Abstract
The current work aims at evaluating a proposed method based on a computational tool developed using Object-Oriented Programming to identify the status of micro-structured surfaces. In this case, these are micro-structured coatings with riblet microstructure developed by Fraunhofer Institute–IFAM, by building a graphical reproduction of the analyzed surface and calculating an expected laser reflection intensity acquired by a laser sensor device, the proposed method is assessed by using the simplest case: a flat surface, and an optimal case: an intact riblet surface. The results corroborate the calculations to be applied to further steps from more complex cases of degradation and to diverse riblets geometries. Based on Huygens-Fresnel and Fraunhofer diffraction theories, the calculations developed and demonstrated in this paper improved the nondestructive tests to support the status identification of the micro structured coatings, e.g. riblet structures based on shark skin used in shipping and aerospace industries. This work is assured required quality of the riblet coating identifying the number of structures and expected geometry using implemented calculations to foresee the laser reflection intensity acquired by a laser sensor device with 3 detectors, for instance, a riblet structure could be graphically reproduced, analyzed and completely identified based on the application of the theoretical optics applied on this work.
Highlights
These are micro-structured coatings with riblet microstructure developed by Fraunhofer Institute–IFAM, by building a graphical reproduction of the analyzed surface and calculating an expected laser reflection intensity acquired by a laser sensor device, the proposed method is assessed by using the simplest case: a flat surface, and an optimal case: an intact riblet surface
Based on Huygens-Fresnel and Fraunhofer diffraction theories, the calculations developed and demonstrated in this paper improved the nondestructive tests to support the status identification of the micro structured coatings, e.g. riblet structures based on shark skin used in shipping and aerospace industries
This work is assured required quality of the riblet coating identifying the number of structures and expected geometry using implemented calculations to foresee the laser reflection intensity acquired by a laser sensor device with 3 detectors, for instance, a riblet structure could be graphically reproduced, analyzed and completely identified based on the application of the theoretical optics applied on this work
Summary
Status identification of structured surfaces used in aviation industry, e.g. shark skin, called tiny ribs (riblets), is an option to support the quality assurance and keep desired performance of these coatings. Riblets are used as an alternative to decrease drag and save fuel and reduce Greenhouse gas (GHG) emissions [1] These riblets are part of strategical and technological possibilities to fulfill the decision taken by European Union that CO2 emissions from the aviation and shipping industry must be reduced by 10% and 20% respectively, in a period of medium to long term [2], for instance, due to climate change caused by GHG emissions [3]. According to the American Society for Testing and Materials [5], the concept of NDT is based on the “development and application of technical methods that examine materials and components, in order to detect, measure and evaluate discontinuities, defects and other imperfections. Among the methods of possible tests to be applied to this specific analysis of coatings based on riblet structures, nondestructive testing tends to be powerful for this application
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