METHOD FOR NON-DESTRUCTIVE TESTING OF COMPONENTS PRODUCED FROM CARBON FIBER REINFORCED COMPOSITE MATERIALS

Abstract

The invention relates to the field of research and analysis of materials, in particular, to methods for testing the integrity of components produced from carbon fiber based composite materials, and can be used to detect manufacturing defects and damages received during service in components produced from carbon fiber reinforced composite materials.

The claimed method for non-destructive testing of carbon fiber reinforced composite materials includes heating the material with an external source, recording the temperature distribution pattern of the tested material, analyzing the recorded temperature distribution pattern and detecting the presence of defective areas, wherein the material is heated by exposing the carbon fiber included in the material to a high-frequency electromagnetic field.

Thus, the claimed invention is a method for non-destructive testing of the components produced from carbon fiber reinforced composite materials which allows for an efficient and reliable assessment of their condition over the entire depth of the material structure without exposing the coating layers to excessive load, if any.

Claims

1. A method for non-destructive testing of the components produced from carbon fiber reinforced composite materials comprising heating the material with an external source, recording the temperature distribution pattern of the tested material, analyzing the recorded temperature distribution pattern and detecting the presence of defective areas, characterized in that the material is heated by exposing the carbon fiber included in the material to a high-frequency electromagnetic field.

2. The method of claim 1, wherein the material is heated by a high-frequency electromagnetic field at a frequency of 50-500 kHz.

3. The method of claim 1, wherein the temperature distribution pattern is recorded by means of a thermal imaging device.

Description

[0029] The claimed invention is explained in more detail using the following figures:

[0030] FIG. 1 is a schematic diagram of physical processes that occur in a defective component produced from a carbon fiber reinforced composite material as a result of its exposure to a high-frequency magnetic field;

[0031] FIG. 2 is a schematic diagram of an installation for conducting one-sided thermal non-destructive testing according to one of the preferred embodiments of the claimed method;

[0032] FIG. 3 is a schematic diagram of an installation for conducting two-sided thermal non-destructive testing according to another preferred embodiment of the claimed method;

[0033] FIG. 4 is an example of an image of the recorded temperature distribution pattern of a tested component produced from a carbon fiber reinforced composite material.

[0034] FIG. 1 schematically illustrates physical processes occurring in an example of a defective component produced from a carbon fiber reinforced composite material as a result of its exposure to a high-frequency magnetic field. A component 1 produced from a layered structure composite material comprising a carbon fiber layer 2 is shown in section view. Around the inductor 3 located near the material of the component 1 a high-frequency electromagnetic field is generated, when exposed to which eddy currents 4 are induced in the carbon fiber layer 2 according to the laws of electrodynamics, causing it to heat.

[0035] In accordance with the Joule-Lenz law quantifying the electric current thermal effect, the amount of heat released in an area of a circuit per unit time is proportional to the resistance of the area. The defective area 5 of the carbon fiber layer 2 will have greater resistance due to the violation of continuity and, as a consequence, the electrical conductivity of the layer 2 therefore will have more heat when uniformly exposing the layer 2 to electromagnetic field.

[0036] FIG. 2 schematically illustrates an installation for conducting one-sided thermal non-destructive testing according to a preferred embodiment of the claimed method. When conducting one-sided testing, the inductor 3 and the thermal imaging device 6 are placed on one side of the component 1 produced from a carbon fiber reinforced composite material. The material of the component 1 is heated by moving along it in the direction 7 of the inductor 3 around which a high-frequency electromagnetic field is excited by means of an alternating current generator 8. Afterwards, the thermal imaging device 6 records the temperature distribution pattern of the material of the tested component 1 for further analysis thereof and detecting the presence of defective areas.

[0037] FIG. 3 schematically illustrates an installation for conducting two-sided thermal non-destructive testing according to a preferred embodiment of the claimed method. When conducting two-sided testing, the inductor 3 and the thermal imaging device 6 are placed on different sides of the component 1 produced from a carbon fiber reinforced composite material. Just as when conducting one-sided testing, the material of the component 1 is heated by moving along it in the direction 9 of the inductor 3 around which a high-frequency electromagnetic field is excited by means of an alternating current generator 8. Here, as an example only, the inductor 3 is moved in the direction 9, which is different from the direction 7 presented in the one-sided testing example (FIG. 2). Afterwards, the thermal imaging device 6 records the temperature distribution pattern of the material of the tested component 1 for further analysis thereof and detecting the presence of defective areas.

[0038] FIG. 4 is an example of an image (thermogram) recorded by a thermal imaging device 6 (not indicated in the figure) of the recorded temperature distribution pattern of a tested component 1 produced from a carbon fiber reinforced composite material. The material under examination of the component 1 is heated by exposure to a high-frequency electromagnetic field of the inductor 3 (not indicated in the figure), which is moved in the direction 7. As can be seen in the presented example, the heated material of the component 1 has a uniform temperature distribution over the entire surface of the tested component with the exception of a significantly stronger heated area 10, clearly distinguished in the image of the temperature distribution pattern. Excessive heating of the area 10 is due to the increased electrical resistance of the carbon fibers in it, which is indicative of its defectiveness. The area 11, also characterized by an elevated temperature, corresponds to the spot where the inductor 3 passes at the moment of recording the temperature distribution pattern of the tested article 1.

[0039] It is obvious that the claimed method is applicable both to non-destructive testing of a carbon fiber reinforced composite material as an entire part and of its individual area. It will be appreciated that the temperature distribution pattern can be recorded both simultaneously with the process of heating the material and immediately after heating.

[0040] Detecting the presence of defective areas, in turn, may include establishing the fact of the presence/absence of defective areas and determining the location of the defective areas, if any. Though, it should be understood that in specific embodiments of the present method these two actions being related by their meaning, may not be individually included into the stages of the claimed method. For one, the articles the materials of which are tested by this method at the production stage can be automatically rejected even when it is detected that there is at least one defective area without intentional determining of its location.

[0041] Thus, the claimed invention is a method for non-destructive testing of the components produced from carbon fiber reinforced composite materials which allows for an efficient and reliable assessment of their condition over the entire depth of the material structure without exposing the coating layers to excessive load, if any.

[0042] It will be appreciated that the claimed method as defined in the appended claims is not necessarily limited to the specific features and embodiments described above. By contrast, the specific features and embodiments described above are disclosed as examples implementing the claims and other equivalent features may be covered by the claims of the present invention.