Surendran Sankunny

Container ships move at a higher speed compared to other merchant ship types. A fin attached to the ship hull proves to be more efficient in controlling the moving ship. However, such attachments on the naked hull attract additional problems such as slamming, requirement of continuous maintenance, etc. The main objective of this study is to find the influence of fin action at various angles of attack with the incoming flow and recommend the best possible fin position for the least resistance. While experiments were performed for different angles of attacks of the fin with respect to the flow, a reduction in resistance was observed for an Fn range of 0.13–0.26. The fin was fitted at the lowest possible location of the hull surface at the bow part of the ship. Experimental investigation was done using model tests in a towing tank to determine the resistance of a scaled down model and it was compared with computer simulation. The interaction of a bow fin fitted to a container ship with its own generated and encountering waves are discussed in this paper. It was observed that at certain angles of attack of the fins favourable resistance characteristics were observed. Modifications from the expected resistance due to fin effect are paid attention in this study. Various resistance values for different angles of attack of the fin were compared and an angle of attack of 5° is found to be the best.

The very purpose of attaching fins to the hull is to reduce the roll motions of a ship. Roll minimization is a requisite for various operations in the seas. The presence of fin system provides enhanced state of stabilization especially when the vessel is performing a fast maneuvering amidst rough environmental disturbance. The fins in turn are activated by electro-hydraulic mechanism based on the in-built intelligence as per control theory like proportional-integral-derivative (PID) or fuzzy logic. As per this paper, fin system is activated using PID control algorithm. A frigate-type warship is considered for the demonstration purpose. Nonlinear roll motions are controlled using active fins. Lift characteristics of the fins in hydrodynamic flow were studied using CFD package fluent. Good amount of reduction in roll amplitude is achieved from various simulations in random sea. The approach can be used for any irregular sea conditions. © 2006 Elsevier Ltd. All rights reserved.

This study proposes a procedure to determine the optimal design parameters and target reliability based on Life cycle cost (LCC) based analysis. An iterative design procedure is performed for different levels of reserve strength ratio (RSR), and LCC is calculated. A case study is carried out for installation of the bottom fixed jacket support structure for offshore wind turbines (OWT) system subjected to extreme loading condition. To determine the ultimate capacity of the structure, static pushover analysis is integrated with the proposed design methodology. An evolutionary based particle swarm algorithm is selected for the structural design optimization of offshore jackets. The RSR evaluated from pushover analysis assists to determine the probability of failure based on the first order reliability method (FORM). Based on a set of LCC values, which are the collective sum of capital expenditure (CAPEX), operational cost (OPEX), and risk cost (RISKEX), the optimal design is reached.

The prediction of ship stability during the early stages of design is very important from the point of safety. Ships experience six modes of rigid body motions in a seaway, which can be split into two groups as translatory and oscillatory motions. Out of the six motions of a ship, the critical motion leading to capsize of a vessel is the rolling. In the present study, particular attention is paid to the performance of a ship in beam sea. The rolling motion of a ship has been described by a nonlinear differential equation taking into account the nonlinearities in both the restoring moment and the damping moment. Solution of differential equation of roll motion is sought using MATLAB. The effect of different representation of restoring moment on roll motion is investigated. It is seen that, the effect of different representation of restoring moment on roll motion depends on the characteristics of the GZ curve. A parametric investigation is undertaken to identify the effect of different parameters viz., wave steepness, encountering frequency etc., on the capsizing conditions of a ship. The rolling response of ship is determined in the frequency domain. The analysis has been carried out by varying both the wave steepness and the wave frequency. The approach has been demonstrated considering a Ro-Ro ship as test vessel.

Impact loads from incoming waves always challenge the strength of structural parts of a ship. Modern high-speed crafts including naval vessels are subjected to impact loads during high speed and sudden manoeuvre. Wave slamming may damage structural parts and cause flooding of compartments due to impact. Hydrodynamic impact load results in structural damage in conventional marine vehicles. Loads during cargo loading, unloading, shipping of green water, impact with icebergs etc. come under low-velocity impact loads. The structural parts of a ship can also be damaged due to the impact of collision with icebergs as in the case of the Titanic accident. Weapon discharge, flight operation, bulk cargo operation and collision with other structures are other examples of impact load acting on marine vehicles. Severe hydrodynamic impact load may cause damage of shell plating, collapse of bow part, damage of hatch covers, collapse of hull girder etc. Such structural parts should possess sufficient impact strength. Composite shells can be used for hull, deck or hatch covers of bulk carriers to reduce the weight of vehicle and to indirectly increase the pay load capacity. In the present work, cost-effective composites are prepared by adding fillers to improve impact strengths and tested to verify the same. The main objective of the study is to develop a cost-effective composite to be used as part of hull, deck and hatch cover of bulk carrier. Feasibility and selection of fillers to improve impact strength are established. Prior to this, different sizes of fillers and the chemical treatment of filler with acid were considered. Calcium carbonate (CaCO3), silicon carbide (SiC) and alumina (Al2O3) are considered with glass epoxy composite for the above analysis. The additional impact strength due to the application of fillers is determined using Izod impact strength tests. Contact force is considered as a scale parameter for the impact response for composite laminates. Contact force is the force against impact load on composite structures. Contact force and deflection history of composite panels are affected by a number of parameters such as fibres angle, laminate geometry, impactor energy, stiffeners, surface area of impactor and loading eccentricity. Effects of all possible parameters are included and their influence on the response is determined using the well-known package based on finite element method (FEM), ABAQUS. The FEM analysis of Khalili et al. (2011 Compos Struct 93:1363-1375) is used for comparison of results of the present numerical analysis. The study leads to many new insights to designers of cost-effective composite structures. © 2013 Taylor & Francis.

Composite materials are increasingly being used as an accepted alternative to traditional structural materials throughout the globe for various engineering applications. Because of their superior properties and flexibility, these materials are beginning to find innumerable applications replacing existing materials, especially in high-performance engineering domains. The electrospinning process adds a further dimension to enhance the properties of the composite material family by incorporating fibers at their microscale to even sub-nanoscale, enabling the development of advanced composites with enhanced properties. Over the past decades, much research work has understandably been done on these exciting materials. This paper aims to comprehensively map some of the trends in electrospun nanofiber interleaved laminated composite development, marking the milestones achieved and challenges faced. A brief review of the potential applications for these materials will also be put forward in the research outlook for these advanced nanoengineered composites.

This review paper initially summarizes the latest developments in impact testing on polymer matrix composites collating the various analytical, numerical, and experimental studies performed since the year 2000. Subsequently, the scientific literature investigating nanofiller reinforced polymer composite matrices as well as self-healing polymer matrix composites by incorporating core-shell nanofibers is reviewed in-depth to provide a perspective on some novel advances in nanotechnology that have led to composite developments. Through this review, researchers can gain a representative idea of the state of the art in nanotechnology for polymer matrix composite engineering, providing a platform for further study of this increasingly industrially significant material, and to address the challenges in developing the next generation of advanced, high-performance materials.

Container ships are prone to move at a greater speed compared to other merchant ships. The slenderness of the hull of container vessel is for better speed, but it leads to unfavorable motions. The pitch and roll are related and sometimes the vessel might be forced to parametric roll condition which is very dangerous. A fin attached to the ship hull proves to be more efficient in controlling the pitch. The fin is fitted at a lowest possible location of the hull surface and it is at the bow part of the ship. Simulations are done using proven software package ANSYS AQWA and the results are compared. Simulations are done for both regular and irregular seas and the effect of fin on ship motion is studied. P-M spectrum is considered for various sea states.

The prediction of ship stability during the early stages of design is very important from the point of vessel's safety. Out of the six motions of a ship, the critical motion leading to capsize of a vessel is the rolling motion. In the present study, particular attention is paid to the performance of a ship in beam sea. The linear ship response in waves is evaluated using strip theory. Critical condition in the rolling motion of a ship is when it is subjected to synchronous beam waves. In this paper, a nonlinear approach has been tried to predict the roll response of a vessel. Various representations of damping and restoring terms found in the literature are investigated. A parametric investigation is undertaken to identify the effect of a number of key parameters like wave amplitude, wave frequency, metacentric height, etc. © 2002 Elsevier Science Ltd. All rights reserved.

The world container fleet shows the fastest growth of any ship type. The infrastructure for loading and unloading container ships are also growing in many ports around the world. Such a trend is due to the fact that the containerized transportation is becoming more and more attractive due to many factors. The increasing demand in container transportation is met by use of more number of container ships including Post-Panamax and Malacca-max containers. Loss of containers in seas and accidents of container vessels are reported from many parts of seas. New generation containers are severely hit by parametric rolling. Pure loss of stability, due to exponential increase of roll in either broaching-to or head sea conditions, is called parametric rolling, is subjected to rigorous investigation by many researchers. Algebraic expression based on well known Duffing's method is proposed for solutions in parametric rolling. The variation in GM and damping values from trough to crest conditions associated with bow flare immersion and emergence in head sea conditions with pitch resonance with the heading waves are said to be the prime reason for parametric rolling. A simple model to predict the beginning of parametric rolling is described in this paper. © 2006 Elsevier Ltd. All rights reserved.