Using Holograms Helps in Studying the Quality of Composite Materials

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Composite materials have a complicated structure and specified mechanical or physical properties. The materials are used in various spheres of the industry: from medicine to aviation and due to it they are of high demand. However, there is a problem in the quality control of such materials.

Recently, an article was published in the IEEE Transactions on Industrial Informatics scientific journal, where the method of digital holography for assessing the parameters of composite materials was described. In particular, materials with ceramic spraying, which significantly increase resistance to temperature influences. And the spraying is carried out by a plasma jet at a very high temperature. After cooling the material, residual stresses arise in it, which can affect its strength characteristics. Thus, it is necessary to create a method for recording and evaluating such deformed states immediately after the spraying is completed.

One of the study authors, Head of the IKBFU Coherent-optical Measuring Systems Laboratory, Igor Alekseenko told us:

“There is a well-known and affordable method of controlling such stresses. A special sensor is attached to the sample, then a technological hole is made at one point, after which the residual stresses are released and recorded, and then analyzed. This method has two drawbacks. The first is that the sensor is attached to the sample, distorts the results. The second is that using this method it is possible to study the material at only a few points. In our work, we used the method of optical non-destructive testing, which, firstly, is non-contact, that is, localized sensors do not need to be installed on the material, and, secondly, it allows us to register strains at every point of the image. A sophisticated and highly sensitive measuring technique registers several hundreds of digital holograms, which make it possible to study mechanical processes in time on a set of points on the surface of a sample. The result is more accurate and complete information about the state of the object. At the first stage, the studies were conducted mainly by our German colleagues from the Institute of Technical Optics at the University of Stuttgart. Then the research was already carried out together with the specialists of the laboratory of Coherent-optical Measuring Systems of the IKBFU, whose employees have extensive experience in the field of digital holography and optical non-destructive testing”

According to Igor Alekseenko, the implementation of the adapted control method will improve the production process of composite materials and significantly improve their characteristics.