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Study on the hydroelastic slamming of elastic wedges vertically entering shallow water

OCEAN ENGINEERING 2024年第Part1期311卷

作者： Feng, Song Zhang, Guiyong Ma, Yuxiang Sun, Lei Zhou, Bo Dalian Univ Technol Sch Naval Architecture State Key Lab Struct Anal Optimizat & CAE Software Dalian 116024 Peoples R China Collaborat Innovat Ctr Adv Ship Deep Sea Explorat Shanghai 200240 Peoples R China Dalian Univ Technol State Key Lab Coastal & Offshore Engn Dalian 116024 Liaoning Peoples R China

The numerical simulation of elastic wedges entering shallow water and the investigation of the corresponding shallow water effect are presented. This study employs a coupled numerical algorithm, integrating the Boundary Element Method (BEM) for fluid dynamics and the Mode Superposition Method (MSM) for solid mechanics, in a partitioned approach. The shallow water effect is modeled by applying an impermeability boundary at the fluid domain's base. A dynamic coupling equation, incorporating the fluid added mass and considering the shallow water effect, is developed to facilitate the time-marching process and maintain solver stability. The simulation encompasses both impact and separation stages, addressing the non-linear dynamic and kinetic aspects of the free surface, along with grid handling. Validation of the algorithm is achieved through replicating fluid and solid dynamics under shallow water condition. The study proceeds to examine the influence of the condition on free surface motion, fluid pressure, and structural dynamics, including the wet natural period. The hydroelastic effect arising from shallow water condition is elaborated. Findings indicate an increase in free surface motion, fluid pressure, and structural dynamic response due to shallow water condition.

关键词： Water entry Hydroelastic slamming Shallow water fluid-structure interaction

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Data Informed Model Test Design With Machine Learning-An Example in Nonlinear Wave Load on a Vertical Cylinder

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JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME 2024年第2期146卷 021204-021204页

作者： Tang, Tianning Ding, Haoyu Dai, Saishuai Chen, Xi Taylor, Paul H. Zang, Jun Adcock, Thomas A. A. Univ Oxford Dept Engn Sci Oxford OX1 3PJ England Univ Bath Dept Architecture & Civil Engn Bath BA2 7AY England Univ Strathclyde Ocean & Marine Engn Dept Naval Architecture Glasgow City G1 1XQ Scotland Univ Bath Dept Comp Sci Bath BA2 7AY England Univ Western Australia Oceans Grad Sch 35 Stirling Highway Crawley WA 6009 Australia

Model testing is common in coastal and offshore engineering. The design of such model tests is important such that the maximal information of the underlying physics can be extrapolated with a limited amount of test cases. The design of experiments also requires considering the previous similar experimental results and the typical sea-states of the ocean environments. In this study, we develop a model test design strategy based on Bayesian sampling for a classic problem in ocean engineering-nonlinear wave loading on a vertical cylinder. The new experimental design strategy is achieved through a GP-based surrogate model, which considers the previous experimental data as the prior information. The metocean data are further incorporated into the experimental design through a modified acquisition function. We perform a new experiment, which is mainly designed by data-driven methods, including several critical parameters such as the size of the cylinder and all the wave conditions. We examine the performance of such a method when compared to traditional experimental design based on manual decisions. This method is a step forward to a more systematic way of approaching test designs with marginally better performance in capturing the higher-order force coefficients. The current surrogate model also made several "interpretable" decisions which can be explained with physical insights.

关键词： fluid-structure interaction machine learning hydrodynamics

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A comprehensive review of water entry/exit of lifeboats and occupant safety

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OCEAN ENGINEERING 2024年第Part2期310卷

作者： Wang, Di Fan, Ningge Liang, Binyi Chen, Gong Chen, Shunhua Xinjiang Univ Dept Mech Engn Urumqi Peoples R China Sun Yat Sen Univ Sch Ocean Engn & Technol Zhuhai Peoples R China Southern Marine Sci & Engn Guangdong Lab Zhuhai Zhuhai Peoples R China Sun Yat Sen Univ Key Lab Comprehens Observat Polar Environm Minist Educ Zhuhai Peoples R China

Lifeboats have been serving as an essential maritime life-saving equipment in the case of emergency situations. In recent decades, much effort has been devoted to investigating water entry/exit behaviors of lifeboats as well as occupant safety. However, there exist very few review papers related to such an important topic. In light of this, the purpose of the current work is to present a comprehensive literature review to fill the gap. This is achieved by firstly summarizing the existing studies concerned with water entry/exit of lifeboats from the perspective of numerical simulations and experimental investigations. To be specific, numerical approaches for fluids, structures, and fluid-lifeboat interactions, are categorized, followed by two major experimental methods for water entry/exit of lifeboats. We then present common evaluation criteria, numerical approaches, and experimental methods for occupant safety during water entry/exit process. Finally, the performance of numerical approaches and experimental methods for water entry/exit of lifeboats and occupant safety is discussed, and some future directions are pointed out. The present review can serve as a useful guidance for researchers who are interested in this topic.

关键词： Water entry/exit of lifeboats Occupant safety fluid-structure interaction Numerical approaches Experiments

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Mechanism and risk assessment of baffle-jetting-induced vibrations in fuel rods

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NUCLEAR ENGINEERING AND DESIGN 2024年 416卷

作者： Gad-el-Hak, Ibrahim Mureithi, Njuki Karazis, Kostas Painter, Brian Polytech Montreal Dept Mech Engn Montreal PQ H3C 3A7 Canada Framatome Inc 3315 Old Forest Rd Lynchburg VA 24506 USA

As nuclear reactor cores approach the end of their lifespans, it is a crucial aspect to ensure that the structural integrity of the reactor internals is not affected. The baffle-former bolts are subjected to significant mechanical stress and neutron irradiation from the reactor core during the plant operation. These circumstances can cause the bolts to degrade and lose some of their load-bearing capacity over the reactor lifespan. The degraded baffle-former bolts can lead to separation/openings between the baffle plates which cause water jet cross-flow injecting through these openings. This phenomenon is called baffle jetting. This jet flow can induce the vibration of fuel rods located near the baffle gaps, resulting in grid-to-rod fretting and, in extreme cases, fuel rod failures. This paper investigates the risk of baffle jetting-induced fluidelastic instability in fuel assemblies. A 6 x 5 axisymmetric flexible rod bundle having a prototypical nuclear fuel assembly is designed and fabricated to simulate a part of a fuel assembly under combined axial flow and baffle jetting. A special displacement mechanism is used to vary the position of jet flow relative to the array (i.e. jet eccentricity). Two cases, the jet-gap aligned case, and the jet-rod aligned case, are investigated to determine the variation of critical jet velocity with the jet eccentricity. In addition, three axial flow velocity cases, V-Axtal = 1.0 m/s, 1.5 m/s, and 2.0 m/s are tested in order to determine the stability effect of axial flow velocity on jet-induced instability. The experiments show that the mock-up array response resembles fluidelastic instability behavior. The stability threshold of the mock-up array depends strongly on the relative position of the jet flow with respect to the array centerline. In the jet-rod aligned case, the axial flow shows a strong effect on the combined flow-induced instability.

关键词： PWR fuel rods Baffle jetting Baffle-former bolt failures fluid-structure interaction Jet cross-flow induced vibrations fluidelastic instability tests

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A rate-dependent peridynamic-SPH coupling model for damage and failure analysis of concrete dam structures subjected to underwater explosions

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INTERNATIONAL JOURNAL OF IMPACT ENGINEERING 2025年 200卷

作者： Huang, Xieping Zhu, Bin Chen, Yunmin Zhejiang Univ Ctr Hypergrav Expt & Interdisciplinary Res Hangzhou 310058 Peoples R China

This study introduces a coupled peridynamics (PD) and smoothed particle hydrodynamics (SPH) model to handle the complex physical processes in concrete dam structures subjected to near-field underwater explosions. A robust coupling algorithm is applied to ensure accurate data exchange between PD and SPH domains, enabling the simulation of fluid-structure interactions. To account for the material behavior under high strain rates, a rate- dependent concrete model is integrated into the PD-SPH framework. The developed PD-SPH model is validated through simulations of centrifugal model tests, with results benchmarked against experimental findings and finite element method (FEM) predictions. The simulation captures key damage features, including horizontal tensile cracking at the dam head and an oblique penetrating crack in the dam body, forming an angle of approximately 17 degrees relative to the horizontal. Velocity and strain responses at critical monitoring points demonstrate strong agreement with FEM results, showcasing the model's capability in accurately predicting the structural responses and failure of concrete dams caused by underwater explosions. To the best of the authors' knowledge, research applying a coupled PD-SPH model to concrete structures under blast loading is still rare, particularly when considering the entire physical process, from explosive detonation to structural failure, accounting for fluid-structure interactions.

关键词： Peridynamics Underwater explosion Concrete dam fluid-structure interaction Smoothed particle hydrodynamics Tensile crack

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Underwater dynamic modeling and experiments of flexible structure with harmonic actuation of macro fiber composites

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MECHANICS OF ADVANCED MATERIALS AND structureS 2025年第2期32卷 203-216页

作者： Jin, Aiguo Lou, Junqiang Chen, Tehuan Wei, Yanding Xu, Chao Liu, Li Ningbo Univ Fac Mech Engn & Mech Ningbo Zhejiang Peoples R China Ningbo Polytech Intelligent Equipment Res Inst Ningbo Peoples R China Zhejiang Univ Key Lab Adv Mfg Technol Zhejiang Prov Hangzhou Peoples R China Zhejiang Univ State Key Lab Ind Control Technol Hangzhou Peoples R China

Flexible structures driven by smart actuators are promising alternatives for aquatic bionic propulsion vehicles. However, the hydrodynamic effects induced by viscous fluids on the dynamic response of flexible structures remain an ongoing challenge. Thus, this article presents a fluid-structure interaction dynamic model of a flexible underwater structure actuated by macro fiber composite actuators, and the underwater multimodal vibration characteristics are studied. The model is based on the extended Hamilton's principle, which considers the effects of hydrodynamic forces. The segmented mode shape functions of the flexible structure are derived using the assumed mode method. The study shows that the first two mode shapes of the beam predicted by the model agrees with the experimental results. The underwater dynamic responses of the flexible structure in a board band covering the first two resonance frequencies are also investigated at different actuation levels. The underwater results indicate that the first two resonance frequencies are 1.05 and 6.1 Hz respectively, basically consistent with the simulation ones (1.07 and 6.61 Hz). Correspondingly, the maximum transverse deflections at the end of the beam are 4.81 and 1.31 mm respectively, which are slightly lower than the predicted values of 5.75 and 1.62 mm. Therefore, the validity of the proposed coupled dynamic model is verified, which can be utilized to predict the multimodal dynamic responses of underwater flexible structures actuated by MFC or other smart actuators.

关键词： Dynamic model flexible structures macro fiber composite fluid-structure interaction hydrodynamic forces underwater dynamic responses

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Pressure drop reduction due to coupling between shear-thinning fluid flow and a weakly deformable channel wall: A reciprocal theorem approach

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JOURNAL OF NON-NEWTONIAN fluid MECHANICS 2025年 335卷

作者： Pande, Shrihari D. Christov, Ivan C. Purdue Univ Sch Mech Engn W Lafayette IN 47907 USA

We employ the Lorentz reciprocal theorem to derive a closed-form expression for the pressure drop reduction due to the coupling between shear-thinning fluid flow and a weakly deformable channel wall in terms of the shear rate and the viscosity function (and its derivative) of the underlying rigid-channel flow. The methodology is applied in parallel to fluids for which the generalized Newtonian viscosity depends on either the shear rate or the shear stress magnitude. When the viscosity model allows fora closed-form solution for the axial velocity profile in a straight and rigid channel, the pressure drop reduction can be evaluated in closed form, which we demonstrate for the power-law and Ellis viscosity models as featured examples and to enable comparisons to previous works. Importantly, the pressure drop reduction under the Ellis model is valid for both small and large Carreau (or Ellis) numbers, and we show that it reduces to the analytical expression under the power-law model for large Carreau (small Ellis) numbers.

关键词： fluid-structure interaction Shear thinning Reciprocal theorem Lubrication theory Pressure drop

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Dynamic Response and Energy Absorption of Lattice Sandwich Composite structures Under Underwater Explosive Load

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MATERIALS 2025年第6期18卷 1317-1317页

作者： Zhang, Xiaolong Sun, Shengjie Kang, Xiao Huang, Zhixin Li, Ying Wuhan Univ Technol Sch Naval Architecture Ocean & Energy Power Engn Wuhan 430064 Peoples R China Beijing Inst Technol Inst Adv Struct Technol Beijing 100081 Peoples R China

This study investigates the underwater explosion resistance of aluminum alloy octet-truss lattice sandwich structures using shock tube experiments and LS-DYNA simulations. A systematic analysis reveals key mechanisms influencing protective performance. The sandwich configuration mitigates back plate displacement through quadrilateral inward deformation, exhibiting phased deformation responses between face plates and back plates mediated by lattice interactions. Increasing the lattice relative density from 0.1 to 0.3 reduces maximum back plate displacement by 22.2%. While increasing the target plate thickness to 1.5 mm reduces displacement by 47.6%, it also decreases energy absorption efficiency by 20% due to limited plastic deformation. fluid-structure interaction simulations correlate well with 3D-DIC deformation measurements. The experimental results demonstrate the exceptional impact energy absorption capacity of the octet-truss lattice and highlight the importance of stiffness-matching strategies for enhanced energy dissipation. These findings provide valuable insights for optimizing the design of underwater protection structures.

关键词： lattice structure underwater explosion dynamic response energy absorption fluid-structure interaction

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Semi-Active Groundhook Control of Offshore Tension Leg Platforms Using Tuned Mass Damper With Optimized Parameters and Magneto-Rheological Damper Under Multiple Hazards

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JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME 2025年第1期147卷 011701页

作者： Patra, Suryasish Das, Diptesh Govt West Bengal KG Engn Inst Civil Engn Dept Bishnupur 722122 India Natl Inst Technol Durgapur Durgapur 713209 India

The purpose of the current study is to recommend an offshore tension leg platform (TLP)semi-active control system to lessen vibrations caused by various risks, such as the windload and regular and irregular waves. State-of-the-art indicates that there has not beenmuch study on semi-active management of offshore TLPs exposed to numerous hazardswhile taking into account system nonlinearities and employing a control method that isresilient to uncertainty. An augmented velocity-displacement-based groundhook (AVDB-GH) semi-active control scheme using magneto-rheological (MR) dampers, which is animprovement over the displacement-based groundhook (DB-GH) control algorithm, isproposed. The proposed controller uses a semi-active tuned mass damper (SATMD) consist-ing of a passive tuned mass damper (TMD) and two semi-active MR dampers as the controldevices. Constrained nonlinear optimization is used to determine the SATMD's optimizedparameters in order to produce the best control performance. A significant reduction insurge response of TLP is observed both in the time domain and the frequency domain. Com-pared to the SATMD using the usual DB-GH algorithm, the suggested control strategy moresuccessfully decreases the key response variables-deck displacement, power spectraldensity, and acceleration. The effectiveness of the controller is better for regular wavesthan for irregular waves and wind forces. Because the performance of the controller is unaf-fected by changes in the mass and stiffness of the TLP, the controller can be regarded asrobust.

关键词： tension leg platform optimized semi-active tuned mass damper MR damper multiple hazards augmented groundhook control dynamics of structures fluid-structure interaction hydrodynamics

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Blast resistance performance and failure modes of prestressed thin-walled aqueducts subjected to underwater contact explosion

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THIN-WALLED structureS 2024年第PartB期201卷

作者： Peng, Tao Wang, Gaohui Lu, Wenbo Gao, Zheng Pan, Xinhao Shu, Yizhan Wuhan Univ State Key Lab Water Resources Engn & Management Wuhan 430072 Peoples R China Wuhan Univ Key Lab Rock Mech Hydraul Struct Engn Minist Educ Wuhan 430072 Peoples R China

To solve the problem of regional water resource shortage, water diversion projects have been built around the world. As an essential lifeline project, the prestressed aqueduct is commonly used in cross-regional water transfer and diversion projects. However, the prestressed aqueduct is inclined to damage and collapse under explosion loading due to its thin structure. The main purpose of this paper is to investigate the nonlinear dynamic performance and failure modes of the large prestressed U-shaped thin shell aqueduct to underwater contact explosion. The prestress application approach is validated by theoretical calculations. The reliability of the analysis method of underwater contact explosion for reinforced concrete structures is verified by the underwater contact explosion test. Damage cracking process and nonlinear dynamic response characteristics of prestressed aqueducts to the underwater contact explosion with different explosive weights are performed. Blast resistance performances of prestressed aqueducts are discussed in terms of the crack length, residual displacement, and prestressing force loss. The influence of prestress level on the damage modes of the prestressed aqueduct under the blast loading is discussed. The results indicate that thin-walled U-shaped structures are extremely vulnerable to localized damage from underwater contact explosions. The blast-resistance performance of the U-shaped thin shell aqueduct can be significantly improved by applying prestress.

关键词： Prestressed thin-walled aqueduct Contact explosion Dynamic performances Failure modes fluid-structure interaction

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