JPS63210640A - Apparatus for testing twist fatigue of composite material - Google Patents

Abstract

PURPOSE:To detect only pure twist fatigue without acting load other than a twist on a sample, by making one of both grasping parts of a tubular composite material freely movable in the axial direction. CONSTITUTION:Both ends of a tubular composite material S are grasped by grasping parts 5, 6 and twist load within such a range that vibration frequency is 1-4Hz and amplitude is pi/2-pi/3 rad is repeatedly applied to the composite material S while internal pressure of 200-300KPa is applied by a compressor 8. The tubular composite material S generates change such that said material S shrinks in the diameter direction and axial direction thereof and extends to the original state when the load is released. However, the composite material S is held to an almost constant diameter corresponding to extension and shrinkage change so that the generation of collapse is prevented with respect to the shrinkage in the diameter direction by the internal pressure from the compressor 8 and the generation of tensile stress is prevented with respect to the shrinkage in the axial direction by the movement of the grasping part 6 toward the grasping part 5. Therefore, only pure twist fatigue is detected by a torque meter 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for testing torsional fatigue of composite materials mainly made of plastic, rubber, etc.

[Prior art]

Materials such as plastics and rubbers may be reinforced with reinforcing cords, or plastics, rubbers, etc. with different properties may be combined with each other to form a composite material.

When using such composite materials, torsional fatigue properties are one of the important evaluation factors. However, conventional torsional fatigue test equipment for composite materials has a problem in that the measurement data contains a lot of noise and has low reliability.

For example, in the torsional fatigue test device described in U.S. Pat. No. 2,412,524, both ends of a tube-shaped sample are held and one end is twisted. , by adding this distortion,
The problem is that pure torsional fatigue cannot be measured because the sample contracts in the axial direction (longitudinal direction) and generates tensile stress.

[Purpose of the invention]

The purpose of the present invention is to provide a torsional fatigue testing device for composite materials that can eliminate the drawbacks of conventional testing devices as described above, and can measure only pure torsional fatigue without applying any load other than tearing to the sample. Our goal is to provide the following.

[Structure of the invention]

The apparatus of the present invention for achieving the above object is provided with a gripping part that grips both ends of a tubular composite material of a measurement sample, and a pressurizing part that applies internal pressure to the tubular composite material, and a pressure part that applies internal pressure to the tubular composite material. The gripping portion is connected to a reciprocating rotation drive portion, and the other is connected to a tear fatigue detection portion, and one of the gripping portions is movable in the axial direction of the tubular composite material. .

In the present invention, the composite material measurement sample is formed into a tube shape. More preferably, at least two sheets of calendar material are pasted together at different angles. Figure 5 shows an example of this, where plastic is reinforced with cords a and b, respectively.

Sheet layers A and B made of rubber or the like are laminated to form a tubular composite material S.

The torsional fatigue testing device of the present invention grips one end of such a tubular composite material with a gripping section connected to a reciprocating rotation drive section, while gripping the other end with a gripping section connected to a torsional fatigue detection section. While internal pressure is applied by the pressure part, a reciprocating torsional load is applied to the sample by the former reciprocating rotation drive part, and at this time, one of the gripping parts is made freely movable in the axial direction of the tubular composite material. It is something. The movable side is preferably the gripping part on the torsional fatigue detection part side as in the embodiment described later, but the gripping part on the reciprocating rotation driving part side may be made movable. The torsional load applied by the reciprocating rotation drive unit has a frequency of 1 to 4 Hz and an amplitude of π/2 to π/
A range of 3 rad is preferable, and a range of 200 to 300 KPa is preferable as the internal pressure applied in the pressurizing section.

In the present invention, it is preferable to use a servo motor as the reciprocating rotation drive section, a torque meter is preferably used as the torsional fatigue detection section, and a near compressor is preferable as the pressurization section that applies internal pressure load. In addition, as a mechanism for making the grip part movable, it is preferable to use a mechanism that allows for smooth movement without generating frictional resistance as much as possible. It is preferable to place it on top and be able to slide it along the rail.

Further, it is preferable that the gripping part is capable of reliably fixing the tubular composite material without slipping, and a chuck is excellent for such a gripping part in the case of tapered clamping as in the embodiments described below. This tapered clamping can provide an accurate twist angle to the tubular composite material by using a chuck, allowing accurate torsional fatigue measurements.

FIG. 1 schematically shows an alternative fatigue testing apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a base that supports the entire device, and a servo motor 2 is installed at one end of the base 1 as a reciprocating rotation drive unit, and a torque meter 3 is installed at the other end as a tear fatigue detection unit. has been done.

The servo motor 2 is controlled by a drive unit 7 and is capable of reciprocating rotation within a frequency range of 1 to 4 Hz and an amplitude of π/2 to π/3 rad.

Further, a recorder 11 is connected to the torque meter 3, and the detected torque change is outputted as torsional fatigue.

The servo motor 2 is fixed on the heath 1,
The torque meter 3 is supported on a pair of left and right rails 4.4 via bearings, and is movable in the direction of arrow E. That is, this movable mechanism is shown in FIGS. 2 and 3A.

As shown in B, a pair of left and right sliders 12.12 is fixed to the bottom surface of the torque meter 3.
A thrust bearing 1 is installed between the rails 4 and 4, respectively.
3.13 is interposed to significantly reduce frictional resistance.

Such a movable mechanism may not be provided on the torque meter 3 side as described above, but may be provided on the servo motor 2 side. Further, although it is preferable to provide a thrust bearing in the movable mechanism to reduce frictional resistance, a spline fitting may be used instead of the thrust bearing.

Reference numeral 5.6 denotes gripping parts for removably fixing both ends of the tubular composite material S, which is a sample. Of these, the grip portion 5 is connected to the servo motor 2, and the grip portion 6 is connected to the torque meter 3. Further, a kelp L/, 8 is connected to the gripping portion 6 via a pulp 9, and is configured to supply compressed air into the tubular composite material S.

10 is a pressure gauge. Of course, the compressor 8 may be connected to the grip portion 5.

Preferably, each of the gripping parts 5.6 comprises a tapered chuck, as described above. FIG. 4 shows the holding part 6 as a representative, and this tapered mold tightening is performed by fitting a male mold 15 having an annular tapered surface 15a and a female mold 16 having an annular tapered surface 16a into each other. A plurality of bolts 17 arranged together and circumferentially
．．・It is designed to be tightened by -117.

During this tightening, the ends of the tubular composite material S are clamped and fixed from the inner and outer surfaces between the annular tapered surfaces 15a and 16a. The air passage 18 provided in the male mold 15 is for connecting to the near compressor 8.

Using the tear fatigue test device described above, the tubular composite material S
When measuring the crushing fatigue of the tubular composite material S
is held at both ends by the gripping parts 5 and 6, and while an internal pressure of 200 to 300 KPa is applied by the compressor 8, the servo motor 2 is used to generate vibrations at a frequency of 1 to 4 Hz and an amplitude of π/2 to π/3 ra.
A torsional load within the range of d is applied repeatedly.

Then, when a torsional load is applied, the tubular composite material S contracts in the radial direction and axial direction, and when the torsional load is released, it repeats a change in which it stretches back to its original state. However, in the testing device of the present invention, in response to the changes in the expansion and contraction of the sample, the diameter is maintained at a substantially constant value for radial contraction so as not to collapse due to the internal pressure from the compressor, and the diameter for axial contraction is maintained at a substantially constant value. By moving the gripping part 6 toward the gripping part 5 side, tensile stress is prevented from being generated. Therefore, the torque meter 3 detects only pure tear fatigue.

In addition, since the gripping portion 5.6 of the above embodiment is a tapered type clamping chuck, it is possible to securely fix the tubular composite material S without slipping, thereby accurately fixing the tubular composite material S. It is possible to add a twist angle.

〔Effect of the invention〕

As described above, in the torsional fatigue testing device of the present invention, one of the gripping parts that grip both ends of the tubular composite material is made movable in the axial direction of the tubular composite material, so that No load other than torsion is applied (only pure torsional fatigue can be detected).

Furthermore, if the gripping part is a tapered chuck as in the embodiment, it is possible to apply an accurate torsion angle to the sample, making it possible to measure torsional fatigue even more accurately.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the torsional fatigue testing apparatus according to the present invention;
The figure is a view from the ■ arrow in Figure 1, and Figure 3 A. B is a vertical cross-sectional view and a front view showing details of the moving mechanism, FIG. 4 is a vertical cross-sectional view of the gripping part, and FIG. 5 is a partially cutaway perspective view of the sample tubular composite material. 2... Servo motor (reciprocating rotation drive unit), 3... Torque meter (torsional fatigue detection unit), 4... Rail, 5.
6... Gripping part, 8... Near compressor, 12...
・Slider, 13...Thrust bearing.

Claims (8)

[Claims] (1) A gripping section that grips both ends of the tubular composite material of the measurement sample and a pressurizing section that applies internal pressure to the tubular composite material are provided, one of the gripping sections is connected to a reciprocating rotation drive section, and the other A torsional fatigue testing device for a composite material, characterized in that the gripping portion is connected to a torsional fatigue detection portion, and either one of the gripping portions is movable in the axial direction of the tubular composite material. (2) The torsional fatigue testing device for composite materials according to claim 1, wherein the movable gripping section is on the side of the torsional fatigue detection section. (3) The torsional fatigue testing device for composite materials according to claim 1, wherein the support base connecting the movable gripping portion is supported by a rail via a bearing, and is movable on the rail. (4) The reciprocating torsional load due to the reciprocating rotation drive unit has a frequency of 1 to
4 Hz and an amplitude in the range of π/2 to π/3 rad. The torsional fatigue testing device for composite materials according to claim 1. (5) The torsional fatigue testing device for composite materials according to claim 1, wherein the reciprocating rotation drive unit is a servo motor. (6) The torsional fatigue testing device for composite materials according to claim 1, wherein the torsional fatigue detection section is a torque meter. (7) The internal pressure applied to the tubular composite material is 200 to 300
The torsional fatigue testing device for composite materials according to claim 1, wherein the test device is KPa. (8) The torsional fatigue testing device for composite materials according to claim 1, wherein the gripping portion is a tapered clamping chuck.