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Standard structural assessments of ship hulls include the evaluation of the elastic structural response. Elastic analysis neglects extreme and unpredicted loadings, which can produce catastrophic outcomes, such as the loss of the ship’s ultimate strength. Moreover, hull elements are considered unaffected by age-related degradation. Therefore, this study models and quantifies the effect of corrosion-induced structural degradation on the ultimate strength of a high-tensile-steel (HTS) cargo ship using progressive collapse and nonlinear finite element methods. Uniform and pitting corrosion are modeled through selected scenarios, which hull elements might encounter during exploitation, producing a total of 148 calculation models. The findings show that corrosion-induced degradation can significantly decrease the ultimate strength of the hull (up to 30% for the most severe scenarios assessed). Furthermore, ultimate strength decreases almost proportionally to the amount of wastage considered. It was found that stiffener corrosion has a significant effect on the total ultimate strength. This study’s aim is to emphasize the vast importance of including ultimate strength along with ageing effects in industry-standard structural assessments of large HTS ship structures, designed to last for several decades whilst exposed to excessive and unpredicted bending moments.

In service, ships are likely to be subjected to various types of loads which are foreseen in the design phase. In addition, ships can experience rare events and consequently, extreme or oncein- a-lifetime loads (Paik, 2018). The cause of these loads can be attributed to failed attempts to evade storms, ship overloading, incidents of grounding and collisions. Such scenarios might produce a hull girder bending moment reaching the hull’s collapse, i.e., hull girder ultimate capacity (UC). Thus, the main idea behind the ultimate strength assessments of ships is to predict the structural capacity of the hull girder until its collapse. Rules and regulations for sea-going ships have acknowledged the issue (IACS, 2022). Nevertheless, for inland vessels (or even river-sea ships), no fully developed technical standards and studies involving state-of-the-art methods for UC assessments exist in practice. Moreover, studies using sophisticated progressive collapse analysis (PCA) are rare, see one in (Ilić & Momčilović, 2023). Compared to sea-going ships, inland vessels have a larger length to height ratio and low hull modulus, and thus, they are prone to longitudinal strength issues. Coupled with the prolonged service life of inland vessels, UC can be vastly affected. This can significantly reduce UC and decrease the margin between the elastic and the ultimate strength response. Therefore, in order to benchmark the phenomena, the effects of corrosion-induced degradation on UC of a typical inland waterway vessel are explored by using incremental-iterative progressive collapse analysis (PCA), a procedure thoroughly defined in (IACS, 2022). The selected inland vessel is a typical Danube mild steel made barge with the following dimensions: Loa = 72.9 m, B = 11.40 m, H = 3.7 m, T = 3.55 m. The cross-section of the vessel is divided into segments according to (IACS, 2022), see Figure 1. The vessel is already assessed for UC (Ilić & Momčilović, 2023), but just for intact condition. Firs

International Maritime Organization (IMO) and regional authorities have been gradually introducing decarbonization policies and regulations. Shipping sector’s primary response remains the reduction of the cruising speed. Other solutions can include hull optimization, application of energy saving devices, alternative fuels. Alternative fuels are still under the development and could significantly reduce emissions, through the application of batteries, hydrogen, ammonia, etc. However, domestic voyages by ferries have not been exposed to the regulations’ scrutiny. Nevertheless, in the regions such as the Bay of Kotor (Montenegro), protected by UNESCO, maritime transport is expected to follow environmental policies. In order to encourage the decarbonization of such regions, this paper offers a preliminary concept solution of an electric ferry for the Bay of Kotor with reduced onboard emissions. The concept is based on available data on the most energy demanding ferry in Bay of Kotor that has operated for the past decade. The ferry follows the short route suitable for the application of electric drive. Analysis of an operational profile and the ferry concept design parameters are presented, as well as the advantages and disadvantages of electric ferry proposal.

Traditional approach in construction designing and structural integrity assessment implies numerical calculations performed on the construction including construction elements that affect rigidity and strength, without welded joints. That structure is evaluated in elastic response, and the results are compared to yield strength, as shown in [1]. That approach is good enough for workloads for most of the constructions. In that scenario, sudden overloading that led to structural collapse is neglected. In those scenarios, within the plastic deformation domain, the differences in mechanical properties of welded joint regions have vast influence to structural integrity. Mechanical properties of welded joint regions are obtained using inverse methodology, that is mentioned in [2]. That methodology included tensile testing of a specimen containing welded joint. During the experiment strain field was continuously measured using stereo cameras, and results are processed using system based on Digital Image Correlation. Numerical computational model of test specimen is formed using the same parameters, as in the experiment (shape of welded joint, boundary conditions, loads, etc.). To improve numerical model, deformations of all regions of welded joint (base material, weld metal, and heat affected zone) are imported into numerical model. Consequently, material properties of all three welded joint regions were obtained. Material properties are then used in analysis of welded joint influence to structural integrity of several constructions, such as pipeline, pressure vessel, bucket wheel excavator computational models. For all those constructions, two computational models are made, the one without (classical approach) and the other containing welded joints. Results showed that there is no difference between the two computational models during service operations (elastic structural behaviour). However, within the plastic deformation domain, the differences between the models are c

Inland waterways vessels (IWV) have no mandatory regulations regarding their energy efficiency, as sea-going ships have. So far, there are just two proposed design energy efficiency evaluation methods, both based on IMO EEDI approach and data on EU inland navigation. Operational indicators and real-time navigation measurements from available literature do not exist. Therefore, this paper aims to introduce the energy efficiency in operation (EEO), assessed for the typical Danube cargo vessel. Firstly, an operational profile is acquired by tracking the vessel’s voyages, and by identifying actual constraints of each sector the vessel has sailed during the designated time. Secondly, EEO is incorporated within two available methods and calculated based on acquired operational data considering different navigational conditions. The paper shows how the energy efficiency vastly depends on variables such as water depth, current speed, draught, deadweight, river constraints. Analysis is performed for the most employed month of the vessel navigation, and annually. Depending on water level scenarios and during the selected month of sailing, the total amount of CO2 emitted is estimated to be between 22.7 t and 29.9 t, while the necessary average speed reduction (i.e., slow steaming) per sectoral voyage for the requirement compliance is calculated to be in between 4.8%-26%. Slow steaming is assessed to extend the time of voyage for 6.1-10.7 hours on monthly basis and 49-87 hours annually.

In this paper, a material characterization inverse methodology is used to obtain structural parameters for all welded joint regions. Furthermore, such are applied for the more realistic analysis of the pipeline numerical model structural response. Material characterization methodology included tensile testing of specimen containing welded joint. During the experiment strain field was continuously measured using stereo cameras, and results are processed using system based on Digital Image Correlation. Numerical computational model of test pipe is formed using the same parameters, as in the experiment (shape of welded joint, boundary conditions, loads, etc.). To improve numerical model, deformations of all regions of welded joint (base material, weld metal, and heat affected zone) are imported into numerical model. Consequently, material properties (Young’s modulus of elasticity, yield strength, tensile strength) of all three welded joint regions were obtained. Material properties are then used in analysis of welded joint influence to structural integrity. Three different numerical computational models are produced. The first model represents the classical approach in which the welded joint parameters are not considered. The second model contained welded joints, but with orientational mechanical properties of base and weld metal, and with heat affected zone having properties same as base material. The third one included properties of all three welded joint regions, obtained using inverse methodology. Results showed that there is no difference between the models during service operations (elastic structural behaviour). However, within the plastic deformation domain, which for instance, accounts for hydraulic shocks, the differences are considerable. When orientational mechanical properties of base and weld material are included, stress concentration in welded joint is 1.59. When real properties of material are included, stress concentration is decreased to 1.49, while

Due to the sudden nature of hull girder collapse caused by extreme loadings, the ultimate strength of ships, i.e., ultimate capacity, has to be evaluated. Ultimate strength analysis procedures have already been provided within the rules of the classification societies for sea-going ships. However, rules for inland vessels are not fully addressing the issue. In addition, literature data on the ultimate strength of inland vessels are almost negligible, which is alarming, considering the frequency of grounding and overloading events in inland navigation. Moreover, inland vessels' structural elements are prone to buckling due to their slender plates. In order to evaluate ultimate strength, an inland waterway (IW) barge is chosen for progressive collapse analysis (PCA) employment. PCA has demonstrated that the buckling collapse of structural elements vastly governs a vessel's ultimate capacity. Results show the extent of the safety zone between the actual loss of the ultimate capacity and the linear-elastic behavior of the structure.

The Vessel Train is a novel semi-autonomous waterborne transport concept which implies a convoy of digitally connected vessels. Only the first vessel in the Vessel Train (the so-called “lead vessel”) is fully manned, while the remaining vessels (the so-called “following vessels”) are remotely controlled from the lead vessel and thus may sail either with a reduced crew or with the crew off-duty. The Vessel Train was the subject of the research project NOVIMAR (NOVel Iwt and MARitime transport concepts), funded by the European Commission within the framework of the Horizon 2020 program. One of the tasks of the project concerned the design of novel vessels for the Vessel Train. The Vessel Train ships were designed in compliance with a specific requirement: to utilize the horizontal (Ro-Ro) container handling. Additionally, two inland vessels had to fulfil another condition: to have as low design draught as possible, so as to provide for uninterrupted navigation even during the low-water periods which tend to be extended and more extreme on all major European inland waterways. Both the Ro-Ro handling of containers and the shallow draught considerably affect the ship general arrangement, cargo stowage and handling, structural strength, intact and damage stability, etc. Thus, this paper discusses the challenges encountered in design of large inland container Ro-Ro vessels with extremely shallow draughts, intended for the use in the Vessel Train.

The longitudinal girder (LG) between fuel oil tanks (FOT) and water ballast tanks in the double bottoms of ships represent critical structural parts whose watertight nature could be harmed by corrosion, thus, causing the pollution of water ballast tanks and adjacent areas. The new common structural rules (CSR) define the minimum thickness values of structural elements and corrosion margins. The assessment of the deviations from the prescribed values during ship operation could optimize the prescribed criteria. Assuming that corrosive processes begin after four years of operation, the paper analyzes a linear model that describes the percentage of plate wear as a function of the built-in thickness of LG of FOT. The research included 20 ships and provided the database for 1918 corrosion depth values. The gauging records included the average values of the original thickness of steel plates grouped in three intervals (11–13 mm, 13–15 mm, 15–18 mm). Based on the difference between the built-in and subsequently measured values, the paper analyzes the percentage of thickness reduction due to corrosion, concerning the original plate thickness. The findings of the research should facilitate the optimization of corrosion margins and prevent potential structural collapse and pollution.

In order to address the decarbonization policy, International Maritime Organization (IMO) has been dealing with energy efficiency of ships for more than a decade. Firstly, procedures for energy efficiency assessment are introduced through the regulative, but only for new ships. Consequently, IMO also introduced energy efficiency criterion for already built ships that is set to be applicable starting from 2023. Regulative is already having an impact on ship design. While the new ships can be adapted in design phase, built ones will not have so many options. So far, almost all the solutions include reduction of the speed, i.e., slow steaming. Nevertheless, there are numerous technical and operational measures. The paper presents the calculation of energy efficiency performed for the fleet of existing 11 cargo ships categorized into four different ship classes. Calculation is based on the current IMO regulations covering the evaluation of energy efficiency of existing ships index (EEXI). Input parameters for analysis are obtained using two approaches: technical files (design parameters of the ship) & sea-trial reports and statistical method (when technical files & sea-trail reports are not available). Authors examined if the difference in two input approaches and potential class notation change could lead to different energy efficiency evaluation results. Moreover, the main goal of the research was to investigate on how the present conventionally designed cargo ships compare to the novel regulations.

In order to address the environmental concerns and reduce the air pollution from traditional diesel engines, maritime authorities have been gradually introducing the energy efficiency requirements for ships. Mostly, the shipping sector response consists of measures such as power reduction, application of various energy saving devices and alternative fuels. The latter presents the radical and an efficient way to almost completely reduce onboard emissions, by installing the propulsion systems powered by batteries (electric drive), hydrogen, ammonia, or other “carbon-free” sources of energy. Therefore, this paper presents an early-stage design of the electrification concept of the ferry regularly navigating in the Bay of Kotor between the ports of Kamenari and Lepetani. Such short-routed operation can be practical for the application of electric drive with batteries, as a sole source of power. Preliminary design methodology for the calculation of the ship’s operational profile is presented, along with the electrification concept for the ferry on the specific route. Findings showed that the proposed design can be viable for the small-scale Ro-Ro navigation in the Bay of Kotor aquatorium, especially given the UNESCO World Heritage site status of the area.

Inland waterway industry is far smaller than maritime and therefore, provides less environmental impact. However, its local effect is not negligible. Even though maritime practice has been addressing energy efficiency of ships for decade, no corresponding measures were delivered in inland waterway industry, considering the Green Deal goals. However, there are few proposals for addressing the energy efficiency of inland vessels. Hence, this work tries to gather such proposals and provide a review on their current status.

There are numeruos examples of failure of responsible parts of steel structures. When failure occurs, series of procedures are performed in order to obtain the cause of failure and to repair the damage. However, prevention of failure should be given higher importance. That means that one can predict reaction of construction in any unexpected circumstances, having owerall knowledge about construction. Actually, dynamic reanalysis method and model testing could give comprehensive insight into structural behavior of construction. Dynamic reanalysis method implies that the stress is not the only indicator of weak points in structural design. One should know modal shapes and natural frequencies, and distribution of potential and kinetic energy in the main modes. In fact, the main mode shapes show how the structure behaves under some possible load. Reanalysis method is based on distribution (of difference) of kinetic and potential energy and involves the transformation of the existing models in the new (better) one. Model testing represents one of the solutions to obtain the whole picture of construction behavior and includes creation of sub-scaled model in order to anticipate the behavior of the real construction, regarding the behavior of the model. Model testing enables to predict the stresses and deformations, and dynamic behaviour of the real structure regarding the stresses and deformations of the model, and testing on the model instead of the actual construction results in a great saving of money and time. Once again, dynamic reanalysis method and model testing give owerall knowledge about construction.

In this paper, structural reliability is applied to compare the original bucket wheel boom (BWB) of excavator SchRs 740 and the series of boom structures obtained by lengthening the original boom from 0 to 10 m. Stress field of BWE is acquired using finite element method. Then, stresses and yield criterion are modeled using probability density functions to account for uncertainties in their randomness. This stochastic approach is used to determine BWB’s reliability, reliability index and probability of failure, with respect to various cases of optimization, namely, structure lengthening. Consequently, it enabled the evaluation, quantification and comparison of overall response of the similar structures taking into account range of stress rather than conventionally based single value approach. So, structural reliability approach can be used to evaluate, compare similar structures and thus, provide more sophisticated assessment than most of the structural analysis that are deterministic in their nature.

After introducing an energy efficiency design index (EEDI) in 2011, International Maritime Organization (IMO) pursued their short- and long-term goals to reduce greenhouse gas (GHG) emissions from ships by presenting, among others, an energy efficiency existing ship index (EEXI). Contrary to EEDI which is used for new ships solely, EEXI is addressing an energy efficiency of already built ships and is set to become formally applicable starting from 2023. Existing designs cannot be essentially and rapidly changed to comply the criterion. The only main particular from the preliminary design phase that can be meaningly optimized ???post festum??? is a required engine power, and thus, the speed. Therefore, the paper explores the effect of EEXI policy on a fleet of 153 bulk carriers built between 2000 and 2020 in order to address their near future and prompt design changes, specifically considering the power reduction. For that purpose, an attained and a required EEXI are calculated for each ship. The results showed that only 15% of the ships built in 2000-2012 satisfied 2013-2014 IMO criterion. This impacted the design of ships built in 2013-2022, as they complied the same criterion by 88% of share. However, no ship from the whole database satisfied the present day EEDI requirement and only one ship fulfilled the contemporary EEXI requirement meaning that the current designs are not able to match the emerging criteria to a large extent. In order to meet an energy efficiency criterion, a main engine power reduction and speed are predicted assuming that the engine power and shaft limiter are installed. The investigation showed that MCR reduction of the total fleet taken into account had to be reduced by 50% and speed by 15% on average in order for ships to meet current requirements. Moreover, a graphic method is developed for the estimation of EEXI by using only deadweight (DWT) and could be used on existing bulk carriers with an aim to satisfy novel regulation with reliab

Although the International Maritime Organization (IMO) introduced the energy efficiency requirements for ships more than a decade ago, to date, inland navigation has not been affected by corresponding regulations at all. Therefore, inland waterway vessels are left with no mandatory requirements that could push their technology into more energy efficient design. Fortunately, there are certain pioneering attempts to define energy efficiency criteria for inland vessels. This paper tries to gather and provide a review of such methods. Moreover, a typical Danube cargo inland vessel's data are used to evaluate their current energy efficiency levels with respect to provisional criteria. Consequently, two methods are found and used here. They are both based on IMO's energy efficiency concept but modified for the inland waterway vessels. The methods delivered a significant difference in applicability and were difficult to compare. Moreover, shallow and deep-water effects are explored in the same regard but provided unsound conclusions. The final results displayed discrepancies in energy efficiency levels for the same vessels and so the methodology should be improved and harmonised, if it is to be introduced as mandatory for inland waterway vessels. The analysis provided a glimpse into the current condition of the traditional design of the Danube inland fleet, with respect to the emerging energy efficiency policies.

Due to climate change, extreme navigation conditions are being increasingly encountered on inland waterways worldwide. In Europe, a sustained low-water periods have been recorded in recent years. As a consequence, the current European inland fleet is expected to experience extended periods of suspended navigation, which could disrupt the logistic chains and may result in decrease of GDP of countries relying on inland navigation, as reported. Even though it may be argued that inland vessel design is already optimized with respect to specific fairway constraints (bridge heights, lock dimensions, fairway depth, etc.), the recent low water level issues naturally govern the ship design toward the shallow-draught concepts. The paper mainly focuses on an innovative approach to design inland vessels, which implies considerable altering of main dimensions of standard vessels, i.e., a reduction of the design draught followed by an increase of ship beam. As a result of such modifications, the length-to-height ratios of the proposed novel designs exceed the applicability range of classification rules and the vessels are regarded as “unconventional” or “unusual”. Consequently, the structural design of novel vessels is to be verified by direct calculation procedures that include longitudinal strength and buckling calculations, as well as the use of finite element analysis. The paper discusses challenges in structural design of unconventional inland vessels and outlines potential benefits.

Energy efficiency policy has been evolving in the shipping industry over the past decade since the decarbonization has become the main goal. After the energy efficiency design index (EEDI) is introduced in 2011 by International Maritime Organization (IMO) to propel the emission reduction for new ships, the same has been pursued in case of existing ships by presenting the energy efficiency of existing ship index (EEXI), that will enter into force on 1st of January 2023. Thus, existing ships are already being adapted in that regard, through the speed and power reduction, finer design hull optimization and application of energy saving devices (ESD). Therefore, this paper presents the EEXI calculation for four specific ship types: general cargo ship, container ship, bulk carrier and oil tanker. EEXI calculation is performed in two ways here. In the first case, input parameters are obtained from available sea trials data and technical files already used for EEDI calculation; and in other case, all input parameters are acquired solely according to the latest IMO regulations and guidelines. The difference of using these two input approaches and their effect on EEXI are outlined. Further adaptation measures are described in case of these four ship representatives. Moreover, since some of the ships can be potentially classified for more than one purpose, also a short discussion is given considering such effect on EEXI performance.

This book addresses key aspects for the design of contemporary, shallow draught IW vessels for the transport of dry cargo (containers and bulk cargo). Most of the logic that is presented is applicable to the design of river vessels for any river, but the material that is presented is focused on vessels for the River Danube and its tributaries. The term ‘contemporary river vessel’ assumes that the present-day technology and current Danube river infrastructure are taken into consideration in its design. It is believed that the technologies and concepts that are proposed here are applicable for all new vessel designs for the next 10 to 15 years. Other innovative technologies should be considered for designs beyond that horizon. Moreover, nowadays contemporary IW vessel must be in harmony with the Environmentally Sustainable Transport (EST) policies and hence special attention is paid to both ecology and efficiency. Note however that shipowners and ship operators usually tend to choose the conventional cost-effective transport technologies. Given that potential divergence of interests, the concepts and technologies treated here may be regarded as innovative.

To ensure the better structural integrity and maximum safety of bulk carriers in the ship design phase, an appropriate corrosion margin is introduced by the classification societies, which should enable the exploitation of ships during the projected 25-year life cycle. The new Common Structural Rules introduce even higher corrosion margin value to ensure the structural integrity of the ship. This directly affects the increase in hull weight and thus the need for more total installed power and higher fuel consumption. Higher fuel consumption results in increased emissions which directly affects environmental pollution. For these reasons, efforts are being made to introduce alternative energy sources, cleaner fuel, ship weight reduction, and the overall economic efficiency of ships. Therefore, using experimental data collected on aging bulk carriers, the paper explores the corrosion margin reduction potential considering its impact on hull weight. Assuming that the corrosive processes occur after four years of operation, a linear model that describes the percentage of plate wear as a function of the as build-in the thickness of inner bottom plates (IBP) of fuel oil tanks (FOT) located on the double bottom of aging bulk carriers, is analyzed. Over the course of 25 years, the IBP segment was monitored on 36 different ships surveys. In this way, 520 input data describing the depth of corrosion were formed. At the same time, records were kept on the mean thickness of the original metal plate, which enabled systematization of the empirical database and grouping of measured values by intervals of original plate thicknesses, and simple conversion of corrosion depth into adequate percentage values. Depth corrosion percentages were represented by standard linear models known in the literature. Based on this analysis, representative numerical and graphical results were obtained. Conclusions from the paper can assist to optimize corrosion margin and the energy efficiency of futu

The possibilities of testing real constructions are often limited, especially in case of large constructions. The idea of model testing is to create a sub-scaled model in order to anticipate the behavior of the real construction, regarding the behavior of the model, with sufficient accuracy. The aim of this paper is to demonstrate that model testing of bucket wheel excavator structure, from the aspect of the strength of the constructions, is possible. In order to prove this assumption, firstly, numerical calculations of a real construction and its sub-scaled model were performed using the Finite Element Method. Sub-scaled structure is 10 times scaled real structure (in size and plates thickness). Within the static calculation, the analysis of the stress mapping from sub-scaled model to real structure was carried out, by partial groups of construction. The coefficients connecting stresses of sub-scaled model and stresses of real construction were formulated. Dynamic calculations of sub-scaled model and real structure were also performed. Then, a physical model was produced and subjected to experimental testing. Experimental testing was performed in order to verify the numerical models. A parallel testing of the model with strain gauges and a system for non-contact measurement of displacement and deformation was performed. High matching results were obtained of two experimental methods on one side, and numerical calculation on the other side. The physical model and the successful experiments carried out on it confirmed that these structures can be subjected to model testing, without important constraints and with sufficient accuracy.

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustainable production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco-friendliness, lowers manufacturing price and increases market competitiveness.

The preliminary design stage is a starting and vital step in the ship design process which generally involves the adaptation of a prototype selected from an available and trustworthy vessel database. This investigation was prompted by the noticeable lack of systematic literature data on multi-purpose cargo vessels (MPCV), especially in the range of medium size fleet, with respect to gross tonnage. A procedure is presented for optimum MPCV characteristics determination in the preliminary design stage. It is grounded on a statistical analysis of the database gathered upon reliable MPCV built over the past 30 years. Using the proposed set of diagrams and formulas, the designers could determine ship principal dimensions upon required deadweight as a main prerequisite, as well as optimum energy efficiency design index, tank capacities, lightweight, etc.