JP7778635B2 - Centrifugal Load Testing Equipment - Google Patents

Description

The present invention relates to a centrifuge loading testing device that performs tests by simultaneously applying centrifugal acceleration and vibration acceleration to a test specimen, such as a scale model of ground. In particular, it relates to a centrifuge loading testing device that applies vibration acceleration in two directions: parallel to and perpendicular to the surface of the table on which the test specimen is mounted.

For example, when creating a scale model of the ground and conducting tests in a gravitational field, a load simulating gravity is applied to the test specimen by applying centrifugal acceleration to replicate the stress caused by gravity. Also, earthquake vibration acceleration is applied to the test specimen to replicate the shaking of the ground caused by an earthquake.

Centrifugal loading testing equipment, which simultaneously applies centrifugal acceleration and vibration acceleration to a test specimen, is equipped with a vibration table equipped with a table and vibration exciter that apply vibration acceleration, mounted on a swinging base supported by pin supports on the rotating arms. The test specimen is placed on the table, and centrifugal acceleration is applied to the test specimen by rotating the rotating arms at high speed, and vibration acceleration is applied to the test specimen by vibrating the table.

To precisely reproduce the shaking caused by an earthquake, it is necessary to apply vibration acceleration to the test specimen in both the horizontal and vertical directions. Patent Document 1, for example, is an example of a vibration table structure that can apply vibration acceleration in both the horizontal and vertical directions.

In the device described in Patent Document 1, the vibration table structure consists of a concave support base, a vibrator fixed at one end to the support base, and a vibration table (table) connected to the vibrator via bearings. The vibration table can be vibrated in the horizontal and vertical directions by the vibrators located on the left, right, and below the vibration table.

Japanese Patent Application Laid-Open No. 2018-115914

With a vibration table structure such as that described in Patent Document 1, if the concave support frame that supports the vibrator lacks rigidity, the vibration (resonance) of the support frame can prevent the vibration force of the vibrator from being sufficiently transmitted to the vibration table. In this case, the specified vibration performance (vibration acceleration) of the vibration table cannot be achieved.

In particular, the side wall (convex portion) of the concave support frame has a cantilever-like structure with the bottom surface of the central recess as the fixed end. Therefore, when the vibration table is vibrated using a horizontal vibrator fixed to the side wall, the side wall of the concave support frame can collapse horizontally (cantilever bending), causing significant vibrations that can be problematic.

To solve this problem, it is common to increase the thickness of the support frame or add rigidity reinforcing members such as ribs to compensate for the lack of rigidity of the support frame. However, when trying to apply such methods of increasing rigidity to a centrifuge testing apparatus, the swinging frame becomes heavier, increasing the centrifugal force acting on the rotating arm. This makes it necessary to increase the rigidity of the entire centrifuge testing apparatus, including the rotating arm, which results in an increase in the weight of the entire centrifuge testing apparatus.

The object of the present invention is to provide a centrifuge loading testing device that can apply a predetermined vibration acceleration to the test specimen by suppressing the vibration of the concave support frame that supports the vibrator that vibrates in a direction parallel to the surface of the table on which the test specimen is mounted and the vibrator that vibrates in a direction perpendicular to the surface without increasing the weight of the support frame.

In order to solve the above problem, the centrifugal loading testing device of the present invention comprises a rotating shaft arranged in the vertical direction, a rotating arm fixed to the rotating shaft, a swinging base supported swingably on a pin fulcrum provided on the rotating arm, and a rotation drive unit that drives the rotating shaft. When the direction along the central axis of the pin fulcrum is defined as the Y direction, the direction along a line passing through the center of gravity of the swinging base and perpendicular to the central axis of the pin fulcrum is defined as the Z direction, and the direction perpendicular to the Y direction and the Z direction is defined as the X direction, the swinging base is flat on the Z-X plane. The device comprises a support frame that is concave when viewed in cross section, a table on which a test specimen is mounted, an X-direction vibrator that vibrates the table in the X direction, and a Z-direction vibrator that vibrates the table in the Z direction. The support frame has a central recess and protrusions on both sides of the recess. The Z-direction vibrator is installed on the bottom surface of the recess of the support frame, and the X-direction vibrator is installed on the protrusion of the support frame, and the Z-direction vibrator and the protrusion of the support frame are connected by a connecting member.

This invention provides a centrifuge loading testing device that can apply a predetermined vibration acceleration to a test specimen by suppressing the vibration of a concave support frame that supports a vibrator that vibrates in a direction parallel to the surface of the table on which the test specimen is mounted and a vibrator that vibrates in a direction perpendicular to the surface without increasing the weight of the support frame.

1 is a longitudinal sectional view of a centrifugal load testing apparatus according to a first embodiment of the present invention. 1 is a longitudinal sectional view of an oscillating gantry according to a first embodiment of the present invention. 1 is a top view of an oscillating gantry according to a first embodiment of the present invention. 5A and 5B are diagrams illustrating vibration deformation of a table when it is vibrated in the X direction when there is no connecting member according to the first embodiment of the present invention. FIG. 10 is a longitudinal sectional view of a swinging gantry according to a second embodiment of the present invention.

An embodiment of the present invention will now be described with reference to the drawings. The following description illustrates one embodiment of the present invention, and the present invention is not limited to this embodiment.

First Embodiment
FIG. 1 shows the configuration of a centrifugal load testing apparatus according to a first embodiment of the present invention.
As shown in FIG. 1, the basic configuration of a centrifugal loading testing device for applying centrifugal acceleration includes a rotating shaft 1, a rotating arm 3, swinging stands 5a and 5b, a rotation drive unit 6, an upper rotating shaft support member 7, and a lower rotating shaft support member 8.

The rotating shaft 1 is arranged vertically. The rotating arms 3 are fixed to the rotating shaft 1. Specifically, the rotating arms 3 extend horizontally from the rotating shaft 1 and rotate together with the rotating shaft 1 around the central axis 2 of the rotating shaft 1. The oscillating bases 5a and 5b are swingably supported and suspended from pin fulcrums 4 provided on the rotating arms 3. The rotation drive unit 6 drives the rotating shaft 1. The upper rotating shaft support member 7 and the lower rotating shaft support member 8 support the rotating shaft 1 via bearings (not shown).

The upper part of the rotating shaft 1 is supported on the upper building floor 9a via an upper rotating shaft support member 7, and the lower part is supported on the lower building floor 9b via a lower rotating shaft support member 8, with the lower end connected to the rotation drive unit 6. The rotating arm 3 consists of a center frame 3a fixed to the rotating shaft 1, side frames 3b extending horizontally from the center frame 3a, and end frames 3c attached to the tips of the side frames 3b.

The swinging pedestals 5a and 5b are positioned symmetrically with respect to the rotation axis 1. When the rotating arm 3 is stationary, it is suspended vertically as shown by the solid lines in Figure 1. On the other hand, when the rotating arm 3 receives the driving force from the rotary drive unit 6 and rotates, the resulting centrifugal force causes the swinging pedestals 5a and 5b to swing up to a horizontal position as shown by the dotted lines in Figure 1. The test specimen 10 is placed on a table 11 installed on the swinging pedestal 5a. A balance weight (not shown) is attached to the swinging pedestal 5b so that the centrifugal force acting on the swinging pedestal 5b is the same as that on the swinging pedestal 5a. By adjusting the weight and center of gravity of the swinging pedestal 5b in this way, unbalanced rotational vibrations during rotation of the centrifuge testing equipment are suppressed.

FIG. 2 shows the detailed structure of the swinging platform 5a on which the specimen 10 is mounted.
For ease of explanation, the direction along the central axis 41 of the pin support 4 is defined as the Y direction, the direction along a line that passes through the center of gravity (not shown) of the oscillating stand 5a and is perpendicular to the central axis 41 of the pin support 4 is defined as the Z direction, and the direction perpendicular to the Y direction and the Z direction is defined as the X direction. Here, the X direction is the in-plane direction of the flat table 11 on which the specimen 10 is mounted, and the Z direction is the out-of-plane direction of the table 11.

As shown in Figure 2, the oscillating stand 5a comprises a side plate 12, a support stand 13, a table 11, an X-direction vibrator 15, and a Z-direction vibrator 14. The side plate 12 is supported so that it can oscillate on a pin fulcrum 4 provided on the rotating arm 3. A support stand 13, which has a concave shape with a recess in the center when viewed in a cross section parallel to the X-Z plane, is installed on the end of the side plate 12 opposite the pin fulcrum 4. A test specimen 10 is placed on the table 11. The X-direction vibrator 15 vibrates the table 11 in the X direction, and the Z-direction vibrator 14 vibrates the table 11 in the Z direction.

The support frame 13 has a central recess 21 (a concave portion) and protrusions 22 located on either side of the recess 21. A Z-direction vibration exciter 14 is installed on the bottom surface 21a of the recess 21 of the support frame 13, and an X-direction vibration exciter 15 is installed on the top surface 22a of the protrusion 22 of the support frame 13. The Z-direction vibration exciter 14 is connected to the table 11 via a Z-piston 14a that moves in the Z direction, a flat Z-base 16, an X-linear guide rail 17a arranged in the X direction, and an X-linear guide block 17b that moves in the X direction. The X-direction vibration exciter 15 is connected to the table 11 via an X-piston 15a that moves in the X direction, a Z-linear guide block 18b that moves in the Z direction, and a Z-linear guide rail 18a arranged in the Z direction.

The side surface 14b of the Z-direction vibrator 14 and the inner surface 22b of the convex portion 22 of the support frame 13 are connected by a connecting member 19. Here, the connecting member 19 is joined to the Z-direction vibrator 14 and the convex portion 22 of the support frame 13 by welding, but this is not limited to this and the joining may also be by screw fastening, for example. The shape of the connecting member 19 is a rectangular parallelepiped here, but it may also be a cylinder, or a hollow circular or square pipe. The connecting member 19 is made of a metal such as steel, for example.

Figure 3 shows the oscillating platform 5a as seen from above (X-Y plane). To simplify the illustration, Figure 3 shows only the table 11, side panel 12, support platform 13, Z-direction vibrator 14, X-direction vibrator 15, and connecting member 19 from the components shown in Figure 2.

As shown in Figure 3, this embodiment provides an example in which four Z-direction vibrators 14 and four X-direction vibrators 15 are arranged. A pair of side plates 12 are provided, and the pair of side plates 12 are attached so as to sandwich both end faces of the support frame 13 in the Y direction. The connecting member 19 that connects the Z-direction vibrators 14 to the convex portion 22 of the support frame 13 is arranged perpendicular to the surface of the convex portion 22 facing the Z-direction vibrators 14, i.e., the inner surface 22b.

When vibrating the table 11 in the Z direction, the Z-piston 14a moves in the Z direction by the Z-direction vibrator 14, and the Z base 16, X linear guide 17, table 11, and Z linear guide rail 18a vibrate together in the Z direction. When vibrating the table 11 in the X direction, the X-direction vibrator 15 moves the X-piston 15a in the X direction, and the Z linear guide 18, table 11, and X linear guide block 17b vibrate together in the X direction. In this way, the support frame 13 has a concave structure with a recess in the center, and the Z-direction vibrator 14 is located below the table 11 (when not in operation), and the X-direction vibrator 15 is located to the side of the table (when not in operation). This makes it possible to generate vibration acceleration in directions parallel to and perpendicular to the surface of the table 11.

In Figure 2, only the outer shape of the structure of the support frame 13 is shown, but the weight is reduced by using a honeycomb structure made by assembling plate members by welding, etc. In this embodiment, an example is described in which four Z-direction vibrators 14 and four X-direction vibrators 15 are arranged, but the number of each vibrator 14, 15 is not limited to this. In addition, the X linear guide 17 and Z linear guide 18 may be arranged so that the rail and block positions are reversed.

The driving force of the vibrators 14, 15 generates vibration acceleration in the table 11, but at this time, the support frame 13 vibrates due to the reaction force of the driving force of the vibrators 14, 15. When the support frame 13 vibrates (resonates) significantly, there may be a 180-degree phase shift between the driving force of the vibrators 14, 15 and the vibration of the support frame 13 on which the vibrators 14, 15 are mounted. In such cases, the driving force of the vibrators 14, 15 may not be sufficiently transmitted to the table 11, or the vibration driving force may not be sufficiently controlled, making it impossible to generate the desired vibration acceleration in the table 11.

Figure 4 is a schematic diagram showing the vibration deformation of the table 11 when it is vibrated in the X direction when there is no connecting member 19 installed between the side surface 14b of the Z-direction vibrator 14 and the inner surface 22b of the convex portion 22 of the support frame 13. In a concave support frame 13, if there is no connecting member 19, vibration deformation of the support frame 13 and the vibrators 14 and 15 as shown in Figure 4 can occur when the table 11 is vibrated in the X direction, which can be problematic. In the deformation shown in Figure 4, the convex portion 22 of the support frame 13 and the X-direction vibrator 15 installed on its upper surface 22a lean in the X direction, and the Z-direction vibrator 14 installed on the bottom surface 21a of the concave portion 21 of the support frame 13 leans in the X direction. Furthermore, the X-direction vibrator 15 (and the convex portion 22) and the Z-direction vibrator 14 fall in opposite directions (in Figure 4, the X-direction vibrator 15 falls to the right on the page, and the Z-direction vibrator 14 falls to the left on the page), meaning that they vibrate in opposite phases.

The deformation shown in Figure 4 is caused by deformation of the support pedestal 13 in the X direction, particularly cantilever bending deformation of the convex portion 22 of the concave support pedestal 13. To suppress this deformation, it is generally considered to change the structure to increase the rigidity of the convex portion 22 of the support pedestal 13, such as by increasing the plate thickness of the convex portion 22 of the support pedestal 13 or adding a rib member. However, increasing the thickness of the support pedestal 13 or adding a rib member increases the weight of the support pedestal 13, which in turn increases the weight of the oscillating pedestal 5a, making this unacceptable from the perspective of increasing the weight of the device. In consideration of the above issues, the present invention provides a structure that suppresses deformation of the support pedestal 13 shown in Figure 4, particularly vibrations caused by bending of the convex portion 22 of the support pedestal 13, without increasing the weight of the concave support pedestal 13.

2 and 3 , the concave support frame 13 has a recess 21 located in the center and protrusions 22 located on both sides of the recess 21. The Z-direction vibration exciter 14 is installed on the bottom surface 21a of the recess 21 of the support frame 13, and the X-direction vibration exciter 15 is installed on the protrusion 22 of the support frame 13. The Z-direction vibration exciter 14 and the protrusion 22 of the support frame 13 are connected by a connecting member 19. This has the effect of canceling out the vibrations of the Z-direction vibration exciter 14 and the protrusion 22 (inner surface 22b) of the support frame 13, which vibrate in opposite phases as described in FIG. 4 , thereby suppressing the vibrations of both.
Therefore, according to this embodiment, it is possible to provide a centrifugal loading testing apparatus that can suppress the vibration of the concave support frame 13 that supports the X-direction vibrator 15 and the Z-direction vibrator 14 simply by adding the connecting member 19, without increasing the weight of the support frame 13, and can apply a predetermined vibration acceleration to the test specimen 10.

If the connecting member 19 has too little rigidity, it will be difficult for the vibrations to be transmitted and canceled out, so it is preferable that the connecting member 19 has a certain level of rigidity, such as at least the same level as the Z-direction vibrator 14 and the protrusion 22 of the support frame 13.

The connecting member 19 preferably connects the entire connectable surface between the Z-direction vibrator 14 and the inner surface 22b of the convex portion 22 in the Z direction, but it may also connect only the upper portion of the connectable surface where vibration deformation is large, as shown in Figure 4. Even with this configuration, a sufficient vibration suppression effect can be achieved. In this case, there is no need to install the connecting member 19 from the bottom surface 21a of the recess 21 of the support frame 13, so the connecting member 19 can be made smaller and lighter.

In addition, in this embodiment, the connecting member 19 is arranged perpendicular to the inner surface 22b of the convex portion 22, which is the surface facing the Z-direction vibrator 14. With this configuration, deformation of the support frame 13 in the X direction can be more effectively suppressed. However, the connecting member 19 may also be arranged at an angle to the inner surface 22b. Also, in Figures 2 and 3, one Z-direction vibrator 14 and the inner surface 22b of the convex portion 22 are connected by one connecting member 19, but they may also be connected by multiple connecting members 19.

Second Embodiment
FIG. 5 shows a vertical cross-sectional view of an oscillating platform according to a second embodiment of the present invention.
The second embodiment is premised on a structure in which a plurality of Z-direction vibrators 14 (two in FIG. 5) are installed in the X direction. In the second embodiment, the structures and arrangements of the components of the oscillating frame, such as the support frame 13, the X-direction vibrators 15, and the Z-direction vibrators 14, are the same as those in the first embodiment (see FIG. 2).

In the second embodiment, in addition to the connecting members 19 that connect the Z-direction vibrators 14 and the protrusions 22 of the support frame 13 in the first embodiment, there are additional connecting members 19a that connect the Z-direction vibrators 14 arranged in the X direction to each other. The rigidity, connecting area, and number required for the connecting members 19a are the same as those for the connecting members 19 described in the first embodiment.

As described above, in the second embodiment, the Z-direction vibrator 14 and the convex portion 22 of the support frame 13 are connected by the connecting member 19, and the Z-direction vibrators 14 are connected to each other by another connecting member 19a. This configuration achieves the effect of canceling out the vibrations of the Z-direction vibrator 14 and the convex portion 22 (inner surface 22b) of the support frame 13, which vibrate in opposite phases as described in the first embodiment. In addition, by connecting the inner surfaces 22b of the opposing convex portions 22 to the Z-direction vibrator 14 via the connecting members 19, 19a, the bending rigidity of the convex portion 22 of the support frame 13 is improved, resulting in a greater vibration suppression effect than in the first embodiment. In other words, according to the second embodiment, a centrifuge loading testing apparatus can be provided that can suppress the vibration of the support frame 13 and apply a predetermined vibration acceleration to the test specimen 10 simply by adding the connecting members 19, 19a, without increasing the weight of the concave support frame 13 that supports the X-direction vibrator 15 and the Z-direction vibrator 14.

In Figure 5, the connecting member 19a connects the Z-direction vibration exciters 14 arranged in the X direction. This configuration can more effectively suppress X-direction vibration of the support frame 13. However, the connecting member 19a may also connect any two of the multiple Z-direction vibration exciters 14.

The present invention has been described above based on an embodiment, but the present invention is not limited to the above-described embodiment and includes various modifications. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to having all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of the above-described embodiment with other configurations.

REFERENCE SIGNS LIST 1 Rotation axis 3 Rotation arm 4 Pin support 5a Swinging base 6 Rotation drive device 10 Test specimen 11 Table 41 Central axis 13 Support base 14 Z-direction vibrator 14b Side surface 15 X-direction vibrator 19 Connecting member 19a Connecting member 21 Recess 21a Bottom surface 22 Convex portion 22a Top surface 22b Inner surface

Claims (3)

a rotation axis disposed in a vertical direction;
A rotating arm fixed to the rotating shaft;
a swinging base swingably supported on a pin fulcrum provided on the rotating arm;
a rotation drive device that drives the rotation shaft,
When the direction along the central axis of the pin fulcrum is defined as the Y direction, the direction along a straight line passing through the center of gravity of the oscillating platform and perpendicular to the central axis of the pin fulcrum is defined as the Z direction, and the direction perpendicular to the Y direction and the Z direction is defined as the X direction,
The swinging platform is
A support base having a concave shape with a recess in the center when viewed in a cross section parallel to the X-Z plane;
a table on which a specimen is placed;
an X-direction vibrator that vibrates the table in the X-direction;
a Z-direction vibrator that vibrates the table in the Z direction,
The support base has a recessed portion located at the center and protruding portions located on both sides of the recessed portion,
The Z-direction vibrator is installed on the bottom surface of the recess of the support frame,
the X-direction vibration exciter is installed on the protrusion of the support frame,
A centrifugal loading testing apparatus, characterized in that the Z-direction vibrator and the protrusion of the support frame are connected by a connecting member. The Z-direction vibrator is provided in plurality,
2. The centrifugal loading testing apparatus according to claim 1, wherein the Z-direction vibration exciters are connected to each other by a separate connecting member. The centrifuge testing apparatus described in claim 1, characterized in that the connecting member is arranged perpendicular to the surface of the convex portion facing the Z-direction vibrator.