Simulation of guided-waves propagation in 3D visco-elastic structures coupled with fluids using semi-analytical isogeometric analysis
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The assessment of visco-elastic materials using non-destructive evaluation (NDE) plays an important role in various engineering domains. In recent decades, Guided Wave (GW) technologies have emerged as efficient tools for NDE, thanks to their sensitivity to both material and structural properties. When confronted with complex geometries in coupled fluid-solid waveguides, the semi-analytical finite element (SAFE) method often requires extensive computational cost, especially at high-frequency ranges. In this investigation, we investigate the efficacy of a robust computational technique known as semi-analytical isogeometric analysis (SAIGA) [1], which employs the Non-Uniform Rational B-splines (NURBS) for geometry representation and the approximation of pressure/displacement fields, in computing wave dispersion within 3D anisotropic visco-elastic waveguides coupled with fluids. Our findings indicate that SAIGA consistently achieves significantly faster convergence rates in computing guided wave dispersion compared to the conventional SAFE method, even when employing the same order of shape functions. Notably, for hollow prismatic structures immersed in fluids, the use of high-order NURBS (e.g., p=8) proves remarkably efficient, demanding only a few elements to match the precision of SAFE, which, in turn, requires up to five times the number of DOFs. Additionally, the inherent smoothness of NURBS significantly enhances the continuity of normal displacement at fluid-solid interfaces. This feature demonstrates the advantage of SAIGA over SAFE when evaluating the shape modes of guided waves in coupled fluid-solid systems. Some examples on the simulation of wave propagation in cortical bones [2] will also presented, showing the potential of SAIGA method on the assessment of bone properties by using axial transmitted ultrasonic technique.
