JP7826437B2 - LOAD TEST DEVICE, LOAD DETECTION UNIT, AND LOAD TEST METHOD - Google Patents

Description

The present invention relates to a load testing device for measuring horizontal loads on test specimens such as laminated rubber bearings.

Conventionally, there is known a load testing device that measures the horizontal load (horizontal resistance) on a test specimen, such as a laminated rubber bearing, when a vertical load is applied to the top surface of the test specimen while the bottom surface of the test specimen is displaced horizontally.

For example, the load testing device described in Patent Document 1 includes a movable base on which a test object is placed and which can be moved horizontally by a horizontal actuator, a first pressure member that contacts the top surface of the test object, a laminated rubber placed on the first pressure member, a second pressure member that is placed on the laminated rubber and can be moved vertically by a vertical actuator, and a load cell that measures the horizontal load applied to the first pressure member.

In the load testing device described in Patent Document 1, the horizontal load applied to the first pressure member measured by the load cell is the sum of the horizontal loads of the test specimen and the laminated rubber, and does not include the frictional force of the means for horizontally moving the movable base (roller bearings, linear guides, etc.). Furthermore, laminated rubber has high vertical stiffness but low horizontal stiffness, and its horizontal load is proportional to the amount of horizontal displacement. Therefore, if the horizontal movement of the movable base is extremely small, the horizontal load of the laminated rubber included in the load cell measurement can be reduced. Therefore, the load testing device described in Patent Document 1 can measure the horizontal load of the test specimen with high accuracy.

JP 2016-45100 A

As mentioned above, laminated rubber has high vertical stiffness but low horizontal stiffness, and its horizontal load is proportional to the amount of horizontal displacement. For this reason, in the load testing device described in Patent Document 1, as the horizontal movement of the movable base increases, the horizontal load of the laminated rubber included in the load cell measurement value also increases proportionally. The lower the horizontal stiffness of the laminated rubber, the smaller the load can be made, but to do so, it is necessary to increase the number of laminated rubber layers, which results in an increase in the size of the load testing device.

The present invention was made in consideration of the above circumstances, and its object is to make it possible to measure the horizontal load on a test specimen with greater accuracy.

To solve the above problem, the present invention uses a load detection unit that has a mounting table on which a test specimen such as a laminated rubber bearing is placed and which can be moved horizontally by a horizontal actuator.

Here, the load detection unit according to the present invention further includes a support plate that is movable in the horizontal direction, a bearing placed on the support plate and supporting the mounting table so that the mounting table is movable in the horizontal direction relative to the support plate, a first load cell that measures the horizontal load applied to the mounting table, and a second load cell that is arranged between the mounting table and the support plate and measures the horizontal load applied to the support plate. The bearing may be a rubber bearing or a roller bearing.

For example, the load testing device according to the present invention may include:
A load testing device that measures a horizontal load applied to a test body when a vertical load is applied to an upper surface of the test body and a lower surface of the test body is displaced in the horizontal direction,
a load detection unit having a mounting table on which the test object is placed and which is movable in a horizontal direction by a horizontal actuator;
a pressure plate that contacts the upper surface of the test piece and is movable in the vertical direction by a vertical actuator;
The load detection unit
A support plate that is horizontally movable;
a support placed on the support plate and supporting the placement table so as to be horizontally movable relative to the support plate;
a first load cell for measuring a horizontal load applied to the mounting table;
The apparatus further includes a second load cell disposed between the mounting table and the support plate, for measuring a horizontal load applied to the support plate.

In the present invention, when a vertical load is applied to the pressure plate by the vertical actuator while the mounting table is moved horizontally by the horizontal actuator, the horizontal load applied to the mounting table, which is the measurement value of the first load cell, is the sum of the horizontal load of the test object and the frictional force of the means for horizontally moving the support plate (roller bearings, linear guides, etc.), and can be expressed as the sum of the horizontal load of the test object, the horizontal load applied to the support plate, and the horizontal load of the bearing, which are measurements of the second load cell. Therefore, the horizontal load of the test object can be calculated by subtracting the measurement value of the second load cell and the horizontal load of the bearing from the measurement value of the first load cell.

Here, the horizontal load applied to the support plate, which is the measurement value of the second load cell, is the value obtained by subtracting the horizontal load of the support from the frictional force of the means for moving the support plate horizontally (roller bearings, linear guides, etc.). Therefore, in the above calculation of the horizontal load on the test specimen, by subtracting the measurement value of the second load cell from the measurement value of the first load cell, which is the sum of the horizontal load on the test specimen and the frictional force of the means for moving the support plate horizontally, the influence of the frictional force of the means for moving the support plate horizontally can be removed from the calculated value.

Furthermore, if the bearing is a rubber bearing, the horizontal load on the bearing is the product of its shear spring constant and its horizontal displacement. Here, the horizontal displacement of the bearing is the same as the displacement of the second load cell, so it can be expressed using the measurement value and stiffness of the second load cell. Therefore, the horizontal load on the bearing can be expressed using the shear spring constant of the bearing and the measurement value and stiffness of the second load cell. Therefore, the horizontal load on the test specimen calculated using the measurements of the first and second load cells depends on the shear spring constant of the bearing. However, the shear spring constant of the bearing is extremely small compared to the stiffness of the second load cell. The influence of this can be minimized by determining the shear spring constant of the bearing in advance or periodically. Meanwhile, the load detection unit configuration can be simplified, allowing for a more compact load testing device.

Furthermore, if the bearing is a roller bearing, the horizontal load applied to the bearing is the product of its friction coefficient and the vertical load applied by the vertical actuator. Therefore, the horizontal load of the test specimen calculated using the measurements of the first and second load cells depends on the friction coefficient of the bearing. Therefore, in order to determine the horizontal load of the test specimen with high accuracy, it is necessary to make the friction coefficient of the bearing as low as possible. By determining the friction coefficient of the bearing in advance or periodically, its influence can be reduced. At the same time, the load detection unit can be simplified in configuration, allowing the load testing device to be made smaller.

FIG. 1 is a schematic diagram of a load testing device 1 according to a first embodiment of the present invention. FIG. 2 is a diagram for explaining the loads applied to the various components of the load testing device 1. As shown in FIG. FIG. 3 is a flow diagram for explaining a load testing method using the load testing device 1. As shown in FIG. FIG. 4 is a schematic diagram of a modified example 1a of the load testing device 1. In FIG. FIG. 5 is a diagram for explaining the loads applied to the various components in the modified example 1b of the load testing device 1. In FIG. FIG. 6 is a schematic diagram of a load testing device 2 according to a second embodiment of the present invention. FIG. 7 is a diagram for explaining the loads applied to the various parts of the load testing device 2. As shown in FIG. FIG. 8 is a flow diagram for explaining a load testing method using the load testing device 2. FIG. 9 is a diagram for explaining the load applied to each part in the modified example 2a of the load testing device 2.

The following describes an embodiment of the present invention with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic diagram of a load testing device 1 according to the present embodiment.

The load testing device 1 according to this embodiment is a device for measuring the horizontal load (horizontal resistance) of a test specimen 3, such as a laminated rubber bearing, and as shown in the figure, is equipped with a fixed base 10 with a U-shaped cross section, a load detection unit 11, a pressure plate 12, a vertical actuator 13, a horizontal actuator 14, a horizontal movement mechanism 15, and a vertical movement mechanism 16.

The horizontal movement mechanism 15 is composed of roller bearings, linear guides, etc., and supports the load detection unit 11 so that it can move horizontally relative to the fixed base 10.

The vertical movement mechanism 16 is composed of roller bearings, linear guides, etc., and supports the pressure plate 12 so that it can move vertically relative to the fixed base 10.

The vertical actuator 13 is attached to the fixed base 10 and applies pressure to the pressure plate 12 in the vertical direction.

The horizontal actuator 14 is attached to the fixed base 10 and applies pressure to the load detection unit 11 in the horizontal direction.

The pressure plate 12 abuts against the upper surface of the test specimen 3 and applies pressure to the test specimen 3 by moving it vertically using the vertical actuator 13 and vertical movement mechanism 16.

The load detection unit 11 is used to measure the values required to calculate the horizontal load on the test specimen 3, and includes a mounting table 110 for mounting the test specimen 3, a first support plate 111, a first rubber bearing 112, a second support plate 113, a second rubber bearing 114, a third support plate 115, a third rubber bearing 116, a first load cell 117, a second load cell 118, and a third load cell 119.

The first support plate 111 is placed on the horizontal movement mechanism 15 and is movable horizontally relative to the fixed base 10. A first rubber bearing 112 is placed on the first support plate 111.

The second support plate 113 is placed on the first rubber bearing 112 and is movable horizontally relative to the first support plate 111. A second rubber bearing 114 is placed on the second support plate 113.

The third support plate 115 is placed on the second rubber bearing 114 and is connected to the first support plate 111 by a connecting portion 1151 so that it moves in the same direction and by the same amount as the first support plate 111 relative to the second support plate 113. A third rubber bearing 116 is placed on the third support plate 115.

The loading table 110 is placed on a third rubber bearing 116 and is movable horizontally relative to the third support plate 115. The loading table 110 also has side walls 1101 and 1102 at both ends, and moves horizontally when the side wall 1101 is pressed horizontally by the horizontal actuator 14.

The first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116 have the same shear spring constant.

The first load cell 117 is positioned between the side wall 1101 of the mounting table 110 and the horizontal actuator 14, and measures the horizontal load applied to the mounting table 110 (the horizontal load between the mounting table 110 and the fixed base 10).

The second load cell 118 is positioned between the side wall 1101 of the mounting table 110 and the connecting portion 1151 of the first support plate 111 and the third support plate 115, and measures the horizontal load applied to the first support plate 111 and the third support plate 115 (the horizontal load between the first support plate 111 and the third support plate 115 and the mounting table 110).

The third load cell 119 is positioned between the side wall 1102 of the mounting table 110 and the second support plate 113, and measures the horizontal load applied to the second support plate 113 (the horizontal load between the second support plate 113 and the mounting table 110).

Figure 2 is a diagram illustrating the loads applied to each part of the load testing device 1 according to this embodiment.

As shown in the figure, when a vertical load N is applied to the pressure plate 12 by the vertical actuator 13 while the mounting table 110 is moved horizontally by the horizontal actuator 14, the horizontal load F1 applied to the mounting table 110, which is the measurement value of the first load cell 117, is the sum of the horizontal load Fh of the test specimen 3 and the friction force of the horizontal movement mechanism 15. If the friction coefficient of the horizontal movement mechanism 15 is μ, the measurement value F1 of the first load cell 117 can be expressed by Equation 1.

Furthermore, the measurement value F1 of the first load cell 117 can be expressed as the sum of the horizontal load Fh of the test specimen 3, the horizontal load F2 applied to the first support plate 111 and the third support plate 115, which is the measurement value of the second load cell 118, the horizontal load F3 applied to the second support plate 113, which is the measurement value of the third load cell 119, and the horizontal load of the third rubber bearing 116. Therefore, the horizontal load Fh of the test specimen 3 can be calculated by subtracting the measurement value F2 of the second load cell 118, the measurement value F3 of the third load cell 119, and the horizontal load of the third rubber bearing 116 from the measurement value F1 of the first load cell 117. Here, if the shear spring constant of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116 is kr and the displacement of the third rubber bearing 116 is dx2, the horizontal load Fh on the test specimen 3 can be expressed by Equation 2.

Here, the horizontal load F2 applied to the first support plate 111 and the third support plate 115, which is the measurement value of the second load cell 118, is the friction force μ·N of the horizontal movement mechanism 15 minus the horizontal loads of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116. Because the first support plate 111 and the third support plate 115 move the same amount in the same direction relative to the second support plate 113, the displacement amounts of the first rubber bearing 112 and the second rubber bearing 114 are the same. If the displacement amounts of the first rubber bearing 112 and the second rubber bearing 114 are dxr, the horizontal load F2 applied to the first support plate 111 and the third support plate 115, which is the measurement value of the second load cell 118, can be expressed by Equation 3.

As shown in Equation 3, the measurement value F2 of the second load cell 118 includes the frictional force μ·N of the horizontal movement mechanism 15. Therefore, in Equation 2, by subtracting the measurement value F2 of the second load cell 118 from the measurement value F1 (see Equation 1) of the first load cell 117, which is the sum of the horizontal load Fh of the test specimen 3 and the frictional force μ·N of the horizontal movement mechanism 15, the influence of the frictional force μ·N of the horizontal movement mechanism 15 can be removed from the calculated value of the horizontal load Fh of the test specimen 3.

Furthermore, the horizontal load F3 applied to the second support plate 113, which is the measurement value of the third load cell 119, is the sum of the horizontal loads applied to the first rubber bearing 112 and the second rubber bearing 114, and can be expressed by Equation 4.

Furthermore, from Equation 4, the shear spring constant kr of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116 can be expressed by Equation 5 using the measurement value F3 of the third load cell and the displacement dxr of the first rubber bearing 112 and the second rubber bearing 114.

Furthermore, the displacement dxr of the first rubber bearing 112 and the second rubber bearing 114 is the value obtained by subtracting the displacement of the third load cell 119 from the displacement of the second load cell 118, and the displacement of the second load cell 118 is the same as the horizontal displacement dx2 of the third rubber bearing 116. If the displacement of the third load cell 119 is dx3, the displacement dxr of the first rubber bearing 112 and the second rubber bearing 114 can be expressed by Equation 6.

Furthermore, the measurement value F2 of the second load cell 118 is the product of the stiffness of the second load cell 118 and the displacement dx2. Therefore, if the stiffness of the second load cell 118 is k2, the displacement dx2 of the second load cell 118 can be expressed by Equation 7.

Similarly, the measurement value F3 of the third load cell 119 is the product of the stiffness of the third load cell 119 and the displacement dx3. Therefore, if the stiffness of the third load cell 119 is k3, the displacement dx3 of the third load cell 119 can be expressed by equation 8.

From equations 5 to 8, the shear spring constant kr of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116 can be expressed by equation 9 using the measured values F2 and F3 and stiffness k2 and k3 of the second load cell 118 and the third load cell 119, respectively.

Therefore, the horizontal load Fh on test specimen 3 can be expressed by equation 10, and the horizontal load Fh on test specimen 3 can be calculated using the measured values F1 to F3 of the first to third load cells 117 to 119, without relying on the shear spring constant kr of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116.

Figure 3 is a flow diagram illustrating a load testing method using the load testing device 1 according to this embodiment.

First, while a vertical load N is applied to the pressure plate 12 by the vertical actuator 13, the horizontal actuator 14 moves the mounting table 110 in the horizontal direction (S10). As a result, the upper surface of the test specimen 3 is pressurized by the vertical load N, while the lower surface is displaced horizontally, generating a horizontal load Fh.

Next, the measurement values F1 to F3 of the first to third load cells 117 to 119 are obtained (S11). The obtained measurement values F1 to F3 of the first to third load cells 117 to 119 are then sent to an information processing device such as a personal computer, and the information processing device then substitutes the measurement values F1 to F3 into the above-mentioned equation 10 to calculate the horizontal load Fh of the test specimen 3 (S12).

In this embodiment, the horizontal load Fh of the test specimen 3 is calculated by substituting the measured values F1 to F3 of the first to third load cells 117 to 119 into the above-mentioned equation (10), thereby eliminating the influence of the friction force μ·N of the horizontal movement mechanism 15 from this calculated value. Furthermore, the horizontal load Fh of the test specimen 3 can be calculated without relying on the shear spring constant kr of the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116. Therefore, this embodiment allows the horizontal load Fh of the test specimen 3 to be measured with higher accuracy.

In this embodiment, when the horizontal actuator 14 moves the mounting table 110 horizontally, causing the test specimen 3 to deform as shown in Figure 2, if the amount of deformation becomes large, a rotational moment acts on the mounting table 110, causing the mounting table 110 to tend to rotate (tilt) clockwise. Rubber has low tensile stiffness and is prone to deformation. Therefore, to counter this, a rotation prevention mechanism may be employed for the first rubber bearing 112, second rubber bearing 114, and third rubber bearing 116.

In the modified example 1a of the load testing apparatus 1 shown in Figure 4, a bolt 17 having a horizontal movement mechanism 170 such as a roller bearing or a sliding bearing is used as the anti-rotation mechanism for the first rubber bearing 112, the second rubber bearing 114, and the third rubber bearing 116. The mounting table 110, the second support plate 113, and the third support plate 115 are respectively formed with through holes 1103, 1130, and 1150 having a diameter larger than the diameter of the bolt 17, and the top surface of the first support plate 111 (the mounting surface of the first rubber bearing 112) is formed with a screw hole 1110 that screws into the threaded portion formed at the tip of the bolt 17. The bolt 17 is passed through the through-hole 1103 in the mounting table 110, the through-hole 1150 in the third support plate 115, and the through-hole 1130 in the second support plate 113, and with the horizontal movement mechanism 170 interposed between the screw head and the upper surface of the mounting table 110 (the surface on which the test specimen 3 is mounted), the tip of the bolt is screwed into the threaded hole 1110 in the first support plate 111. This allows horizontal movement of the mounting table 110 and second support plate 113 relative to the first support plate 111 while restricting vertical movement, preventing rotation of the first rubber bearing 112, second rubber bearing 114, and third rubber bearing 116.

In addition, in this embodiment, rubber bearings with the same spring shear constant are used as the first bearing that supports the second support plate 113 so that it can move horizontally relative to the first support plate 111, the second bearing that supports the third support plate 115 so that it can move horizontally relative to the second support plate 113, and the third bearing that supports the loading table 110 so that it can move horizontally relative to the third support plate 115. However, the present invention is not limited to this. Roller bearings, sliding bearings, etc. with the same friction coefficient may also be used as the first to third bearings.

In the modified example 1b of the load testing device 1 shown in Figure 5, instead of the first rubber bearing 112, second rubber bearing 114, and third rubber bearing 116, which have the same shear spring constant, a first roller bearing 120, second roller bearing 121, and third roller bearing 122, which have the same friction coefficient, are used.

As shown in the figure, when a vertical load N is applied to the pressure plate 12 by the vertical actuator 13 while the loading table 110 is moved horizontally by the horizontal actuator 14, the horizontal load F1 applied to the loading table 110, which is the measurement value of the first load cell 117, is the sum of the horizontal load Fh of the test specimen 3 and the friction force μ·N of the horizontal movement mechanism 15, as shown in equation 1.

Furthermore, the measurement value F1 of the first load cell 117 can be expressed as the sum of the horizontal load Fh of the test specimen 3, the horizontal load F2 applied to the first support plate 111 and the third support plate 115, which is the measurement value of the second load cell 118, the horizontal load F3 applied to the second support plate 113, which is the measurement value of the third load cell 119, and the horizontal load Fh of the third roller bearing 122. Therefore, the horizontal load Fh of the test specimen 3 can be calculated by subtracting the measurement value F2 of the second load cell 118, the measurement value F3 of the third load cell 119, and the horizontal load Fh of the third roller bearing 122 from the measurement value F1 of the first load cell 117. Here, if the friction coefficient of the first roller bearing 120, the second roller bearing 121, and the third roller bearing 122 is μr, the horizontal load Fh on the test specimen 3 can be expressed by equation 11.

Here, the horizontal load F2 applied to the first support plate 111 and the third support plate 115, which is the measurement value of the second load cell 118, is the friction force μ·N of the horizontal movement mechanism 15 minus the horizontal loads of the first roller bearing 120, the second roller bearing 121, and the third roller bearing 122, as shown in equation 12.

As shown in Equation 12, the measurement value F2 of the second load cell 118 includes the frictional force μ·N of the horizontal movement mechanism 15. Therefore, in Equation 11, by subtracting the measurement value F2 of the second load cell 118 from the measurement value F1 of the first load cell 117 (see Equation 1), which is the sum of the horizontal load Fh of the test specimen 3 and the frictional force μ·N of the horizontal movement mechanism 15, the influence of the frictional force μ·N of the horizontal movement mechanism 15 can be removed from the calculated value of the horizontal load Fh of the test specimen 3.

Furthermore, the horizontal load on the first roller bearing 120, second roller bearing 121, and third roller bearing 122 is the product of their friction coefficient μr and the vertical load N from the vertical actuator 13. Here, the horizontal load F3 applied to the second support plate 113, which is the measurement value of the third load cell 119, is the sum of the horizontal loads on the first roller bearing 120 and the second roller bearing 121, and can be expressed by equation 13.

Therefore, the friction coefficient μr of the first roller bearing 120, the second roller bearing 121, and the third roller bearing 122 can be expressed by equation 14 using the measurement value F3 of the third load cell 119.

Therefore, the horizontal load Fh on test specimen 3 can be expressed by equation 15.

Therefore, the horizontal load Fh applied to the test specimen 3 can be calculated using the measured values F1 to F3 of the first to third load cells 117 to 119, without relying on the friction coefficient μr of the first roller bearing 120, the second roller bearing 121, and the third roller bearing 122.

Second Embodiment
FIG. 6 is a schematic diagram of a load testing device 2 according to this embodiment.

The load testing device 2 according to this embodiment, like the load testing device 1 according to the first embodiment of the present invention, is a device for measuring the horizontal load (horizontal resistance) of a test specimen 3 such as a laminated rubber bearing, and as shown in the figure, is equipped with a fixed base 20 with a U-shaped cross section, a load detection unit 21, a pressure plate 22, a vertical actuator 23, a horizontal actuator 24, a horizontal movement mechanism 25, and a vertical movement mechanism 26.

The horizontal movement mechanism 25 is composed of roller bearings, linear guides, etc., and supports the load detection unit 21 so that it can move horizontally relative to the fixed base 20.

The vertical movement mechanism 26 is composed of roller bearings, linear guides, etc., and supports the pressure plate 22 so that it can move vertically relative to the fixed base 20.

The vertical actuator 23 is attached to the fixed base 20 and applies pressure to the pressure plate 22 in the vertical direction.

The horizontal actuator 24 is attached to the fixed base 20 and applies pressure to the load detection unit 21 in the horizontal direction.

The pressure plate 22 abuts against the upper surface of the test specimen 3 and applies pressure to the test specimen 3 by moving it vertically using the vertical actuator 23 and vertical movement mechanism 26.

The load detection unit 21 is used to measure the values necessary to calculate the horizontal load on the test specimen 3, and includes a mounting table 210 for mounting the test specimen 3, a support plate 211, a rubber bearing 212, a first load cell 213, and a second load cell 214.

The support plate 211 is placed on the horizontal movement mechanism 25 and is movable horizontally relative to the fixed base 20. A rubber bearing 212 is placed on the support plate 211.

The loading table 210 is placed on a rubber bearing 212 and is movable horizontally relative to the support plate 211. The loading table 210 also has a side wall portion 2101 at one end, and moves horizontally when the side wall portion 2101 is pressed horizontally by the horizontal actuator 24.

The first load cell 213 is positioned between the side wall 2101 of the mounting table 210 and the horizontal actuator 24, and measures the horizontal load applied to the mounting table 210 (the horizontal load between the mounting table 210 and the fixed base 20).

The second load cell 214 is positioned between the side wall 2101 of the mounting table 210 and the support plate 211, and measures the horizontal load applied to the support plate 211 (the horizontal load between the support plate 211 and the mounting table 210).

Figure 7 is a diagram illustrating the loads applied to each part of the load testing device 2 according to this embodiment.

As shown in the figure, when a vertical load N is applied to the pressure plate 22 by the vertical actuator 23 while the horizontal actuator 24 moves the mounting table 210 in the horizontal direction, the horizontal load F1 applied to the mounting table 210, which is the measurement value of the first load cell 213, is the sum of the horizontal load Fh of the test specimen 3 and the friction force of the horizontal movement mechanism 25. If the friction coefficient of the horizontal movement mechanism 25 is μ, this can be expressed by the above-mentioned equation 1.

Furthermore, the measurement value F1 of the first load cell 213 can be expressed as the sum of the horizontal load Fh of the test specimen 3, the horizontal load F2 applied to the support plate 211, which is the measurement value of the second load cell 214, and the horizontal load of the rubber bearing 212. Therefore, the horizontal load Fh of the test specimen 3 can be calculated by subtracting the measurement value F2 of the second load cell 214 and the horizontal load of the rubber bearing 212 from the measurement value F1 of the first load cell 213. Here, if the shear spring constant of the rubber bearing 212 is kr and its displacement is dx2, the horizontal load Fh of the test specimen 3 can be expressed by Equation 16.

Here, the horizontal load F2 applied to the support plate 211, which is the measurement value of the second load cell 214, is the value obtained by subtracting the horizontal load of the rubber bearing 212 from the friction force μ·N of the horizontal movement mechanism 25, and can be expressed by equation 17.

As shown in Equation 17, the measurement value F2 of the second load cell 214 includes the frictional force μ·N of the horizontal movement mechanism 25. Therefore, in Equation 16, by subtracting the measurement value F2 of the second load cell 214 from the measurement value F1 of the first load cell 213 (see Equation 1), which is the sum of the horizontal load Fh of the test specimen 3 and the frictional force μ·N of the horizontal movement mechanism 25, the influence of the frictional force μ·N of the horizontal movement mechanism 15 can be removed from the calculated value of the horizontal load Fh of the test specimen 3.

Furthermore, the displacement of the second load cell 214 is the same as the displacement dx2 of the rubber bearing 212. The measurement value F2 of the second load cell 214 is the product of the stiffness of the second load cell 214 and the displacement dx2. Therefore, if the stiffness of the second load cell 118 is k2, the displacement dx2 of the second load cell 214 can be expressed by equation 18.

Therefore, the horizontal load Fh on test specimen 3 can be expressed by equation 19.

According to equation 19, the horizontal load Fh on the test specimen 3 depends on the shear spring constant kr of the rubber bearing 212, unlike in the first embodiment of the present invention. However, the shear spring constant kr of the rubber bearing 212 is generally extremely small compared to the stiffness k2 of the second load cell 214. By determining the shear spring constant kr of the rubber bearing 212 in advance or periodically, its influence can be reduced. On the other hand, compared to the first embodiment of the present invention, the configuration of the load detection unit 21 can be simplified, allowing the load testing apparatus 2 to be made more compact.

Figure 8 is a flow diagram illustrating a load testing method using the load testing device 2 according to this embodiment.

First, while a vertical load N is applied to the pressure plate 22 by the vertical actuator 23, the horizontal actuator 24 moves the mounting table 210 in the horizontal direction (S20). As a result, while the upper surface of the test specimen 3 is pressurized by the vertical load N, its lower surface is displaced horizontally, generating a horizontal load Fh.

Next, the measurement values F1 and F2 of the first and second load cells 213 and 214 are obtained (S21). The obtained measurement values F1 and F2 of the first and second load cells 213 and 214 are then sent to an information processing device such as a personal computer, and the information processing device then substitutes the measurement values F1 and F2 into the above-mentioned equation 19 to calculate the horizontal load Fh of the test specimen 3 (S22).

In this embodiment, the horizontal load Fh of the test specimen 3 is calculated by substituting the measured values F1 and F2 of the first and second load cells 213 and 214 into the above-mentioned equation (19), thereby eliminating the effect of the friction force μ·N of the horizontal movement mechanism 25 from this calculated value. Also, unlike the first embodiment of the present invention, the calculated value of the horizontal load Fh of the test specimen 3 depends on the shear spring constant kr of the rubber bearing 212. However, the shear spring constant kr of the rubber bearing 212 is generally much smaller than the stiffness k2 of the second load cell 214. By determining the shear spring constant kr of the rubber bearing 212 in advance or periodically, this effect can be reduced. Meanwhile, compared to the first embodiment of the present invention, the configuration of the load detection unit 21 can be simplified, allowing for a more compact load testing apparatus 2.

In this embodiment, rubber bearings 212 are used as bearings that support the loading table 210 so that it can move horizontally relative to the support plate 211. However, the present invention is not limited to this. Roller bearings, sliding bearings, etc. may also be used as bearings that support the loading table 210 so that it can move horizontally relative to the support plate 211.

In the modified example 2a of the load testing device 2 shown in Figure 9, a roller bearing 215 is used instead of the rubber bearing 212.

As shown in the figure, when a vertical load N is applied to the pressure plate 22 by the vertical actuator 23 while the horizontal actuator 24 moves the mounting table 210 horizontally, the horizontal load F1 applied to the mounting table 210, measured by the first load cell 213, is the sum of the horizontal load Fh applied to the test specimen 3, the horizontal load F2 applied to the support plate 211, measured by the second load cell 24, and the horizontal load on the roller bearing 215. Therefore, the horizontal load Fh on the test specimen 3 can be calculated by subtracting the measurement F2 of the second load cell 214 and the horizontal load on the roller bearing 215 from the measurement F1 of the first load cell 213. Here, if the coefficient of friction of the roller bearing 215 is μr, the horizontal load Fh on the test specimen 3 can be expressed by Equation 20.

According to equation 20, the horizontal load Fh of the test specimen 3 depends on the friction coefficient μr of the roller bearing 215, unlike in variant 1b of the first embodiment of the present invention. Therefore, to reduce the influence of the horizontal load of the roller bearing 215 on the calculated value of the horizontal load Fh of the test specimen 3, it is necessary to reduce the friction coefficient μr of the roller bearing 215. By determining the friction coefficient μr of the roller bearing 215 in advance or periodically, this influence can be reduced. On the other hand, compared to variant 1b of the first embodiment of the present invention, the configuration of the load detection unit 21 can be simplified, allowing the load testing apparatus 2 to be made more compact.

The above describes an embodiment of the present invention.

The present invention is not limited to the above-described embodiments, and many variations are possible within the scope of its essence.

For example, in each of the above embodiments, a load testing device that measures the applied load in one horizontal direction of the test specimen 3 has been described as an example. However, the present invention is not limited to this. The present invention can also be applied to a load testing device that measures the applied load in two orthogonal directions to the horizontal direction of the test specimen 3.

For example, in the load testing apparatus 1, 1a shown in Figures 1 and 4, an XY stage or the like is used as the horizontal movement mechanism 15, which supports the load detection unit 11 so that it can move in two orthogonal directions relative to the fixed base 10. Then, in each of the cross-sectional views in the two orthogonal directions in the horizontal direction, the fixed base 10 and the mounting table 110 are formed to have the configuration of the load testing apparatus 1, 1a shown in Figures 1 and 4, and two horizontal actuators 14, two vertical movement mechanisms 16, two first load cells 117, two second load cells 118, and two third load cells 119 are provided.

In addition, in the load testing apparatus 1b shown in Figure 5, an XY stage or the like is used as the horizontal movement mechanism 15, which supports the load detection unit 11 so that it can move in two orthogonal directions horizontally relative to the fixed base 10; instead of the first roller support 120, an XY stage or the like is used, which supports the second support plate 113 so that it can move in two orthogonal directions horizontally relative to the first support plate 111; instead of the second roller support 121, an XY stage or the like is used, which supports the third support plate 115 so that it can move in two orthogonal directions horizontally relative to the second support plate 113; and instead of the third roller support 122, an XY stage or the like is used, which supports the mounting table 110 so that it can move in two orthogonal directions horizontally relative to the third support plate 115. Then, in each of the two cross-sectional views in two directions perpendicular to the horizontal direction, the fixed base 10 and the mounting table 110 are formed to have the configuration of the load testing device 1b shown in Figure 5, and two horizontal actuators 14, two vertical movement mechanisms 16, two first load cells 117, two second load cells 118, and two third load cells 119 are provided.

In addition, in the load testing device 2 shown in Figure 6, an XY stage or the like is used as the horizontal movement mechanism 25, which supports the load detection unit 21 so that it can move in two orthogonal horizontal directions relative to the fixed base 20. The fixed base 20 and mounting table 210 are formed so that the load testing device 2 has the configuration shown in Figure 6 in each of the two orthogonal horizontal cross-sectional views, and two horizontal actuators 24, two vertical movement mechanisms 26, two first load cells 213, and two second load cells 214 are provided.

In addition, in the load testing apparatus 2a shown in Figure 9, an XY stage or the like is used as the horizontal movement mechanism 25, which supports the load detection unit 21 so that it can move in two orthogonal directions relative to the fixed base 20, and an XY stage or the like is used instead of the roller bearings 215, which supports the mounting table 210 so that it can move in two orthogonal directions relative to the support plate 211. Then, in each of the two orthogonal horizontal cross-sectional views, the fixed base 20 and mounting table 210 are formed to have the configuration of the load testing apparatus 2a shown in Figure 9, and two horizontal actuators 24, two vertical movement mechanisms 26, two first load cells 213, and two second load cells 214 are provided.

1, 1a, 1b, 2, 2a: Load testing device 3: Test piece 10, 20: Fixed base 11, 21: Load detection unit 12, 22: Pressure plate 13, 23: Vertical actuator 14, 24: Horizontal actuator 15, 25, 170: Horizontal movement mechanism 16, 26: Vertical movement mechanism 17: Bolt 110, 210: Placement table 111: First support plate 112: First rubber bearing 113: Second support plate 114: Second rubber bearing 115: Third support plate 116: Third rubber bearing 117, 213: First load cell 118, 214: Second load cell 119: Third load cell 120: First roller bearing 121: Second roller bearing 122: Third roller bearing 211: Support plate 212: Rubber bearing 215: Roller bearing 1151: Connecting portion 1101, 1102, 2101: Side wall portion 1103, 1130, 1150: Through hole

Claims (7)

A load testing device that measures a horizontal load applied to a test body when a vertical load is applied to an upper surface of the test body and a lower surface of the test body is displaced in the horizontal direction,
a load detection unit having a mounting table on which the test object is placed and which is movable in a horizontal direction by a horizontal actuator;
a pressure plate that contacts the upper surface of the test piece and is movable in the vertical direction by a vertical actuator;
The load detection unit
A support plate that is horizontally movable;
a support placed on the support plate and supporting the placement table so as to be horizontally movable relative to the support plate;
a first load cell for measuring a horizontal load applied to the mounting table;
a second load cell disposed between the mounting table and the support plate, for measuring a horizontal load applied to the support plate. 2. The load testing apparatus according to claim 1 ,
The load testing device, wherein the bearing is a rubber bearing. 2. The load testing apparatus according to claim 1 ,
The load testing device, wherein the bearing is a roller bearing. A load detection unit used to measure a horizontal load applied to a test specimen,
a mounting table on which the test specimen is placed and which is movable in a horizontal direction;
A support plate that is movable in a horizontal direction;
a support placed on the support plate and supporting the placement table so as to be horizontally movable relative to the support plate;
a first load cell for measuring a horizontal load applied to the mounting table;
a second load cell disposed between the mounting table and the support plate, the second load cell measuring a horizontal load applied to the support plate. A load test method for measuring a horizontal load on a test specimen using a load test device, comprising:
The load testing device
a load detection unit having a mounting table on which the test object is placed and which is movable in a horizontal direction by a horizontal actuator;
a pressure plate that contacts the upper surface of the test piece and is movable in the vertical direction by a vertical actuator;
The load detection unit
A support plate that is horizontally movable;
a support placed on the support plate and supporting the placement table so as to be horizontally movable relative to the support plate;
a first load cell for measuring a horizontal load applied to the mounting table;
a second load cell disposed between the mounting table and the support plate and configured to measure a horizontal load applied to the support plate;
a vertical actuator is used to move the pressure plate in a vertical direction, thereby applying a vertical load to the upper surface of the test body, and a horizontal actuator is used to move the mounting table in a horizontal direction, thereby displacing the lower surface of the test body in a horizontal direction, thereby obtaining measurement values of the first load cell and the second load cell;
a load applied to the test body in the horizontal direction is calculated using the acquired measured values of the first load cell and the second load cell. 6. The load testing method according to claim 5 ,
The bearing is a rubber bearing,
The horizontal load Fh of the test specimen is expressed as follows: F1 is the measurement value of the first load cell, F2 is the measurement value of the second load cell, k2 is the rigidity of the second load cell, and kr is the shear spring constant of the support.
A load testing method characterized by calculating the load. 6. The load testing method according to claim 5 ,
the bearing is a roller bearing;
The measurement value of the first load cell is F1, the measurement value of the second load cell is F2, the friction coefficient of the bearing is μr, and the vertical load applied to the pressure plate by the vertical actuator is N, then the horizontal load Fh of the test specimen is
A load testing method characterized by calculating the load.