A Simplified Procedure to Assess the Strength of a Ship Impacting a Lock Miter Gate

peer reviewe

Numerical crashworthiness analysis of an offshore wind turbine monopile impacted by a ship

peer reviewedThe consequences of collision events can range from minor structural damages of the supporting structure to complete collapse of the wind turbine, which may lead to disruptions of the electricity production and, at worst, to sinking of the striking ship with probability of loss of human lives or/and pollution. For all these reasons, a collision risk analysis becomes mandatory at the pre-design stage in order to identify the collision scenarios having the greatest probabilities of occurrence, to estimate the consequences of collision events and to ensure safe operations through the wind farm service life. The goal of this paper is to outline the behavior of the monopile foundations during ship collision by performing non-linear finite element simulations. Many collision scenarios are analyzed in order to study the sensitivity of the monopile to various parameters like impact striking ship velocity, nacelle mass, wind direction, soil stiffness, vertical location of the impact point, wind orientation … The internal energy dissipated by deformation of the monopile, the crushing force and the indentation of the crushed area are compared for different situations, as well as the overall displacements of the supporting structure

Simulation couplée Fluide-Structure d'un hydrofoil en composite sous écoulement stationnaire et instationnaire

Ces travaux s'inscrivent dans un contexte grandissant de développement de concepts innovants d'hélices marines en composites dans l'optique d'en améliorer les performances. En effet, les matériaux composites offrent des perspectives intéressantes en termes de légèreté des structures, mais aussi de modifications des propriétés structurelles permettant de réduire les niveaux de vibrations générées par l'écoulement, [1]. Ces deux propriétés des matériaux composites en font une technologie de premier plan dans une actualité mondiale préoccupée par la réduction des émissions de CO2. Par ailleurs, l'adaptation de la structure composite à l'écoulement sous l'effet du chargement hydrodynamique entraine également un retard d'apparition de la cavitation présentant un fort intérêt opérationnel pour les Marines. Ce papier présente plus spécifiquement la validation d'une boucle de calculs couplés fluide-structure à l'aide des logiciels commerciaux de CFD (Starccm+) et de CSD (Abaqus) des déformations d'un profil composite sous chargement hydrodynamique. Le cas de validation envisagé ici est un NACA0009 développé initialement par l'Australian Maritime College (AMC) et testé expérimentalement dans [2], puis optimisé plus récemment à l'aide de codes numériques dans [3]. L'hydrofoil est encastré à sa base, et son extrémité laissée libre afin d'obtenir un comportement s'approchant de l'hélice marine. La mise en place et la validation préalable des modèles fluide 3D RANS et structure sera présentée, puis les résultats numériques seront confrontées aux données d'expériences issues de la littérature [2]. Il est montré que le modèle fluide prédit correctement les coefficients hydrodynamiques jusqu'au décrochag

Extension of the Super-Elements Method to the Analysis of Oblique Collision Between Two Ships

Extension of the Super-Elements Method to the Analysis of Oblique Collision Between Two Ship

A Simplified procedure to assess the dynamic pressures on large reservoirs

peer reviewe

Analytical method to assess the crashworthiness of a Floating Offshore Wind Turbine (FOWT)

With the purpose of using more renewable energies and the decarbonisation of EU, some European countries are implementing floating wind farms, which are closer to traffic lanes. It is important to have a complete scope of the structure’s response to a ship impact, in order to implement a risk assessment of the floating wind turbines. In this regard, finite elements solvers are widely used nowadays, which provide accurate results but are time-demanding, not suitable for an early design stage. A faster and reliable method is required in order to study a wide range of parameters: impact velocity, impact location, wind-wave-structure interaction, mooring system response and overall dynamics. This poster presents the methodology used to develop an analytical method to compute the crashworthiness of FOWT

Simplified analytical method for estimating the resistance of lock gates to ship impacts

The present paper is concerned with the design of lock gates submitted to ship impacts. In this paper, a simplified analytical method is presented to evaluate the resistance of such structures under collision. The basic idea is to assume that the resistance is first provided through a local deforming mode, corresponding to a localized crushing of some impacted structural elements. For consecutive larger deformations, the resistance is then mostly provided through a global deforming mode, corresponding to an overall movement of the entire gate. For assessing the resistance in the case of the local deforming mode, the structure is divided into a given number of large structural entities called "superelements." For each of them, a relation between the resistance of the gate and the penetration of the striking ship is established. However, as some results are already available in the literature, this subject is not treated extensively in this paper. On the contrary, the calculation of the resistance of the gate provided through the global mode is detailed and the strategy to switch from local to global deformation is highlighted. Finally, we propose to validate our developments by making a comparison between results obtained numerically and those predicted by the present analytical approach

A Rapid Procedure for Estimating the Ability of Lock Gates to Withstand Ship Collisions

peer reviewe

Ship collision analysis on Offshore Wind Turbines with monopile foundations

Every year the offshore wind industry is expanding and new offshore wind farms are built in deeper waters and closer to the traffic lanes for commercial and passenger ships leading to possible collision events. The consequences of such events can range from minor structural damage to collapse of the Offshore Wind Turbine (OWT), with probability of ship sinking, pollution and at worst, to loss of human lives. Therefore, a collision risk analysis becomes a necessity in the pre-design stage of an offshore wind farm in order to identify the collision scenarios having the greatest probabilities of occurrence but also the most dangerous ones. The objective of this research is to investigate numerically the influence of the impact velocity and wind loads on the OWT’s behaviour when subjected to ship impact. A 5 MW wind turbine was considered for this research and the striking ship was conservatively assumed to be rigid. The description of the Finite Element model is presented as well as the main results obtained

ASimplified Analytical Method for Estimating the Crushing Resistance of an Inclined Ship Side

This paper provides a new contribution to the simplified analytical treatment of collisions between two ships. It is directly connected to the well-known super-elements method, which is a simplified procedure allowing for a quick estimation of the damages caused to both the striking and struck vessels during such events. In this article, a new analytical formulation is presented for estimating the impact resistance provided by inclined ship side panels. Two different scenarios are treated. We first deal with the case of an impact between the oblique plate and the stem of the striking ship, and then we consider the situation where the inclined panel is impacted by the bulb. For these two scenarios, an analytical formulation relating the force and the penetration is provided and these developments are validated by comparing them to the results of finite elements simulations. Finally, the new inclined plate super-element is integrated in a simplified model of a frigate collided by another ship, and the resistance given by the superelements method is then compared to the one obtained by a numerical simulation of this collision