9 th European Workshop on Structural Health Monitoring July 10-13, 2018, Manchester, United Kingdom Creative Commons CC-BY-NC licence https://creativecommons.org/licenses/by-nc/4.0/ Efficient modelling of guided ultrasonic waves using the Scaled Boundary FEM towards SHM of composite pressure vessels Yevgeniya Lugovtsova 1 , Jannis Bulling 1 , Jens Prager 1 , Christian Boller 2 1 Bundesanstalt für Materialforschung und –prüfung (BAM), Germany yevgeniya.lugovtsova@bam.de 2 Chair of NDT and Quality Assurance (LZfPQ), Saarland University, Germany c.boller@mx.uni-saarland.de Abstract The Scaled Boundary Finite Element Method (SBFEM) is a semi-analytical method that shows promising results in modelling of guided ultrasonic waves. Efficiency and low computational cost of the method are achieved by a discretisation of the boundary of a computational domain only, whereas for the domain itself the analytical solution is used. By means of the SBFEM different types of defects, e.g. cracks, pores, delamination, corrosion, integrated into a structure consisting of anisotropic and isotropic materials can be modelled. In this contribution, the SBFEM is used to analyse the propagation of guided waves in a structure consisting of an isotropic metal bonded to anisotropic carbon fibre reinforced material. The method allows appropriate wave types (modes) to be identified and to analyse their interaction with different defects. Results obtained are used to develop a structural health monitoring system for composite pressure vessels used in automotive and aerospace industries. 1. Introduction Guided ultrasonic waves (GWs) have been shown to be particularly suitable for structural health monitoring (SHM) of such safety relevant components as oil and gas pipelines, and rails [1-3]. Techniques based on GWs are still under development for more complex applications considering wave propagation in structures made of fibre reinforced plastic materials only or in combination with metals [4-6]. Due to dispersion and multimodal character of GWs, development of a technique based on GWs requires careful modelling and analysis of wave propagation and defect-mode interaction. At first, a tool for calculation of dispersion curves and mode shapes is needed. Based on these curves appropriate modes depending on application can be selected for further analysis. At next, a tool for modelling of propagation of chosen GW modes is required. The Scaled Boundary Finite Element Method (SBFEM) is suitable for this purpose allowing for calculation of dispersion curves, mode shapes and modelling of GWs [7-9]. This semi-analytical method is highly efficient for geometries with a constant cross- section, which is the part to be discretised, see Fig. 1 (a) compared to the FEM discretisation in Fig. 1 (c) [9-10]. Another feature of the SBFEM is that an infinite domain can be modelled avoiding unwanted reflections, see Fig. 1 (b). Also, the method provides an elegant solution for modelling of a crack, describing a crack tip analytically and thus avoiding the singularity, see Fig. 1 (d) [9]. More info about this article: http://www.ndt.net/?id=23339