Search

This study presents a comprehensive analysis using the finite element method (FEM) to examine and evaluate the behavior of fuel carrier ship structure. Sandwich panels are effective structures for use in ship structures due to their lightweight yet robust nature. Sandwich panels used in ship structures have various core shapes, such as hexagonal, circular, and square, as needed. The sandwich panel structure can be widely implemented in ship construction, for example, on the deck, hull, and bulkhead of the ship’s cabin. Hydrogen is an alternative fuel that can replace fossil fuels. In this modern era, hydrogen is high valuable energy commodity, so accidents involving carrier ships could have significant consequences. Hydrogen is produced from liquefied natural gas (LNG), so if a leak occurs, for instance, in a storage tank or fuel tank, it has the potential to lead to accidents such as fires. Corrosion is a significant concern for the maritime industry, as it can jeopardize the structural integrity of these vessels and pose substantial safety and environmental risks. In this research, FEM was utilized to model and simulate the effects of corrosion on hydrogen carrier ships when exposed to fire, considering various environmental and operational factors. Through a systematic investigation, it is aimed to gain insights into the impact of corrosion on ship structural components during fires, such as hulls and storage tanks. The result of this study will contribute to improving corrosion and fire mitigation strategies, ensuring the safety and longevity of hydrogen and LNG carrier ships, and supporting the sustainable transportation of hydrogen to meet global energy demands. No research has been conducted on the structural behavior resulting from hydrogen fires and corrosion simultaneously. To achieve this, it is assumed to use the corrosion properties of steel in heavily traveled ship routes such as the Panama Canal Zone, Barent Sea, North Sea, and Suez Canal Zone. This study utilized an approach by modeling corrosion using shell thickness in Abaqus Quasi-Static and applying boundary conditions in the form of temperature increase up to 800°C and subsequent cooling back to the initial temperature. At the maximum temperature, the most significant mid-span displacement occurred in the circular core sandwich panel, with a value of 4 mm. The axial force in the structure was inversely proportional to the mid-span displacement. In the case of the circular core sandwich panel, the axial force was 96 kN. The most resilient core type was hexagonal because it experiences the least deformation when compared to circular and square cores.

Antiballistics are used as personal protective equipment required by military and police personnel. They have been mentioned frequently in recent decades due to the increasing cases of war. Several studies have reviewed the development of antiballistic technology. However, there needs to be more discussion on and systematic reviews of the current milestones of antiballistic materials, testing, and procedures. In addition, compared to other fields, antiballistic studies are rarely carried out by public researchers because research on weapons is still a sensitive topic. Researchers who want to discuss antiballistics must cooperate with the country's defense and security agencies. This article aims to present a summary on and the development of scientific research on the theoretical concept of impact, the experimental approach for ballistic tests on advanced materials, the idealization of ballistic tests in computational mechanic simulations, and milestones of technical apparatus for ballistic performance measurement, over a period of more than 500 years. Thus, this analysis makes an excellent contribution to the field of antiballistics. This article review is based on hundreds of international journals and websites that are still active and can be accounted for legally. The results show that research related to antiballistics will continue to grow yearly.

The rising demand for liquefied natural gas (LNG)-fueled ships requires the LNG bunkering facility that partially uses a ship-to-ship operation. The bunkering process of LNG fuel may have a greater risk due to LNG volatility. The cryogenic temperature of LNG poses a threat to the personnel and structural embrittlement to ships. Therefore, cryogenic spill protection optimization was introduced concerning the structural strength analysis using finite element (FE) by utilizing cryogenic temperature loads provided by the computational fluid dynamics (CFD) model of an LNG release. This study aims to build a platform for transferring the temperature load profile from CFD to FE software accurately. The CFD model usually uses a structured Cartesian grid, and the FE method adopts an unstructured tetrahedral or hexahedral mesh. As a result, both configurations store results at different positions, and it is not preferred for the load profile to be transferred directly. The error will be greater due to the variance of positions. Random Forest, a machine learning method, has been employed that uses a regression technique to deal with a continuous variable. An accurate load profile for the FE model can be obtained by adopting decision tree learning in Random Forest. The procedure for determining the temperature load profile is presented in this article.

The development of the global economy has led to a rise in ship traffic. As a result, the risk of accidents, such as collisions between ships and grounding, has also increased. Different failure criteria to capture these accidents have been introduced by researchers. Therefore, the purpose of this study was to determine the essential distinction between these failure criteria. The simulations suggest that failure criteria based on the maximum stress result in a slightly higher rupture strain value, greater crack propagation, and higher internal energy than those based on the maximum strain. Furthermore, using a larger mesh size compared with the size of the test specimen appears to greatly affect the validity of the simulation results.

This work aims to investigate the mechanical behavior of steel-plated structures under a raking incident and to quantify the effect of the mesh size in nonlinear finite element (NLFE) analysis. To conveniently comprehend nonlinear phenomena, i.e., the grounding which takes place in this work, a series of theoretical contact formulations was defined. In the main analysis, raking, which is a part of the grounding scenario, was strictly assumed as contact between a tanker, which was assumed to have thin-walled steel, and a seabed rock in the form of a solid obstruction. Designed raking scenarios were calculated using the FE method by using the nonlinear phenomena of the material behavior in the calculation. The findings of this work indicated that the possibility of expanding the recommended mesh size in FE simulation should be evaluated by quantifying the behavior of structural responses, such as energy, the force damage pattern, and acceleration, subjected to a variety of applied meshing techniques. The results concluded that a notable difference occurred when the mesh size was more than 132 mm (ratio 11 based on the plate dimension in this work), and this size is strictly recommended to be used for calculation of the element length-to-thickness (ELT) ratio. Assessment in time simulation showed that applying larger mesh sizes will reduce the simulation time but increase the maximum values of the crashworthiness parameters, i.e., energy, force, acceleration, and displacement.

In this study, a numerical investigation tensile test using ANSYS on three different carbon and alloy sheets of steel: AISI 1030 medium carbon steel, AISI 1080 high carbon steel and high-strength low-alloy (HSLA) A606 steel, has been carried out. The influences of three different specimen geometries on the stress–strain curve were also investigated. Understanding the properties of these materials, such as stress–strain obtained from a tensile test, is important. Materials are subjected to forces or loads when in use, for example, steel in a ship’s hull experiences significant stresses and strains. In such situations, it is necessary to understand the characteristics of the material because grounding or collisions can occur, which deform the materials. The differences in stress and strain obtained from three specimens with different geometries and mesh sizes of 2.5, 5, 7.5, and 10 mm for all proposed steels, were observed. The results showed that the ultimate tensile strength was always lower in specimen 2 compared to the other specimens. Furthermore, the highest von Mises stress and strain contour was located in the midsection of specimens 1 and 3 in all of the proposed materials.

Indonesia has the abundant potential of hydropower but not yet processed optimally, which intensely depends on fossil fuel. Hydropower installed in Indonesia is only 11,272 MW, from the estimated potential approximately 94,476 MW. This data shows that 89% of the hydropower potential in Indonesia has not been processed. One of the present efforts to utilize this resource is addressed to develop the Savonius water turbine. Conventional water Savonius turbines have a comprehensible structure and easy to be applied. However, the turbines produce relatively small power, which requires further assessment to improve its performance. The current study is performed by considering geometric changes on the water Savonius turbine to observe their effect on power characteristics. Considered changes are made on the number of stages, and the angle between stages, specifically a single-stage, two-stage 0°, Two-stage 90°, three-stage 0°, and three Stage 120°. The research was carried out by designing simulation model using ANSYS software with CFX Solver. Water speed is determined to 0.8 m/s, while plates with 110 mm in diameter and 110 mm in height are incorporated as rotor configuration. Based on this study, it can be concluded that the addition of the stage affected improving the performance of the Savonius water turbine, where the multi-stage turbine experienced an increment compared to conventional water turbines. The interesting tendency was found on the two-stage rotors with angle of 0° which produced a smaller Cpmax compared to the conventional water Savonius turbines.

Hip joint is an important human joints system. The damaged hip joints need to be replaced with artificial hip joints. The Study of the hip joint is very costly therefore another calculation method is demanded to produce good result in acceptable time and cost. Considering this problem, a series of study to assess hip joint performance is conducted using numerical approach. Important parameter for example applied materials are used in the modelling by idealizing Ti-6Al-4V compared to SS 316 L, and stemlengthwas chosen to be 128 mm. ANSYS software was used to analyze models, and designed element size variations were set to be in range 1 to 2.5 mm. The magnitude of force was placed on the femoral head with an angle of 16∘C from the vertical axis. Results showed that SS 316 L material has smaller deformation than Ti material. Whereas Central Processing (CP) time decreases in increasing element size for both materials. In addition, more variations in mesh size are needed to get more accurate convergent results.

Transporting mass products from one country to others is essential activities in industrial cycle. Ships are selected as reliable carriers for this objective considering traveling time and operational cost. During its operational, accidental events such as storm, high tide and bad weather may cause the products which are usually packed in freight containers fall into sea, and impacts the ship structure. In this situation, casualties on both involved structures can be detrimental. This work analyzes a series of ship-container collision in maritime territory in order to investigate resulting structural phenomena. The finite element approach is selected to solve the designed collision cases where the discussion is directed to selected crash-worthiness criteria. Impact speed between ship and container structures is chosen as the main parameter in the designed scenario by judging whether this parameter is a good representative of sea state. Overall results indicate that the indication for container rebounding after impact was high. It was followed by a significant increment of the internal energy after higher velocity, which was more than 5 m·s−1, had been applied to the scenario. Quantification of specific structural performance suggests that approximately more than 80% of the damage occurrs on the contacted area of the container structure.

Shipping time, cargo handling and quality as well as operational cost are main aspects of success in trading and shipping, which leads to high demand for ship safety. During freight shipping is conducted for various cargoes, the ship structure is subjected to numbers of loads, which several of them have been predicted during ship design. Nevertheless, incidental type in form of impact load can deliver massive blow to ship safety and cause immense loss. This phenomenon may be worse than initial condition if structure of chemical-oil carrier experiences impact, which possibly evokes environmental damage to maritime territory. This work is addressed to assess crashworthiness performance of structural part, i.e. bottom tank of chemical carrier. This part is one of center point of oil spill during occurrence of the impact load. The loading conditions are defined as configuration of interaction between ship structure and rock when the ship is stranded on shallow water. A series of data observations produced by finite element analysis (FEA) provide a prediction regarding local member’s motions during the rock breaches lower parts of the bottom tank. Consequences of the plate towards failure are quantified to obtain effect of the selected impact loading conditions to directly involved (main) member and other affected local member.

Ship collision appears as the most threatening loading accounting for structural casualties and numbers of casualties after impact on the target ship. In order to avoid such losses against collision, better safety during activities in maritime environment is demanded. Therefore, assessment of ship structure is needed to understand dynamic effect of the impact and quantify nonlinear behavior of local members. This study is conducted to achieve those aims by deploying nonlinear finite element analysis (NLFEA) to idealized ship collision event. Validation of the numerical method is performed by comparing results of a modeled collision case with various empirical calculations. Design for impact loading in main analysis considers side collision to main hull structure, which single side skin (SSS) and double side skin (DSS) types are modeled. Investigation is also directed to influence of the target members on the main hull to capacity of absorbed energy and characteristic of structural resistance. Analysis results indicate that good understanding is successfully obtained in terms of structural damage-energy relation. Confirmation of the current calculation using numerical calculation is also confirmed considering the modeled cases and empirical results agree well. Tendency of hull responses concluded that the longitudinal members contribute more to structural resistance against side collision.

During ship collision, hull crashworthiness is an important data which needs to be assessed as rapid development of hull structure has taken into consideration since several notable dangerous events. After catastrophic accidents cause both tragic loss of life and destruction of maritime environment, double skin system is applied for almost all ships, including RoRo passengers. This work aimed to assess effects of selected internal parameters to crashworthiness criteria, considering a passenger vessel as the target of a series of impact loads. A set of collision scenario was numerically designed using finite element (FE) method by involving single and double skin structures, target location and material grade to obtained estimation of hull crashworthiness. Assessment was focussed on the energy absorption, crushing force, stress level and failure strain of the target ship after experiencing side collisions. It was obtained from the analyses regarding role of the inner skin on tendency of the energy absorption. Failure progress on the proposed structures was successfully quantified based on stress expansion. Minimum value of material strength was concluded in final discussion to reduce more massive failure.

Remarkable consequences of maritime accident can be various, including structural damage, loss of life and marine pollution. During an accidental phenomenon, such as ship grounding, the amount of oil spillage indicates casualties’ extent of surrounding sea water. Effort to provide protection for sea environment against such event has been conducted actively by developing navigational instruments, and passively using structural development and assessment. The accidental grounding is, however, a very complicated process with high sensitivity to given factors during its occurrence. Variety in ship type, location, obstruction etc. affected by advance improvement in naval technology, invites sustainable analysis for structural crashworthiness and failure to produce evaluation data.

Demands for water transportation modes are continuously increasing as rapid economic and industrial growths in the recent decade. Ship as representative of the water transportation is generally needed to carry various products from one location to another. Besides as product carrier, ship also acts as public facility to transport human across islands for number of reasons, such as tourism and vehicle. Considering its importance, structural damage due to accidental loads or so-called impact can cause unacceptable casualties which threat ship passenger, shipping industry and maritime environment in same time. The most frequent impact phenomena occur in forms of collision and grounding, which are targeting side structure and double bottom consecutively. However, since responses of the impacts on structure are highly nonlinear and vary due to development of ship structures, sustainable analysis as an update of pioneer calculation can be beneficial as rational reference for improving safety and navigational instruments. This work aims to assess failures of the side structures subjected to penetration of striking bow in ship-ship collision scenario. Locations of impact are idealized to happen on after-end, midsection and fore-end to provide complete assessment. Striking bow is to be deployed by varying input velocity to observe significance of the fractures on the side structure. This configuration is implemented on the designed collision scenario, and later calculated using nonlinear finite element method (NLFEM). Summary of the solution indicated that the midsection produced the highest resistance against side collision. Breaching of the inner shell was successfully avoided on the fore-end, but the critical damage to the cargo was observed during bow penetration to the after-end region. This location was recommended to be added by longitudinal framing to increase its resistance against ship collision.

The main goal of the present paper was to study the physical response of a double side skin (DSS) structure under impact load in a collision event between two ships. Collision energy and damage extent (size and location) during the collision process were observed together with damage patterns on side structure. The ships were modeled after a Ro-Ro passenger ship and cargo reefer which were involved in a ship collision on the Sunda Strait while the analyseswere performed using non-linear simulations FEMto produce virtual simulation data. Several caseswere proposed to be investigated in this work with involvement of parameters i.e. penetration location and ship materials which were embedded on the structure model. A series of material experiments and testing was conducted to obtain detailed material properties which were to be deployed in simulation. It was shown that, after penetration at the transition location, the striking ship was successfully deforming and forming tears to the inner skin. On the other hand, with identical structure and identical mass of construction, the use of high-strength low-alloy (HSLA) steel as the repair material offered considerably better capacity in absorbing the impact load than plain-carbon steel.

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.

Ship grounding is considered as a serious maritime accident which highly contributes to environmental pollution. This impact phenomenon attracts audiences to be studied and assessed since in an instantaneous moment, oil or waste from the damaged bottom tank can spill and contaminate wide water territory. In this study, grounding scenario is modelled as hard grounding where a rock geometry is chosen as representative of oceanic obstruction. The contribution of several main parameters, such as target component and oceanic obstruction are evaluated. The method is to apply a virtual experiment by nonlinear finite element (FE) method to conduct a simulation. A chemical tanker is taken as representative of a marine structure which is subjected to impact load on its bottom structure during interaction with the obstruction. The results indicate that the space between girders provides less resistance in the crushing process. The internal energy in this work is presented to estimate the strength capability of the impacted component, which is followed by the deformation pattern on the lower part of the bottom structure. Finally, the effect of the obstruction on failure sequences in grounding is summarised.

The remarkable influence of the global warming to Arctic environment opens a possibility to conduct a voyage from Asia to Europe through the Northern Sea Route (NSR). This option is considered as a decent solution to reduce fuel consumption and increase time efficiency in delivering cargo to the designated destination. However, this alternative comes with a challenge to keep safety of ship structures against an impact with obstacles which are possibly encountered at the Arctic. Solid ice can be considered as a serious threat to the double bottom of ship structures in impact phenomena, especially ship grounding. In this work, a series of grounding calculations are conducted to produce estimation of structural crashworthiness during interaction between double bottom and conical type ice. Material characteristics based on tensile testing of polar class material are applied to calculation and compared with non-polar steel.

Vibration analysis is a crucial process in ship design to guarantee crew’s comfortability and to save operating costs by predicting problematical resonance in advance. This study focuses on idealizing fluid mass in tanks by positioning point mass element and quad elements inside the tanks. Also, the added mass effect induced sea water surrounding a ship was included in the present study. The natural frequency obtained from free and forced ship vibration analysis were compared and assessed in the manner of ISO regulation. Finally, it was concluded that the quad element was more adequate to idealize fluid entities in tanks since it was difficult in arranging point mass elements at each grid points properly.

Composite materials are increasingly utilized in engineering due to their superior properties such as strength, flexibility, and corrosion resistance. However, accurately predicting the buckling pressure of composite cylindrical shells under external loads remains challenging due to the complexities introduced by various stacking methods. This study addressed this challenge by integrating advanced machine learning techniques with simulation-based data generation through finite element analysis (FEA). A comprehensive dataset comprising 1369 simulation results was generated using ANSYS ACP, focusing on cylindrical shells modeled with an 8-mm-thick filament winding technique and T700 material. The stacking angles ranged from −90 degrees to 90 degrees in 5-degree increments. Stacking configurations (inputs) and their corresponding buckling strength (outputs) were generated using ANSYS ACP. Machine learning models, including linear regression, elastic net, polynomial regression, random forest, support vector regression, XGBoost regression, and artificial neural networks, were implemented using Python 3.8 and Scikit-learn (version 0.24.2). A comparative analysis of these methods revealed their model performance, providing insights into the most effective approaches. Additionally, the accuracy of these models was then evaluated on previously unseen input data, allowing for a comparison of their out-of-sample accuracy. The results demonstrated that the random forest model and XGBoost regression achieved superior accuracy with minimal prediction errors. The study highlights the critical role of machine learning in predicting buckling pressure, which is essential for ensuring structural integrity and optimizing performance in marine engineering and other applications involving composite materials. [ABSTRACT FROM AUTHOR]