MODELING OF ULTRASONIC TESTING OF WOVEN FABRICLAMINATES: A MICROSTRUCTURE APPROACH

摘要

New complex materials constitute new challenges for the well established non-destructive ultrasonic testing (UT) methods. In aeronautic industry Carbon Fiber Reinforced Plastics(CFRP) with a high level of inner inhomogeneity are used. New construction methods of thesematerials lead to manufacturing problems that cannot be monitored satisfactorily yet. Therefore aconsolidated knowledge of the materials and of the interactions during testing is necessary. Modelingis a promising tool to improve the understanding of physical backgrounds and thus, to reduce testingcosts. In this work UT of three-dimensional models of woven fabrics on microstructure level issimulated for the first time. Therefore, model generation and simulation performance are performedseparately. The inner geometry of laminates made of woven fabrics is modeled using the softwaremodule WiseTex, a textile pre-processor developed by the Catholic University of Leuven, Belgium.In these models the wave propagation is numerically calculated using the Elastodynamic FiniteIntegration Technique (EFIT) implemented with C++. The calculations are performed for fullyorthotropic and heterogeneous media. The resolution of the investigated inner structure is in the rangeof micrometers depending on the frequency range. The possibility of introducing defects in thestructure is shown. The influence of the interfaces between carbon fiber rovings, matrix and defectson the wave propagation is investigated. Finally comparisons of the results with experimental data arepresented.