JPH0618384A - Method and apparatus for measuring poisson's ratio of wire material - Google Patents

Abstract

PURPOSE:To measure the Poisson's ratio of a heterogeneous wire material composed of a high-molecular resin. CONSTITUTION:A wire material 4 is inserted in a hermetically closed container 1 through the insertion ports 5 equipped with the seal devices 6 provided to the container 1 and an air vent 13 is opened to introduce a liquid into the container 1 from a liquid introducing port 11 to fill the container 1. When tensile force is applied to the wire material 4, the wire material 4 is stretched through the hermetically closed container 1 and the volume thereof is reduced in the hermetically closed container 1. The volumetric change of the wire material 4 is measured by measuring the pressure head of the liquid and the measured value is used as the fundamental data in the calculation of a Poisson's ratio. Since the volumetric change of the wire material reduced by tension is measured, the average strain of the wire material 4 can be simply calculated even when non-uniform strain is generated in the wire material 4 in the direction right-angled to the axial direction of the wire material 4 and the Poisson's ratio can be accurately measured as compared with a case using a strain gauge and the Poisson's ratio of the wire material such as a twist wire incapable of using the strain gauge can be also measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the Poisson's ratio of a wire such as a single wire or a stranded wire.

[0002]

2. Description of the Related Art Conventionally, the Poisson's ratio of a wire rod such as a reinforcing bar or a steel rod such as an H-shaped steel is obtained by pulling a wire rod to which a strain gauge is attached and stretching the wire rod in the axial direction and shrinking or pulling in the direction perpendicular to the shaft. Is generally measured and calculated.

[0003]

According to the above-mentioned conventional measuring method, when the material such as the wire is homogeneous, it is possible to measure the measured value without any trouble in practical use. However, in recent years, polymeric resin materials have become widely used, and with wire rods made of such materials, different measured values are detected depending on the location where the strain gauge is attached, and Poisson calculated based on the measured values. There was an inconvenience that we could not rely on the ratio. Such disturbances in the measured values appear not only in the case of polymer resin materials but also in the case of wires made of materials that are not homogeneous (homogeneous), and it is extremely difficult to calculate the Poisson's ratio in the case of braided wires and twisted wires. there were.

A first object of the present invention is to provide a method capable of simply and accurately measuring the Poisson's ratio of a non-homogeneous material or a twisted wire, and to provide an apparatus suitable for carrying out this method. The purpose is 2.

[0005]

According to the present invention, when a wire is provided by inserting an airtight container into and out of the airtight container, a liquid is filled in the airtight container, and then a tensile force is applied to the wire. By detecting the change in the volume of the liquid in the closed container of, and calculating the Poisson's ratio of the wire based on the detected value and the axial deformation value of the wire and the tensile load, I tried to achieve it.

A second object of the present invention is to form an insertion port for inserting a wire into the inside and outside of the closed container at a position opposite to the wall surface of the closed container provided with a liquid inlet and an air vent. Achieved by providing the mouth with a seal device that allows the wire rod to move and seals the periphery of the wire rod, and further attach a detection device that detects a change in the volume of the liquid filled in the closed container. To be done.

[0007]

When a tensile force is applied to the wire rod provided in the closed container in the axial direction, the wire rod expands and its cross-sectional area, that is, volume decreases.
Since the pressure head of the liquid filled in the closed container decreases with the decrease of the volume of the wire rod, if the pressure difference before and after applying the tensile force or the change of the liquid column of the liquid is detected, the change of the volume is detected. It is possible to measure, and the Poisson's ratio of the wire can be calculated from the measured value, the measured elongation of the wire and the tensile load. The change in the volume of the liquid in the closed container is detected by an electric signal from a pressure sensor attached to the container or by a liquid column type manometer. The elongation of the wire required for calculating the Poisson's ratio can be measured by a simple electrical or mechanical method, and the tensile load can also be measured by measuring the force generated in the hydraulic cylinder that pulls the wire. .

When a tensile force is applied to the wire rod, the wire rod extends from the insertion port of the closed container to the outside thereof. However, since the periphery of the wire rod is watertightly sealed by the sealing device, the amount of liquid in the container is constant. The volume of the liquid in the container is increased by the amount of the wire rod which is maintained at the above value and the pressure head is decreased, or the liquid column is decreased. Therefore, even if the wire material is not homogeneous such as polymer resin or twisted wire, it is possible to measure the average deformation in the direction perpendicular to the axis of the wire material, and to measure the Poisson's ratio with high reliability. You can do it.

[0009]

Embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a closed container composed of a cylindrical main body 2 and end plates 3a and 3b for closing the openings at both ends of the main body 2, and the end plates 3a and 3b are provided at positions facing each other. An insertion port 5 for inserting the wire 4 whose Poisson's ratio is to be measured into and out of the closed container 1 is formed. The insertion port 5 is provided with a sealing device 6 that hermetically seals the periphery of the wire 4. In the illustrated example, a flexible packing 7 is provided in which the sealing device 6 is housed in a step portion provided in the insertion port 5. And the packing 7
With a hollow bush 8 that presses against the step. The wire 4 is provided by inserting the insertion ports 5 of the respective end plates 3a and 3b, fixes one end of the wire 4, and applies a tensile force in the direction of the arrow to the other end with a hydraulic cylinder or the like. The bush 8 is screwed in from the direction opposite to the tensile force so that the circumference of the wire 4 is watertightly sealed even if the wire 4 and the packing 7 move relatively.

One end plate 3a is provided with a liquid inlet 11 and a detection port 12 connected to an external liquid supply pipe 10 via a valve 9, and the other end plate 3b is provided with an air vent 13. did. The detection port 12 is provided with a pressure sensor 14 as shown in FIG. 1 or a detection device such as a liquid column type manometer 16 connected through a pipe 15 as shown in FIG. In addition, the liquid inlet 11 and the air vent 1 are provided on one end plate.
3 may be provided.

The tensile load applied to the wire 4 is detected by a general load measuring device, and the elongation of the wire 4 is detected by a general length measuring device. When electrically detecting the load and elongation, the Poisson's ratio can be automatically calculated by connecting the load measuring device, the length measuring device and the pressure sensor 14 to a computer.

The liquid column type manometer 16 is constructed, for example, by attaching a glass tube 16a having a diameter of 1 mm, the tip of which is open to the atmosphere, to a scale plate 16b, and reading changes before and after applying a tensile force to the wire 4. The change in volume of the wire 4 in the closed container 1 can be known, and the Poisson's ratio can be calculated based on the detected value and the tensile load and elongation.

The liquid to be filled in the closed container 1 is preferably filled at a pressure slightly higher than the atmospheric pressure in order to make the liquid conform to the wire 4.

According to the present invention, the material of the wire 4 may be a polymer or a metal, and the Poisson's ratio can be measured even if it has a flat cross section, a twisted wire or a braided wire.
If the temperature of the liquid changes during the measurement, the temperature is corrected.

A concrete example thereof is a liquid column type manometer 16
The case of using the
In a closed container 1 having a space of 0 mm and a diameter of 50 mm, an aramid continuous fiber 4 having a diameter of 15 mm as shown in FIG.
A wire 4 which is formed by braiding a in a braided shape and impregnated with a resin is inserted into the insertion port 5, and the periphery of the wire 4 is sealed by the sealing device 6. Next, the air vent port 13 is opened, and a liquid such as water or oil is injected from the liquid inlet port 11 until the closed container 1 is filled, and then the air vent port 13 is closed. Then, after reading the water level of the manometer 16, the wire 4
Apply tensile force in the direction of arrow. At this time, the water level of the manometer 16 decreases and the wire rod 4 extends. A highly reliable Poisson's ratio could be calculated based on this measured value.

[0016]

As described above, according to the method of the present invention,
A wire is provided by inserting the airtight container inside and outside, and after filling the liquid in the airtight container, a tensile force is applied to the wire and the change in the volume of the liquid in the airtight container when the tensile force is applied is detected. However, since the Poisson's ratio of the wire is calculated based on the detected value, the average strain of the inhomogeneous wire such as polymer resin or stranded wire in the direction perpendicular to the axial direction can be accurately measured, and the Poisson's ratio is simple. According to the device of the present invention, this method can be easily carried out, and the structure is simple and can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a cutaway side view of an embodiment of the present invention.

FIG. 2 is a cutaway side view of essential parts of another embodiment of the present invention.

FIG. 3 is a perspective view of a wire rod.

[Explanation of symbols]

1 closed container 2 main body 3a,
3b End plate 4 Wire rod 5 Insertion port 6 Sealing device 11 Liquid introduction port 13 Air vent port 14
Pressure sensor 16 Liquid column manometer

Claims (4)

[Claims] 1. A wire is provided by inserting an airtight container into the inside and outside,
A tensile force is applied to the wire rod after the closed container is filled with a liquid, and a change in the volume of the liquid in the closed container when the tensile force is applied is detected, and the detected value and the axial direction of the wire rod are detected. A Poisson's ratio measuring method for a wire, comprising calculating a Poisson's ratio of the wire based on a deformation value and a tensile load. 2. An insertion opening for inserting a wire into the inside and outside of the closed container is formed at an opposite position of a wall surface of a closed container having a liquid introduction port and an air vent, and the wire is moved to the insertion port. Is provided and a sealing device for sealing the periphery of the wire is provided, and a detection device for detecting a change in the volume of the liquid filled in the sealed container is further attached to the Poisson's ratio measurement of the wire. apparatus. 3. The closed container comprises a cylindrical main body and end plates for closing axial ends of the main body, each end plate having an insertion port provided with the sealing device, 3. The Poisson's ratio measuring device for a wire according to claim 2, wherein the end plate has a liquid introduction port, and the other end plate has an air vent port. 4. The Poisson's ratio measuring device for a wire according to claim 2, wherein the detecting device is a pressure sensor or a liquid column type manometer for electrically detecting the pressure of the liquid.