At IRDL, Franki Lionel Tausse Kamdoum studied the hydroelastic response of metallic tubular structures to hydrodynamic impacts.
Key Takeaway: At IRDL, Franki Lionel Tausse Kamdoum studied the hydroelastic response of metallic tubular structures to hydrodynamic impacts.
Franki Lionel Tausse Kamdoum, researcher at IRDL (Institut National Polytechnique de Bretagne).
Thesis defended in 2026 at the doctoral school École doctorale Sciences pour l'ingénieur et le numérique.
Referenced in the ABES/STAR network, this thesis meets the rigor standards of French higher education.
Context and Problem Statement
The hydrodynamic impact between a tubular structure and a fluid is a complex problem, marked by nonlinear coupling between structural dynamics and fluid flow. This phenomenon presents significant challenges due to the various response regimes observed, which can range between impulsive, dynamic, or quasi-static situations. These variations depend on several factors, notably impact velocity and angle of incidence, making the modeling of these interactions difficult. Although numerical tools such as computational fluid dynamics (CFD) are widely used, their validation for fast transient events remains insufficient. Consequently, developing semi-analytical models and collecting experimental data in simple configurations are crucial to improving the understanding of these phenomena.
The thesis by Franki Lionel Tausse Kamdoum, carried out at the Institut National Polytechnique de Bretagne, focuses on studying the hydroelastic response of cylindrical tubes subjected to a hydrodynamic impact on a still free surface. This research aims to establish a theoretical and experimental framework for better understanding the interactions between fluids and tubular structures, particularly under controlled conditions.
Methodology
The methodological approach adopted in this thesis is based on developing a semi-analytical model that integrates proven theoretical tools. The model relies on an Euler–Bernoulli beam and a Wagner-type impact model. The hydrodynamic loading is handled using a strip method, allowing the force to be expressed as a function of the structure's deflection, velocity, and acceleration. This approach draws on the modified Logvinovich model, enriched with a fictitious body extension concept, in order to account for flow separation.
The impact problem is solved using modal decomposition, which makes it possible to analyze the hydroelastic coupling mechanisms, in particular hydrodynamic damping. To validate this model, an experimental campaign was conducted using ENSTA's hydraulic shock testing machine. Tests were carried out with horizontal and inclined impacts, allowing a direct comparison between theoretical results and experimental measurements.
Key Findings
The results of this research highlight several key aspects of the hydroelastic response of tubular structures to a hydrodynamic impact. The semi-analytical model developed made it possible to accurately simulate the response regimes of cylindrical tubes under various impact scenarios. The comparison between experimental data and numerical simulations reveals the relevance of the model while also highlighting some of its limitations.
The experimental tests showed that the response regimes of the structures can be strongly influenced by impact conditions, particularly velocity and angle of impact. The experimental results also indicate a complex interaction between flow dynamics and structural deformation, underscoring the importance of accurate modeling to anticipate the response of tubular structures.
The influence of hydroelastic coupling was particularly pronounced, with significant variations observed in the measured responses depending on the impact configurations. This coupling revealed nonlinear behavior, requiring a tailored approach for each impact situation.
Discussion and Outlook
Kamdoum's work opens up interesting prospects for maritime engineering and construction, where understanding hydrodynamic impacts on tubular structures is essential to ensuring the safety and durability of infrastructure. The semi-analytical modeling developed in this research could serve as a basis for designing structures that are more resistant to extreme events.
Future research could focus on extending the model to include additional effects, such as those related to composite materials or complex geometries. In addition, integrating advanced measurement techniques could further refine the validation of the models by capturing transient phenomena that are difficult to observe.
Finally, the continuous improvement of semi-analytical models and their experimental validation are crucial steps in addressing the challenges posed by hydrodynamic impacts. This could also foster the development of innovative solutions for protecting structures and making them more resilient to environmental hazards.
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Sources and Access
Franki Lionel Tausse Kamdoum. Etudes expérimentale et théorique de la réponse hydroélastique de structures tubulaires métalliques suite à un impact hydrodynamique. Mécanique des fluides [physics.class-ph]. École Nationale Supérieure de Techniques Avancées, 2026. Français. ⟨NNT : 2026ESTA0002⟩. ⟨tel-05624996⟩