Dong Myung Bae

Numerical Simulation for the Collision Between Side Structure and Level Ice in Event of Side Impact Scenario

WITH THE OPENING OF THE NORTHERN SEA FOR INTERNATIONAL SHIPPING ROUTES, VARIOUS VESSELS PREFER TO USE THIS OPTION TO REACH EUROPE AS DISTANCE IS SIGNIFICANTLY REDUCED IF A SHIP IS SAILING THROUGH THIS ROUTE. IN THE SAME TIME, THE DEMAND TO ENSURE SHIP SAFETY RISES AS IMPACT PHENOMENON BETWEEN SHIP STRUCTURES AND ICE CAUSES NUMEROUS CASUALTIES. THIS WORK PRESENTED A NUME-RICAL STUDY WITH A CONCENTRATION ON CONTACT BETWEEN SHIP STRUCTURES AND LEVELS. THE DOUBLE SIDE SKIN OF A CHEMICAL TANKER WAS MODELLED WITH A SHELL ELEMENT WHILE A DEFORMABLE CHARACTERISTIC WAS IMPLEMENTED ON THE ICE AS AN INDENTER. SEVERAL TARGET AREAS ON THE SIDE STRUCTURE WERE SET AS IMPACT POINTS BASED ON ITS STIFFENER COMPONENT. DIFFERENT MODELS OF INDENTER WERE TAKEN INTO ACCOUNT IN ORDER TO OBSERVE STRUCTURAL RESPONSES AND INFLUENCES OF EXTERNAL PARAMETERS, NAMELY ICE TOPOLOGY, WHILE THE DESCRIBED LOCATION PARAMETERS WAS TAKEN AS THE SHIP’S INTERNAL PARAMETERS. IMPACT FORCE WAS PRESENTED WITH TOTAL ENERGY, AS WELL AS THE RATIO BETWEEN KINETIC AND INTERNAL ENERGY. THE DEFORMATION PATTERN WAS USED AS A VERIFICATION OF THE COLLISION PROCESS AND ITS SUBSEQUENT RESULTS. FINALLY, THE BEHAVIOR OF THE INNER WALLS SUBJECTED TO TYPE INDENTERS WAS OBSERVED AS THIS COMPONENT IS THE FINAL COMPONENT THAT MAINTAINS LIQUID CARGO AND RESISTS AN IMPACT LOAD.

Energy behavior on side structure in event of ship collision subjected to external parameters

The safety of ships in regards to collisions and groundings, as well as the navigational and structural aspects of ships, has been improved and developed up to this day by technical, administrative and nautical parties. The damage resulting from collisions could be reduced through several techniques such as designing appropriate hull structures, ensuring tightness of cargo tanks as well as observation and review on structural behaviors, whilst accounting for all involved parameters. The position during a collision can be influenced by the collisions’ location and angle as these parts are included in the external dynamics of ship collisions. In this paper, the results of several collision analyses using the finite element method were used and reviewed regarding the effect of location and angle on energy characteristic. Firstly, the capabilities of the structure and its ability to resist destruction in a collision process were presented and comparisons were made to other collision cases. Three types of collisions were identified based on the relative location of contact points to each other. From the results, it was found that the estimation of internal energy by the damaged ships differed in range from 12%–24%. In the second stage, the results showed that a collision between 30 to 60 degrees produced higher level energy than a collision in the perpendicular position. Furthermore, it was concluded that striking and struck objects in collision contributed to energy and damage shape.

Rapid prediction of damage on a struck ship accounting for side impact scenario models

Abstract The impact phenomenon is inseparable part of every physical things, from substantial particle until macrostructure namely ship. In ship collisions, short-period load is distributed during impact process from striking ship into struck ship. The kinetic energy that is used to move striking ship is absorbed by struck ship that makes its structure undergoes plastic deformation and failure. This paper presents study that focuses on predicting occurred damage on side hull of struck ship for various impact scenario models. These scenarios are calculated by finite element approach to obtain characteristic on damage, energy as well as load during and after impact processes. The results indicate that the damages on impact to longitudinal components such as main and car decks are smaller than impact to transverse structure components. The damage and deformation are widely distributed to almost side structures including inner structure. The width between outer and inner shells is very affecting the damage mode where the width below the two meters will make inner shell experience damage beyond plastic deformation. The contribution of structure components is proofed deliver significant effect to damage mode and material strengths clearly affect the results in energy and load characteristic.

THE EFFECTIVENESS OF THIN-WALLED HULL STRUCTURES AGAINST COLLISION IMPACT

THE IMPACT PHENOMENON IS ONE OF MANY SUBJECTS THAT IS INTERESTING AND HAS BECOME AN INSEPARABLE PART OF NAVAL ARCHITECTURE AND OCEAN ENGINEERING FIELDS. LIMITLESS POSSIBILITIES IN CAUSE AND SCENARIO MAKE THE DEMAND TO UNDERSTAND THE PHYSICAL BEHAVIOR OF SHIP STRUCTURES DUE TO IMPACT PHENOMENON IS INCREASING. IN PRESENT WORK, A SERIES OF VIRTUAL EXPERIMENT IS PERFORMED BY FINITE ELEMENT METHOD TO SOLVE SEVERAL DEFINED COLLISION SCENARIOS. TWO INVOLVED SHIPS ARE CLASSIFIED AS THE STRIKING SHIP WHICH PENETRATES THE TARGET AND STRUCK SHIP AS THE TARGET. HULL ARRANGEMENT OF THE STRUCK SHIP IS CONSIDERED AS MAIN PARAMETER WHICH SINGLE AND DOUBLE HULL CONFIGURATIONS ARE PROPOSED TO BE ASSESSED. AN OBSERVATION OF THE DAMAGE EXTENT ON STRUCK SHIP SUBJECTED TO COLLISION LOADS ARE PRESENTED. THE RESULTS INDICATE THAT THE INTERNAL ARRANGEMENT OF THE STRUCK SHIP PROVIDES SIGNIFICANT EFFECTS TO RESISTANCE CAPABILITY AND STRUCTURAL FAILURE AFTER COLLISION PROCESS. FINALLY, AN ANALYSIS REGARDING THE EXTENT OF THE DAMAGE IS SUMMARIZED WITH A STATISTICAL CALCULATION TO PROVIDE DISTRIBUTION OF CRASHWORTHINESS CRITERIA OF THE DEFINED SCENARIOS.

ANALYSIS OF STRUCTURAL CRASHWORTHINESS AND ESTIMATING SAFETY LIMIT ACCOUNTING FOR SHIP COLLISIONS ON STRAIT TERRITORY

A SERIES OF ANALYSES ARE CARRIED OUT TO PREDICT THE STRUCTURAL CRASHWORTHINESS OF A SHIP DURING A COLLISION. THE NUMERICAL CONFIGURATION IS VERIFIED BY STRUCTURAL SIMULATIONS BASED ON A LABORATORY EXPERIMENT WHEREIN A PENETRA-TION TEST IS CONSIDERED AS THE EXPERIMENTAL REFERENCE. COMPARATIVE OBSERVA-TIONS OF STRUCTURAL BEHAVIOUR ARE CAREFULLY CONDUCTED TO ENSURE THE RELIABILITY OF THE PRESENT METHOD FOR CONDUCTING LARGE-SCALE COLLISIONS. AT THIS STAGE, THE PROPER PROCEDURE AND CONFIGURATION FOR STRUCTURAL CALCULATIONS SUBJECT TO ACCIDENTAL LOADS ARE DETERMINED. THE SECOND STAGE ADDRESSES THE CALCULA-TIONS FOR VARIOUS SIDE COLLISION SCENARIOS. THE SIMULATIONS CONSIDER A DOUBLE HULL RO-RO PASSENGER SHIP BEING STRUCK AT VARIOUS LOCATIONS, AND THE OVERALL BEHAVIOUR OF THE SIDE HULL ALONG THE LONGITUDINAL AXIS IS OBSERVED. THE MAIN STUDY CONSIDERS THE TARGET LOCATION AND STRIKING SPEED TO OBTAIN ADEQUATE DATA RELATED TO CRASHWORTHINESS CRITERIA, I.E. THE INTERNAL ENERGY AND EXTENT OF DAMAGE. FINALLY, THE CRITERIA OF VARIOUS SCENARIOS ARE SUMMARIZED. FUR-THER CALCULATIONS COMPARING THE RESULTS WITH A SAFETY FACTOR ARE PRESENTED TOGETHER WITH A CONSIDERATION OF STRUCTURAL BEHAVIOUR TO ESTIMATE THE SAFETY LIMIT WITHIN THE CONFINES OF STRAIT TERRITORY.

Structural Analysis of the Double Bottom Structure During Ship Grounding by Finite Element Approach

CONCERN OF WATER-TRANSPORTATION MODE WHEN EXPERIENCES NUMEROUS ACCIDENTAL LOADS IS PREDICTED LIMITLESS AND ALWAYS DEMAND SUSTAINABLE ANALYSIS. IMPACT PHENOMENON RAISES AS MAIN REASON OF ENVIRONMENTAL DAMAGE, WHICH GROUNDING CONTRIBUTES IN FORM OF SHORT-TIME IMPACT AND PRODUCES MASSIVE DAMAGE ON BOTTOM STRUCTURE OF MARINE VESSELS, E.G. SHIP. IN THIS WORK, A SERIES OF NUMERICAL EXPERIMENT IS CONDUCTED WITH CONSIDERING CONTRIBUTION OF SEVERAL PARAMETERS, NAMELY IMPACT LOCATION AND SEABED TOPOLOGY ON THE TARGET OBJECT WHICH IS DETERMINED TO BE THE BOTTOM STRUCTURE OF A TANKER SHIP. THE INITIAL STAGE IS CONDUCTED TO OBTAIN VALIDATION OF NUMERICAL METHOD AND CONFIGURATION USING IMPACT TEST TO ENSURE RELIABILITY OF THE PRESENT METHODOLOGY. IN THE SECOND STAGE, PROPOSED SCENARIOS ARE CALCULATED AND OVERALL EVALUATION OF DAMAGE EXTENT IS PERFORMED TO OBSERVE RESISTANCE AND BEHAVIOUR OF THE BOTTOM STRUCTURE. STRUCTURAL CONDITION AFTER GROUNDING, RUPTURE ENERGY, AND CRUSHING FORCE ARE PRESENTED TO OBSERVE HISTORY OF GROUNDING. CONTRIBUTION OF NUMERICAL PARAMETER IN FORM OF MESHING SIZE IS PRESENTED TO PROVIDE ADEQUATE CONSIDERATION IN BOTH OF PHYSICAL AND NUMERICAL PARA-METERS. FINALLY, TENDENCY OF THE TARGET STRUCTURE IS SUMMARIZED TO PROVIDE PREDICTION OF FURTHER BEHAVIOUR DURING THE BOTTOM STRUCTURE EXPERIENCES GROUNDING WITH OTHER SCENARIO. AN ALTERNATIVE SOLUTION IN RESPECTING TIME COST IS PROPOSED AND CAN BE CONSIDERED FOR OTHER IMPACT SIMULATION.

Comparisons of Multi Material ALE and Single Material ALE in LS-DYNA for Estimation of Acceleration Response of Free-fall Lifeboat

An interest in Arbitrary Lagrangian Eulerian (ALE) finite element methods has been increased due to more accurate responses in Fluid-Structure Interaction(FSI) problems. The multi-material ALE approach was applied to the prediction of the acceleration response of free-fall lifeboat, and its responses were compared to those of the single-material ALE one. It could be found that even though there was no big difference in the simulation responses of two methods, the single-material and multi-material ALE ones, the latter multi-material ALE method showed a little bit more close response to those of experimental results compared to the former single-material ALE one, especially in the x- and z-direction acceleration responses. Through this study, it could be found that several parameters in the ALE algorithms have to be examined more carefully for a good structural safety assessment of FSI problems.

Behavior Prediction of Ship Structure due to Side Impact Scenario by Dynamic-Nonlinear Finite Element Analysis

The development of safety has become issue especially for marine and ocean vessels. However, the limitless possibilities of various phenomenon on the sea, make the observation and prediction of ship structure are continuously needed. Side impact is one of those phenomenon. Due to the complexity of ship structure, this phenomenon occurs and produces high nonlinearities, which influence the extent and contour of structural behavior. Such interesting phenomenon was reviewed and studied in present paper using dynamic finite element analysis as the effect of the dependent characteristic of phenomenon to time. Several side scenario models were used to obtain different results in respect of impact location. The kinetic and total energies were presented together with the contours of stress and displacement at two sides of side constructions. Results indicated that the contribution of construction arrangement was significantly affected stress distribution in longitudinal direction of ship hull, while displacement contour from certain scenario produced high intensity on longitudinal member of side construction.

Nonlinear structural behaviour of membrane-type LNG carrier cargo containment systems under impact pressure loads at −163 °C

ABSTRACT This paper is a sequel to the paper dealing with quasi-static responses previously studied by the authors. The structural failure of membrane-type liquefied natural gas carrier (LNGC) cargo tank is an important issue in the construction of ultra-large an LNG carrier. However, quasi-static analysis to investigate the structural failure is difficult and tends to give conservative results. To compensate the weak points of the quasi-static analysis, a procedure for the dynamic analysis was developed to assess the structural failure using nonlinear finite element method. A nonlinear finite element method is employed to model metal membrane, insulation and surface contacts. Various element formulations are tested at different points along a corrugated surface to optimise the accuracy of the model with respect to computation time. Material properties used in the model are calibrated based on experimentally measured values at cryogenic conditions (−163 °C). The model is used to predict the structural failure under different impact pressure loads and loading patterns. It is concluded that the structural damage is less likely to occur under 30 bar.

Structural Analysis for Estimating Damage Behavior of Double Hull under Ice-Grounding Scenario Models

Demand to increase safety for water transportation, namely ship is continuously rising as various accidental loads may threat condition of target structure, i.e. ship. Several possibilities of impact scenario can occur with various indenters, for example stranding to a grounded ice. In this work, a study of structural behaviour accounting for interaction between the ship structure and indenter is conducted. Numerical simulation is performed using finite element method to estimate damage extent of the double bottom. In analysis, the indenter for grounding scenario is applied by characteristic of the ice properties to obtain estimated response of the structure in experiencing impact on polar territory. Impact scenario is defined into three different locations, namely girder and space between two girders. Finally, tendency of the damage per destroyed component is summarized.