JPS6189538A - Apparatus for testing ceramic material - Google Patents

Abstract

PURPOSE:To accurately calculate the stress intensity factor of a ceramic material, by providing a means which has a pressurizing element operated by a motor and a displacement meter and controls the motor so as to maintain the displacement imparted to a test piece at a high speed by the pressurizing element. CONSTITUTION:A pressurizing part 13 is contacted with the almost central part of the test piece T placed on a support part 6 and, when an objective displacement signal is applied to a control means consisting of a displacement meter 7 and amplifiers 19, 20 to operate a motor 14, a screw shaft part (pressurizing part) 12 is fallen to bent the test piece T and the central part thereof is displaced. This displacement amount is measured by the displacement meter 7 and the motor 14 is operated corresponding to the deviation amount of the measured value and the objective displacement signal. When the displacement amount is kept at the point of time when the test piece T was quickly displaced to a predetermined value, a crack gradually advances and the load received by the test piece T is detected by a load cell 8 to be recorded as a load wave form and a stress intensity factor and a crack growing speed are calculated from said wave form.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a ceramic material testing device, and more specifically, it is a method for measuring a stress intensity factor of 1 and a crack growth rate of a ceramic material. the law of nature.

Double torsion technique
que).

[Conventional technology]

In recent years, the use of ceramic materials in various fields has been considered, and for this reason, it has become necessary to accurately measure the stress intensity factor of 1 and the crack growth rate V, which provides valuable data for predicting the life of ceramic materials. Became.

The C, B, method (Double
cantilever beam technique
e) Tori, T.

The law is known.

In the D, C, B method, the stress intensity factor is 1 and the crank length is required to determine the crank growth rate (■).Moreover, when determining the crank growth rate (■), the crack length is measured using a microscope. To observe changes over time,
In the case of opaque ceramic materials, there are fundamental problems in that measurements are difficult.

On the other hand, in the D, T, method, the stress intensity factor K.

It is convenient in principle because it is not necessary to measure the crank length to determine the crack growth rate, and it is not necessary to measure the change in crack length over time using a microscope to determine the crack growth rate.

Figure 5 shows the shape of the test piece T used in the beam, T, method. The test specimen T is supported along both ends in the longitudinal direction, and a crank previously generated along the central groove t grows under a load P at one end.

The crack growth rate ■ is determined by the following procedure.

First, after a predetermined displacement is rapidly caused in the test piece using a pressurizer, the displacement is maintained so as not to change, and the change in the load applied to the test piece at this time is determined using a recorder. In this specification, "displacement of a test piece" refers to the position in the axial direction of the center of the test piece under no load, and when the periphery of the center is pressurized, the test piece curves and the axis of the center It means a change in the position of a direction.

Further, the stress intensity factor of 1 can be determined by substituting the load P that the test piece receives into the following equation.

Here, γ is Poisson's ratio.

In addition to this method, the D, T, method involves rapidly applying a load to a test piece with a pressurizer at a constant speed up to a predetermined load, and stopping the pressurizer when the predetermined load is reached. Although there are other methods, in this specification, "glue", "T", and "method" refer to the above-mentioned method (a method in which a predetermined displacement is rapidly caused in a test piece).

Conventionally, D, T, and method tests have used testing machines with a "screw rod" structure that is used in ordinary material testing. However, this test machine has a configuration in which the load is applied by lowering the moving platform itself (see Figure 1), and it is structurally impossible to rapidly lower the heavy moving platform because the inertia is too large. For this reason, it is difficult to rapidly produce a predetermined displacement in the test piece, and the load curve acting on the test piece has a gentle rising part (see the solid line in Figure 3), and the stress intensity factor (especially The portion close to the critical stress intensity factor Kle (see FIG. 4) could not be accurately determined.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above circumstances, and its purpose is to provide a ceramic material testing device that can accurately determine the stress intensity factor Kl.

[Means to solve the problem]

The present inventor has solved the above problem (as a result of intensive research, the load applied to the ceramic material is on the order of kg, unlike metal materials, it is not required to be on the order of a ton, and the load applied to the ceramic material is not required to be on the order of a ton, and the load applied to the ceramic material is not required to be on the order of tons, and only the pressurizer can be applied without moving the movable table itself. We have discovered that a sufficient load can be applied simply by moving it with a motor, and that by controlling the motor, a load curve with a rapid rise as shown by the dotted line in Figure 3 can be easily obtained, and the present invention has been made based on this discovery. It's arrived.

That is, the present invention includes an indenter that is moved in the axial direction by a motor to displace the test piece, and a displacement detection means that detects the displacement of the test piece, so that the indenter rapidly applies a predetermined displacement to the test piece. and a control means for controlling the motor so as not to change the displacement after the displacement is caused to occur.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example in which a material testing device of the present invention is attached to a testing machine having a "wajizao" structure. In the figure, reference numeral 1 is the main body of the testing machine with a "wajizao" structure, 2 is the base that constitutes this main body 1, 3, 3 is a pair of screw supports erected on this base Z, and 4 is this This is a movable platform supported by a pair of vertical struts 3, 3 and moved in the axial direction.

A support stand 5 for the test piece T is provided approximately in the center of the base 2 between the pillars 3, 3. On the upper surface of this support stand 5, support parts 6, 6 having a triangular cross-section and supporting the test piece T near both ends thereof are provided. Further, a displacement gauge 7 is installed in the internal space of the support base 5, and a detection pin 7a of the displacement gauge 7 protrudes from the upper surface of the support base 5 through a hole 5a, so that a detection pin 7a of the displacement gauge 7 protrudes from the upper surface of the support base 5 through a hole 5a. (see Figure 5). When the central portion of the test piece T is bent and displaced, the detection bottle 7a is pushed, and the displacement meter 7 measures the amount of displacement.

A load cell 8 and a ball screw 9 are provided on the lower surface of the movable table 4 at a substantially central position between the screw supports 3 and 3. The load cell 8 is fixed to the movable table 4, and a nut portion 10 constituting a ball screw 9 is rotatable relative to the load cell 8 via a thrust bearing 11.

A screw shaft portion 12 constituting the ball screw 9 serves as a pressurizer, and moves in the axial direction by rotation of the NAND portion 10 to press and displace the test piece T. A bifurcated pressing section 13 is provided at the end of the screw shaft section 12 on the side that presses the test piece T.

Further, a servo motor 14 is provided on the moving table 4 in parallel with the ball screw 9, and the rotation of the servo motor 14 is caused by the rotation of the gear 15 provided on the drive shaft 14a, the intermediate gear 16, and the outer circumferential surface of the nut portion IO. The signal is transmitted to the NAND unit 10 via the gear 17. The NAND portion 10 thereby rotates and moves the screw shaft portion 12 in the axial direction.

The control means 18 that controls the servo motor 14 includes the aforementioned displacement meter 7 and an amplifier 19 that amplifies the measurement signal of the displacement meter 7.
and an amplifier 20 that amplifies the deviation amount between the measurement signal amplified by the amplifier 19 and the target displacement signal (see second reference) given to the test piece T and outputs it to the servo motor 14 to perform foot bank control. conduct.

Next, the operation of the above embodiment will be explained.

A test piece T is set on the support parts 6, 6, and the pressurizing part 13 is brought into contact with approximately the center of the test piece T.

Then, a target displacement signal having a displacement waveform as shown in FIG. 2 is set in a setting section (not shown) of the control means 18, and the servo motor 14 is operated.

Then, the screw shaft portion 12 descends, the test piece T is bent, and the central portion is displaced. This amount of displacement is measured by the displacement meter 7 and compared with the target displacement signal to determine the amount of deviation, and the servo motor 14 operates according to this amount of deviation.

As a result, the center part of the test piece T becomes as shown in FIG.
At first, the displacement is rapidly reached to a predetermined value, and when the displacement amount reaches the predetermined value, the amount of displacement is maintained at the predetermined value. If the amount of displacement is maintained at a predetermined value in this way, cracks will gradually progress. The load (reaction force) that the test piece T receives at this time is
, the nut portion 10, and the thrust bearing 11, and are detected by the load cell 8. The detection signal from the load cell 8 is input to an X-Y recorder (not shown), and the recorder records a load waveform as shown by the dotted line in FIG. 3.

From this load waveform, the stress intensity factor and the crack growth rate V are determined.

Figure 4 shows the stress magnification factor # calculated in this way! 1. K.

It is a graph showing the relationship between the crack growth rate and the crack growth rate. As is clear from this graph, + (the part surrounded by the dashed-dotted line) can be accurately determined for the stress intensity coefficient close to Klc.

When performing a normal material test, move the moving table 4 to the supporting column 3.
, 3, the screw shaft portion 12 serving as a pressurizer applies a load to the test piece T.

〔Effect of the invention〕

As explained above, the present invention includes an indenter operated by a motor and a displacement detection means, and after the indenter rapidly causes a predetermined displacement on a test piece, the displacement is changed. Since the present invention includes means for controlling the motor so that the stress intensity factor of the ceramic material does not increase, the stress intensity factor of the ceramic material can be accurately determined to be 1.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially cutaway schematic side view, Fig. 2 is a graph showing a displacement waveform, Fig. 3 is a graph showing a load curve, and Fig. 4 is a graph showing a load curve. The figure is a graph showing the relationship between stress intensity factor and crack growth rate.
FIG. 5 is a perspective view of the test piece. 7...Displacement meter, 9...Ball screw, 1
2... Pressure element (screw shaft part), 14...
Motor (servo motor), 18... Control means. Patent Applicant Saginomiya Seisakusho Co., Ltd. - Shou M Figure 3 - j18 - Eyebrows Wa 1 ε Main City Shoulder 3 Mawa: (Voluntary) March 260, 1985 Commissioner of the Patent Office Shi 2 Manabu Tono 1, 1H Cow Showa 1959 Patent Application No. 210510 2 Name of the invention Ceramic material testing device 3 Relationship to the amended person's case Patent applicant address 2-55-5 Wakamiya, Nakano-ku, Tokyo Name Saginomiya Seisakusho Co., Ltd. 4, Agent

Claims (1)

[Claims] A presser that is moved in the axial direction by a motor to displace the test piece, and a displacement detection means that detects the displacement of the test piece, and after the presser rapidly causes a predetermined displacement on the test piece, A ceramic material testing device comprising: control means for controlling the motor so as not to change the displacement.