_ Anisotropy is one of the common problems in additive manufacturing. The texture within the layer and the longitudinal partitioning are closely related to the remelting and solidification temperature field and are the main reasons for the anisotropy of 316L stainless steel in arc additive manufacturing. When depositing the top layer, the maximum height of the remelted metal in the subtop layer in the longitudinal direction is 2.28 mm, whereas the maximum longitudinal height of the zone with no obvious grain directionality at the top of the layer is .988 mm. Therefore, there is a texture throughout the entire layer after remelting. During the solidification process, the temperature gradient and cooling rate vary greatly in different zones within the layer, resulting in a partitioned structure in the longitudinal direction. The average cooling rates of typical nodes in the top, central, and remelting zones of the top layer from 1450 to 800°C are 782.3, 842.5, and 1865.8°C/s, respectively, and the temperature gradients are 1.41 x 104, 5.45 x 104, and 4.55 x 105°C/m, respectively. Keywords remelting; temperature field; anisotropy; 316L stainless steel; wire arc additive manufacturing
_ European shipbuilding’s multiparty strategies create complex data integration challenges that are often not experienced by more centralized industries. This study evaluates digital tool requirements through case studies with two European shipbuilding companies. We set the context for the case studies by reviewing the current digital landscape in terms of tools and an example of information architecture used in the industry. Then, we decompose and specify the concept of “data integration” based on related functionalities found in the literature. The data handling processes in both companies are mapped and used as a basis to identify and rank each company’s needs concerning their digital process. Finally, the needs are mapped back to the integration functionalities identified in the literature using Systems Engineering House of Quality method. We find that as process and design ownership become more distributed, the effectiveness of conventional centralized approaches diminishes, highlighting the importance of information architecture aligning with organizational and shipbuilding strategies and with their level of design ownership. As an alternative, we suggest investigation of federation-based information architectures enabling autonomous systems to cooperate while maintaining data sovereignty. Keywords shipbuilding; systems engineering; computers in design; computers in construction; modernization; design (vessels)
_ In this study, we present a sophisticated nonlinear finite element approach for forecasting the remainder compressive strength of reinforced corroded plates. On a macroscale, the nonuniformity explains the decrease of plate thickness. On the other hand, the constitutive model is used to modify mechanical characteristics in order to account for the microscale influence of corrosion deterioration. The study examines three distinct thicknesses of stiffened plates and analyzes their final compressive capacity for varying levels of corrosion degrading severity. The deterministic analysis is carried out first, and the experiment is used to validate the numerical results. It was discovered that, even at 50%, significant corrosion deterioration may result in an unsustainable decrease of structural capability. Finally, a comparison between the current study’s findings and previously researched corrosion models reveals a very nonconservative solution for the latter, in which the corrosion degradation process alone causes the plate thickness to decrease. Keywords Al8011; corrosion; FEA; mechanical properties; stiffened plates
_ To address the challenges of experience-dependent lifting point layout and the insufficient consideration of interference between the ship block and lifting slings in block lifting process design, this study proposes a block lifting process automated selection (LPAS) algorithm. The proposed LPAS consists of two core components: the block lifting process automated (LPA) algorithm and the block lifting process selection (LPS) algorithm. The LPA handles automatic identification of lifting point, lifting point number estimation, block coordinate transformation, regional partitioning, and preliminary design plan generation. The LPS focuses on interference detection between the block and the lifting slings, solving key issues such as the calculation of the lug-hole center, lifting lug installation interference, and the hook point transformation. By integrating LPAS with a block lifting simulation module, automatic meshing module, and a finite element solver, an independent system for block lifting process design is established. Case analysis on a wind turbine installation vessel block (MD03P) shows that proposed system achieves stress and displacement results closely aligned with MSC.NASTRAN, with a maximum stress deviation of 7.04% and an average deviation of 1.44%, demonstrating both accuracy and engineering applicability of the method. Keywords block lifting process; automated selection algorithm; lifting point layout; AVEVA Marine; Möller-Trumbore
_ International research and development work have begun to focus on a trimaran ship design; however, very little systematic experimental data are available to aid the designer. The study presents a systematic calm water resistance experimental study on a practical trimaran hull form. The objectives of the study are to better understand the trimaran resistance characteristics and to create a dataset convenient for designers to optimize the side-hull location for minimum resistance of similar trimaran designs. Keywords trimaran design; model test; optimization; resistance; side-hull
_ In the manufacturing industry, the problem of circle plate packing processing is common and important. In this study, an innovative algorithm is proposed to transform the packing of a circle in a rectangular container into the motion of a disturbed object group. First, the discrete element method (DEM) is used to construct the mathematical model of equal circle motion. By establishing the time domain and complex frequency domain models, the internal stability of the motion system and the feasibility of the algorithm implementation are confirmed. Second, the sweep and prune method and the quadtree method are introduced for collision detection, and the continuous collision detection is used to deal with the tunneling phenomenon caused by high-speed motion. Then, based on the impulse method, the collision circle is processed, and the impulse size is accurately calculated from the two aspects of velocity change and position constraint. The error compensation is introduced to reduce the calculation error, and the calculated impulse updates the circular velocity and position in real time. Finally, the feasibility of the algorithm is verified by an example test, which provides a new direction for solving the circle packing problem. Keywords two-dimensional packing; equal circle packing; stability analysis; collision detection; collision response
This study aims to analyze the cost and duration optimization in ship maintenance and repair processes and analyze costs according to different ship types and maintenance items. It seeks to analyze the maintenance costs incurred, especially in cargo, container, and tanker ships, to provide strategic suggestions for more efficient use of resources and cost optimization. The analyses revealed that costs differ significantly according to ship types and maintenance items. Although steel and pipe works create high costs, especially in cargo and tanker ships, lower daily ton costs were observed in container ships. It was determined that there is a strong correlation between the maintenance period and cost. Although the age and construction years of ships have a great effect on maintenance costs, the maintenance costs of older ships are generally higher. Therefore, it is of great importance to develop different strategies according to the ship type and to ensure cost efficiency and optimize maintenance processes. It has been observed that the maintenance costs of electrical and electronic systems are generally lower than other items. Effective management of ship maintenance and repair processes is important in terms of optimizing costs and shortening durations. Unique strategies should be developed for each ship type, and cost efficiency should be achieved, especially in steel and pipe works in tankers and cargo ships. These results can help ship owners improve their cost management strategies and increase operational efficiency.
The reliable operation of gas turbine engines in combat vehicles is largely dependent on the cleanliness of the air entering the engine. For naval vehicles, this means removing seawater salts, while for ground vehicles like tanks, it involves filtering out sand and dirt. Air cleaning is performed by separators installed in the engine's air intake system, whose efficiency depends on the velocity of the air passing through them. This velocity is determined by the engine's power mode at a given speed. Deviations from the optimal air flow velocity, whether higher or lower, result in decreased separator efficiency. As a result, when engine power fluctuates over a wide range during vehicle operation, the separators often operate at reduced efficiency, allowing contaminants to enter the engine and increasing the need for maintenance. A new method and system for air cleaning is proposed, radically improving the initial design. It allows for maintaining consistent efficiency across the entire power range-from idle to maximum power.
Aiming at the problem of online and real-time measurement of sheet metal bending angle, a monocular vision measurement method is proposed in this paper. The principle of this method is that a light beam is projected onto a plane to form a light stripe. When the relative angle between the reflecting plane and the light beam changes, the inclination angle u of the light stripe changes synchronously. According to this characteristic, this paper proposes to monitor the change of the light stripe through a camera, reverse study the change of the inclination angle h of the reflecting plane, and achieve online measurement of the bending angle /. In this paper, the geometric relationship between the inclination angle u of the light stripe and the bending angle / is derived, and a bending angle measurement model based on two-dimensional light stripe information is established. An optimized gray centroid algorithm is used to identify the light stripe centerline, and a subpixel-level light stripe center extraction algorithm is established. Intelligent algorithms are used for parameter correction to reduce the impact of calibration errors. The bending angle measurement model test was completed. The analysis results show that the method proposed in this paper is correct and feasible, and can achieve high-precision, low-cost, and rapid bending angle measurement. After further improvement, the method proposed in this paper is suitable for online measurement of bending angle and can provide a methodological basis and reference for the development of bending CNC systems.
To enhance the digitalization level of shipbuilding, this study focuses on the construction methods and applications of digital shipyards. The design of different quantities and layouts of reference points is based on the dock's spatial dimensions, the principles of reference point arrangement, and the required measurement accuracy. An assembly coordinate system is established using the horizontal reference plane determined by the electronic level and the longitudinal movement direction of the assembly system equipment. A digital measurement process specification is developed based on the constructed spatial measurement field. Finally, using a specific ship structure model as an example, three typical application scenarios are introduced: segment assembly positioning measurement, total segment alignment positioning measurement, and structural internal equipment base positioning measurement. The construction of the spatial measurement field in the shipyard lays an important foundation for the subsequent creation of a digital shipyard.
_ Based on the practical problem of cumbersome traditional ship lifting scheme design, an automated ship lifting lug arrangement system has been developed with the algorithm design of the lifting lug arrangement scheme as the core. Taking the bottom block of an LNG ship as an example, SPD software is used for secondary development and data extraction to identify key areas of the ship structure. By summarizing the characteristics of the actual bottom block lifting lug layout, an algorithm for the lifting lug layout of the bottom block is designed following the design and statics principles of the lifting lug scheme. The lifting lugs were efficiently arranged and optimized through the PSO algorithm, and a ship lifting lug automation layout system was applied. Therefore, an automated lifting lug layout algorithm system for the bottom block of LNG ships has been established. Compared with manual design, it not only ensures the safety of the lifting lug layout scheme design but also saves a lot of design time, providing a reference for designing other types of blocks in the future. Keywords LNG ship; algorithm design; SPD; lifting lug; arrangement system; lifting scheme design; PSO algorithm
_ In the design stage of marine structures, the calculations of drift force due to drag considering the viscous effect have not been well performed recently. It is very important to consider the drift force acting on vertical cylindrical marine structures such as offshore wind substructure, semisubmergible by considering both waves and currents. In this paper, we obtained an analytical solution for the drift force acting on a cylindrical structure considering waves and currents. The part of the cylinder that is above the free surface is called the splash zone, and the part that is submerged under the free surface is called the submerged zone. When waves are only present, they are considered only in the splash zone, and when waves and currents are included, equations were derived for both the splash zone and the submerged zone, and the drift forces acting on fixed and floating types of marine structures were compared. Except for the case where only waves are considered in the splash zone, the magnitude of the drift force acting on the floating cylinder is found to be larger than that acting on the relatively fixed cylinder in most frequency ranges, and it can be seen that the increase is greater especially when the current is considered to be relatively more important. Therefore, it is possible to calculate the drift force by given design variables using the formulas derived in this study so far, and determine whether the magnitude of the drift force corresponding to each case has a quantitative effect within a specific physical range. Keywords Marine structure; Drift force; Waves; Currents; Splash zone; Submerged zone
As a key to assessing productivity and cost control, man-hour is an important basis for scheduling planning in shipyards. Aiming at the lack of underlying data on ship production design man-hour, which makes it difficult to predict, resulting in delivery delays, cost overruns, and management confusion. This paper proposes a data expansion and prediction model with an improved generative adversarial network (WGAN-GP) and a human evolutionary optimization algorithm optimized BP neural network (HEOABP). First, under the premise of full attendance, the production design process is divided into two parts: drawing and nondrawing, and the man-hour model is constructed. Second, WGAN-GP is used to learn the nonlinear relationships in the original data and generate high-quality samples, which are predicted by the HEOABP neural network. The results show that the prediction accuracy of the HEOA-BP neural network is high, and the relative error of the prediction value is only 1.605%, and a 300% expansion of the training set by WGAN-GP reduces the relative error to .14%. The combined model has good performance in generating high-quality samples and prediction accuracy, and provides a new method for predicting man-hour in the production phase with fewer samples.
In this paper, vessels from the offshore oil and gas industry are explored in the conceptual design of value-robust deep-sea mining vessel solutions. The responsive systems comparison method is applied in a case addressing two hypothetical stakeholders: a mining company and a vessel operator. Their value propositions are outlined and pave the ground for important attributes that consolidate into conceptual vessel design solutions. The cost-benefit trade-offs for various design solutions and technology choices are discussed for different future scenarios. The results indicate that complexity drives high CAPEX generation, yielding so-called gold-plated designs. Lower cost mitigation measures should be taken to ensure future missions of a deep-sea mining vessel. The consequences of design choices on commercial considerations are discussed, such as the vessels' second-hand value in the market and alternative uses.
_ Despite the limited use of artificial intelligence/knowledge-based engineering (AI/KBE) in industries with small series or one-off designs, our study demonstrates the technical feasibility and potential benefits of implementing AI/KBE in ship design processes. This research presents the development of “ACQUAINT,” uniquely designed to address the complexities inherent in bespoke shipbuilding. Central to this module is a robust AI-driven inference engine, integrated seamlessly with AutoCAD through a Python-based interface, facilitating a novel approach in shipbuilding’s detail and production design phases. The module’s capability to generate optimal designs autonomously—grounded in a deep understanding of design rules, constraints, and requirements—substantially reduces the reliance on human interaction. Our initial proof of concept with “ACQUAINT” showcases measurable advancements in ship design accuracy and efficiency, highlighting AI KBE’s transformative impact in shipbuilding and setting a foundation for future research and practical applications. Keywords ship design; artificial intelligence; knowledge-based engineering; self-learning system; software development; ACQUAINT; CAD/CAM software; computers in construction; computers in design; modernization; ship structure
_ The decarbonization of the maritime industry is a problem where a clear and wide-sweeping solution has not yet been found. Suggested methods for immediate action have included route optimization and speed reduction. Although these proposals have the potential to reduce overall emissions, they will not lead to net zero emissions. Proposed solutions that require a greater investment but have the potential for net zero emissions are alternative fuels to diesel. Research into diesel alternatives, which has focused on ships making transoceanic voyages, has uncovered problems that make these alternatives an unsuitable replacement for diesel as of this writing. However, ships on the Great Lakes have a greater potential to successfully implement diesel alternatives based on the length of typical shipping routes and the size of the operational profile of the ship. This paper seeks to frame the problem of implementing diesel alternatives for Great Lakes bulk carriers from a supply chain and port perspective and provide suggestions on possible solutions to be further developed. Liquified natural gas, hydrogen, and biodiesel were considered. The results of this investigation show that these three alternatives are viable options for Great Lakes bulk carriers; however, each comes with a unique set of challenges. These challenges cannot be solved by one institution alone and only through extensive cooperation between all relevant stakeholders can the Great Lakes achieve decarbonization. Keywords Great Lakes; LNG; hydrogen; biodiesel; bulk carrier; decarbonization
The ship construction process is characterized by a sequential workflow, with pivotal workstations double dagger playing a crucial role. Initially, steel plates are introduced to these stations in sheet form, undergoing a transformation process that culminates in the creation of segments known as blocks double dagger. These blocks are individually constructed and subsequently assembled at the final workstation, denoted as the block joining station. Upon completing block fabrication, a deliberate tolerance allowance is retained on the plates to accommodate deformations induced by heat treatment during the transformation from plates to blocks. The alignment process involves aligning the reference points (master reference line) of the blocks on a common axis, facilitating the identification of excess material and deformations. This alignment process encompasses aligning the blocks with each other, employing either a three-dimensional measurement device or manual methods to obtain necessary measurements for determining excess material. In an effort to optimize time spent on block alignment and machine usage, a comprehensive methodology has been developed. This methodology involves determining excess material cuts on the blocks, performing virtual alignment operations using laser scanning techniques in a virtual environment, and conducting the cutting process on the slipway prior to placing the block excesses on it.
_ The paper proposes an innovative methodology of Human Cognitive Reliability- Cognitive Reliability and Error Analysis Method (HCR-CREAM) coupled with A* search and genetic algorithm (GA) to tackle ship cabin equipment layout considering human factor reliability optimization with the goal of minimizing human error probability (HEP) subjected to practical requirements. After establishing the mathematical model of cabin equipment inspection tasks in ship cabin equipment layout problem through HCR-CREAM and equipment geometric simplification, a method of the horizontal movement based on minimum distance is presented to avoid the equipment overlapping, then A* search is used for planning inspection paths and GA with selection, crossover, and mutation operators is applied to solve equipment layout results. A case of equipment layout in a certain ship engine room has been taken to carry out parameter sampling experiments by Latin Hypercube for GA. The results show the solution effect of GA is less affected by its parameter variation. And through the comparison with the initial equipment layout, the indicators influencing the HEP of the optimized result have been improved, thus significantly reducing HEP. Keywords ship cabin equipment layout; human factor reliability optimization; HCRCREAM; A* search; genetic algorithm
Domestic U.S. flagged liftboats have relatively low length-to-beam ratios (L/B), compared with typical vessels, and operate with minimal freeboard and high vertical centers of gravity. As such, domestic liftboats can have poor righting arm characteristics that may not be revealed by conventional regulatory stability analyses that evaluate in the pure heel direction. This study adapts a novel energy-to-incline method and varying axis stability analysis developed by Andrew Breuer for Mobile Offshore Drilling Units to low L/B liftboats. This method of generating energy-to-incline surfaces was applied to the limiting case of a low L/B 1/4 1 liftboat and to the liftboat SEACOR POWER (L/B 1/4 2.02) to produce energy contour plots for a range of heel and trim values and to identify capsize points. Righting arm curves were mathematically computed from these surfaces by extracting incremental energy along pathways to capsize. For the low L/B ratio vessels, this resulted in truncated righting arm curves for inclinations in many directions, associated with the computational approach and the physics of orthogonal tipping. Analysis of the results revealed that low L/B liftboats have their lowest-energy pathways to capsize in inclination directions different from the traditionally assumed heel direction. As such, it is proposed that much of the U.S. domestic liftboat fleet may also exhibit such "off axis" weakest capsize directions. Finally, standard hydrostatic stability software was used to compute righting arms for the L/B 1/4 1 liftboat when inclined directly from the point of static equilibrium to a known capsize point, while fixing the angle of rotation in the direction orthogonal to the straight-line path. The resulting righting arm approximated well the lowest-energy righting arms from the more computationally intensive energy-to-incline method. Future research would be to assess whether such straight-line, fixed-rotation paths provide a good approximation for the minimum energy righting arms for liftboats over a range of L/B. If so, this method would provide an efficient means to produce liftboat righting arms with two zero-crossing points necessary for comparison with stability regulations.
_ Traditional accuracy check methods for cargo hold in container ships rely solely on manual and visual operations, which are time-consuming and resource-intensive. Addressing the challenge of extracting and analyzing key data, such as cell guides and container pedestals, from large-scale point clouds obtained through three-dimensional (3D) laser scanning in container ship trial runs, this paper proposes an algorithmic framework based on 3D laser scanning. Building upon this framework, an improved coordinate-axis filtering RANSAC algorithm is employed to optimize the extraction of cell guide planes. Additionally, an algorithmic process based on Bhattacharyya distance is utilized to automatically extract container pedestal point clouds. Furthermore, a combination of the genetic algorithm and the ICP algorithm is proposed to achieve the fitting of the container pedestal edge contour through point cloud registration. Experimental results demonstrate the consistency between the extracted cell guide and container pedestal data and the actual results, indicating the high practical value of the proposed methodology. Keywords container ship loading test; cargo hold accuracy check; 3D point cloud processing
