JPS6359459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring directionality in anisotropic materials such as fiber reinforced composite materials.

The mechanical properties and other properties of fiber-reinforced plastics (FRP) are greatly influenced by the content, orientation, and distribution of fibers.
Therefore, it is extremely important to investigate the orientation of fibers in order to understand the various properties of these materials.

The present invention provides a non-destructive, non-contact method for measuring the directionality of an anisotropic material such as a fiber-reinforced composite material, in which the dielectric constant of the anisotropic material varies depending on the direction of the fibers. This method takes advantage of the fact that horizontally polarized waves and vertically polarized waves of microwaves transmitted through this anisotropic material change in different ways depending on the anisotropy.

The directionality measurement method of the present invention transmits microwaves to a subject placed in a circular waveguide or between circular horn antennas placed oppositely on the same axis, and then measures the horizontal polarization of the microwaves. The wave and vertical polarization are separated and detected in a polarization splitter placed on the same axis, and the directionality of the subject is determined based on the phase difference and intensity difference between the horizontal and vertical polarization. It is characterized by learning.

The method of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows the configuration of a measuring device used to implement the method of the present invention, and the main parts of this measuring device are a microwave generator that generates microwaves,
A rectangular waveguide, a rectangular-circular conversion waveguide, a circular waveguide and a polarization splitter into which the microwave is introduced, and the phase difference and intensity of the horizontally and vertically polarized waves separated in the polarization splitter. It is equipped with a phase difference/intensity difference detection device to detect the difference.

In the above measurement device, first, microwaves from a microwave generator are guided into a rectangular waveguide.
Propagate as TE ₁₀ mode. After the polarization plane of this microwave is twisted by a torsion waveguide as necessary, it is guided to a rectangular/circular conversion waveguide and converted into the TE ₁₁ mode as the fundamental wave of the circular waveguide.
The TE ₁₁ mode of the circular waveguide can be separated into two orthogonal polarization components E ₁ and E ₂ .
The circular waveguide to which the microwave converted into TE ₁₁ mode is guided has a subject to be measured whose directionality is to be measured, and the TE ₁₁ mode microwave passes through the subject. Due to the dielectric constant of , the horizontal polarization component E ₁ and the vertical polarization component E ₂ undergo phase changes and amplitude attenuation, respectively. Therefore, if the above-mentioned object is an isotropic material, the horizontal and vertical polarization components E ₁ and E ₂ undergo similar phase changes and amplitude attenuation depending on the dielectric constant. When a material has anisotropy, for example, a fiber-reinforced composite material in which fibers are oriented in a certain direction, the dielectric constant has directionality due to the difference in dielectric constant between the fibers and the matrix, and therefore the above-mentioned The horizontally and vertically polarized components E ₁ and E ₂ undergo different phase changes and amplitude attenuations depending on the dielectric constants of the respective polarized waves in the electric field direction. The TE ₁₁ mode microwave, in which each polarization component has undergone phase changes and amplitude attenuation, is separated into horizontal and vertical polarization components E ₁ and E ₂ in the polarization splitter, and these polarization components By guiding the signal to a phase difference/intensity difference detection device to obtain the phase difference and intensity difference,
It is possible to learn the orientation in the subject.
When detecting the phase change and attenuation amount using a bridge circuit composed of a resistive attenuator, a phase shifter, and a magic T as the above-mentioned phase difference/intensity difference detection device, The orientation direction within the fiber can be detected independently of the fiber content and sample thickness. In addition, if a network analyzer or the like is used as the above-mentioned detection device to measure the absolute value of the phase change and attenuation amount for each polarization component, it is possible to detect only the fiber orientation by using it in combination with the reflectance that can be obtained from standing wave measurement. Therefore, it is possible to quantitatively detect the fiber content and the sample thickness independently.

The measurement results detected and measured by the phase difference/intensity difference detection device in this manner can be displayed and recorded by the next-stage display/recording device.

In addition, although the case where the test object is mounted inside a circular waveguide has been explained above, it is possible to hold a test object of any size in free space and direct the micro wave with a specific polarization toward the test object. In addition to emitting waves from a horn antenna, slot antenna, etc., it is also possible to receive the microwaves that have passed through the subject using a circular horn antenna, etc. placed facing each other on the same axis, and introduce the waves into a polarization splitter. , this allows measurement without cutting the subject.

Further, the rectangular waveguide includes a unidirectional tube, a standing wave measuring device, and the like.

As is clear from the detailed description above, according to the method of the present invention, the directionality of various materials can be measured very easily in a non-destructive and non-contact manner. Alternatively, after transmitting the microwave to a test object placed between horn antennas placed oppositely on the same axis, the horizontally polarized wave and vertically polarized wave in the microwave are separated in a polarization splitter placed on the same axis. By employing detection means, it is possible to perform accurate measurements with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus for implementing the present invention.

Claims (1)

[Claims] 1. After transmitting microwaves to a subject placed within a circular waveguide or between circular horn antennas placed oppositely on the same axis, horizontally polarized waves and vertically polarized waves in the microwaves are Anisotropic material that is characterized in that the directionality of the subject is determined based on the phase difference and intensity difference between horizontally polarized waves and vertically polarized waves, which are detected separately in a polarization splitter. Directionality measurement method.