Yixi Zhao

With increasingly stringent global requirements on emission reduction and environmental protection in the maritime industry, lithium battery-powered ships have developed rapidly due to their near-zero emissions and low noise characteristics. However, the transition to power systems also introduces new safety challenges, particularly the risk of thermal runaway in lithium batteries under mechanical abuse conditions. To address the complex external loads encountered during actual ship operations, this study establishes a mechanical simulation model of a marine battery rack and battery modules based on Abaqus finite element software. By applying longitudinal, transverse, and vertical accelerations, the stress responses and failure characteristics of the battery rack under different operating conditions are systematically investigated.

With the rapid advancements in the aerospace field, the demand for lightweight carrier rockets is constantly increasing. Some scholars have proposed the design of thin-walled cylindrical rings with multi-level ribs (TCRMR). This structure not only minimizes the component’s weight but also maintains the bearing capacity. Currently, research on TCRMR primarily remains at the design and validation stages. This paper establishes an experimental platform for thermal spin extrusion forming (TSEF) processing. TCRMR with a diameter of 550mm, a high longitudinal rib (HLR) height of 7mm, and a low longitudinal rib (LLR) height of 4mm is manufactured by TSEF processing, demonstrating its feasibility. The experimental results indicate that when the height difference between high and low ribs is significant, there is a risk of breakage of the feeding roll during TSEF processing. Additionally, the finite element (FE) simulation model for TSEF processing is established, and the material flow pattern and the reason for the breakage of the roller are analyzed. Before LLR reaches the target height, the forming patterns of HLR and LLR are similar, and the material flows in the circumferential and positive radial directions. After LLR reaches the target height, the material flow situation of HLR remains the same, and LLR flows in the circumferential and negative radial directions. This is because LLR is directly squeezed by the feeding roll while generating shear stress on the feeding roll. When this stress is larger than the shear strength of the feeding roll’s material, the feeding roll will break at the keyway.

During the plastic forming process, the change of loading mode directly affects the deformation condition of the material. In this study, two forming methods are applied in the forming process of the thin-walled structure with external cross-ribs. The forming characteristics differences between the point loading mode and the line loading mode were investigated in terms of material flow behavior, stress-strain distribution, and forming uniformity. The results indicate that the non-essential axial deformation was reduced and the directional deformation was accomplished by the line loading mode. Compared to the point loading mode, the forming loading was reduced by approximately 30%. The material deformation mainly focused on the surface region of the workpiece since the loading deformation area was small under the point loading mode, and the part showed a significant delamination deformation and stress concentration. However, under the line loading mode, these phenomena can be improved. The radial equivalent strain gradient of the external cross-ribs formed by the line loading mode is about 1/3 of that by the point loading mode. Additionally, the height discrepancy of transverse ribs between the spin-in and spin-out sides was reduced under the fixed diversion surface, and the forming uniformity of the external cross-ribs was improved.

The utilization of PMCUs (Prefabricated Modular Cabin Units) is a key strategy for enhancing the efficiency and reducing the costs of large cruise ship construction. Effective transportation planning for multiple PMCU cabins, including the paths and sequence, is vital to ensure smooth and timely installation. However, traditional A-Star algorithms for path planning face limitations when it comes to accounting for boundary obstacles, and existing routine sequence planning methods can hardly tackle multi-cabin coupled blocking effects. To address these challenges, an enhanced A-Star algorithm is introduced and designed to handle both grid-based and boundary obstacles in the path planning process for cabin transportation onboard. Additionally, a novel reverse planning strategy is further proposed that addresses the coupling effects arising from inter-cabin mutual blocking by determining the optimal collision-free installation sequence. Integrated with the enhanced A-Star algorithm, this reverse planning strategy effectively eliminates interference between cabin transportation sequences and transportation paths, significantly improving operational efficiency. A comparative analysis across various scenarios further substantiates the practicality and effectiveness of the proposed method, highlighting its potential for real-world application in large-scale cruise ship construction.

In the construction process of large cruise ships, there are numerous cabin components, and the number of assembly sequences will experience a “combinatorial explosion”, which will become a complex NP hard problem. This article proposes an assembly sequence planning method based on practical engineering problems in the construction process of large cruise ships. The cabin components are modularized, and an optimization algorithm is designed for multi-objective problem solving to obtain the optimal assembly sequence of cabin components. This article analyzes the impact of six constraint conditions on the assembly plan, including geometric constraints, sequence constraints, number of assembly reversals, number of tool replacements, stable connection relationships, and selection of reference components. A fitness function is designed and a mathematical model is established. On this basis, a genetic greedy combination algorithm is proposed to solve the optimal assembly sequence. Compared with traditional genetic algorithms, this improves computational efficiency and solves complex problems in a better manner. Multiple unique optimal solutions can be obtained in one solution process. The feasibility and effectiveness of this method were verified through examples.

The diverse nature of hull components in shipbuilding has created a demand for intelligent robots capable of performing various tasks without pre-teaching or template-based programming. Visual perception of a target’s outline is crucial for path planning in robotic edge grinding and other processes. Providing the target’s outline from point cloud or image data is essential for autonomous programming, requiring a high-performance algorithm to handle large amounts of data in real-time construction while preserving geometric details. The high computational cost of triangulation has hindered real-time industrial applications, prompting efforts to improve efficiency. To address this, a new improvement called Directive Searching has been proposed to enhance search efficiency by directing the search towards the target triangle cell and avoiding redundant searches. Another improvement, Heritable Initial, reduces the search amount by inheriting the start position from the last search. Combining Directive Searching and Heritable Initial into a new method called DSHI has led to a significant efficiency advancement, with a calculation efficiency improvement of nearly 300–3000 times compared to the ordinary Bowyer–Watson method. In terms of outlines extraction, DSHI has improved the extraction efficiency by 4–16 times compared to the ordinary Bowyer–Watson methods, while ensuring stable outlines results, and has also increased the extraction efficiency by 2–4 times compared to PCL. The DSHI method is also applied to actual ship component edge-grinding equipment, and its effect meets the shipbuilding process requirements. It could be inferred that the new method has potential applications in shipbuilding and other industries, offering satisfying efficiency and robustness for tasks such as automatic edge grinding.