Multi-layer composite materials are widely used in various structures of modern airframes. Defects may appear in composite materials under dynamic load conditions, aging, atmospheric influence, therefore such objects must be constantly or periodically checked and monitored during their operation time. One of the monitoring methods that provide the most information about the object under investigation are ultrasonic methods based on the application of guided waves. The main advantage of guided waves is the dependence of their parameters on the elastic properties of the material and low attenuation, so with a relatively limited number of measurement positions, it is possible to monitor these objects and detect existing damage in them. However, due to relatively low attenuation of guided waves, dispersion, multimode, mode conversion, multiple reflections from the boundaries of the object under investigation, the signals measured during objects monitoring are complex and difficult to interpret. Another relevant problem in the non-destructive testing of composite materials is the determination of the location, size and depth of detected defects and inhomogeneities. Images obtained by conventional visualization methods are usually of insufficient quality and do not meet modern requirements, and their acquisition requires scanning of the object under investigation.
The aforementioned shortcomings of the regularity of the propagation of ultrasonic guided waves and currently used defect detection methods allow us to formulate a scientific and technological hypothesis: it is possible to develop ultrasonic guided wave inspection method that would allow measuring the parameters of defects in aviation composites and increase the spatial resolution of the resulting images, with a relatively limited number of measurement positions . The aim of this work is to develop and investigate ultrasonic guided wave monitoring methods that would allow the detection, characterization and determination of the location and size of defects and inhomogeneities in composite materials used in the fields of aviation and transport engineering by applying advanced data and signal processing methods. One such method is ultrasound guided wave tomography. Tomographic visualization is much more detailed than other forms of visualization, because this method reproduces the image of the object in one selected plane of the three-dimensional object.
Project funding:
KTU Business Support Fund
Project results:
During the period of the project, an ultrasonic guided wave monitoring method was developed, which allows detecting and determining the location and size of defects and inhomogeneities in composite materials. For the spatial location of defects in composite materials, a tomographic reconstruction method is proposed, based on the application of filtered back projection, using a fan-shaped projection data collection configuration and linking the decrease in the amplitude of the considered wave mode with the establishment of the fact of the occurrence of the defect.
Period of project implementation: 2018-09-17 - 2019-09-16
Project coordinator: Kaunas University of Technology
