A segmented elastic model for wave load test of liquid cargo ship

Abstract

The application discloses a sectional elastic model for wave load test of liquid cargo ship, which comprises a hull module, a liquid tank module and a keel beam module; the hull module comprises sectional hulls; the geometric shape of the hulls combined is consistent with that of the actual ship; the liquid tank module comprises a liquid tank model arranged in the sectional hulls; the keel beam module is a planar frame structure located in the longitudinal section of the sectional hulls, which comprises upper longitudinal beams, lower longitudinal beams and vertical longitudinal beams; the upper longitudinal beams are arranged above the liquid tank model, the lower longitudinal beams are fixedly arranged at the center of the bottom surface of the sectional hulls; the vertical longitudinal beams are arranged at the two ends of the upper longitudinal beams and the lower longitudinal beams and used for connecting the upper longitudinal beams and the lower longitudinal beams. The combined frame type keel beam can ensure the rigidity distribution regularity of the hull structure and provide space positions for the installation of the liquid tank, thereby solving the problem that the conventional keel beam scheme cannot be applied to the wave load test of the liquid tank ship.

Description

Technical Field

[0001] This invention belongs to the field of ship wave load testing technology, specifically relating to a segmented elastic model for wave load testing of liquid cargo ships. Background Technology

[0002] The increasing size, speed, and lightweight of liquid-carrying vessels, along with the globalization of transportation and trade, has made the issues of hull motion, wave loads, and structural strength increasingly prominent when navigating in harsh ocean conditions. During the transport of liquid cargo, ships are subjected to external environmental loads such as wind, waves, and currents, causing hull rolling motion and wave loads on the hull structure. Furthermore, the liquid within the tanks also sloshes under the excitation of the hull rolling motion, generating enormous liquid impact forces on containment systems such as elastic bulkheads, potentially leading to catastrophic consequences such as hull structural damage, capsizing, and marine environmental pollution. Therefore, for the design analysis of liquid-carrying vessels such as LNG carriers, it is crucial to accurately predict ship motion, wave loads, tank sloshing loads, and structural strength. However, for a long time, tank sloshing tests and hull motion and load tests in waves for LNG carriers have mostly been conducted independently, failing to adequately simulate the complex fluid-structure interaction phenomena of real LNG carriers during maritime transport.

[0003] Tank model testing is one of the most widely used testing methods in shipbuilding. Tank model tests of ship wave loads and hydroelasticity generally use a segmented hull model. These segments are connected by longitudinally installed keel beams inside the hull. The segmented hull transfers the external hydrodynamic forces experienced by the hull to the continuous keel beams, which simulate the actual hull structure and measure the hull section loads. The overall longitudinal bending stiffness distribution of the keel beams along the ship's length is similar to that of a real ship, simulating the hull beam structure. Currently, the keel beams of existing segmented ship models are generally installed at the neutral axis height inside the hull. However, LNG carriers and other liquid cargo ships have internal liquid tanks, making it impossible to directly place keel beams at the neutral axis height inside the hull, thus hindering the conduct of related tests. Summary of the Invention

[0004] The main objective of this invention is to overcome the shortcomings and deficiencies of the prior art and to propose a segmented elastic model for wave load testing of liquid cargo ships.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A segmented elastic model for wave load testing of a liquid cargo ship includes a hull module, a liquid tank module, and a keel beam module;

[0007] The hull module consists of segmented hull sections; the geometric shape formed by the combination of these hull sections is consistent with that of the actual ship.

[0008] The liquid tank module includes a liquid tank model, which is set inside the segmented hull.

[0009] The keel beam module is a planar frame structure located in the longitudinal section of the segmented hull, including an upper longitudinal beam, a lower longitudinal beam, and a vertical longitudinal beam. The upper longitudinal beam is located above the liquid tank model, and the lower longitudinal beam is fixed at the center of the bottom surface of each segmented hull. The vertical longitudinal beam is located at both ends of the upper and lower longitudinal beams and is used to connect the upper and lower longitudinal beams.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0011] 1. The segmented model keel beam scheme with liquid tank proposed in this invention can be applied to conduct wave load and hydroelasticity tests on liquid cargo ships, thereby comprehensively considering the coupling effects of hull motion, wave load, and liquid tank sloshing load.

[0012] 2. The combined frame-type keel beam proposed in this invention can not only ensure the stiffness distribution characteristics of the hull structure, but also provide space for the installation of liquid tanks, thus solving the problem that conventional keel beam schemes cannot be applied to wave load tests of ships with liquid tanks.

[0013] 3. The combined frame-type keel beam used in this invention can be adjusted by changing the relative positions of the upper and lower parts, thus making it suitable for keel beam schemes of ship models with different vertical bending stiffness. Attached Figure Description

[0014] Figure 1 This is a segmented elastic model structural diagram of the wave load test of the box-shaped liquid cargo barge in the embodiment;

[0015] Figure 2 This is a segmented elastic model structural diagram of the wave load test of a box-shaped liquid cargo barge without liquid tanks in the embodiment.

[0016] Figure 3 This is a structural diagram of the keel beam module;

[0017] Figure 4 This is a structural diagram of the liquid tank module;

[0018] Figure 5 This is a structural diagram of the segmented elastic model of the wave load test of a real LNG ship in the embodiment;

[0019] Figure 6 This is a segmented elastic model structural diagram of a wave load test of a real LNG ship without liquid tanks in the embodiment;

[0020] Figure 7 This is a structural diagram of the liquid tank module and keel beam module of the segmented elastic model of the actual LNG ship wave load test in the embodiment.

[0021] Explanation of reference numerals: 1-Sectional hull; 2-Elastic sealing strip; 3-Base; 4-Clamp; 5-Liquid tank model; 6-Bulkhead fixing unit; 7-Upper longitudinal beam; 8-Lower longitudinal beam; 9-Vertical longitudinal beam; 91-Upper vertical section; 92-Lower vertical section; 93-Middle vertical section. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] Example

[0024] The example uses a segmented elastic model of a box-shaped liquid cargo barge and a real LNG ship for wave load testing as an example.

[0025] like Figure 1 , Figure 2 , Figure 5 , Figure 6 as well as Figure 7 As shown, a segmented elastic model for wave load testing of a liquid cargo ship includes a hull module, a liquid tank module, and a keel beam module.

[0026] The hull module specifically includes segmented hull sections 1, elastic sealing strips 2, a base 3, and clamps 4; the geometric shape of the assembled hull sections is consistent with that of the actual ship; the elastic sealing strips are placed in the gaps between adjacent hull sections to seal the cuts between them and prevent external water from entering the hull; the base is fixed to the bottom surface of each hull section and is fixedly connected to the lower longitudinal beams via clamps. Figure 1 and Figure 6 As shown, in this embodiment, the segmented elastic model of the box-shaped liquid cargo barge for wave load testing has 4 hull segments, while the actual LNG ship has 6 hull segments.

[0027] like Figure 4 As shown, the liquid tank module specifically includes a liquid tank model 5 and a bulkhead fixing unit 6. The liquid tank model is set inside the segmented hull, and its geometric shape is consistent with that of the actual ship's liquid tank. During implementation, each segmented hull can only accommodate one liquid tank model, and the number of segments in the hull is greater than the number of liquid tank models. The number of hull segments without liquid tank models can be determined according to specific experimental requirements. The bulkhead fixing unit is fixed on both sides of the liquid tank model and is used to fix and connect the liquid tank model to the inner wall of the segmented hull, such as... Figure 4 As shown, two bulkhead fixing units are set on each of the two sides of the liquid tank model; force sensors are also installed on the bulkhead fixing units to measure the overall external force of the liquid tank model's swaying.

[0028] like Figure 1 and Figure 5As shown, in this embodiment, the segmented elastic model for the wave load test of the box-shaped liquid cargo barge has two liquid tank models, respectively set within the second and third hull segments from the bow. In contrast, the actual LNG carrier has four liquid tank models, respectively set within the second, third, fourth, and fifth hull segments from the bow. The geometry and dimensions of both the hull segments and the liquid tank models are scaled down from the actual ship.

[0029] The keel beam module is a planar frame structure located within the longitudinal section of the segmented hull, comprising an upper longitudinal beam 7, a lower longitudinal beam 8, and a vertical longitudinal beam 9. The upper longitudinal beam is positioned above the liquid tank model, while the lower longitudinal beam is fixed at the center of the bottom surface of each segmented hull. The vertical longitudinal beam is located at both ends of the upper and lower longitudinal beams, connecting them. The upper longitudinal beam has a U-shaped cross-section, and the lower longitudinal beam has a rectangular cross-section. A gap exists between the keel beam module and the liquid tank model to ensure that their mutual stress distribution is not affected.

[0030] like Figure 3 As shown, the vertical longitudinal beam is specifically divided into three parts: the upper vertical part 91, the middle vertical part 93, and the lower vertical part 92. The upper vertical part is connected to the upper longitudinal beam as a whole, and the lower vertical part is connected to the lower longitudinal beam as a whole. The upper and lower vertical parts are connected through the middle vertical part, and the relative positions of the upper, middle, and lower vertical parts are adjustable, thereby adjusting the bending stiffness of the overall keel beam structure. Several circular holes are provided at different height positions of the upper, middle, and lower vertical parts. Fixing bolts (pins) are used to fix the middle vertical part to the upper and lower vertical parts. By inserting the fixing bolts (pins) into the circular holes at different heights, the relative positions of the three parts can be adjusted, thereby adjusting the vertical bending stiffness and neutral axis position of the keel beam module to achieve the effect consistent with the target values ​​of the actual ship.

[0031] It should also be noted that, in this specification, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A segmented elastic model for wave load testing of liquid cargo ships, characterized in that, This includes hull modules, liquid tank modules, and keel beam modules; The hull module consists of segmented hull sections; the geometric shape formed by the combination of these hull sections is consistent with that of the actual ship. The liquid tank module includes a liquid tank model, which is set inside the segmented hull. The keel beam module is a planar frame structure located within the longitudinal section of the segmented hull, including an upper longitudinal beam, a lower longitudinal beam, and a vertical longitudinal beam. The upper longitudinal beam is positioned above the liquid tank model, and the lower longitudinal beam is fixed at the center of the bottom surface of each segmented hull. The vertical longitudinal beam is located at both ends of the upper and lower longitudinal beams and is used to connect the upper and lower longitudinal beams. The vertical longitudinal beam is specifically divided into three parts: the upper vertical section, the middle vertical section, and the lower vertical section. The upper vertical section is connected to the upper longitudinal beam as a whole, and the lower vertical section is connected to the lower longitudinal beam as a whole. The upper and lower vertical sections are connected through the middle vertical section, and the relative positions of the upper, middle, and lower vertical sections are adjustable. By adjusting the relative positions of the upper, middle, and lower vertical sections, the vertical bending stiffness and neutral axis position of the keel beam module can be adjusted to achieve the same effect as the target value of the actual ship. Several round holes are provided at different height positions of the upper vertical section, the middle vertical section and the lower vertical section. The middle vertical section is fixed to the upper vertical section and the lower vertical section by fixing bolts or pins. The relative position of the three can be adjusted by inserting the fixing bolts or pins into the round holes at different heights.

2. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, The hull module also includes elastic sealing strips, a base, and clamps; Elastic sealing strips are installed in the gaps between adjacent hull sections to seal the cuts between them. The base is fixed to the bottom surface of each section of the hull and is fixedly connected to the lower longitudinal beam by clamps.

3. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, The liquid tank model is set up inside the segmented hull, specifically: Each hull section can only accommodate one liquid tank model. The number of hull sections is greater than the number of liquid tank models. The number of hull sections without liquid tank models is determined according to the test requirements.

4. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, The liquid tank module also includes bulkhead fixing units; the bulkhead fixing units are fixed on both sides of the liquid tank model and are used to fix and connect the liquid tank model to the inner wall of the segmented hull.

5. The segmented elastic model for wave load testing of a liquid cargo ship according to claim 4, characterized in that, The bulkhead fixing unit is also equipped with a force sensor to measure the overall external force on the liquid tank model as it sways.

6. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, The upper longitudinal beam has a U-shaped cross-section, while the lower longitudinal beam has a rectangular cross-section.

7. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, There is a gap between the keel beam module and the liquid tank model.

8. The segmented elastic model for wave load testing of liquid cargo ships according to claim 1, characterized in that, The liquid tank model has the same geometric shape and structure as the actual ship's liquid tank; The segmented hull and liquid tank models are obtained by scaling down the actual ship and the scale.

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