Nonlinear hydroelastic responses of a submerged horizontal plate under focused wave conditions: a cumulative fatigue perspective

Most current analytical research on the hydroelastic interaction between water waves and submerged horizontal elastic plates remains within the scope of linear theory due to the underdevelopment of mathematical methods for solving nonlinear problems. To address this gap, this work employs an approach that combines computational fluid dynamics (CFD) with computational solid mechanics (CSM) to dynamically simulate the fully coupled nonlinear hydroelastic interactions between ocean waves and a submerged horizontal plate. This research highlights the significance of nonlinear point responses of a submerged horizontal plate under focused wave conditions. A phase-based harmonic separation method (i.e., phase-decomposition method) is used to isolate wave amplitude and force harmonic components in complex wave scenarios. This approach allows for the clean delineation of individual harmonics from the total wave force by controlling the phase of incident focused waves and is for the first time applied to the response analysis of elastic structures. This paper successfully used the phase-decomposition method to separate the individual harmonics of the point displacement of a horizontal elastic plate, directly demonstrating the significance of nonlinear responses. Additionally, the impact of plate rigidity, which relates to natural frequency, on nonlinear responses is investigated. The results indicate that plates with a certain dimensionless plate rigidity will exhibit more significant nonlinear responses. By cleanly separating each individual harmonic response, this study provides new insights into the nonlinear hydroelastic responses of a horizontal plate interacting with water waves and offers a new perspective on fatigue analysis, underscoring the importance of nonlinearity for future engineering designs.