Centrifugal Load Testing Equipment

Abstract

To provide a centrifugal load tester which can give prescribed vibration acceleration to a sample by suppressing vibration of a support frame without increasing the weight of the recessed support frame that supports an excitor that excites in the direction in parallel to a surface of a table on which the sample is placed and an excitor that excites in the vertical direction.SOLUTION: A recessed support frame 13 includes a recess 21 which is located on the center and protrusions 22 which are located on both sides of the recess 21. A Z direction excitor 14 is installed on a bottom surface 21a of the recess 21 of the support frame 13 and an X direction excitor 15 is installed in the protrusion 22 of the support frame 13. The Z direction excitor 14 and the protrusion 22 of the support frame 13 are connected with each other by a connection member 19.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a centrifugal 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, and in particular to a centrifugal loading testing device that applies vibration acceleration in two directions: parallel to the surface of a table on which the test specimen is mounted, and perpendicular to it. [Background technology]

[0002] For example, when conducting a gravitational field test using a scale model of the ground, a load simulating gravity is applied to the test specimen by applying centrifugal acceleration to reproduce the stress caused by gravity. Also, earthquake vibration acceleration is applied to the test specimen to reproduce the shaking of the ground caused by an earthquake.

[0003] A centrifuge testing device that simultaneously applies centrifugal acceleration and vibration acceleration to a test specimen has a vibration table equipped with a table and a vibration exciter that apply vibration acceleration to a swinging base supported by pin supports of a rotating arm.The test specimen is placed on the table, and centrifugal acceleration is applied to the test specimen by rotating the rotating arm at high speed, and vibration acceleration is applied to the test specimen by vibrating the table.

[0004] To reproduce the shaking caused by an earthquake in detail, it is necessary to apply vibration acceleration in both the horizontal and vertical directions to the test specimen. Patent Document 1 and other examples of vibration table structures that can apply vibration acceleration in both the horizontal and vertical directions are given.

[0005] In the device described in Patent Document 1, the vibration table is structured to include a concave support base, a vibration exciter fixed at one end to the support base, and a vibration table (table) connected to the vibration exciter via bearings. The vibration exciters, which are located on the left, right, and bottom of the vibration table, can vibrate the vibration table in the horizontal and vertical directions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-115914 Summary of the Invention [Problem to be solved by the invention]

[0007] In the vibration table structure described in Patent Document 1, if the concave support frame that supports the vibrator does not have sufficient rigidity, the vibration (resonance) of the support frame will prevent the vibration force of the vibrator from being sufficiently transmitted to the vibration table. In this case, the desired vibration performance (vibration acceleration) of the vibration table cannot be achieved.

[0008] 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 by a horizontal vibrator fixed to the side wall, the side wall of the concave support frame will bend horizontally (cantilever bending), causing significant vibration and creating problems.

[0009] 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 such methods of increasing rigidity are applied to a centrifuge, the swinging frame becomes heavy, and the centrifugal force acting on the rotating arm increases. Therefore, it becomes necessary to increase the rigidity of the entire centrifuge, including the rotating arm, which results in an increase in the weight of the entire centrifuge.

[0010] An object of the present invention is to provide a centrifugal loading testing apparatus 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 a 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. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the centrifugal loading testing apparatus of the present invention comprises a rotation axis arranged in a vertical direction, a rotation arm fixed to the rotation axis, a swinging base supported swingably on a pin fulcrum provided on the rotation arm, and a rotation drive device that drives the rotation axis, wherein when the direction along the central axis of the pin fulcrum is defined as the Y direction, the direction along a line that passes through the center of gravity of the swinging base and is 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 parallel to the ZX plane. The test specimen is provided with 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 having a centrally located concave portion and convex portions located on both sides of the concave portion, the Z-direction vibrator is installed on the bottom surface of the concave portion of the support frame, the X-direction vibrator is installed on the convex portion of the support frame, and the Z-direction vibrator and the convex portion of the support frame are connected by a connecting member. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a centrifugal loading testing apparatus that can apply a predetermined vibration acceleration to the 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 a 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. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a longitudinal sectional view of a centrifugal load testing apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a longitudinal sectional view of an oscillating gantry according to a first embodiment of the present invention. [Figure 3] 1 is a top view of an oscillating gantry according to a first embodiment of the present invention. [Figure 4] 5A and 5B are diagrams illustrating vibration deformation of the table when it is vibrated in the X direction when there is no connecting member according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a longitudinal sectional view of an oscillating gantry according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. The following description shows one embodiment of the present invention, but the present invention is not limited to this embodiment.

[0015] First Embodiment FIG. 1 shows the configuration of a centrifugal loading testing device 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.

[0016] The rotating shaft 1 is disposed 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 a pin fulcrum 4 provided on the rotating arm 3. A rotation drive unit 6 drives the rotating shaft 1. An upper rotating shaft support member 7 and a lower rotating shaft support member 8 support the rotating shaft 1 via bearings (not shown).

[0017] The upper part of the rotating shaft 1 is supported on the upper floor 9a of the building via an upper rotating shaft support member 7, and the lower part is supported on the lower floor 9b of the building via a lower rotating shaft support member 8, and the lower end is connected to a rotation drive device 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 provided at the tip ends of the side frames 3b.

[0018] 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 line in FIG. 1. On the other hand, when the rotating arm 3 receives the driving force from the rotary drive unit 6 and rotates, the swinging pedestals 5a and 5b are subjected to the centrifugal force caused by the rotation, and swing up to a horizontal position as shown by the dotted line in FIG. 1. The 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 device are suppressed.

[0019] FIG. 2 shows the detailed structure of the swinging stand 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 a flat table 11 on which the specimen 10 is mounted, and the Z direction is the out-of-plane direction of the table 11.

[0020] As shown in FIG. 2, the oscillating stand 5a includes a side plate 12, a support base 13, a table 11, an X-direction vibrator 15, and a Z-direction vibrator 14. The side plate 12 is supported so as to be able to oscillate on a pin support 4 provided on the rotating arm 3. A support base 13 having a concave shape with a recess in the center when viewed in a cross section parallel to the XZ plane is installed on the end of the side plate 12 opposite the pin support 4. A test piece 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.

[0021] Support frame 13 has a recess 21 (a hollowed-out concave portion) located in the center and protrusions 22 located on both sides of recess 21. Z-direction vibration exciter 14 is installed on bottom surface 21a of recess 21 of support frame 13, and X-direction vibration exciter 15 is installed on top surface 22a of protrusion 22 of support frame 13. Z-direction vibration exciter 14 is connected to table 11 via Z-piston 14a that moves in the Z direction, flat Z base 16, X-linear guide rail 17a arranged in the X direction, and X-linear guide block 17b that moves in the X direction. X-direction vibration exciter 15 is connected to table 11 via X-piston 15a that moves in the X direction, Z-linear guide block 18b that moves in the Z direction, and Z-linear guide rail 18a arranged in the Z direction.

[0022] Furthermore, the side surface 14b of the Z-direction vibration exciter 14 and the inner surface 22b of the protrusion 22 of the support frame 13 are connected by a connecting member 19. Here, the connecting member 19 is joined to the Z-direction vibration exciter 14 and the protrusion 22 of the support frame 13 by welding, but this is not limitative and the joining may be by, for example, screw fastening. The shape of the connecting member 19 is a rectangular parallelepiped here, but it may also be a cylinder, or a hollow circular pipe or square pipe. The connecting member 19 is made of a material such as steel.

[0023] A view of the oscillating stand 5a from above (XY plane) is shown in Fig. 3. For simplicity of illustration, Fig. 3 shows only the table 11, side plate 12, support stand 13, Z-direction vibrator 14, X-direction vibrator 15, and connecting member 19 from among the components shown in Fig. 2.

[0024] 3, this embodiment shows 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 in the Y direction of the support frame 13. A connecting member 19 that connects the Z-direction vibrators 14 and the protrusion 22 of the support frame 13 is arranged perpendicular to the surface of the protrusion 22 that faces the Z-direction vibrators 14, i.e., the inner surface 22b.

[0025] 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.

[0026] 2 only shows the outer shape of the structure of support frame 13, but the weight is reduced by using a honeycomb structure made by assembling plate members by welding or the like. 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. Furthermore, the X linear guide 17 and the Z linear guide 18 may be arranged such that the arrangement of the rails and blocks is reversed.

[0027] The driving force of the vibrators 14, 15 generates vibration acceleration in the table 11, and 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, and the predetermined vibration acceleration may not be generated in the table 11.

[0028] 4 is a diagram schematically showing vibration deformation of table 11 when it is vibrated in the X direction when there is no connecting member 19 installed between side surface 14b of Z-direction vibrator 14 and inner surface 22b of protrusion 22 of support frame 13. In a concave support frame 13, if there is no connecting member 19, vibration deformation of support frame 13 and vibrators 14 and 15 as shown in FIG. 4 can occur when table 11 is vibrated in the X direction, which can be problematic. In the deformation shown in FIG. 4, convex portion 22 of support frame 13 and X-direction vibrator 15 installed on its upper surface 22a tilt in the X direction, and Z-direction vibrator 14 installed on bottom surface 21a of recess 21 of support frame 13 tilts in the X direction. Moreover, the X-direction vibrator 15 (and the convex portion 22) and the Z-direction vibrator 14 fall in opposite directions (in FIG. 4, the X-direction vibrator 15 falls to the right on the paper, and the Z-direction vibrator 14 falls to the left on the paper), meaning that they vibrate in opposite phases.

[0029] 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 protruding 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 protruding portion 22 of the support pedestal 13, such as by increasing the plate thickness of the protruding 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, that is, the weight of the oscillating pedestal 5a, and is therefore difficult to adopt from the perspective of increasing the weight of the device. In view of the above-mentioned problems, the present invention provides a structure that suppresses the deformation of the support pedestal 13 shown in Figure 4, particularly vibrations caused by bending of the protruding portion 22 of the support pedestal 13, without increasing the weight of the concave support pedestal 13.

[0030] 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 vibrator 14 is installed on the bottom surface 21a of the recess 21 of the support frame 13, and the X-direction vibrator 15 is installed on the protrusion 22 of the support frame 13. The Z-direction vibrator 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 vibrator 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 without increasing the weight of the support frame 13, and can apply a predetermined vibration acceleration to the test specimen 10, simply by adding the connecting member 19.

[0031] If the connecting member 19 has too little rigidity, it will be difficult for the vibrations to be transmitted and cancelled out, so it is preferable that the connecting member 19 has a certain level of rigidity, such as at least the same as that of the Z-direction vibrator 14 and the protrusion 22 of the support frame 13.

[0032] 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 obtained. In this case, there is no need to install the connecting member 19 from the bottom surface 21a of the concave portion 21 of the support frame 13, so the connecting member 19 can be made smaller and lighter.

[0033] In this embodiment, the connecting member 19 is disposed perpendicular to the inner surface 22b of the protrusion 22, which is the surface facing the Z-direction vibrator 14. This configuration can more effectively suppress deformation of the support frame 13 in the X direction. However, the connecting member 19 may be disposed at an angle to the inner surface 22b. In addition, although one Z-direction vibrator 14 and the inner surface 22b of the protrusion 22 are connected by one connecting member 19 in FIGS. 2 and 3, multiple connecting members 19 may be used for connection.

[0034] Second Embodiment FIG. 5 shows a vertical cross section of an oscillating gantry 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 members of the oscillating frame, such as the support frame 13, the X-direction vibrator 15, and the Z-direction vibrator 14, are the same as those in the first embodiment (see FIG. 2).

[0035] The second embodiment has another connecting member 19a that connects the Z-direction vibrators 14 arranged in the X direction to each other, in addition to the connecting member 19 in the first embodiment that connects the Z-direction vibrators 14 to the protrusions 22 of the support frame 13. The rigidity, connecting area, and number required for the connecting member 19a are the same as those of the connecting member 19 described in the first embodiment.

[0036] 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 can cancel 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, thereby achieving a greater vibration suppression effect than in the first embodiment. In other words, according to the second embodiment, it is possible to provide a centrifuge loading testing apparatus 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.

[0037] 5, the connecting member 19a connects the Z-direction vibrators 14 arranged in the X direction to each other. In this configuration, vibrations in the X direction of the support frame 13 can be more effectively suppressed. However, the connecting member 19a may connect any two of the multiple Z-direction vibrators 14.

[0038] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of the above-described embodiments with other configurations. [Explanation of symbols]

[0039] 1 Rotation axis 3 Spinning Arm 4-pin fulcrum 5a Swing stand 6 Rotational drive unit 10 Specimen 11 tables 41 Center axis 13 Support stand 14 Z direction vibration exciter 14b Side 15 X direction vibration exciter 19 Connecting members 19a Connecting member 21 Recess 21a Bottom 22 Convex part 22a Top side 22b Inside surface

Claims

1. 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 mounted; 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.

2. 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.

3. 2. The centrifuge testing apparatus according to claim 1, wherein the connecting member is disposed perpendicular to a surface of the convex portion facing the Z-direction vibrator.

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