JPS606853A - Measuring device detecting crack - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides that a crack detector, which is attached to a specimen and serves to operate a crack indicator, is constructed from an optical fiber that can be inserted into a specimen made of plastic to supply light. This invention relates to a measuring device for detecting cracks in a specimen.

In such measuring devices, an optical fiber, for example a plastic fiber, a glass fiber or a quartz fiber, is integrated into a specimen made of plastic. Light is fed into these optical fibers via an optical coupler and its transmission is monitored at the other end. The damage caused to the optical fiber by the crack reduces the transmission of light by a factor of 7; ζ, which causes the fiber's photodetector to respond and generate a signal to initiate activation of the crack indicator. In this case, can high detection sensitivity be achieved by embedding an optical fiber in a plastic specimen? Xl
41 is particularly advantageous in that it does not cause corrosion problems. Furthermore, such crack detectors have the advantage that they are irreversible, ie the cracks that occur and are displayed continue to be displayed even after the load on the specimen is removed.

In addition to crack monitoring of such plastic parts with optical fibers, it is also important to monitor the production of such plastic parts.

It is unavoidable that the optical fibers will be damaged during manufacture or not installed properly. It is therefore very necessary to have confidence in the satisfactory condition of the plastic parts thus produced for use 1) IJ.

The intelligence on which the present invention is based is to perform reliable manufacturing monitoring of plastic parts with optical fibers. According to the present invention, this problem is solved when glass optical fibers are laid between the individual layers of the laminate during 11IJ construction of fiber-reinforced plastic, so that the fiber structure is visible when intense light is passed through the fibers after the plastic has hardened. Solved by displaying.

This measure according to the invention has the advantage that it can also be used for installation monitoring of fiber-reinforced plastics made of glass fibers used for crack detection. During the production of plastic parts, glass optical fibers are laid out in a grid between the individual layers of the stack, so that an externally visible indication of the path of the fibers is provided when the light passes through.

Any movement or deformation of the fiber structure that may occur during compression can thus be made visible by the inserted fiber for the activation of the crack indicator. When producing fiber-reinforced plastics, it is preferable to interpose pre-manufactured fibers (glass fibers, carbon fibers) or so-called prepregs between the optical fibers in order to increase the strength.

The laid optical fibers are passed through with a strong force, preferably laser light, so that the laid optical fibers are visible through the plastic parts, making it possible to monitor the parts produced in this way.

Furthermore, it is advantageous for the surface of the optical fiber to have a particularly good adhesion to its implants by roughening. Furthermore, the roughening of the optical fiber creates microscopic cuts in the surface of the optical fiber, reducing the elongation rate of the fiber and thus increasing the blowout sensitivity of the crack detector.

Optical fiber agitation for surface roughening can be done with glass etch ink or other chemical etchant that erodes the fiber. 'Furthermore, it is preferable to roughen the surface of the optical fiber and cover a part of it with a synthetic resin jacket. This provides the fiber with a protective jacket that allows it to be routed around edges or corners. The portion of the optical fiber that acts as a crack detector is not provided with a coating. 4”I
The roughening of the optical fiber to improve the adhesion and increase the detection sensitivity of the crack detector can be carried out partially and only in the optical fiber laid in the area of the detector.

This is possible, for example, by providing the optical fiber with a protective jacket that is resistant to corrosive liquids, so that only the parts that act as crack detectors without a protective jacket are roughened. Optical fibers roughened in this way can be applied to the surface of plastic, metal or other specimens with the same advantage as crack detectors.

Claims (1)

[Scope of Claims] 1. A crack detector attached to a specimen and serving to operate a crack indicator is composed of an optical fiber capable of being inserted into a specimen made of plastic and supplying light. In some embodiments, during the manufacture of fiber-reinforced plastics, glass optical fibers are laid between the individual layers of the laminate to make the fiber structure visible when intense light is passed through the fibers after the plastic has hardened. A measuring device that detects cracks within a specimen. 2. The device according to claim 1, characterized in that the glass optical fibers are laid in a grid-like arrangement. 3. The device according to claim 1, wherein a laser beam is used as the strong light. 4 Pre-manufactured fiber materials such as Karas, carbon, etc. to increase strength are used for installation monitoring and (or >
7'8% detection 1. 20. The device according to claim 19, characterized in that it is interposed between LJ optical fibers. 5. The device according to claim 1 or 2 of the patent, characterized in that the optical fiber is treated with a surface-roughening corrosive solution in 1) when the optical fiber is inserted into the specimen. 6. The device according to claim 5, characterized in that the optical fiber that has been subjected to m1nj with a mlnj solution is partially coated with a synthetic resin jacket. 7. Corrosion that roughens the surface of the optical fiber. Claim 5, characterized in that glass corrosion ink is used as the liquid.
Equipment described in Section.