A device and design method for simulating the quality of water attached to a cabin structure

Abstract

The present invention proposes a device and a design method for simulating the mass of water attached to a cabin structure, which belongs to the technical field of ship model testing. The device solves the problem of equivalent simulation of the mass of water attached to a cabin model in tests such as vibration and explosion. The device includes a tire frame, a horizontal spring vibrator and a vertical spring vibrator. The cabin model to be tested is arranged on the tire frame. The horizontal spring vibrators and the vertical spring vibrators are both multiple in number. The multiple horizontal spring vibrators are symmetrically connected on both sides of the cabin model to be tested, and the multiple vertical spring vibrators are symmetrically connected at the bottom of the cabin model to be tested. Each horizontal spring vibrator and vertical spring vibrator includes a spring and an equivalent additional mass block. One end of the spring is connected to the equivalent additional mass block, and the other end is connected to the cabin model to be tested. It is mainly used to simulate the mass of water attached to a cabin structure.

Description

Technical Field

[0001] The invention belongs to the technical field of ship model testing, and in particular relates to a device and a design method for simulating the quality of water attached to a cabin structure. Background Art

[0002] When a ship sails in water, water has a significant effect on its vibration, which can be described by the attached water mass. Due to factors such as gravity, damping and inertia, the surrounding water area causes the cabin structure to interact with the fluid. The dynamic effect of this fluid on the cabin structure can be attributed to the mass attached to the structure, which is called the attached water mass.

[0003] The influence of attached water mass must be considered in ship model tests, including ship vibration tests, explosion tests, etc. However, many of these tests are conducted on land, but the effect of attached water mass is completely ignored. Some other tests are conducted in water tanks, but the water tanks are generally shallow and the attached water mass is completely different from that of the actual ship. Therefore, there is no effective method to simulate the attached water mass at this stage. Summary of the invention

[0004] In view of this, the present invention aims to propose a device and a design method for simulating the mass of water attached to a cabin structure, so as to solve the problem of equivalent simulation of the mass of water attached to a cabin model in tests such as vibration and explosion.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a device for simulating the mass of water attached to a cabin structure, comprising a tire frame, a horizontal spring vibrator and a vertical spring vibrator, the cabin model to be measured is arranged on the tire frame, the horizontal spring vibrators and the vertical spring vibrators are both multiple in number, the multiple horizontal spring vibrators are symmetrically connected on both sides of the cabin model to be measured, and the multiple vertical spring vibrators are symmetrically connected at the bottom of the cabin model to be measured, each of the horizontal spring vibrator and the vertical spring vibrator comprises a spring and an equivalent additional mass block, one end of the spring is connected to the equivalent additional mass block, and the other end is connected to the cabin model to be measured.

[0006] Furthermore, the horizontal spring vibrator and the vertical spring vibrator are respectively arranged in the sleeve, and the horizontal spring vibrator and the vertical spring vibrator are connected to the sleeve through a slideway.

[0007] Furthermore, the sleeve is a split structure, the split structural parts are connected by bolts, and the slideway is an aluminum alloy double slideway.

[0008] Furthermore, the horizontal spring vibrator is arranged on a spring vibrator bracket, and the tire frame and the horizontal spring vibrator are both arranged on a cement foundation.

[0009] Furthermore, the spring vibrator support is a frame structure, the cement foundation is a reinforced concrete structure with embedded metal inside, and the tire frame and the horizontal spring vibrator are both connected to the embedded metal.

[0010] Furthermore, the tire frame is a truss type tire frame.

[0011] Furthermore, the horizontal spring oscillator is arranged on each plate frame structure on the side of the measured cabin model, the plate frame structure is a plate frame structure interval surrounded by two decks and a main transverse bulkhead on the side, and the horizontal spring oscillator is connected to the center position of the strong member of the plate frame structure.

[0012] Furthermore, the vertical spring oscillator is arranged on each plate frame structure of the bottom of the measured cabin model, and the plate frame structure is a plate frame structure interval of the bottom of the ship surrounded by two longitudinal girders and the main transverse bulkhead.

[0013] Furthermore, the spring is a 55Si2Mn alloy spring, and the equivalent additional mass block is a regular rectangular steel block.

[0014] The present invention also provides a design method for a device for simulating the mass of water attached to a cabin structure, wherein the stiffness of the horizontal spring oscillator is K i , mass is M i , i=1,…,N, where N is the number of side plate frame structures, K i With M i The selection of is in accordance with formula (1):

[0015]

[0016] Where: a is the mass ratio of the mass block to the plate frame structure a = M i / M ei , M ei is the equivalent mass of the i-th plate-frame structure, K ei is the equivalent stiffness of the i-th plate frame structure, b is the plate frame width, h is the average plate frame thickness, γ0 is the liquid specific gravity, γ is the structural specific gravity, and ν is the attached water mass coefficient;

[0017] The stiffness of the vertical spring oscillator is k i , mass is m i , i = 1, ..., n, where n is the number of bottom plate frame structures, k i With m i The selection of is the same as that of formula (1).

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a device and a design method for simulating the attached water mass of a cabin structure, which solves the equivalent simulation problem of the attached water mass of a cabin model in vibration and explosion tests. Springs with a certain stiffness and equivalent additional mass steel blocks are added to the side and bottom of the cabin, and the influence of the attached water mass on the dynamic characteristics of the hull structure is simulated by a spring oscillator, which can ensure that the horizontal vibration of the cabin structure is similar to that of a real ship, and does not affect the overall strength of the cabin. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the structure of a device for simulating the quality of water attached to a cabin structure according to the present invention;

[0021] Figure 2 It is a schematic diagram of the connection structure between the horizontal spring vibrator and the sleeve according to the present invention;

[0022] Figure 3 This is a schematic diagram of the connection structure between the vertical spring vibrator and the sleeve according to the present invention;

[0023] Figure 4 This is a schematic diagram of the cement foundation structure of the present invention;

[0024] Figure 5 This is a schematic diagram of the cabin section A model below the water level of the present invention;

[0025] Figure 6 It is a schematic diagram of the division of the side plate frame below the water level of the present invention;

[0026] Figure 7 It is a schematic diagram of the division of the bottom plate frame below the water level of the present invention;

[0027] Figure 8 It is a schematic diagram of the plate frame structure connected to the spring oscillator of the present invention;

[0028] Fig. 9 It is a schematic diagram of simulation results of the spring oscillator before deformation according to the present invention;

[0029] Fig.10 It is a schematic diagram of the simulation results after the spring oscillator described in the present invention is deformed.

[0030] 1-tested cabin section model, 2-tire frame, 3-horizontal spring vibrator, 4-vertical spring vibrator, 5-sleeve, 6-spring vibrator bracket, 7-cement foundation, 8-bolts, 9-embedded metal. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0032] See also Figure 1-10 The present embodiment is described as a device for simulating the mass of water attached to a cabin structure, comprising a frame 2, a horizontal spring oscillator 3 and a vertical spring oscillator 4. A cabin model 1 to be measured is arranged on the frame 2. There are multiple horizontal spring oscillators 3 and multiple vertical spring oscillators 4. Multiple horizontal spring oscillators 3 are symmetrically connected on both sides of the cabin model 1 to be measured. Multiple vertical spring oscillators 4 are symmetrically connected at the bottom of the cabin model 1 to be measured. Each of the horizontal spring oscillators 3 and the vertical spring oscillators 4 comprises a spring and an equivalent additional mass block. One end of the spring is connected to the equivalent additional mass block, and the other end is connected to the cabin model 1 to be measured.

[0033] Since CO2 gas shielded welding is suitable for all-position welding, with fast welding speed, high efficiency and relatively low cost, the tested cabin model 1 is connected with the horizontal spring vibrator 3 and the vertical spring vibrator 4 by carbon dioxide gas shielded welding. Since the horizontal spring vibrator 3 and the vertical spring vibrator 4 do not require strict process processing, the equivalent additional steel block adopts low-carbon steel with low strength and hardness, good plasticity and toughness. The sea area is concentrated around the first, second and third cabins and the bottom of the cabin, producing an attached water effect.

[0034] In order to simulate the attached water mass of the side and bottom structures of the ship in the navigation state, it is considered to add springs with a certain stiffness to the outer bottom plate of the side and the bottom of the cabin, and the hull and the equivalent additional mass steel block are connected with springs to form an attached water mass equivalent spring oscillator to simulate the influence of the attached water mass on the dynamic characteristics of the hull structure. In this way, the vibration of the cabin structure can be ensured to be similar to that of the real ship, and the overall strength of the cabin can be not affected.

[0035] The tire frame 2 is a shape mold and workbench for manufacturing the curved surface segment and the curved three-dimensional segment of the hull. It has a steel frame structure that supports the strength of the cabin structure and can bear the weight of the spring vibrator. Preferably, the tire frame 2 is a truss-type tire frame, and the top of the tire frame structure is in close contact with the cabin line. The design complies with the "Code for Design of Steel Structures" (GB50017-2003). In order to consider the equivalent attached water mass, it is as consistent as possible with the actual situation of the tested cabin model 1 being placed in water and exploded. According to the cabin structure line, the tire frame 2 of the cabin structure is designed and installed to fix the cabin structure.

[0036] like Figure 2-4As shown, the horizontal spring vibrator 3 and the vertical spring vibrator 4 are respectively arranged in the sleeve 5, and the horizontal spring vibrator 3 and the vertical spring vibrator 4 are connected to the sleeve 5 through a slideway. The sleeve 5 is a split structure, and the split structural parts are connected by bolts 8. The slideway is an aluminum alloy double slideway. The horizontal spring vibrator 3 is arranged on the spring vibrator bracket 6, and the tire frame 2 and the horizontal spring vibrator 3 are both arranged on the cement foundation 7. The spring vibrator bracket 6 is a frame structure. The cement foundation 7 is a reinforced concrete structure and is provided with embedded metal 9. The tire frame 2 and the horizontal spring vibrator 3 are connected to the embedded metal 9. The sleeve 5 is divided into two parts and fixed by two bolts, and the sleeve 5 of the vertical spring vibrator 4 is fixed to the cement foundation 7 by two bolts, and the mass block of the spring vibrator is embedded in the middle. The spring vibrator is connected to the sleeve 5 through an aluminum alloy double slideway, so that the horizontal spring vibrator 3 can only move in the horizontal direction, and the vertical spring vibrator 4 can only move in the vertical direction. The embedded metal 9 is welded to the tire frame 2 and connected to the sleeve 5 with embedded bolts to ensure the stability of the test model.

[0037] The horizontal spring vibrator 3 is arranged on each plate frame structure on the side of the tested cabin model 1, and the plate frame structure is a plate frame structure interval surrounded by two decks and the main transverse bulkhead on the side. The horizontal spring vibrator 3 is connected to the center position of the plate frame structure strong member, and the vertical spring vibrator 4 is arranged on each plate frame structure on the bottom of the tested cabin model 1, and the plate frame structure is a plate frame structure interval surrounded by two longitudinal girders and the main transverse bulkhead on the bottom. The spring is preferably a 55Si2Mn alloy spring, and the equivalent additional mass block is preferably a regular rectangular steel block.

[0038] The horizontal spring oscillator 3 and the vertical spring oscillator 4 are placed at the intersection of the strong member of the plate frame structure. In order to avoid the rigid reflection phenomenon and meet the equivalence with the boundary conditions of the real ship, the sleeve 5 is installed to constrain the freedom degree of the spring oscillator.

[0039] This embodiment is a design method for a device simulating the mass of water attached to a cabin structure. The stiffness of the horizontal spring oscillator 3 is K i , mass is M i , i=1,…,N, where N is the number of side plate frame structures, K i With M i The selection of is in accordance with formula (1):

[0040]

[0041] Where: a is the mass ratio of the mass block to the plate frame structure a = M i / M ei , M ei is the equivalent mass of the i-th plate-frame structure, K eiis the equivalent stiffness of the i-th plate frame structure, b is the plate frame width, h is the average plate frame thickness, γ0 is the liquid specific gravity, γ is the structural specific gravity, and ν is the attached water mass coefficient;

[0042] The stiffness of the vertical spring oscillator 4 is k i , mass is m i , i = 1, ..., n, where n is the number of bottom plate frame structures, k i With m i The selection of is the same as that of formula (1).

[0043] The formula is derived as follows:

[0044] In order to determine the connection stiffness of the spring, the above spring connection structure is simplified. For example, for the i-th plate frame structure and the additional spring mass system, the additional mass block and the dry modal plate frame structure are regarded as the master-slave system, the dry modal plate frame is the master system, and the equivalent mass is M ei , mass block M i For the slave system, under the impact load, the added mass effect of the main hull mainly appears in the free vibration stage of the hull after the shock wave ends. The vibration frequency of the plate frame structure in single-sided contact with attached water:

[0045]

[0046] in, is the vibration frequency of the plate frame structure with one side in contact with water and the attached water mass, ω i It is the natural frequency of the plate-frame structure not in contact with water (the frequency of free vibration existing alone in the air).

[0047] For the coupling system of the plate frame structure and the horizontal spring oscillator, its natural frequency adopts the natural frequency calculation formula of the master-slave coupling system:

[0048]

[0049] Among them, K ei is the equivalent stiffness of the plate frame structure, M ei is the equivalent mass of the plate frame structure.

[0050] The natural frequency of the main system (i.e. the frame structure) vibrating alone is:

[0051] ω1=ω i (4)

[0052] The natural frequency of the slave system (i.e. the attached spring oscillator) vibrating alone is:

[0053]

[0054] The mass ratio of the coupled system is:

[0055]

[0056] The frequency shift coefficient is:

[0057]

[0058] Then the two dimensionless natural frequencies of the coupled system are:

[0059]

[0060] in,

[0061]

[0062] Among them, Ω1 and Ω2 are the first and second natural frequencies of the master-slave coupling system respectively.

[0063]

[0064] It is assumed that the natural frequency of the plate frame structure under the action of attached water is equal to the first-order natural frequency of the master-slave coupling system, and the attached water mass can be effectively simulated.

[0065]

[0066] Finally, formula (1) is derived.

[0067] To verify formula (1), a typical cabin model of a ship (ship A) is selected for theoretical and numerical verification. Take the cabin model of ship A below the water level, as Figure 5 shown.

[0068] The plate frame structure is the plate frame structure area surrounded by two decks and the main transverse bulkhead on the side. Therefore, the side of the hull is divided into nine plate grids, a total of three plate frame structures, and the outer bottom plate of the bottom is divided into six plate grids, a total of two plate frame structures. Figure 6 and Figure 7 shown.

[0069] According to the structural data of the A cabin section model, some structural parameters of the A cabin section model can be obtained. The specific structural parameters are shown in Table 1.

[0070]

[0071] Table 1 Structural parameters

[0072] The longitudinal spacing is 600mm, and the longitudinals are rolled T-shaped steel. There is a longitudinal keel between the inner bottom and the outer bottom. The transverse structure constitutes a rib frame, and the beam spacing is 2.4 meters. The plate frame structure is considered to be fixed on all sides. The attached water mass coefficient ν is determined by the width-to-length ratio of the plate frame structure, and the attached water mass coefficient ν can be obtained by measuring the width of each plate frame on the side and bottom of the ship. The first-order natural frequency ω of each plate frame structure is numerically simulated by Abaqus simulation i , we get ω i , 3D modeling such as Figure 8 The simulation results before and after deformation are shown in Fig. 9 and Fig.10 shown.

[0073] ω i Substituting into formula (2), the vibration frequency of the plate frame structure with one side in contact with water and the attached water mass is obtained: In addition, the mass M of each plate frame structure on the side and bottom of the ship is obtained by measurement and calculation. ei , M ei and ω i Substituting into formula (3), we can get the structural stiffness K of each plate frame: ei .

[0074] Select the stiffness K of the spring oscillator i and k i 1.3*10 6 N / m, mass M of the horizontal spring oscillator i is 100kg, the mass of the vertical spring oscillator is m i It is 1850kg, which is verified by simulation. The theoretical result obtained from formula (2) The specific parameters and calculation results are shown in Table 2.

[0075] The natural frequency in Table 2 is expressed as f i and f i * , in Hz, and its relationship with the circular frequency is:

[0076]

[0077]

[0078]

[0079] Table 2 Plate frame structural parameters and calculation results

[0080] Since a=M i / M ei , b, h, γ0, γ, ν and other parameters are known, and K i and M i, K ei and M ei Substituting them into equation (7) respectively, we can get the frequency offset coefficient of the system Substituting into formula (1), the equation holds. In summary, the theoretical formula (1) is verified to be reasonable.

[0081] In addition, f i * The errors between the simulation results and the theoretical results are both within 0.5%, and the errors can be ignored, so this method is feasible.

[0082] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A design method for a device for simulating the quality of water attached to a compartment structure, characterized in that: The device comprises a tire frame (2), a horizontal spring vibrator (3) and a vertical spring vibrator (4); a cabin section model (1) to be measured is arranged on the tire frame (2); the horizontal spring vibrators (3) and the vertical spring vibrators (4) are both in plurality; the plurality of horizontal spring vibrators (3) are symmetrically connected to both sides of the cabin section model (1) to be measured; the plurality of vertical spring vibrators (4) are symmetrically connected to the bottom of the cabin section model (1) to be measured; each of the horizontal spring vibrators (3) and the vertical spring vibrators (4) comprises a spring and an equivalent additional mass block; one end of the spring is connected to the equivalent additional mass block, and the other end is connected to the cabin section model (1) to be measured; The design method is: The stiffness of the horizontal spring oscillator (3) is K i , mass is M i , i=1,L,N, where N is the number of side plate frame structures, K i With M i The selection of is in accordance with formula (1): Where: a is the mass ratio of the mass block to the plate frame structure a = M i / M ei , M ei is the equivalent mass of the i-th plate-frame structure, K ei is the equivalent stiffness of the i-th plate frame structure, b is the plate frame width, h is the average plate frame thickness, γ0 is the liquid specific gravity, γ is the structural specific gravity, and ν is the attached water mass coefficient; The stiffness of the vertical spring oscillator (4) is k i , mass is m i , i = 1, L, n, where n is the number of bottom plate frame structures, k i With m i The selection of is the same as that of formula (1).

2. The design method of a device for simulating the quality of water attached to a compartment structure according to claim 1 is characterized by: The horizontal spring vibrator (3) and the vertical spring vibrator (4) are respectively arranged in a sleeve (5), and the horizontal spring vibrator (3) and the vertical spring vibrator (4) are connected to the sleeve (5) via a slideway.

3. The design method of a device for simulating the quality of water attached to a compartment structure according to claim 2 is characterized in that: The sleeve (5) is a split structure, the split structural parts are connected by bolts (8), and the slideway is an aluminum alloy double slideway.

4. The design method of a device for simulating the quality of water attached to a compartment structure according to claim 1 is characterized by: The horizontal spring vibrator (3) is arranged on a spring vibrator bracket (6), and the tire frame (2) and the horizontal spring vibrator (3) are both arranged on a cement foundation (7).

5. The design method of a device for simulating the quality of water attached to a compartment structure according to claim 4 is characterized by: The spring vibrator support (6) is a frame structure, the cement foundation (7) is a reinforced concrete structure and is provided with embedded metal (9), and the tire frame (2) and the horizontal spring vibrator (3) are both connected to the embedded metal (9).

6. The design method of a device for simulating the quality of water attached to a compartment structure according to claim 1 is characterized by: The tire frame (2) is a truss type tire frame.

7. The design method of a device for simulating the quality of water attached to a cabin structure according to claim 1 is characterized by: The horizontal spring oscillator (3) is arranged on each plate frame structure on the side of the measured cabin section model (1), the plate frame structure is a plate frame structure interval surrounded by two decks and a main transverse bulkhead on the side, and the horizontal spring oscillator (3) is connected to the center position of the plate frame structure strong component.

8. The design method of a device for simulating the quality of water attached to a cabin structure according to claim 1 is characterized by: The vertical spring oscillator (4) is arranged on each plate frame structure of the bottom of the measured cabin section model (1), and the plate frame structure is a plate frame structure interval surrounded by two longitudinal girders and a main transverse bulkhead on the bottom of the ship.

9. The design method of a device for simulating the quality of water attached to a cabin structure according to claim 1 is characterized by: The spring is a 55Si2Mn alloy spring, and the equivalent additional mass block is a regular rectangular steel block.

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