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Analysis of the influence of spherical bulkhead reinforcement ring structure type on the strength of the structure
Published in C. Guedes Soares, Y. Garbatov, Progress in the Analysis and Design of Marine Structures, 2017
The traditional way of reinforcing bulkheads is to weld flitch reinforcement ring on the inner surface of the pressure hull. The reinforcement ring is connected to the spherical bulkhead through welding, as shown in Figure 4(a). Geometric parameters of its section include the length and thickness of the flitch. The integrated reinforcement ring made of tapered thick plate is connected and integrated to the pressure hull through a tapered transitional ring structure. The spherical bulkhead is directly welded to the transitional ring to provide support, as shown in Figure 4(b). It consists of the rectangular part and the trapezoidal enveloped part, with the trapezoid slope angle of 45°. To facilitate the comparison of mechanical properties between the two, it is assumed that the length of the two types of reinforcement ring are equal, the thickness of the rectangular part of the tapered reinforcement ring equals that of the pressure hull, and that the sectional area of the trapezoidal enveloped part equals that of the flitch in the flitch reinforcement ring structure. For the convenience of description, the hull part with the length of 100 mm and embedded flitch reinforcement ring thickness of 24 mm is named as traditional; the corresponding integrated reinforcement ring made of tapered thick plate is named as new type. Other computation models are named with similar rules.
Allowable differential air pressure during offshore transportation of composite bucket foundation
Published in Ships and Offshore Structures, 2023
Xinyi Li, Jijian Lian, Zhaolin Jia, Han Wu, Shuaiqi He, Xiaoxu Zhang, Qixiang Zhao
Because the differential air pressure between compartments required for leveling the eccentric load during the floatation test is 1.48 kPa, the conditions of 1 and 2 kPa differential air pressure between compartments were selected for analysis. Figure 6 shows that the stress of the bulkhead structure is 78.59 MPa because of the differential air pressure of 1 kPa between compartments. The maximum stress occurred at the welds between the bulkhead and bucket skirt and the mid-compartment bulkhead; the maximum deformation of the bulkhead structure reached 11.99 cm at the middle and upper parts of the bulkhead structure. Figure 7 shows that the differential air pressure of 2 kPa between compartments causes the maximum stress of the bulkhead structure to reach 152 MPa, and the maximum displacement of the bulkhead reaches 23.85 cm. Although the stress of the bulkhead structure did not exceed its plastic damage value, the differential air pressure had an excessive effect on the deformation of the bulkhead structure, which in turn affected the penetration installation of the CBF. Hence, the influence of the differential air pressure on the bulkhead deformation is crucial for controlling the differential air pressure.
A new method of the top-down parametric design for quick subdivision based on constraints
Published in Journal of Marine Engineering & Technology, 2019
In the process of hull subdivision design, the designer must take different kinds of regulations and requirements into consideration. These requirements are constraints for subdivision design, which can also be used to guide subdivision design (Koningh et al. 2011). Among them, some requirements are clear before subdivision, such as the number and location of bulkheads, the layout of cabin and hold capacity. This kind of requirements is clearly expressed and can guide the design constraints in the initial design. The other part needs to be checked gradually after subdivision design, such as (damaged) stability, floating state, freeboard, longitudinal strength and ballast water exchange. This kind of requirements needs a large amount of calculation and generally used to check subdivision result and guide the modification after subdivision. The calculation theory of these requirements has been very mature, there is no problem. However, the calculation of the latter type of requirements needs a few hours to complete. Therefore, in order to add constraints to the preliminary design stage and realise the rapid design of subdivision with the real-time guidance of constraint knowledge, the latter kind of requirements is not considered in this stage. At present, consider only the number and location of the bulkhead, the area of the platform and the volume of the compartment. All of these constraints can be defined in preliminary subdivision stage, such as the classification standard provisions of the required number of watertight bulkheads and collision bulkhead positions and the platform area and the cabin volume general required in the design task of the ship owner.
The plastic dynamics and failure analysis of ship broadside protection structures subjected to contacted UNDEX: energy dissipation model and simulation
Published in Ships and Offshore Structures, 2022
Hao Wang, Da-ming Pei, Pan Zhang, Lin Gan
Compared with Figures 10 and 11, the damage crevasse is 98 mm in the diameter located in a frame (which is nearly rectangular 153 mm×127 mm). Besides, the larger crevasse, a smaller crevasse with a radius of 35 mm is also formed. The deformation nephogram is obtained as plotted in Figure 10. The maximum plastic residual deformation of the energy absorption compartment internal bulkhead is 28.0 mm. The residual deformation of the watertight compartment internal bulkhead is about 4.2 mm. It means that the most of kinetic energy of fragments and shock wave energy is dissipated by the absorption compartment internal bulkhead (Figure 11a).