Hull Assembly Research Articles

Modular design of the barge platform

The paper presents the solution of the problem of creating the design of the barge-platform of the "M-SP 3.5" class of the Russian Classification Society (RCS), intended for manufacturing outside the shipbuilding and ship-repair enterprise on the prepared site near the water body. Hull assembly should be made of separate parts (modules), which are manufactured in the conditions of shipbuilding production and delivered to the place of assembly by automobile or railway transport. Welding should not be used in the assembly process. It is suggested to assemble the barge hull from flat sections of 12,00×2,40 m and fractional sizes; bolted joints should be used during assembly. An example of barge construction of op-determined dimensions is considered. Calculation of the overall strength of the hull assembled from individual sections by means of bolted joints is performed using the ANSYS program complex. It is shown that the strength of the hull and bolts is ensured for the load regulated by the Rules of RCO. The use of bolted joints in forming the hull makes it difficult to ensure its impermeability, in this connection the buoyancy and non-floodability of the barge is proposed to be ensured by means of flexible tanks filled with air. Design and production of such tanks is currently carried out by a number of companies in the Russian Federation.

Improving the Accuracy of Predicting the Shaft Part Thermal Deformation of an LNG Fuel Powered Container Ship Based on the Inherent Strain

A ship’s hull, made of steel, is welded together from individual plates. Welding can cause deformation, a common defect. Predicting this deformation is crucial for shipyard design and management. Numerical analysis using finite elements is widely used for this prediction, with extensive research on the inherent strain-based analysis method. However, determining inherent strain requires synchronizing all strain items over time and considering uncertainties like the welder’s posture and skill. This study derives an integrated inherent strain over the welding process, considering the welding position and cooling method. The derived strain has been implemented and reviewed through numerical analysis of the LNG-powered container ship’s hull assembly process. This integrated inherent strain can serve as a basis for further research on welded structures, materials, welding parameters, and inherent strain-based analysis methods.

Verification the Stressed State of the Ships’ Hull during Separate Water Descent

This study evaluates the stressed state of the ship's hull during its welding of separate water descent parts. Separate descent of ship hull is applicable for small and medium sized ship yards (SME), where shipbuilding facilities have restrictions on length and lifting capacity. In the paper different scenarios are developed for verification. It is assumed that separately launched sections of the ship's hull are free of heels and trim, i.e., pre-ballasted, and any initial deformation in connected structures has been eliminated during the stage of hull assembly. In different scenarios, there are varying factors directly related to the strength of the ship, its construction materials, as well as those that have an impact on the production processes. Two of most used welding methods in ship building are analyzed- submerged arc welding and gas metal arc welding. The analysis shows that the stressed state of the ship's hull closely depends on the initial tense state, thickness of plate elements and welding method.

Variation Propagation Analysis of Hull Flat Block Construction Process Based on State Space Model

_ Hull flat block (HFB) construction is a typical discrete manufacturing process, during which block deviation is accumulated. To satisfy the dimensional requirements of shipowners, the variation propagation during HFB construction must be modeled and analyzed. Based on the stream of variation theory, the construction process is analyzed to provide a reference for controlling the deviation. In the hull construction process, the deviation is categorized into part deviation, location deviation, and welding deviation. By analyzing the causes of the different deviations, the different deviations and their accumulations can be calculated. A HFB is used to verify the proposed model, and the results show that the method can be used to calculate the deviation to the HFB. Introduction As a typical large-scale complex equipment, the hull construction process is extremely time-consuming and laborious. The final hull is composed of intermediate products, such as subassemblies, unit assemblies, and grand-assemblies (Cho et al. 1999). Since the group technology was applied in hull construction, a series of production lines has been established based on the process similarity of parts, components, blocks, and grand blocks. The actual dimension of parts would inevitably deviate from the theoretical dimension (Mandal 2017), i.e., dimensional and shape deviations will occur owing to many factors (Okumoto 2002). In the hull construction process, the deviation from the previous process will be propagated to the current process and coupled with the deviation in the current process, thereby affecting the accuracy of the product. Hence, the product must be repaired to satisfy the design requirements (Takechi et al. 1998). This will prolong the production cycle and reduce the production efficiency (Heo et al. 2015). It was discovered that the man-hours of the main operations during hull assembly constituted only one-sixth of the total assembly manhours, whereas the man-hours used for adjustment constituted one-third (Chen et al. 2020). Currently, shipyards need to eliminate the adjustment operation to avoid unnecessary rework, as well as reduce human and material resources in subsequent processes. Tanigawa (2003) estimated that an ideal ship construction accuracy control plan can reduce the production cost by 5%. Therefore, the accuracy of the hull construction process must be controlled and improved in shipyards, and a reasonable accuracy control plan should be devised to improve the product quality.

Development of the ship hull assembly sub-process

Objective: The development of the ship hull assembly pro-cess is possible by changing the method of assembly of basic parts at the building site, which would shorten the duration of the process and lead to cost reduction. One of the pos-sibilities is to increase the dimensions and mass of basic building units, as well as the crane capacity at the building site.Methods: Ship hull assembly methods involving sections, blocks and modules are used in the hull assembly phase. In the world’s best shipyards, ships are built from blocks or modules, in which as much equipment as possible is in-stalled. This paper uses the finite element method (FEM) for structural analysis, and its results serve to define the opti-mal technological instructions for the vertical transport of ship hull structure blocks.Results: The development of the ship hull assembly sub-pro-cess can be achieved by using the hull block assembly meth-od instead of the hull section assembly method. For the ship presented in this paper, the mass of a block transported to the building site was increased 3 times, so the number of building units was reduced by 65%. This reduces trans-port activities on the building site and shortens the dura-tion of the assembly process by 20%. This paper shows that strengthening the block structure with temporary stiffen-ers is necessary for safe transport. It is possible to optimize their number and layout by using structural analysis.Conclusion: The development of numerical finite element methods, software packages, and computers allow wider use of structural analysis in solving engineering problems in shipbuilding technology. The simulation of realistic sit-uations, a wide range of analyses and a large number of results become possible, and they raise the level of knowledge and enable better decision-making in the pro-duction process.

The shipwreck of the Jeanne-Elisabeth, a Swedish merchant ship lost off the French Mediterranean coast in 1755. Hull assembly: three different architectural traditions

The excavation of the Jeanne-Elisabeth began in 2008 and was led by archaeologists from the French Ministry of Culture. This Swedish brig of 200 tons sunk in November 1755 while sailing from Cadiz to Marseilles. The starboard hull is preserved for a length of 23 m, from the stem to the stern timbers, from the keel to the second deck. The assembly of the hull is a synthesis of the three traditions of shipbuilding in use in Wolgast, Germany, during the mid-18th century: Dutch, English and French. The Jeanne-Elisabeth is a great laboratory to study merchant ship construction as designed by a private shipyard in the mid-18th century.

Shock transmission through universal joint of cutter suction dredger

The dredger operation extended from protected water to harsher environments in recent years. This resulted in a change in design strategy. Understanding these complex dynamic interaction during the dredging operation using a Cutter Suction Dredger (CSD) can improve the production by reducing the downtime. CSD consists of the dredge hull, spud and the cutter shaft. A hybrid scaled model of the CSD is developed using Froude and Cauchy scaling for the different section of the CSD. The assembly was modelled in two sections. The spud hull assembly dynamics was modelled using WAMIT and ANSYS. The system was identified and reduced to a SDOF in the surge direction. The surge dynamics was coupled to the cutter shaft assembly using a roller support. Wave excitation acting on the assembly was determined using statistically linearised Morison equation. The assembly was linearised in frequency domain and transformed to state space and the temporal response was determined. A parametric study was carried out to understand the influence of the relative shaft dimensions and the coupling strength on the vibration transmission when subjected to an impulsive load. The results from the study indicated that shaft dimension asymmetry and coupling strength influences the vibration transmission.

Boat hull assembly methods and provision manufacturability of their designs

The design and technological characteristics of modern boats are presented and the technology of block assembly of hulls of large boats, as well as of frame assembly of hulls of small boats, is described. The design and the principle of operation of the equipment used, such as slipway-conductors and readjust able beds, providing the possibility of assembling the hulls of small boats from pre-made modules of the outer skin, representing its development in the plane, are considered. Particular attention is paid to the structural and technological improvement of boat hulls, aimed at replacing welded stiffeners with stamped corrugations and assembly welded joints of the outer skin — mechanical joints on pressed elements made of aluminum alloys. In accordance with the requirements for ensuring quality and reliability of the assembly of boats hulls, as well as their structural and technological improvement, the methods of tightness control used in domestic and foreign shipbuilding are considered.

Determination of Critical Pattern of 60 Meter Ship Construction Project Using Precedence Diagram Method (PDM)

PT. XYZ in Surabaya is engaged in the production of commercial ships, providing ship repair and maintenance services as well as general engineering with specifications based on orders. Along with the development of the technology industry, ship production requires every shipyard to evaluate the system used. The time delay is the problem of building a 60 meter commercial ship. The Precedence Diagram Method (PDM) is a method for scheduling project time and showing critical trajectories of project activities. The results showed that in the project scheduling, there are 13 activities that have a zero value or critical activity which are activities Hull Fabrication, Hull Sub Assembly, Hull Assembly, Hull Erection, Blasting and Painting Raw Material, Finishing Hull, Anode, Machinery Outfitting, Cabling, Computing and Information, Machinery Commisioning, Equipment Commisioning, Harbour Acceptance Test, Yard Trial, Delivery to Customer So that it needs more strict control and supervision from the contractor in carrying out the activities of the 60 meter commercial ship building project activities for each activity/activity so that it does not experience delays and the project can be completed on time.

Assembly of metal-ceramic cases integrated circuit

Technological processes of assembly of the most mass metal-ceramic IC cases with planar and pin contact conclusions on the automatic modular line are considered. It is proposed for the automated shop of assembly of cases to combine the assembly line and a site of automatic cassetting it into a single transport-accumulative system. The introduction of the IC hull assembly line into production provides an increase in labor productivity by 3...5 times while reducing the number of service personnel by an average of 3 times.

Research on Hull Assembly Process Planning Based on Rule Reasoning

Currently, hull assembly process is mainly dependent on experience, and lack of normative standard. In this paper, hull structure for assembly features is systematically studied, and an assembly sequence planning method based on Rule Reasoning is proposed. Firstly, assembly feature and sequence expression of hull structure is analyzed and the constraint relation of connection information is described. Secondly, the relationship between established structures and the constraint function is designed. Setting the double bottom of the ship as an example, hull assembly sequence is obtained based on geometric constraints and optimized by the fuzzy evaluation method and finally realized the computer aided evaluation of the hull assembly sequence.

Review of Assembly Sequence Planning Methods in Terms of Their Applicability in Shipbuilding Processes

Abstract The article characterises the sea-going vessel hull assembly processes and then reviews the existing assembly methods of mechanisms and welded ship structures. Classification of these methods is done with respect to selected criteria of their applicability to hull assembly. Selected methods are used for calculations performed on a model structure and exemplary database. The analysed aspects include the performance of calculation algorithms and the quality of the obtained solutions. Particular attention is paid to the need for reduction of experts’ participation in the planning process due to strong search space explosion effect. The performed analyses have enabled the authors to formulate assumptions for models which would be applicable in real assembly planning in shipyards, as well as to indicate areas of further research which would make it possible to better consider the specificity of production of large-size welded structures.

Self-classification of assembly database using evolutionary method

PurposeThe purpose of the paper is to develop a method of automatic classification of the components of the assembly units. The method is crucial for developing an automatic ship assembly planning tools. The proposed method takes into account the assumptions specific for shipbuilding technology processes: high complexity of structures, difficult expert-based classification of components, fixed priority relations between connections resulting from geometrical constraints and demands of welding processes.Design/methodology/approachThe set of ex post determined liaisons and assembly sequences constitutes the database of structures which have been made-up earlier. The components classification problem is solved using matrix coding of graphs. Information in such form is stored in the database. The minimization of number of cycles in the graph of classes sequence and minimization of diversity of classes within all constructions has been proposed as criteria of optimization. The genetic algorithm has been proposed as a solution method.FindingsThe proposed method solves the problem of components’ classifications. It allows setting the pattern of priorities between classes of various connections. This gives a chance to determine the relationship constraints between the connections of new structures for which assembly sequences are not established.Research limitations/implicationsMathematical formulation of the database is quite laborious. The possibility of partial automation of this process should be considered. Owing to the complexity of the problem, a relatively simple objective function has been proposed. During a ship hull assembly, additional criteria should be taken into account, what will be the direction of further research.Practical implicationsAutomatic classification of components is dedicated for implementation in shipyards and similar assembly systems. Tests performed by the authors confirm efficiency of presented method in supporting management of the database and assembly of new structures planning. Suggested activity-oriented approach allows for easy conversion of any assembly unit structure to the form of a matrix.Originality/valueThe new approach for components classification according to its assembly features distinguishes the proposed method from others. The use of nilpotent matrix theory in an acyclicity of graphs analysis is also a unique achievement. Original crossover and mutation operators for assembly sequence were proposed in the article.

Automatic Design Method and Application in Complex Ship Block Lifting

The traditional block lifting schemes often give rise to a host of problems such as the complexity of the lifting process, low degree of automation, and lack of theoretical guidance. To overcome the deficiencies, the authors of this paper have developed an automatic design system for the complex block lifting. Tribon is adopted as the data extraction method to identify the feature area of a block so as to lay out the lifting lugs properly and efficiently. Besides, Matlab is employed to analyze the stress on lifting wires and 3ds Max to simulate the block lifting process. In this way, the potential problems about mechanics and interference between the block and wires can be forecasted so as to enable the designers to improve the lifting scheme and ensure a safer and more reliable design. 1. Introduction Block lifting operation is a crucial process in shipbuilding since it determines the efficiency of the hull construction as well as the quality of the ship. The traditional artificial block lifting schemes often entail a host of problems such as the complexity of the lifting process, low degree of automationand lack of theoretical guidance. in recent years, scholars have studied the block lifting technologies for several types of ships including Very Large crude carrier (VLcc) and the container vessel. After analyzing the features of block lifting operation and the lifting environment, Li et al. (2013) summarized the principles and requirements of block lifting design, built models for the object to be lifted for the lifting equipment as well, designed an automatic layout algorithm for block lifting scheme and developed a design system for ship block lifting. Li et al. (2014) rebuilt the finite element model under ANSYS environment based on the extracted data of blocks. The calculation results can serve as a guidance for the design of structural reinforcement, which can save materials and reduce workload. In terms of the block lifting technologies used in the building of a 3500 TEU container vessel, Zhang (2010) studied on the lifting technologies employed in lifting some typical blocks such as the stern, broadside, and engine room. Based on the analysis and study on hull assembly method, Yu (2014) took use of computer to successfully simulate the process of hull assembly and save the relevant process information about the hull before shipbuilding. Kim et al. (2005) developed the virtual assembly simulation system for shipbuilding, which can simulate the operation of cranes and the installation of blocks in a virtual shipyard and evaluate the operations. Miura (2011) adopted the three-dimensional computer Aided Design (cAD) to develop a simulation system for block lifting and then he illustrated the features and functions of the system and stressed the importance of threedimensional model used in the process. Takola et al. (2013) established a mathematical model to analyze the constraint conditions in the block lifting process so as to optimize the lifting scheme and improve the efficiency of lifting operations. By applying the theory of combined discrete event and discrete time, Cha J.H. developed an integrated simulation framework for block lifting and erection process (Cha et al. 2010; Cha & Roh 2010). KuN. developed a crane system consists of several crane types, a scenario manager capable of creating and editing lifting process for multibody dynamics-based simulation is proposed (Ku et al. 2014a, 2014b). This study focuses on the complex ship block lifting with an attempt to build a system integrating the design of the complex block lifting scheme, the analysis on the mechanical characteristics in the lifting process and the simulation design of the block lifting operation together (Fig. 1).

Hull mixed-model assembly line balancing using a multi-objective genetic algorithm simulated annealing optimization approach

Hull assembly line balancing has significant impact on performance of shipbuilding system and is usually a multi-objective optimization problem. In this article, the primary objectives of the hull assembly line balancing are to minimize the number of workstations, to minimize the static load balancing index, to minimize the dynamic load balancing index between workstations, and to minimize the multi-station-associated complexity. Because this problem comes under combinatorial optimization category and is non-deterministic polynomial-time hard, an improved genetic algorithm simulated annealing is presented. In genetic algorithm simulated annealing, the task sequence numbers are used as chromosomes, and selection, crossover, and mutation operators only deal with the elements of task set instead of the ones of the problem space. In order to prevent the algorithm appearing early convergence or getting local optimal result, the simulated annealing algorithm is used to deal with the individuals. Meanwhile, the algorithm is embedded with the hierarchical scheduling tactics in order to solve the selection problem on optimal solution in the Pareto-optimal set. A number of benchmark problems are solved to prove the superior efficiency of the proposed algorithm. Finally, a case study of the optimization of a hull assembly line was given to illustrate the feasibility and effectiveness of the method.

A PSO algorithm for multi-objective hull assembly line balancing using the stratified optimization strategy

Hull assembly line (HAL) is a mixed-model assembly line on which different hull blocks can be assembled at the same time. Aiming at the balance problem of HAL, minimizing the cycle time, minimizing the static load balancing between workstations, minimizing the dynamic load balancing in all workstations, and minimizing the multi-station associated complexity are considered as optimization objectives. An improved discrete particle swarm optimization (IDPSO) algorithm based on the stratified optimization idea is developed for scheduling of the multi-objective problem. In the proposed algorithm, particles were coded by a two-dimensional task-oriented representation method, and then collaboration and competition of particle individuals are simulated by crossover and mutation operators in the genetic algorithm (GA). The performance of the proposed hybrid algorithm is examined over several test problems in terms of solution quality and running time. Finally, a practical case is used to analyze the effectiveness and feasibility of the stratified scheduling strategy.

Sequencing problem for a hull mixed-model assembly line considering manufacturing complexity

To ensure effective hull assembly line production, it is vital to consider the problems on delivery date of order and sequencing complexity within mixed-model production environments. In this paper two criteria are considered for stratified optimization according to their importance: to minimize th e satisfaction ratio of delivery date, and to minimize the complexity degree of the system arising from its state frequent changes. Finding an optimal solution for this complicated problem in reasonable computational time is cumbersome. Therefore, this paper presents an improved particle swarm optimization (IPSO) algorithm to solve the multi-objective sequencing problems. Instead of modeling the positions of particles in a continuous value manner in traditional PSO, IPSO uses an encoding and decoding scheme of task-oriented assignment for representing the discrete input sequences of products. Furthermore, dynamic mutation operator and chaos strategy are introduced to help the particles escape from local optima and the strategy for population decomposition is proposed to further improve the efficiency of the optimization. Numerical simulation suggests that the proposed IPSO scheduler can provide obvious improvement on solution quality and running time. Finally, a case study of the optimization of a panel block assembly line was given to illustrate the effectiveness of the method.

Scheduling Ship Hull Assembly Using Lagrangian Relaxation Method

A new Lagrangian Relaxation approach is developed for the scheduling problem of ship hull assembly in a shipyard. It appears to be the first attempt to schedule parallel machines with arbitrary precedence constraints of tasks, capacity constraints of machines (defined in assembly fat-model) and the situation that some tasks must occupy multiple machines simultaneously. The objective is to minimize the weighted total completion time. A mathematical formulation of the problem is presented firstly. Then the task precedence constraints rather than crane machine capacity constraints are relaxed by Lagrangian relaxation method and the subgradient method is used to solve the Lagrangian dual problem. Finally the results are modified by some heuristic operation. This approach can get a lower bound and a feasible solution. A practical example of container vessel that includes 65 blocks is solved by the proposed approach, and the results show that the Lagrangian relaxation method is able to solve industrial-dimensioned problems within reasonable time and accuracy.

Development of Carriage-type Welding Robot for Double Hull Assembly Line in Shipbuilding

Abstract This paper introduces a carriage-type welding robot which is to implement into double hull assembly line in shipbuilding. The developed robot consists of 5-axis carriage-type body, a controller, and a welding power supply and is capable of welding fully automatically such as a commercial industrial robot system without any interruption by an operator in a cell which consists of vertical weld-line and horizontal one. This is also characterized by not only automatic seam tracking ability and automatic feature-point detection function, but also an automatic generation function of job program. This system was already tested in a field and their performance had been proven successfully.

Advanced Welding Robot System to Ship Hull Assembly

Robotics automation has increasingly been used in Japanese shipbuilding companies in accordance with the change of the circumstances i.e. a decreasing of labor force and wage hikes, especially for arc welding at hull block assembly stage. In order to get good cost performance for the investment, the hull production system should be reviewed as suitable to the robot system, and it is necessary to modify and add some functions to the standard model of welding robots. Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI) has developed a new production system "Unit panel and slit process", which is suitable for production automation, and has developed a fully automated robot welding system at the assembly stage. The system includes an automatic material transfer system, robot positioning system and NC (off-line) teaching system. The system has been successfully applied at IHI shipyard.