JPH01173850A - Repetitive fatigue testing device - Google Patents

Abstract

PURPOSE:To release a diaphragm from being restrained at a support position by the deflection of a leaf spring and to place a proper dynamic load on a test piece by coupling one end of the leaf spring which has lower rigidity when the curved plate of a repetitive fatigue testing device for a ceramic sample with one end of the curved plate and supporting the other end of the leaf spring on the base. CONSTITUTION:The test piece (p) is mounted on a sample support member 17, an elevation body 20 is lowered to a proper position, and the test piece (p) abuts on a pressure end 22 between said piece and a support end 18, nabling three-point support. At this time, an elastic support material 2 arranged on the reverse surface of the base 1 is compressed and the diaphragm 3 and base 1 are displaced downward to hold the test-piece (p) with constant pressure. In this state, an AC power source 23 applies a voltage to electrostrictive element layers 5a and 5b, the external end of the leaf spring 8 is clamped by washers 12a and 12b with the strain generated in the layers 5a and 5b, so that the diaphragm 3 held on the base 1 enters curved vibration between said diaphragm and a support position. Then the test-piece (p) has both ends pressed downward by the elevation movement of the support end 18 accompanying the curvature vibration and is applied with the curvature vibration as a dynamic load about a pressure point 22.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a reversing fatigue testing device for testing the strength of ceramic samples and the like.

<Prior art> For cyclic fatigue testing of ceramic samples, etc., one side of the sample is held at two points, the other side is held at its center, and the sample is bent by a three-point bending test where a dynamic load is applied from the negative side. There are means to measure the degree of fatigue.

Conventionally, this cyclic fatigue testing apparatus has used a mechanical linear reciprocating mechanism such as a piston or cylinder as an impact source to apply a dynamic load from one side of the sample.

However, with such a conventional configuration, it is troublesome to adjust and change the driving force, it is not possible to generate a high frequency driving force, and furthermore, it generates a large driving noise, and furthermore, it is caused by mechanical friction. There were drawbacks such as severe wear and tear and difficulty in keeping test conditions constant.

Therefore, one end or both ends of a diaphragm having an electrostrictive element layer arranged on at least one surface of a curved plate are supported on a base, and a sample holding member is attached to the emotional surface of the diaphragm to hold the sample. It has been proposed that the member is provided with a sample pressing end for holding the test piece with the holding member (Japanese Patent Application No. 62-250).
No. 208).

In this configuration, when an alternating voltage of a predetermined frequency is applied to the front and back electrodes of the electrostrictive element layer, a bending vibration is generated in the curved plate. Along with this, the sample holding member supported by the emotional surface of the diaphragm vibrates. Therefore, a sine wave or pulse-like dynamic load based on a predetermined frequency is applied to the test piece, which has one side of the sample supported by the holding member and the other side held by the sample pressing end, due to the vibration of the sample holding member. This eventually leads to damage. At this time, the strength of the sample can be detected by measuring the speed at which breakage occurs and the frequency of the dynamic load.

Therefore, with this configuration, by appropriately selecting the alternating voltage applied to the electrostrictive element layer, the repeated stress and period can be adjusted, and various test conditions can be set at will. Moreover, unlike the conventional means of applying dynamic loads using a mechanical linear reciprocating drive mechanism, this method has the advantage of generating less noise and less wear and tear due to mechanical friction, and making it easier to maintain the same test conditions.

<Problems to be Solved by the Invention> In such a configuration, when both ends of the curved plate are directly supported on the base, it is desirable that this support be complete point support at the vibration node position. In practice, it is not possible to provide point support to achieve the required support strength;
The curved plate is held unbendably around its ends. However, since a curved plate has a test piece mounted on its top surface and is pressed from above by a load cell, it requires a certain amount of holding force, and also requires a certain amount of rigidity in order to keep the resonance frequency within a certain range. be done. Therefore, due to its rigidity, if the support part is held in a plane as described above, vibrations are inhibited by this support part, resulting in a reduction in amplitude.

The present invention aims to solve such technical problems.

<Means for Solving the Problems> The present invention provides a method in which one end of a leaf spring having lower rigidity than a curved plate is connected to a supporting end of the curved plate, and the other end of the leaf spring is supported on a base. It is characterized by this.

Function> The support end of the curved plate is supported on the base via a leaf spring. Therefore, since the leaf spring has lower rigidity than the curved plate, it can easily move. Therefore, even if the outer end of the leaf spring is surface-supported with respect to the base, it will bend due to its deflection.
This means that inhibition of vibration of the diaphragm by the support portion can be prevented as much as possible.

<Example> An embodiment of the present invention will be described with reference to FIGS. 1-3.

Reference numeral 1 denotes a base having an elastic supporting material 2 such as soft rubber, sponge, or metal spring arranged on the lower surface, and is fixed in a semi-floating manner with respect to the installation surface. On this base 1, a bimorph-structured diaphragm 3 serving as an impact source is supported at both ends thereof.

As shown in FIG. 3, the diaphragm 3 includes electrostrictive element layers 5a and 5b provided with electrodes on the top and bottom surfaces of a rectangular curved plate 4.
is arranged. The electrostrictive element layers 5a and 5b are polarized in opposite directions, and their outer electrodes are connected to an AC power source 23, and their inner electrodes are connected to ground via the curved plate 4, and when voltage is applied, one of them expands. Then, the other wire is wired so that it contracts.

Next, the means for supporting the diaphragm 3 with respect to the base l will be explained.

Connecting holes 6 are bored at both corners of the curved plate 4, and one ends of leaf springs 8, 8, which are less rigid than the curved plate 4, are applied to the lower surfaces of both ends of the connecting holes 6, and the plate springs 8.8 are The connecting port 9 is inserted and fixed into the connecting hole IO formed at the corner and the connecting hole 6 of the curved plate 4.

Further, a support bolt 14 is inserted into the connecting hole 10 on the other end side of the leaf spring 8.8 at a required position of the diaphragm 3, with washers 12a and 12b interposed above and below, and is attached to the base 1. Screwed together. The washers 12a and 12b each have a long hole 13 in the front and back direction.
is formed. Therefore, it is possible to move the washers 12a and 12b back and forth, and depending on the holding position, the curved base end O of the leaf spring 8.8 is changed, the rigidity of the leaf spring 8.8 is changed, and the vibration The position of the plate 3 can be determined so that it can curve efficiently. Then,
By means of such support means the outer end of the leaf spring 8.8 is fixed on the base l by means of the support bolt 14. Also leaf spring 8.
At the outer edge of 8, a weight 1 is placed between the support bolts 14 and 14.
5.15 is removably held.

The outer end of the leaf spring 8.8 may be fixed by a clamping means such as a pivot bearing.

On the emotional surface in the middle of the diaphragm 3, as shown in FIG.
A sample holding member 17 is provided. Further, above the diaphragm 3, there is a load cell 2 supported by the elevating body 20.
At the lower end of the load cell 21, a sample pressing end 22 is provided which is located between the supporting ends 18, 18 of the sample holding member 17 and comes into contact with the upper surface of the test piece p.

The operation of the above configuration will be explained.

Place the test piece p on the support end 18.18 of the sample holding member 17, lower the elevating body 20 to the appropriate position, and apply the pressing end 22 on the test piece p between the support ends 18.18. Contact and support at three points. At this time, if the elevating body 20 descends a little too much than the proper position, the elastic support material 2 arranged on the lower surface of the base l is compressed, and the diaphragm 3. Since the base 1 is displaced downward, the test piece p is always held with a constant pressing force without being broken.

Next, an alternating voltage having a predetermined frequency and having an alternating current wave such as a pulse wave, a sine wave, or a triangular wave is applied from the alternating current power supply 23 to the electrostrictive element layers 5a and 5b.

This causes strain in the electrostrictive element layers 5a and 5b, and the diaphragm 3, which is held on the base 1 with the outer ends of the leaf springs 8.8 held between the washers 12a and 12b, is moved to the supporting position. curvature oscillates between. During this vibration, since the weights 23 and 23 are held at both ends of the curved plate 4, the swing width becomes large due to the inertial force thereof. The test piece p is pressed from below on both sides by the vertical movement of the support ends 18 and 18 due to the bending vibration, and is subjected to periodic bending strain around the press end 22, causing fatigue due to this dynamic load. However, it will eventually lead to damage.

Therefore, the time and applied voltage that lead to such damage.

By measuring the number of pulses, etc., it becomes possible to measure the strength, such as the transverse rupture strength, of the test piece p.

During the bending vibration of the diaphragm 3, the bending plate 4 is supported by the base l via the plate springs 8.8. Therefore, even if the outer end of the leaf spring 8.8 is sandwiched between the washers 12a and 12b and supported on the surface, the leaf spring 8.8 is bent around the curved base end 0, and as a result, the diaphragm 3 It does not inhibit the vibration of the Furthermore, by moving the washers 12a and 12b back and forth along the elongated hole 13 as described above, the diaphragm 3 can be positioned so as to most efficiently evoke emotion.

Figure 4.5 shows a second embodiment of the invention.

In this configuration, an electrostrictive element layer 5 is provided on the upper and lower surfaces of the curved plate 4.
A diaphragm 3 similar to the above, in which diaphragms a and 5b are arranged, is used, and one end of a leaf spring 8 is connected to only one edge of the diaphragm 3.
The other end of the leaf spring 8 is supported by a bolt 30 in a cantilevered manner. Further, a weight 31 is fixed to the other side of the curved plate 4.

A sample holding member 17 is provided on the emotional surface in the middle of the diaphragm 3, and the sample holding member 17 is provided with support ends 18, 18 at three locations located in the width direction at the upper part, and above the sample holding member 17, a suppression end 22 is provided on the lower surface. A load cell 21 is provided.

In the above configuration, the test piece p is mounted on the support ends 18.18 so that the upper surface between the support ends 18.18 comes into contact with the pressing end 22, and then the electrostrictive element layers 5a and 5b are placed. When an alternating voltage is applied to the front and back electrodes, distortion occurs in the electrostrictive element layers 5a and 5b, and the other pieces of the diaphragm 3 are held by the inertial force of the weight 6, causing bending vibration. The test piece p is pressed on both sides by the supporting ends 18 and 18, and generates a bending strain vibration corresponding to the applied frequency with the suppressing end 22 as a fulcrum.
Eventually it will be damaged.

At this time, the curvature of the leaf spring 8 can absorb the restraint at the supporting position, and the diaphragm 3 can be released from vibration inhibition due to the rigidity of the curved plate 4. Even in the above embodiment,
Similar to the first embodiment, washers 12a, 1 having elongated holes 13
2b may be applied so that the supporting position of the leaf spring 8 can be changed.

In addition, although the present invention is particularly useful for three-point bending tests, it is also applicable to test modes in which the entire periphery of the test piece p is held by a support edge and the suppressed end is brought into contact with the center of the test piece p. obtain.

<Effects of the Invention> As described above, in the present invention, the base and the diaphragm are supported through the leaf spring, so that the restraint at the supporting position is released by the bending of the leaf spring, which is different from the conventional method. As shown in the figure, there is no vibration inhibition due to the rigidity of the curved plate and the supporting part, and therefore, it is possible to obtain a good amplitude of the diaphragm, and it is possible to apply an appropriate dynamic load to the test piece P. effective.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a partially cutaway front view, FIG. 2 is a side view of the same, and FIG. 3 is a diaphragm 3. Isolated perspective view of handling spring 8 and washers 12a, 12b, No. 4.5
The figure shows the second embodiment, FIG. 4 is a partially cutaway front view, and FIG.
The figure is a longitudinal sectional side view of the sample holding member 17 and the like. 1: Base 3: Diaphragm 4: Curved plate 5a. 5b; Electrostrictive element layer 8.8: Leaf spring 12a. 12b, washer 13; long hole 14: support bolt 17: sample holding member 1B, 18; support end 22; pressing end 21:
Load cell p: Test piece applicant NGK Spark Plug Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1) A diaphragm having an electrostrictive element layer disposed on at least one surface of the diaphragm is supported at one or both ends on a base, and a sample is placed on the curvature surface of the diaphragm. In the case where a holding member is attached and a sample pressing end is provided on the sample holding member to sandwich a test piece between the holding member and the holding member, one end of a leaf spring whose rigidity is lower than that of the curved plate is attached to the supporting end of the curved plate. A cyclic fatigue testing device characterized in that the leaf springs are connected to each other and the other ends of the leaf springs are supported on a base. 2) The cyclic fatigue test device according to claim 1, wherein both ends of the diaphragm are supported, and weights are fixed to both ends. 3) The cyclic fatigue testing device according to claim 1, wherein one end of the diaphragm is held and a weight is fixed to the other end.