JPH07218408A - Dual axis load test device - Google Patents

Abstract

PURPOSE:To provide a dual axis load test device capable of obtaining a test result with high accuracy. CONSTITUTION:A dual axis load test device comprises an oil hydraulic cylinder 14 for a vertical load that loads a shaft force on a sample held by a pair of upper and lower pressure tables 19, 22, a hydraulic cylinder 26 for a horizontal load that relatively conveys the pair of pressure tables 19, 22 by acting the shaft force to the sample and loads a shearing stress thereto in a direction perpendicular to that of the shaft force and a hydraulic cylinder 29 that conveys the pressure tables 19, 22 in such a manner that a central point of the sample and a center of the shaft force are always in agreement with each other when repeatedly loading the shearing stress on the sample.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial loading test apparatus suitable for evaluating the performance of seismic isolation rubber or the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Axle load testing devices are known. In FIG. 9, the sample 1 is held between the lower pedestal 4 and the upper pushing member 5 by the upper and lower platens 2 and 3. The upper pushing member 5 is held on a support frame 7 by a vertical slide guide 6 so as to be vertically movable, and the lower mount 4 is provided on a base 9 so as to be horizontally reciprocally movable by a horizontal slide bearing 8.

The upper pushing member 5 is pushed vertically by a loading actuator (not shown) to apply a compressive load to the test piece 1,
In this state, the lower gantry 4 is horizontally reciprocated by a load actuator (not shown). At that time, the displacement amount of the load actuator is measured by a displacement gauge, and the load load is measured by a load cell interposed between the load actuator and the lower pedestal 4, and the horizontal axis indicates the horizontal movement amount and the vertical axis indicates the load cell output. Is drawn, and the shear energy of the sample 1 is evaluated from the area of the energy curve.

[0004]

However, in the above-mentioned conventional biaxial loading test apparatus, only the lower part of the test piece 1 reciprocates horizontally and the upper position is immovable. Therefore, the sum of the moment due to the horizontal force and the moment due to the vertical force acts on the upper pushing member 5 due to the elastic restoring force of the sample 1 which is deformed as shown by the chain double-dashed line, and the vertical slide guide 6 is undesired. Since a large compressive load works, the upper pressing member 5 and the support frame 7 need to have a great rigidity in order to keep the upper and lower platens 2 and 3 in parallel. Moreover, since the compressive load fluctuates according to the horizontal displacement amount of the specimen, the frictional force of the slide guide 6 also fluctuates and the frictional force of the horizontal slide bearing 8 also fluctuates. As a result, it becomes difficult to perform a correction calculation for canceling the frictional component from the output of the load cell interposed between the horizontal load actuator and the lower platen, and a highly accurate test result cannot be obtained.

It is an object of the present invention to provide a biaxial loading test device which can obtain highly accurate test results.

[0006]

SUMMARY OF THE INVENTION A biaxial loading test apparatus according to the present invention comprises an axial force applying means for applying an axial force to a specimen held by a pair of upper and lower platens, and an axial force acting on the specimen. While keeping the above, the pair of upper and lower platens are relatively moved to repeatedly apply a shearing force perpendicular to the axial force, and a shearing force is repeatedly applied to the specimen, the center point of the specimen is repeatedly applied. Further comprises a platen moving means for moving the upper and lower platens so that they coincide with the axial center of the axial force.
To achieve the above objectives.

[0007]

The axial load is applied to the test piece held by the pair of upper and lower platens while the axial load is applied to the test piece, and the shear load means relatively moves the pair of upper and lower platens to repeatedly apply the shearing force to the test piece.
At this time, the moving means moves the upper and lower platens in the direction of the shearing force so that the center point of the specimen coincides with the axial center of the axial force applying means. As a result, the center point of the test piece coincides with the axial line of the axial force, the moment associated with the shearing force can be reduced, and the test accuracy can be improved.

[0008]

EXAMPLE An example in which the present invention is applied to a shear energy evaluation tester for seismic isolation rubber will be described with reference to FIGS. 1 to 3 are views showing an embodiment of a shear energy evaluation tester for seismic isolation rubber, FIG. 2 is a front view, FIG. 3 is a left side view, and FIG. 1 is a view obtained by removing the support frame of FIG. It is a figure. In these figures, the left and right support frames 11 form a load frame with a base 12 and a cross yoke 13, a hydraulic cylinder 14 for vertical load is installed on the cross yoke 13, and a ball seat 15 is provided on a ram rod 14 a of the hydraulic cylinder 14. The load yoke 16 is connected via. The left and right ends of the load yoke 16 are supported by the column frame 11 via vertical slide guides 17. An upper platen 19 is provided on the lower surface of the load yoke 16 via a slide bearing 18 so as to be movable in the horizontal direction. An upper surface plate 20 is provided on the lower surface of the upper platen 19. The base 12 has a horizontal slide bearing 2
1 is provided with a lower platen 22.
The lower surface board 23 is provided on the upper surface of the. The sample 1 is fixed to the upper and lower surfaces 20 and 23 with bolts and nuts. The upper and lower platens 19 and 22 are moved in the horizontal direction in FIG. 1 by the horizontal slide bearings 18 and 21.

As shown in FIG. 1, upper and lower platens 19 and 22 are provided with brackets 24 and 25, respectively, to which both ends of a horizontal load hydraulic cylinder 26 are connected. The distance between the brackets 24 and 25 changes due to the expansion and contraction of the hydraulic cylinder 26. On the other hand, both ends of a hydraulic cylinder 29 for moving the lower platen are connected to a bracket 27 provided on the base 12 and a bracket 28 provided on the lower platen 22, and the lower platen 22 is horizontally moved by expansion and contraction of the hydraulic cylinder 29. Moving.

FIG. 4 shows the control unit of the test apparatus.
Reference numeral 0 is a control circuit mainly composed of a CPU, 41 is a drive circuit for the vertical load hydraulic cylinder 14, 42 is a drive circuit for the horizontal load hydraulic cylinder 26, and 43 is a drive circuit for the lower platen moving hydraulic cylinder 29. is there. Reference numeral 44 is a load cell for detecting a vertical load, 45 is a displacement gauge for detecting a vertical displacement of the upper platen 19, and 46 is a horizontal load hydraulic cylinder 2.
Load cell that detects the horizontal load acting on 6,
Reference numeral 47 is a displacement gauge for detecting the stroke of the horizontal load hydraulic cylinder 26. Further, 48 is a displacement gauge for detecting the stroke of the lower platen moving hydraulic cylinder 29, and 49 is a load cell for detecting the load acting on the lower platen moving hydraulic cylinder 29. Hydraulic pressure is supplied to each of the drive circuits 41 to 43 from a hydraulic source (not shown), and each drive circuit drives a servo valve or the like based on a control signal from the control circuit 40 to adjust the stroke of each hydraulic cylinder.

The control circuit 40 drives and controls each hydraulic cylinder via the corresponding drive circuit as follows. The vertical load hydraulic cylinder 14 is feedback-controlled by the detection signal of the load cell 44 so that a constant vertical load acts on the sample 1. That is, the detection signal of the load cell 44 is compared with a previously input control signal (for example, a ramp input signal or a frequency signal), and the hydraulic cylinder 14 is fed back so that the deviation becomes zero.

The horizontal load hydraulic cylinder 26 is feedback-controlled by a detection signal of the displacement gauge 47 so that the shearing force acts on the test piece 1 at a predetermined cycle. That is, the detection signal of the displacement gauge 47 is compared with a control signal (frequency signal) input in advance, and the hydraulic cylinder 26 is fed back so that the deviation becomes zero.

The specimen 1 is operated by the operation of the hydraulic cylinder 26.
When it reciprocates horizontally in a predetermined cycle, the lower platen 22 is ½ in a phase opposite to the reciprocating motion so that the center point of the sample 1 always coincides with the axis of the vertical load hydraulic cylinder 14. Reciprocate horizontally. That is, the displacement meter 49
Of the hydraulic cylinder 29 is compared with the control signal (frequency signal) input in advance so that the deviation becomes zero.
Give us feedback. In this case, it is preferable to synchronize with the operation of the hydraulic cylinder 26.

The operation of the biaxial loading test apparatus thus constructed will be described with reference to FIGS. First, a vertical load, horizontal displacement and frequency are set by a test condition input operation member (not shown). When the test is started, pressure oil is supplied to the vertical load hydraulic cylinder 14, and the upper platen 19 presses the sample. Vertical load detection load cell 4
4 detects the vertical load, and the control circuit 40 controls the hydraulic cylinder 1 via the drive circuit 41 so that the vertical load is set.
4 is driven and controlled.

On the other hand, a sine wave signal as shown in FIG. 5A is applied to the drive circuit 42 of the horizontal load hydraulic cylinder 26, so that the hydraulic cylinder 26 expands and contracts by a predetermined amount at a predetermined frequency. . As a result, the interval between the brackets 24 and 25 of the upper and lower platens 19 and 22 is changed, and the shear force of different magnitude is cyclically applied to the sample 1.

At this time, the hydraulic cylinder 29 for moving the lower platen
A sine wave signal as shown in FIG. 5B is input to the drive circuit 43 of FIG. This sine wave signal has an amplitude of 1/2 in antiphase with respect to the sine wave signal of FIG. Pressure oil is also supplied to the lower platen moving hydraulic cylinder 29 via the drive circuit 43.

In FIG. 6, when the lower platen 22 is fixed and the horizontal load hydraulic cylinder 26 (not shown in FIG. 6) provided between the brackets 24 and 25 is extended by S, the upper platen 19 is moved to the left by S. A shear force acts on the test piece 1 by moving only. At this time, the center point O of the sample 1 is shifted to the left by S / 2 as indicated by O '. Therefore, in synchronization with extending the horizontal load hydraulic cylinder 26 by S, the horizontal moving hydraulic cylinder 29 is contracted by S / 2 to move the lower platen 22 to the right by S /.
When it is moved by 2, the specimen 1 is deformed as shown by the chain double-dashed line, the center point of which is always located at the O point, and the vertical load axis V
Matches X. As a result, the moment associated with the shear deformation of the sample 1 can be prevented from acting on the load yoke 16.

In this way, when a predetermined load is applied in the axial direction of the test piece 1 and a shearing force that repeatedly fluctuates in the horizontal direction is applied, the load fluctuation of the horizontal load hydraulic cylinder 26 causes the load cell 46 to displace. Are respectively detected by the displacement gauge 47. The curve a in FIG. 7 shows the horizontal load, and the curve b shows the horizontal displacement. Here, the horizontal load measured by the load cell 46 includes the frictional force of the vertical slide bearings 18 and 21. Therefore, prior to the test, the hydraulic cylinder 2 for horizontal movement should be loaded with a predetermined vertical load.
9 is operated to read the detected value of the load cell 49 and stored in a memory (not shown) as a pair with the vertical load. This stored value is the frictional force of the slide bearings 18 and 21. It is preferable that the vertical load is changed and the frictional force is similarly measured and stored in the memory, but a method of estimating the frictional force of different vertical loads from one type of vertical load and frictional force data may be adopted.

The horizontal bearing load measured by the load cell 46 is stored in the slide bearing 18, which is stored in the memory.
The energy curve of FIG. 8 is obtained by subtracting the frictional force of 21 and expressing it as the horizontal load against the corresponding horizontal displacement. The area within this closed curve represents the shear energy of the sample 1.

In this way, the upper and lower platens 1 while applying the axial force.
When performing a biaxial loading test in which the axial force and the shearing force are simultaneously applied to the test piece 1 by moving 9 and 22 in opposite directions, the center point of the test piece 1 is the axial center of the vertical load hydraulic cylinder 14. By performing an operation that always matches
It is possible to perform a test without generating an undesired compressive load on the vertical slide guide 17, and as a result, it is possible to accurately perform a correction calculation using the frictional force of the horizontal slide bearings 18 and 21 measured in advance. Accuracy is improved.

In the construction of the above embodiment, the vertical load hydraulic cylinder 14 serves as the axial load means, the horizontal load hydraulic cylinder 26 serves as the horizontal load means, and the horizontal moving hydraulic cylinder 2
9 constitutes the moving means respectively.

The structure of the tester main body is not limited to the embodiment. In particular, the hydraulic cylinder 14 and the hydraulic cylinder 26
Although the hydraulic cylinder 29 and the hydraulic cylinder 29 are incorporated in the main body of the test machine, the axial load mechanism and the horizontal load mechanism may be separate mechanisms.

[0023]

As described above, according to the present invention, an undesired moment is prevented from acting on the axial load mechanism due to the shearing force, so that the shear deformation load with high parallelism between the upper and lower surfaces of the specimen is high. In addition, the compressive force of the vertical slide guide can be made almost constant even under shearing force, and the fluctuation of the frictional force of the horizontal slide bearing due to it can be suppressed, so that the test can be performed more accurately than before.

[Brief description of drawings]

FIG. 1 shows an example in which the biaxial loading test apparatus according to the present invention is applied to an evaluation tester for seismic isolation rubber.
It is a figure which removes the support | pillar of FIG.

FIG. 2 is a front view of a seismic isolation rubber evaluation test machine showing an embodiment of the present invention.

FIG. 3 is a right side view of FIG.

FIG. 4 is a block diagram showing a control system of a seismic isolation rubber evaluation tester showing an embodiment of the present invention.

5A and 5B are diagrams showing horizontal displacement, in which FIG. 5A shows the displacement of the horizontal load hydraulic cylinder, and FIG. 5B shows the displacement of the horizontal movement hydraulic cylinder.

FIG. 6 is a diagram illustrating centering of a test piece.

FIG. 7 is a graph showing horizontal load and horizontal displacement.

FIG. 8 is a diagram showing an energy curve.

FIG. 9 is a diagram showing a conventional biaxial loading tester.

[Explanation of symbols]

 11 Struts 12 Base 13 Cross Yoke 14 Vertical Load Hydraulic Cylinder 16 Load Yoke 17 Vertical Slide Guide 18, 21 Horizontal Slide Bearing 19 Upper Platen 22 Lower Platen 26 Horizontal Load Hydraulic Cylinder 29 Horizontal Moving Hydraulic Cylinder 40 Control Circuit 44, 46 , 49 Load cell 45, 47, 48 Displacement meter

Claims (1)

[Claims] 1. An axial force load means for applying an axial force to a test piece held by a pair of upper and lower platens, and the pair of upper and lower platens are relatively moved while applying the axial force to the sample. Shear loading means for repeatedly applying a shearing force orthogonal to the axial force, and the upper and lower platens so that when the shearing force is repeatedly applied to the specimen, the center point of the specimen coincides with the axial center of the axial force. And a platen moving means for moving the two-axis loading test apparatus.