JP7577609B2 - LOAD TESTING APPARATUS, LOAD DETECTION UNIT, AND LOAD TESTING METHOD - Google Patents

Description

The present invention relates to a load testing device that measures the horizontal load on a test specimen such as a laminated rubber bearing.

Conventionally, a load testing device is known that measures the horizontal load (horizontal resistance) applied to a test specimen, such as a laminated rubber bearing, when a vertical load is applied to the upper surface of the test specimen while the lower 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 upper 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 which 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 horizontal movement means of the movable base (roller bearings, linear guides, etc.). Furthermore, the laminated rubber has high vertical stiffness and low horizontal stiffness, and its horizontal load is proportional to the horizontal displacement. For this reason, if the horizontal movement of the movable base is extremely small, the horizontal load of the laminated rubber included in the measurement value of the load cell 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 and 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 measurement value of the load cell 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 higher accuracy.

To solve the above problem, the present invention uses a load detection unit that moves vertically using a vertical actuator to apply pressure to a test specimen such as a laminated rubber bearing.

Here, the load detection unit has a first pressure plate that contacts the upper surface of the test specimen, a first support placed on the first pressure plate, a second pressure plate arranged on the first support and movable horizontally relative to the first pressure plate, a second support placed on the second pressure plate, a third pressure plate arranged on the second support and connected to the first pressure plate so as to move the same amount in the same direction as the first pressure plate relative to the second pressure plate, a third support placed on the third pressure plate, a load transmission frame arranged on the third support and movable vertically by a vertical actuator, a first load cell arranged between the load transmission frame and the first and third pressure plates to measure the horizontal load applied to the first and third pressure plates, and a second load cell arranged between the load transmission frame and the second pressure plate to measure the horizontal load applied to the second pressure plate. The first to third bearings may be rubber bearings with the same shear spring constant, or roller bearings with the same coefficient of friction.

For example, the load testing device of the present invention
A load testing device for measuring a horizontal load on 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 a horizontal direction, comprising:
a mounting table on which the test specimen is placed and which is movable in a horizontal direction by a horizontal actuator;
A load detection unit that is moved vertically by a vertical actuator to apply pressure to the test body,
The load detection unit includes:
A first pressure plate that contacts the upper surface of the test specimen;
a first support placed on the first pressure plate;
a second pressure plate disposed on the first support and horizontally movable relative to the first pressure plate;
a second support placed on the second pressure plate;
a third pressure plate disposed on the second support and connected to the first pressure plate so as to move in the same direction and by the same amount relative to the second pressure plate as the first pressure plate;
a third support placed on the third pressure plate;
a load transfer frame disposed on the third support and vertically movable by the vertical actuator;
a first load cell disposed between the load transmission frame and the first and third pressure plates, the first load cell measuring a horizontal load applied to the first and third pressure plates;
and a second load cell arranged between the load transmission frame and the second pressure plate for measuring a horizontal load applied to the second pressure plate.

In the present invention, when a vertical load is applied to the load transmission frame by the vertical actuator while the mounting table is moved horizontally by the horizontal actuator, the horizontal load applied to the first pressure plate and the third pressure plate, which is the measurement value of the first load cell, is the horizontal load of the test object minus the horizontal loads of the first to third supports. Furthermore, the horizontal load applied to the second pressure plate, which is the measurement value of the second load cell, is the sum of the horizontal loads of the first and second supports. In this way, the measurement values of the first and second load cells do not include the frictional force of the horizontal movement means of the mounting table.

Here, if the first to third bearings are rubber bearings with the same shear spring constant, the horizontal load of these bearings is the product of this shear spring constant and its horizontal displacement. Here, the horizontal load applied to the second pressure plate, which is the measurement value of the second load cell, is the sum of the horizontal loads of the first and second bearings, so the shear spring constant can be expressed by the measurement value of the second load cell and the horizontal displacement of the first and second bearings. In addition, the horizontal displacement of the first and second bearings is the value obtained by subtracting the displacement of the second load cell from the displacement of the first load cell, and the displacement of each of the first and second load cells can be expressed using the respective measurement values and rigidity. Therefore, the horizontal load of the test specimen can be calculated using the measurements of the first and second load cells without depending on the shear spring constants of the first to third bearings.

Furthermore, if the first to third bearings are roller bearings with the same friction coefficient, the horizontal load on these bearings is the product of this friction coefficient and the vertical load from the vertical actuator. Here, the horizontal load applied to the second pressure plate, which is the measurement value of the second load cell, is the sum of the horizontal loads on the first and second bearings, so the friction coefficient can be expressed as the measurement value of the second load cell and the vertical load from the vertical actuator. Therefore, the horizontal load on the test specimen can be calculated using the measurements of the first and second load cells, without relying on the friction coefficients of the first to third bearings.

In this way, the present invention makes it possible to measure the horizontal load on the test specimen with greater precision.

FIG. 1 is a schematic diagram of a load testing device 1 according to an 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 load applied to each part in the modified example 1b of the load testing device 1. In FIG.

Below, one embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a schematic diagram of a load testing device 1 according to this 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 mounting table 11, a load detection unit 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 loading table 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 load detection unit 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 load detection unit 12 in the vertical direction.

The horizontal actuator 14 is attached to the fixed base 10 and applies pressure to the mounting table 11 in the horizontal direction.

The test specimen 3 is placed on the mounting table 11, which is moved horizontally by the horizontal actuator 14 and the horizontal movement mechanism 15, displacing the underside of the test specimen 3 in the horizontal direction.

The load detection unit 12 is for measuring the measurements required to calculate the horizontal load of the test specimen 3, and includes a load transmission frame 120, a first pressure plate 121, a first rubber bearing 122, a second pressure plate 123, a second rubber bearing 124, a third pressure plate 125, a third rubber bearing 126, a first load cell 127, and a second load cell 128.

The first pressure plate 121 is in contact with the upper surface of the test specimen 3. In addition, a first rubber bearing 122 is placed on the first pressure plate 121.

The second pressure plate 123 is disposed on the first rubber bearing 122 and is movable horizontally relative to the first pressure plate 121. The second rubber bearing 124 is placed on the second pressure plate 123.

The third pressure plate 125 is disposed on the second rubber bearing 124 and is connected to the first pressure plate 121 by a connecting part 1251 so that it moves in the same direction and by the same amount as the first pressure plate 121 relative to the second pressure plate 123. The third rubber bearing 126 is placed on the third pressure plate 125.

The load transmission frame 120 has an L-shaped cross section with a side wall portion 1201 formed at the end on the fixed base 10 side, and is placed on the third rubber bearing 126. The load transmission frame 120 also moves vertically by the vertical actuator 13 and the vertical movement mechanism 16. As a result, the third pressure plate 125, the second pressure plate 123, and the first pressure plate 121 are pressurized via the third rubber bearing 126, the second rubber bearing 124, and the first rubber bearing 122, respectively, and finally the first pressure plate 121 presses the test specimen 3.

The first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126 have the same shear spring constant.

The first load cell 127 is disposed between the side wall portion 1201 of the load transmission frame 120 and the first pressure plate 121, and measures the horizontal load applied to the first pressure plate 121 and the third pressure plate 125 connected to the first pressure plate 121 by the connecting portion 1251 (the horizontal load between the first pressure plate 121 and the third pressure plate 125 and the load transmission frame 120).

The second load cell 128 is disposed between the side wall portion 1201 of the load transmission frame 120 and the second pressure plate 123, and measures the horizontal load applied to the second pressure plate 123 (the horizontal load between the second pressure plate 123 and the load transmission frame 120).

Figure 2 is a diagram for explaining the load 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 load transmission frame 120 by the vertical actuator 13 while the mounting table 11 is moved horizontally by the horizontal actuator 14, the horizontal load F1 applied to the first pressure plate 121 and the third pressure plate 125, which is the measurement value of the first load cell 127, is the horizontal load Fh of the test specimen 3 minus the horizontal loads of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126. The horizontal load F2 applied to the second pressure plate 123, which is the measurement value of the second load cell 128, is the sum of the horizontal loads of the first rubber bearing 122 and the second rubber bearing 124. In this way, the measured values F1 and F2 of the first load cell 127 and the second load cell 128 do not include the frictional force of the horizontal movement mechanism 15 (which is μ·N when the friction coefficient of the horizontal movement mechanism 15 is μ).

Here, the first pressure plate 121 and the third pressure plate 125 move in the same direction by the same amount relative to the second pressure plate 123, so the displacement of the first rubber bearing 122 and the second rubber bearing 124 is the same. If the shear spring constant of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126 is kr, the displacement of the first rubber bearing 122 and the second rubber bearing 124 is dxr, and the displacement of the third rubber bearing 126 is dx1, the horizontal load Fh of the test specimen 3 can be expressed by Equation 1 using the measured value F1 of the first load cell 127.

Furthermore, the shear spring constant kr of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126 can be expressed by Equation 2 using the measurement value F2 of the second load cell.

The displacement dxr of the first rubber bearing 122 and the second rubber bearing 124 is the value obtained by subtracting the displacement of the second load cell 128 from the displacement of the first load cell 127, and the displacement of the first load cell 127 is the same as the horizontal displacement dx1 of the third rubber bearing 126. If the displacement of the second load cell 128 is dx2, the displacement dxr of the first rubber bearing 122 and the second rubber bearing 124 can be expressed by Equation 3.

Furthermore, since the measurement value F1 of the first load cell 127 is the product of the stiffness of the first load cell 127 and the displacement amount dx1, if the stiffness of the first load cell 127 is k1, the displacement amount dx1 of the first load cell 127 can be expressed by the following equation 4.

Similarly, the measurement value F2 of the second load cell 128 is the product of the stiffness of the second load cell 128 and the displacement amount dx2, so if the stiffness of the second load cell 128 is k2, the displacement amount dx2 of the second load cell 128 can be expressed by equation 5.

From equations 1 to 5, the horizontal load Fh of test specimen 3 can be expressed by equation 6. Therefore, using the measured values F1 and F2 of the first load cell 127 and the second load cell 128, the horizontal load Fh of test specimen 3 can be calculated without depending on the shear spring constant kr of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126.

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

First, the vertical actuator 13 applies a vertical load N to the load transmission frame 120, while the horizontal actuator 14 moves the mounting table 11 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 of the test specimen 3 is displaced in the horizontal direction, generating a horizontal load Fh.

Next, the measurement values F1 and F2 of the first load cell 127 and the second load cell 128 are obtained (S11). The obtained measurement values F1 and F2 are then transmitted to an information processing device such as a personal computer, and the information processing device substitutes the measurement values F1 and F2 into the above-mentioned equation 6 to calculate the horizontal load Fh of the test specimen 3 (S12).

In this embodiment, the horizontal load Fh of the test specimen 3 can be calculated by substituting the measured values F1 and F2 of the first load cell 127 and the second load cell 128 into the above-mentioned equation 6. This makes it possible to calculate the horizontal load Fh of the test specimen 3 without depending on the shear spring constant kr of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126. Therefore, according to this embodiment, the horizontal load Fh of the test specimen 3 can be measured with higher accuracy.

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 the invention.

For example, in this embodiment, when the horizontal actuator 14 moves the mounting table 11 in the horizontal direction and the test specimen 3 deforms as shown in FIG. 2, if the amount of deformation becomes large, a rotational moment acts on the first pressure plate 121, causing the first pressure plate 121 to rotate (tilt) clockwise. Rubber has low tensile stiffness and is easily deformed. Therefore, to counter this, a rotation prevention mechanism may be adopted for the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126.

In the modified example 1a of the load testing device 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 a rotation prevention mechanism for the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126. The first pressure plate 121, the second pressure plate 123, and the third pressure plate 125 are respectively formed with through holes 1210, 1230, and 1250 having a diameter larger than the diameter of the bolt 17, and the lower surface of the load transmission frame 120 (the surface that abuts against the third rubber bearing 126) is formed with a screw hole 1200 that screws into the screw portion formed at the tip of the bolt 17. The bolt 17 is passed through the through hole 1210 of the first pressure plate 1210, the through hole 1230 of the second pressure plate 123, and the through hole 1250 of the third pressure plate 125, and the tip of the bolt is screwed into the screw hole 1200 of the load transmission frame 120 with the horizontal movement mechanism 170 interposed between the screw head and the lower surface of the first pressure plate 121 (the surface that contacts the test specimen 3). This allows the first pressure plate 121, the second pressure plate 123, and the third pressure plate 125 to move horizontally relative to the load transmission frame 120, while restricting their vertical movement, thereby preventing the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126 from rotating.

In addition, in this embodiment, rubber bearings with the same spring shear constant are used as the first bearing that supports the second pressure plate 123 so that it can move horizontally relative to the first pressure plate 121, the second bearing that supports the third pressure plate 125 so that it can move horizontally relative to the second pressure plate 123, and the third bearing that supports the load transmission frame 120 so that it can move horizontally relative to the third pressure plate 125. However, the present invention is not limited to this. Roller bearings, sliding bearings, etc. with the same friction coefficient may be used as the first to third bearings.

In the modified example 1b of the load testing device 1 shown in FIG. 5, instead of the first rubber bearing 122, the second rubber bearing 124, and the third rubber bearing 126, which have the same shear spring constant, a first roller bearing 130, a second roller bearing 131, and a third roller bearing 132, which have the same friction coefficient, are used.

As shown in the figure, when a vertical load N is applied to the load transmission frame 120 by the vertical actuator 13 while the mounting table 11 is moved horizontally by the horizontal actuator 14, the horizontal load F1 applied to the first pressure plate 121 and the third pressure plate 125, which is the measurement value of the first load cell 127, is the horizontal load Fh of the test body 3 minus the horizontal loads of the first roller bearing 130, the second roller bearing 131, and the third roller bearing 132. The horizontal load F2 applied to the second pressure plate 123, which is the measurement value of the second load cell 128, is the sum of the horizontal loads of the first roller bearing 130 and the second roller bearing 131. In this way, the measured values F1 and F2 of the first load cell 127 and the second load cell 128 do not include the friction force μ·N of the horizontal movement mechanism 15 (when the friction coefficient of the horizontal movement mechanism 15 is μ).

If the friction coefficient of the first roller bearing 130, the second roller bearing 131, and the third roller bearing 132 is μr, the horizontal load Fh of the test specimen 3 can be expressed by equation 7 using the measurement value F1 of the first load cell 127.

Furthermore, the friction coefficient μr of the first roller bearing 130, the second roller bearing 131, and the third roller bearing 132 can be expressed by Equation 8 using the measurement value F2 of the second load cell 128.

Using equations 7 and 8, the horizontal load Fh of the test specimen 3 can be expressed by equation 9. Therefore, using the measured values F1 and F2 of the first load cell 127 and the second load cell 128, the horizontal load Fh of the test specimen 3 can be calculated without depending on the friction coefficient μr of the first roller bearing 130, the second roller bearing 131, and the third roller bearing 132.

In the above embodiment, a load test 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 test 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 device 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 mounting table 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 load transmission frame 120 are formed so as to have the configuration of the load testing device 1, 1a shown in Figures 1 and 4, and two horizontal actuators 14, two vertical movement mechanisms 16, two first load cells 127, and two second load cells 128 are provided.

In addition, in the load testing apparatus 1b shown in FIG. 5, an XY stage or the like is used as the horizontal movement mechanism 15, which supports the loading table 11 so as to be movable in two directions perpendicular to the horizontal direction relative to the fixed base 10; instead of the first roller support 130, an XY stage or the like is used that supports the second pressure plate 123 so as to be movable in two directions perpendicular to the horizontal direction relative to the first pressure plate 121; instead of the second roller support 131, an XY stage or the like is used that supports the third pressure plate 125 so as to be movable in two directions perpendicular to the horizontal direction relative to the second pressure plate 123; and instead of the third roller support 132, an XY stage or the like is used that supports the load transmission frame 120 so as to be movable in two directions perpendicular to the horizontal direction relative to the third pressure plate 132. Then, in each of the two cross-sectional views in two directions perpendicular to the horizontal direction, the fixed base 10 and the load transmission frame 120 are formed to have the configuration of the load testing device 1b shown in FIG. 5, and two horizontal actuators 14, two vertical movement mechanisms 16, two first load cells 127, and two second load cells 128 are provided.

Reference Signs List 1, 1a, 1b: Load testing device 3: Test piece 10: Fixed base 11: Mounting table 12: Load detection unit 13: Vertical actuator 14: Horizontal actuator 15, 170: Horizontal movement mechanism 16: Vertical movement mechanism 17: Bolt 120: Load transmission frame 121: First pressure plate 122: First rubber bearing 123: Second pressure plate 124: Second rubber bearing 125: Third pressure plate 126: Third rubber bearing 127: First load cell 128: Second load cell 130: First roller bearing 131: Second roller bearing 132: Third roller bearing 1201: Side wall 1251: Connection portion 1210, 1230, 1250: Through hole

Claims (7)

A load testing device for measuring a horizontal load on 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 a horizontal direction, comprising:
a mounting table on which the test specimen is placed and which is movable in a horizontal direction by a horizontal actuator;
A load detection unit that is moved vertically by a vertical actuator to apply pressure to the test body,
The load detection unit includes:
A first pressure plate that contacts the upper surface of the test specimen;
a first support placed on the first pressure plate;
a second pressure plate disposed on the first support and horizontally movable relative to the first pressure plate;
a second support placed on the second pressure plate;
a third pressure plate disposed on the second support and connected to the first pressure plate so as to move in the same direction and by the same amount relative to the second pressure plate as the first pressure plate;
a third support placed on the third pressure plate;
a load transfer frame disposed on the third support and vertically movable by the vertical actuator;
a first load cell disposed between the load transmission frame and the first and third pressure plates, the first load cell measuring a horizontal load applied to the first and third pressure plates;
a second load cell disposed between the load transmission frame and the second pressure plate, the second load cell measuring a horizontal load applied to the second pressure plate. 2. The load testing apparatus according to claim 1,
The load testing device according to claim 1, wherein the first bearing, the second bearing, and the third bearing are rubber bearings having the same shear spring constant. 2. The load testing apparatus according to claim 1,
The load testing apparatus according to claim 1, wherein the first bearing, the second bearing, and the third bearing are roller bearings having the same coefficient of friction. A load detection unit used to measure a horizontal load on a test specimen,
A first pressure plate that contacts the upper surface of the test specimen;
a first support placed on the first pressure plate;
a second pressure plate disposed on the first support and horizontally movable relative to the first pressure plate;
a second support placed on the second pressure plate;
a third pressure plate disposed on the second support and connected to the first pressure plate so as to move in the same direction and by the same amount relative to the second pressure plate as the first pressure plate;
a third support placed on the third pressure plate;
a load transfer frame disposed on the third support and vertically movable;
a first load cell disposed between the load transmission frame and the first and third pressure plates, the first load cell measuring a horizontal load applied to the first and third pressure plates;
a second load cell disposed between the load transmission frame and the second pressure plate, the second load cell measuring a horizontal load applied to the second pressure plate. A load test method for measuring a horizontal load on a test specimen using a load test device, comprising:
The load testing device includes:
a mounting table on which the test specimen is placed and which is movable in a horizontal direction by a horizontal actuator;
A load detection unit that is moved vertically by a vertical actuator to apply pressure to the test body,
The load detection unit includes:
A first pressure plate that contacts the upper surface of the test specimen;
a first support placed on the first pressure plate;
a second pressure plate disposed on the first support and horizontally movable relative to the first pressure plate;
a second support placed on the second pressure plate;
a third pressure plate disposed on the second support and connected to the first pressure plate so as to move in the same direction and by the same amount relative to the second pressure plate as the first pressure plate;
a third support placed on the third pressure plate;
a load transfer frame disposed on the third support and vertically movable by the vertical actuator;
a first load cell disposed between the load transmission frame and the first and third pressure plates, the first load cell measuring a horizontal load applied to the first and third pressure plates;
a second load cell disposed between the load transmission frame and the second pressure plate and configured to measure a horizontal load applied to the second pressure plate;
a vertical actuator is used to move the load transmission frame in a vertical direction to apply a vertical load to an upper surface of the test body, while a horizontal actuator is used to move the mounting table in a horizontal direction to displace a 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 horizontal load applied to the test body is calculated using the acquired measured values of the first load cell and the second load cell. The load testing method according to claim 5,
the first bearing, the second bearing, and the third bearing are rubber bearings having the same shear spring constant;
The measurement value of the first load cell is F1, the measurement value of the second load cell is F2, the stiffness of the first load cell is k1, and the stiffness of the second load cell is k2, and the horizontal load Fh of the test body is expressed as follows:

A load testing method comprising the steps of: The load testing method according to claim 5,
the first bearing, the second bearing, and the third bearing are roller bearings having the same coefficient of friction;
The measured value of the first load cell is F1 and the measured value of the second load cell is F2, and the horizontal load Fh of the test body is calculated as follows:

A load testing method comprising the steps of:

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