts 252 and 362, which are fixed to the immovable part 132, for both the second sensor 25 and the third sensor 36. Therefore, the complexity of cable routing caused by the movement of output cables 252c and 362d during the operation of the load generation unit 13 can be suppressed, and the wiring can be simplified. It goes without saying that a similar effect can be obtained for the third sensor 36 even when a linear encoder is used.

[0088] Furthermore, in this embodiment, the deformation amount acquisition unit 181 extracts the excitation frequency component from the measurement results of the first sensor 14, the second sensor 25, or the third sensor 36, and acquires the deformation amount using the extracted result. With this configuration, even if the measurement results of the first sensor 14, the second sensor 25, and the third sensor 36 contain noise other than the excitation frequency and have a low signal-to-noise ratio, the deformation amount can be acquired using the extracted excitation frequency result from which the noise has been removed. By going through such an extraction process, the accuracy of acquiring the deformation amount can be further improved for dynamic tests of a wide excitation frequency range F31, including the measurement range of the third sensor 36.

[0089] Furthermore, the first to third embodiments described above merely represent typical forms of the present invention, and the present invention is not limited thereto. That is, it can be implemented with various modifications without departing from the core principles of the present invention. 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.

[0090] For example, in the first to third embodiments described above, a load-load testing machine 1 is exemplified, in which a rubber product such as an engine mount rubber, which is a type of automobile part, is used as the test specimen M11. However, the load-load testing machine is not limited to this, and can be used to test specimens of any material, not just such rubber products.

[0091] Furthermore, in the first to third 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.

[0092] Furthermore, in the first to third 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.

[0093] Furthermore, in the first to third embodiments described above, an example of a load-bearing-side holding part is shown as a load-bearing-side holding part 121 connected to the movable part 131 of the load-generating part 13. However, the load-bearing-side 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-side holding part.

[0094] Furthermore, in the first to third embodiments described above, a load-load testing machine 1 is provided as an example of a load-load testing machine, in which specific numerical range examples are shown for the excitation frequency ranges F11, F31, the first frequency range F12, the second frequency range F13, and the third frequency range F34. However, the load-load testing machine is not limited to these, and the excitation frequency range by the load generation unit and the frequency range measurable by each sensor can be set arbitrarily.

[0095] Furthermore, in the first to third embodiments described above, a deformation amount acquisition unit 181 is exemplified as an example of a deformation amount acquisition unit, which acquires the deformation amount using the excitation frequency component extracted from the measurement results of the first sensor 14 or the second sensors 15, 25. However, the deformation amount acquisition unit is not limited to this, and the deformation amount may be acquired using the measurement results of the first sensor or the second sensor as is. However, as described 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 dynamic testing. In the first to third embodiments described above, examples of the extraction process here include an extraction process that follows the procedure of Fourier transform → component extraction → inverse Fourier transform, and a process that uses Fourier series expansion. However, the extraction process is not limited to this, and may also be a process that uses a bandpass filter that allows the excitation frequency component to pass through, or any other method can be adopted.

[0096] Furthermore, in the first to third embodiments described above, a deformation amount acquisition unit 181 is exemplified as an example of a deformation amount acquisition unit, which acquires the deformation amount by various processes such as double integration, single integration, or use of the measurement result itself, depending on the frequency of the vibration load and the type of sensor. However, the deformation amount acquisition unit is not limited to this, and the specific processing method for acquiring the deformation amount is not limited. However, as mentioned above, the accuracy of acquiring the deformation amount can be further improved by using the optimal processing for the frequency of the vibration load and the type of sensor.

[0097] Furthermore, in the first to third embodiments described above, a load-load testing machine 1 is exemplified in which the characteristic acquisition unit 182 acquires the spring constant using the deformation amount of the test specimen M11 and the measurement results of the load sensor 16 as an example of a load-load testing machine. However, the load-load testing machine is not limited to this, and the acquisition of the spring constant may be performed by a separately provided processing device. However, by providing the load sensor 16 and the characteristic acquisition unit 182, the series of processes up to the acquisition of the spring constant can be performed automatically.

[0098] Furthermore, in the first to third embodiments described above, the deformation amount acquisition unit 181 and the characteristic acquisition unit 182 are exemplified as examples of the deformation amount acquisition unit and the characteristic acquisition unit, respectively, which acquire the deformation amount and excitation load after extracting the excitation frequency component from the measurement results. However, the deformation amount acquisition unit and the characteristic acquisition unit are not limited to these, and the deformation amount and excitation load may be acquired by directly using the measurement results of various sensors. However, as described above, by going through the extraction process described above, noise included in the measurement results is removed, improving the accuracy of acquiring the deformation amount and excitation load in dynamic tests, and as a result, the accuracy of acquiring the dynamic spring constant can also be improved. In addition, in the first to third embodiments described above, the extraction process for the measurement results of the load sensor 16 is exemplified by an extraction process that follows the procedure of Fourier transform → component extraction → inverse Fourier transform, or a process that uses Fourier series expansion. However, the extraction process here is not limited to these, and any method can be adopted.

[0099] Furthermore, in the first to third embodiments described above, a characteristic acquisition unit 182 is provided as an example of a characteristic acquisition unit that acquires the phase difference between the result extracted from the measurement results of the first sensor 14 or the second sensor 15 and the result extracted from the measurement results of the load sensor 16. However, the characteristic acquisition unit is not limited to this, and may acquire only the spring constant without determining such a phase difference in a dynamic test. However, as described above, by performing such processing in addition to acquiring the spring constant, the phase difference as a characteristic value representing the viscosity response of the test specimen M11 can be acquired with high accuracy.

[0100] Furthermore, in the first to third embodiments described above, second sensors 15 and 25 are exemplified as examples of second sensors, each comprising movable parts 151 and 251 and measuring parts 152 and 252. The movable parts 151 and 251 are parts fixed to the movable part 131, and the measuring parts 152 and 252 are parts fixed to the immovable part 132 and provided with output cables 152a and 252c for measurement results. In the third embodiment, a third sensor 36 is exemplified as an example of a third sensor, similar to the second sensor 25, comprising a movable part 361 and a measuring part 362. However, the second and third sensors are not limited to these, and the specific sensor configuration and installation configuration are not restricted. However, as mentioned above, the second sensors 15, 25 and the third sensor 36, which are equipped with movable parts 151, 251, 361 and measuring parts 152, 252, 362, can suppress a decrease in the responsiveness of the load generation unit 13 and can also simplify the structure of the load testing machine. In addition, when providing the second and third sensors, unlike the third embodiment described above, the third sensor may be equipped with both a movable part and a measuring part, while the second sensor may be equipped with a different sensor configuration.

[0101] Furthermore, in the first to third embodiments described above, a first sensor 14 positioned on the vibration axis X11 of the load-side holding part 121 is exemplified as an example of a first sensor for measuring acceleration. However, the first sensor is not limited to this, and any position can be adopted for its installation as long as it is capable of measuring the acceleration of the load-side holding part. However, as mentioned above, positioning the first sensor 14 on the vibration axis X11 improves the accuracy of acquiring the deformation amount based on the measurement results of the first sensor 14.

[0102] Furthermore, in the third embodiment described above, as an example of a load-load testing machine, a load-load testing machine 1 is provided in which the second sensor 25 is a velocity sensor, and a third sensor 36 is provided that can measure displacement in a third frequency range F34 in the extremely low frequency range where the velocity becomes so low that measurement by the second sensor becomes difficult. However, the load-load testing machine is not limited to this, and as illustrated in the first and second embodiments, the third sensor for the extremely low frequency range described above may not be provided. However, as mentioned above, by providing the third sensor 36, it is possible to obtain the amount of deformation with high accuracy for excitation loads in a wide excitation frequency range F34 including extremely low frequencies.

[0103] Furthermore, in the third embodiment described above, a deformation amount acquisition unit 181 is exemplified as an example of a deformation amount acquisition unit, which extracts the excitation frequency component from the measurement results of the first sensor 14, the second sensor 25, or the third sensor 36, and acquires the deformation amount using the extracted result. However, the deformation amount acquisition unit is not limited to this, and the deformation amount may be acquired by directly using the measurement results of various sensors. However, as described 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 dynamic testing. In addition, in the third embodiment described above, the extraction process for the measurement results of the third sensor 36 is exemplified by an extraction process that follows the procedure of Fourier transform → component extraction → inverse Fourier transform, or a process that uses Fourier series expansion. However, the extraction process here is not limited to this, and any method can be adopted.

[0104] Furthermore, in the first to third embodiments described above, a load-load testing machine 1 having a floating mass / rigid switching function is exemplified as an example of a load-load testing machine. However, the load-load testing machine is not limited to this, and may also have a floating mass / rigid switching function. However, as described above, the load-load testing machine 1 having a floating mass / rigid switching function makes it possible to perform tests at a particularly wide range of excitation frequencies. It is particularly preferable to perform the floating mass / rigid switching within the frequency range of the intermediate region F14 described above. On the other hand, even if, for example, the load-load testing machine does not have a floating mass / rigid switching function, that is, if the load-load testing machine is configured to remain in a rigid state or in a floating mass state, it goes without saying that it is possible to perform tests at a wide range of excitation frequencies by switching the first sensor and the second sensor or the third sensor. [Explanation of Symbols]

[0105] 1. Load-bearing testing machine 11. Equipment Frame 12 Specimen holding part 13 Load generation section 14. First Sensor 15,25 Second sensor 16. Load sensor 17 weights 18 Control Unit 36 Third Sensor 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 151,251,361 moving part 152,252,362 Measurement section 152a, 252c, 362d output cable 181 Deformation amount acquisition unit 182 Characterization Unit 252a Coil 252b, 362c Molding resin 362a Primary coil 362b Secondary coil f frequency f0 is the excitation frequency. s Measurement results t time D11 Clamping direction D12 Vibration direction F11, F31 Excitation frequency range F12 First frequency range F13 Second Frequency Range F34 Third Frequency Range G11, G121, G122, G123 graphs 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 hold the specimen by clamping it in a predetermined clamping direction, A load generating unit capable of operating over a predetermined excitation frequency range for an excitation operation that applies a vibration load to the test specimen by vibrating one of the pair of test specimen holding parts as the load-applying holding part in the vibration direction along the clamping direction, A sensor for measuring the acceleration of the load-side holding part, comprising a first sensor capable of measuring in a first frequency range that occupies the high-frequency side within the excitation frequency range, A sensor for measuring the speed or displacement of the load-side holding part, the second sensor capable of measuring a second frequency range that occupies a lower frequency side than the first frequency range while allowing partial overlap with the first frequency range in the excitation frequency range, A deformation amount acquisition unit that acquires the amount of deformation in the vibration direction generated in the vibration operation of the test specimen based on the measurement results of the first sensor or the second sensor, A load-load testing machine characterized by being equipped with the following features.

2. The deformation amount acquisition unit, If the excitation operation is an operation that applies a vibration load in the first frequency range, the deformation amount is obtained by double integration of the measurement results of the first sensor. If the excitation operation is an operation that applies a vibration load in the second frequency range and the second sensor is a sensor that measures velocity, the amount of deformation is obtained by single integration of the measurement result of the second sensor. The load testing machine according to claim 1, characterized in that the excitation operation is an operation to apply a vibration load in the second frequency range and the second sensor is a sensor that measures displacement, in which case the amount of deformation is obtained from the measurement result of the second sensor.

3. The load testing machine according to claim 1, characterized in that the deformation amount acquisition unit extracts a component of the excitation frequency in the excitation operation from the measurement result of the first sensor or the second sensor, and acquires the deformation amount using the extracted result.

4. A sensor provided on the receiving-side holding part of the pair of specimen holding parts, which receive the specimen and are separate from the loading-side holding part, for measuring the load applied from the specimen, and a load sensor capable of measuring over the entire range of the excitation frequency, 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-load testing machine according to claim 1, further comprising the features described above.

5. The deformation amount acquisition unit extracts the excitation frequency component in the excitation operation from the measurement results of the first sensor or the second sensor, and acquires the deformation amount using the extracted result. The load testing machine according to claim 4, characterized in that the characteristic acquisition unit extracts the excitation frequency component from the measurement result of the load sensor and acquires the excitation load using the extracted result.

6. The load generating unit comprises a movable part that holds the load-bearing side holding part and is movable in the direction of vibration, and a fixed part that is positioned adjacent to the movable part in a fixed state and includes a drive mechanism that moves the movable part in the direction of vibration to cause vibration. The load-load testing machine according to claim 1, characterized in that the second sensor comprises a movable part fixed to the movable part, and a measuring part fixed to the immovable part and provided with an output cable that measures the amount of movement of the movable part and outputs the measurement result.

7. The second sensor is a speed sensor, A sensor for measuring the displacement of the load-side holding portion, further comprising a third sensor capable of measuring displacement in a third frequency range that occupies an even lower frequency range than the second frequency range, while allowing partial overlap with the second frequency range measurable by the velocity sensor within the excitation frequency range, The load testing machine according to claim 1, characterized in that the deformation amount acquisition unit acquires the deformation amount from the measurement result of the third sensor when the excitation operation is an operation that applies a vibration load in the third frequency range.

8. The load generating unit comprises a movable part on which the load-bearing side holding part is provided and which is movable in the direction of vibration, and a fixed part which is positioned adjacent to the movable part in a fixed state and includes a drive mechanism that moves the movable part in the direction of vibration to cause vibration. The load testing machine according to claim 7, characterized in that at least the third sensor among the second and third sensors comprises a movable part fixed to the movable part and a measuring part fixed to the immovable part and provided with an output cable that measures the amount of movement of the movable part and outputs the measurement result.

9. The load testing machine according to claim 7, characterized in that the deformation amount acquisition unit extracts a component of the excitation frequency in the excitation operation from the measurement results of the first sensor, the second sensor, or the third sensor, and acquires the deformation amount using the extracted result.

10. The load generating unit causes the load-bearing holding unit to vibrate in the vibration direction along a predetermined axis, The load-load testing machine according to claim 1, characterized in that the first sensor is positioned on the axis of the load-bearing holding portion.

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