JP2547045B2 - Cyclic fatigue test equipment - Google Patents

Description

The present invention relates to a cyclic fatigue test apparatus for inspecting the strength of a ceramic sample or the like.

<Prior Art> In a cyclic fatigue test of a ceramic sample or the like, one side is held at two points, the other side is held at the center, and a bending fatigue test of the sample is performed by a three-point bending test in which a dynamic load is applied from one side. There are means for measuring the degree.

Conventionally, in this repetitive fatigue test apparatus, a mechanical linear reciprocating drive mechanism such as a piston or a cylinder is used as a shock source to apply a dynamic load from one surface side of the sample.

<Problems to be Solved by the Invention> By the way, in such a conventional configuration, it is troublesome to adjust and change the driving force, a driving force of a high frequency cannot be generated, and a large driving noise is generated. However, there are drawbacks such as the occurrence of abrasion and the severe wear caused by mechanical friction, which makes it difficult to keep the test conditions constant.

The present invention aims to eliminate the above-mentioned conventional defects.

<Means for Solving Problems> According to the present invention, one end or both ends of a diaphragm having an electrostrictive element layer disposed on at least one surface of a curved plate is held on a base, and the diaphragm is further provided. The sample holding member is attached to the moving surface of the above, and a sample pressing end for sandwiching the test piece with the holding member is provided on the sample holding member.

<Operation> When an alternating voltage of a predetermined frequency is applied to the front and back electrodes of the electrostrictive element layer, bending vibration occurs in the bending plate. Along with this, the sample holding member supported on the moving surface of the diaphragm vibrates. For this reason, a test piece in which one surface of the sample is supported by the holding member and the other surface is held by the sample pressing end is subjected to a sine wave or pulse dynamic load based on a predetermined frequency due to the vibration of the sample holding member. It was eventually destroyed. At this time, the strength of the sample can be detected by measuring the speed leading to breakage and the frequency of the dynamic load.

<Example> An example of the present invention will be described with reference to Figs.

Reference numeral 1 denotes a base having an elastic support material 17 such as soft rubber, sponge, and metal spring arranged on the lower surface thereof, and fixed to the installation surface 18 in a semi-floating manner. A vibration plate 2 having a bimorph structure serving as an impact source is supported on the base 1 in a cantilever manner at one edge thereof by a support shaft 3a and a nut 3b screwed to the base 1.

As shown in FIG. 2, the vibrating plate 2 is formed by disposing electrostrictive element layers 5a and 5b having electrodes on front and back sides on the upper and lower surfaces of a rectangular curved plate 4, respectively. A weight 6 is fixed to the other side of the plate 4.

The electrostrictive element layers 5a and 5b are polarized in opposite directions, their outer electrodes are connected to the AC power source 15, and their inner electrodes are connected to the curved plate 4
Is connected to the ground via a wire, and the voltage is applied so that one expands and the other contracts.

As shown in FIG. 3, a sample holding member 7 having two support ends 8 located in the width direction is provided on the upper part of the oscillating surface of the diaphragm 2 as shown in FIG.

A load cell 12 supported by an elevating body 11 is disposed above the vibrating plate 2, and a lower end of the load cell 12 is located between the support ends 8 of the sample holding member 7 and a test piece p. Is provided with a sample pressing end 13 that abuts the upper surface of the.

 The operation of the above configuration will be described.

The test piece p is placed on the supporting ends 8 and 8 of the sample holding member 7, the elevating body 11 is lowered to an appropriate position, and the pressing end 13 is abutted on the test piece p between the supporting ends 8 and 8. Touch and support three points. At this time, when the lifting body 11 is slightly lowered from the proper position, the elastic support 17 arranged on the lower surface of the base 1 is compressed, and the vibrating body 2 and the base 1 are displaced downward. The test piece p is always held with a constant pressing force without breaking.

After that, an alternating voltage having a predetermined frequency having an AC wave such as a pulse wave, a sine wave, or a triangular wave is applied from the AC power supply 15 to the electrostrictive element layers 5a and 5b.

As a result, strain is generated in the electrostrictive element layers 5a and 5b, and the other piece is held by the inertial force of the weight 6 to generate bending vibration. Then, the test pieces p are pressed from below on both sides by the up-and-down movement of the supporting ends 8 and 8 due to the bending vibration, and bending distortion is periodically imparted around the pressing ends 13. Then, the dynamic load causes fatigue and eventually damage. Then, by measuring the time, the applied voltage, the number of pulses, and the like that lead to such damage, it becomes possible to measure the strength of the specimen p, such as the transverse rupture force.

In the above-mentioned configuration, when the sample holding member 7 was held at each of the three positions shown in FIGS. , The test piece p has a swing of 54.3 Kgfp-p, the B position has a frequency of 230.8 Hz, and the test piece p has a swing of 44.1 Kgfp-p,
At position C, the frequency is 339.0 Hz and the amplitude applied to the test piece p is 11.0 Kgfp-p.
The amount of swing was maximum at the position. Therefore, the swing range can be adjusted by changing the mounting position of the holding member 7 along the left-right direction.

 4 and 5 show a second embodiment of the present invention.

Here, the diaphragm 22 is supported by the support pieces 23 on the base 20 at the node position of the bending vibration. A long hole 25 is formed in the center of the curved plate 24 along the left-right direction in the figure, and a total of four electrostrictive element layers 26 separated at the front and rear are attached to both sides of the long hole 25. Further, weights 27, 27 are detachably held by screws 28 at the ends of the curved plate 24 outside the supporting pieces 23, 23.

In the elongated hole 25, the sample holding member 30 has its flexible foot piece 3
Sliding pieces 32, 32 formed on 1, 31 are fixed to enable sliding along the elongated hole 25.

On the upper surface of the sample holding member 30, two front and rear support ends 3
3, 33 are provided, and the pressing end 13 of the load cell 12 is arranged on the upper surface thereof.

In the above structure, the sample holding member 30 is movable along the long hole 25, and the intermediate position of the supporting ends 33, 33 is the diaphragm 2.
The maximum amplitude can be imparted to the test piece p supported on the sample holding member 30 at a position corresponding to the center position of 2, and the amount of amplitude can be reduced by moving along the elongated hole 25. it can. Therefore, it is possible to arbitrarily adjust the amplitude.

In the above structure, the test piece p is mounted on the supporting ends 33, 333, and the upper surface between the supporting ends 33, 33 is brought into contact with the pressing end 13, and then the front and back surface electrodes of the electrostrictive element layer 26. When an alternating voltage is applied to the support ends 33, 33, the support ends 33, 33 are pressed on both sides.
With 3 as the fulcrum, bending strain vibration corresponding to the applied frequency is generated. Thus, the test piece p becomes fatigued and eventually broken.

Due to this vibration, weights 27, 2 are provided on both ends of the curved plate 24.
Since 7 is held, the amplitude is increased due to its inertial force. Further, the sliding movement of the curved plate 24 causes the sliding pieces 32, 32 fixed to the long hole 25 to have a lateral relative movement component, but the strain is absorbed by the flexible foot pieces 31, 31. To be done.

In addition, although the present invention is particularly useful for a three-point bending test,
It can also be applied to a test mode in which the entire periphery of the test piece p is held by a supporting edge and the pressing end is brought into contact with the center of the test piece p.

<Effects of the Invention> As described above, the present invention provides a test piece p made of ceramic or the like.
In addition, a vibrating plate in which electrostrictive element layers are arranged on the front and back surfaces of the curved plate.
Since the bending strain of 22 is to give a dynamic load,
By appropriately selecting the alternating applied voltage to the electrostrictive element layer, the repetitive stress and the cycle can be adjusted, and various test conditions can be arbitrarily set, and the mechanical straight line can be set. Unlike conventional means for applying a dynamic load by a reciprocating drive mechanism, it has excellent effects such as generation of noise and less wear due to mechanical friction, and easy maintenance of the same test conditions.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a front view, FIG. 2 is a perspective view of a diaphragm 2, and FIG. 3 is a vertical sectional side view of a sample holding member 7 and the like. Further, FIG. 4 is a vertical sectional front view of the second embodiment, and FIG. 5 is a plan view of the same. 2; diaphragm, 3a; support shaft, 4; curved plate, 5a, 5b; electrostrictive element layer, 6;
Weight, 7; sample holding member, 8, 8; support end, 13; pressing end, 22; diaphragm, 23, 23; support piece, 24; curved plate, 25; elongated hole, 26; electrostrictive element layer, 27, 27; Weight, 30; Sample holding member, 31, 31; Elastic foot piece, 32, 32; Sliding piece, 33, 33; Support end, p; Test piece

Claims (4)

(57) [Claims] 1. A vibrating plate having an electrostrictive element layer disposed on at least one surface of a curved plate, holding one or both ends of the vibrating plate on a base, and further mounting a sample holding member on the moving surface of the vibrating plate. A repetitive fatigue test apparatus, comprising a sample pressing end for mounting and holding a test piece between the sample holding member and the holding member. 2. The cyclic fatigue test apparatus according to claim 1, wherein one end of the diaphragm is held and a weight is fixed to the other end. 3. The repeated fatigue test apparatus according to claim 1, wherein both ends of the diaphragm are supported, and weights are fixed to both end edges extending from the support. 4. The cyclic fatigue test apparatus according to claim 1, wherein an elastic support material is provided on the lower surface of the base.