| Abstract [eng] |
Polymer composites are increasingly used in aerospace structures, mainly due to the relatively high specific strength and stiffness, and relatively low density and mass. Aviation safety requires reliable testing techniques that allow for the timely detection of defects in individual components or assembly units. In this master's final project, possible defects in composite materials and non-destructive testing methods used to identify defects are examined. The aim of this work is to compare accuracy of different ultrasonic techniques for the sizing of defects/determination of depth of defects in composite materials. Using CIVA software, the test sample was designed and inspected virtually with two techniques of ultrasonic method, i.e., with single-element transducer and phased array probe. “OLYMPUS OMNISCANMX” flaw detector was used for the verification of the results experimentally. It provided an opportunity to examine the propagation of ultrasonic waves in the sample and the interaction with the defects. Studies have shown that using the ultrasonic measurement method, more accurate results are obtained in the presence of a defect inside the carbon fiber reinforced polymer, compared to the results when the defects are relatively close to the surface of the object under study. However, after estimating the absolute errors, deviations from the actual defect sizes are minimal and justify the use of the chosen method. The more accurate determination of the depth of the defect and its lateral size in the composite using a phased array compared to the single-element transducer, obtained in the experimental studies, allowed to conclude that the phased array probe is one of the best of non-destructive test methods for evaluation quality of aerospace structures of polymer composites for in-service application. |
