Vendredi 6 novembre 2026 à 14h30, Mme Yunhe XI soutiendra à ISAE-Supméca (amphi J. Genevois) ses travaux de thèse intitulés Investigation on the low-frequency vibration attenuation strategies through periodic structures et dirigés par Pr Imad TAWFIQ (ISAE-Supméca), Pr Mohamed ICHCHOU (École Centrale Lyon) et Pr Olivier BAREILLE (INSA Rouen Normandie).
Abstract
Structural dynamics can be described in terms of both structural vibration modes and elastic wave propagation. Over the past few decades, periodic structures, periodic materials and mechanical metamaterials have attracted considerable attention because of their remarkable potential for vibration and noise mitigation. Among these, locally resonant periodic structures have emerged as an effective solution for low-frequency vibration attenuation in lightweight engineering applications.
Based on Bloch–Floquet theory and the concept of local resonance, this thesis proposes two novel locally resonant unit cells (UCs): a hollow-cylinder resonator for two-dimensional (2D) periodic structures and a hollow-cube resonator for three-dimensional (3D) periodic
structures. Their band-gap characteristics and wave propagation mechanisms are investigated for various structural configurations and geometric parameters using both theWave Finite Element Method (WFEM) and the conventional Finite Element Method (FEM). To improve computational efficiency for complex periodic structures, a Condensed Wave Finite Element Method (CWFEM), based on modal order reduction (MOR), is developed by combining the advantages of Component Mode Synthesis (CMS) and WFEM.
The results demonstrate that the proposed hollow-cylinder and hollow-cube periodic structures outperform conventional locally resonant configurations by generating wider, lower-frequency and multidirectional Band Gaps (BGs), leading to enhanced vibration attenuation. A notable finding is that expanding the outer radius while keeping the same volume of the hollow-cylinder resonator effectively restores BGs that would otherwise become narrower, whereas the same geometric modification is significantly less effective for the hollow-cube resonator. The transmission loss (TL) of the proposed 2D and 3D periodic structures is further evaluated for longitudinal, transverse and bending wave modes through numerical simulations. The predicted TL spectra show that wave attenuation is most significant for transverse waves and enhances as the number of UCs increases.
Finally, the effectiveness of the proposed periodic structures is assessed through dynamic interaction analyses using a half-space soil model with viscoelastic boundary conditions subjected to wave excitation. The results confirm the excellent capability of the proposed hollow-cylinder and hollow cube periodic structures to attenuate low-frequency vibrations, highlighting their strong potential for vibration isolation barriers and foundation engineering applications.
Keywords
# Periodic structures
# Locally resonant metamaterials
# Low-frequency vibration attenuation
# Band gaps
# Wave Finite Element Method
# Dynamic interaction
