CN110979591A - Simplified structure model for ship water elasticity test and design method thereof - Google Patents
Simplified structure model for ship water elasticity test and design method thereof Download PDFInfo
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Abstract
The invention discloses a simplified structure model for ship water elasticity test and a design method thereof, comprising the following steps: determining the geometric scaling ratio of the simplified structure model; determining corresponding parameters of the model according to the parameter information of the real ship and the similar conversion relation; selecting and determining a processing material of the model; according to the structural form and the rigidity distribution of the real ship, simplifying and designing the thickness of the plate materials of the ship body of the model and the number, the size or the form of the longitudinal aggregate so as to enable the section rigidity distribution of the model to be as close to a target value as possible; designing a counterweight and a ballast scheme of a model ballast block according to the gravity center position and the weight distribution of the real ship to enable the weight distribution, the gravity center position and the moment of inertia of the model ballast block to be as close to target values as possible; and calculating the vibration natural frequency of the model, comparing the relation between the design value of the vibration natural frequency of the model and a target value, and if the difference exists, reasonably adjusting the internal structure size of the hull and the ballast scheme of the counterweight until the vibration natural frequency of the model is equal to the target value.
Description
Technical Field
The invention relates to the technical field of ship tests, in particular to a simplified structure model for a ship hydro-elasticity test and a design method thereof.
Background
The ship sailing on the sea is under the action of waves in most of the whole service period, and the waves can not only induce the six-degree-of-freedom swinging motion of the ship, but also induce the load response of a ship body structure. The wave load of the ship is an important subject for researching the safety of a ship body structure, and the reasonable forecast of the load response of the ship under the action of waves is an important work content in the design and construction stage of the ship. In addition, the deformation of the hull structure of a large ship under the action of the wave load is not negligible, and the structural deformation further influences the flow field information and the wave force applied to the hull, so that the elastic deformation effect of the hull structure also needs to be considered for accurate prediction of the wave load of the ship.
The ship water elasticity test is an effective method for researching the motion, stress and deformation conditions of a ship in waves and is an important means for verifying a theoretical method. The ship model water elasticity test is generally carried out in a water pool laboratory by adopting a reduced-scale ship model, the ship model is obtained by converting real ship parameters and designing and processing according to a certain similarity law, and waves are generated by wave making simulation in a water pool. In the traditional segmental ship model water elasticity test scheme, a hull shell is dispersed into a plurality of segments, a longitudinal continuous elastic keel beam is adopted to connect the segments, each segmental ship shell transmits the fluid force and rigid body inertia force suffered by the segmental ship shell to the keel beam, and the strain gauge is arranged on the keel beam to measure the section load suffered by the ship model. However, since the rigidity distribution and elastic deformation of the segmented ship model are discontinuous, it is difficult to accurately simulate and reproduce the structural deformation of a real ship in waves, which may cause a difference between the test result and the actual situation.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art and provides a design method of a simplified structure model for a ship hydro-elasticity test.
Another object of the present invention is to provide a simplified structural model for a ship water elasticity test, which can reflect the structural form of a real ship more truly, and can accurately measure the overall load of a hull section and the local loads of some high stress danger areas.
The purpose of the invention can be realized by the following technical scheme: a design method of a simplified structure model for a ship water elasticity test comprises the following steps: determining the geometric scaling ratio of the simplified structure model; determining corresponding parameters of the model according to the parameter information of the real ship and the similar conversion relation; selecting and determining a processing material of the model; according to the structural form and the rigidity distribution of the real ship, simplifying and designing the thickness of the plate materials of the ship body of the model and the number, the size or the form of the longitudinal aggregate so as to enable the section rigidity distribution of the model to be as close to a target value as possible; designing a counterweight and a ballast scheme of a model ballast block according to the gravity center position and the weight distribution of the real ship to enable the weight distribution, the gravity center position and the moment of inertia of the model ballast block to be as close to target values as possible; and calculating the vibration natural frequency of the model, comparing the relation between the design value of the vibration natural frequency of the model and a target value, and if the difference exists, reasonably adjusting the internal structure size of the hull and the ballast scheme of the counterweight until the vibration natural frequency of the model is equal to the target value.
As a preferred technical solution, the parameter information of the real ship mainly includes geometric dimensions, displacement, speed, weight distribution, center of gravity position, moment of inertia, longitudinal distribution of stiffness, and natural frequency of vibration.
As a preferred technical solution, the gravity center position includes a longitudinal position, a vertical position and a lateral position of the gravity center; the moment of inertia comprises a roll moment of inertia and a pitch moment of inertia; the stiffness longitudinal distribution comprises vertical bending stiffness longitudinal distribution, horizontal bending stiffness longitudinal distribution and torsional stiffness longitudinal distribution.
As a preferred technical solution, geometric similarity, motion similarity, dynamic similarity and structural rigidity similarity need to be considered for determining the similarity criterion in the similarity conversion.
As a preferred technical solution, the processing material of the model should meet the following requirements: the elastic modulus is far smaller than that of steel used for a real ship; the Poisson ratio is close to that of steel; the elastic limit of the material is higher than the maximum stress of the model under the test working condition; no obvious creep phenomenon exists in the linear elasticity range; isotropy; the processing and forming are convenient, and the method can be applied to the 3D printing technology; the surface can firmly adhere the strain gauge.
As a preferred technical scheme, the simplified design of the internal structure of the model comprises the following steps: firstly, selecting a reasonable ship plate thickness, wherein the plate thickness is larger than that of a plate obtained by scaling the actual ship plate thickness according to equal proportion; and then estimating the size of the longitudinal aggregates, and realizing the accurate adjustment of the section rigidity of the model by adjusting the size and the number of the longitudinal aggregates or replacing the aggregates, so that the section rigidity of the model is similar to that of a real ship, and the height of a neutralization axis of the model is ensured to be similar to that of the real ship.
Preferably, the cross-sectional stiffness of the model is equal to the average of the stiffness of the actual ship in the section between the adjacent transverse bulkheads.
Preferably, the natural frequency of vibration includes a vertical bending natural frequency, a horizontal bending natural frequency, and a torsional natural frequency; the natural frequency of the vertical bending vibration, the natural frequency of the horizontal bending vibration and the natural frequency of the torsional vibration are selected from the natural frequencies of the corresponding first-order vibration modes.
As a preferable technical scheme, after the natural frequency of the model vibration is adjusted to be equal to a target value, the measurement content of the model wave load test is determined according to the ship type and the experiment purpose, and a corresponding arrangement scheme of the strain gauge is made.
The other purpose of the invention can be realized by the following technical scheme: a simplified structure model for a ship water elasticity test comprises a hull shell, a transverse bulkhead, a deck, longitudinal aggregates and ballast blocks, wherein the shape of the hull shell is obtained by scaling a real ship line according to a geometric similarity relation, the position of the transverse bulkhead in the model is consistent with that of the real ship transverse bulkhead, the deck is arranged at the top of the hull shell, and the longitudinal aggregates are arranged in the model along the ship length direction; the section rigidity of the model is similar to that of a real ship; the ballast block is placed in the model, and the hull shell is weighted, so that the water displacement and the draught of the model are equal to target values, and the weight distribution, the gravity center position and the rotational inertia of the model are equal to the target values.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the model design method of the invention simplifies the internal structure of the complex real ship, designs the simplified ship model capable of reflecting the rigidity characteristic of the real ship according to the similar law, and adopts special materials to process the model, and the model designed by the method can reflect the whole and local elastic deformation effect of the real ship more truly.
2. The invention simplifies the mass distribution, the rigidity distribution and the structural form of the structural model to be closer to those of a real ship, and can accurately simulate and reproduce the structural load response of the ship under the coupling action of the inertia force, the fluid force and the elastic force. The simplified structure model can be used for measuring the whole load of the hull section, and can also be used for measuring the local loads and the distribution rules thereof at the positions of a bow slamming wave area, a deck area, a side area, a hatch corner and the like.
3. The simplified structure model can be integrally formed in the processing process, and the model processing can be carried out by means of the current advanced 3D printing technology, so that the efficiency of model processing and manufacturing is greatly improved. The complex processes of hull processing and segmentation, keel beam fixed mounting, cut sealing and the like in the traditional segmented keel beam type ship model processing process are avoided.
Drawings
FIG. 1 is a flow chart of the design of a simplified structural ship model in an embodiment of the present invention;
FIG. 2 is an external profile view of a simplified structural model of a container ship in accordance with an embodiment of the present invention;
FIG. 3 is a simplified structural model internal structural layout of a container ship in accordance with an embodiment of the present invention;
FIG. 4 is a diagram illustrating an exemplary cross-sectional configuration of a container ship in accordance with an embodiment of the present invention;
FIG. 5 is a diagram of an exemplary cross-sectional structural design of a simplified structural model in an embodiment of the present invention;
FIG. 6 is a diagram of the distribution of longitudinal stress of the deck in a state of sagging and bending when the simplified structural model is sailing in the embodiment of the present invention;
FIG. 7 is a midship section stress distribution diagram of the simplified structural model when the simplified structural model is bent purely during the wave-facing navigation in the embodiment of the invention;
FIG. 8 is a simplified structural model of a deck stress distribution diagram during a strafed voyage in an embodiment of the present invention.
Wherein: 1: hull outer shell, 2: transverse bulkhead, 3: longitudinal aggregate, 4: deck, 5: the deck is perforated.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
As shown in fig. 1, a design method of a simplified structure model for a ship hydro-elasticity test includes the following steps:
(1) determination of the scale ratio of a model
The simplified structure model scaling ratio needs to be determined by comprehensively considering factors such as the processing and manufacturing cost of the model, the feasibility of model tests, the problem of scale effect, the scale of a laboratory pool, the capacity range of a wave generator, the navigational speed range of a trailer and the like. For example, the amount of material required for model fabrication increases cubically with increasing model length, and thus increasing the scale of the model leads to a rapid increase in the cost of model fabrication. On the other hand, the too small model dimension can cause the problems of obvious dimension effect, too high requirement on local structure processing technology and difficult realization, and the like, thereby bringing certain interference to test measurement. In addition, the scale ratio of the model is comprehensively selected and determined from the aspects of scale effect, pool wall effect, blocking effect, wave simulatability and the like according to laboratory conditions such as the scale of the pool, the capacity range of the wave generator, the navigational speed range of the trailer and the like.
(2) Determination of similar conditions
The design of the hydro-elastic test model needs to meet the conditions of geometric similarity, motion similarity and power similarity required by the wave resistance test, and also needs to meet the conditions of structural rigidity similarity.
Geometric similarity, i.e., the ratio of the model to the one-dimensional linear scale corresponding to a real ship, is a constant, usually expressed as a scale ratio λ. For example, the length L of the hull satisfies the geometric similarity condition:
where the subscripts m and s represent the model and the real vessel, respectively.
The motion is similar, namely the ratio of the speed V of the model to the corresponding point of the real ship is constant, namely:
the dynamic similarity is that the ratio of a certain force on the model and the corresponding point of the real ship is a constant. The ship body is acted by forces with different properties such as pressure, inertia force, viscous force, gravity and the like, and the forces with different properties can have similar conditions of respective power parts. The partially similar conditions between the inertial forces and gravity, which are most important for studying vessel motion and wave loading, namely the friendship (Froude) numbers are equal:
where g is the acceleration of gravity.
Since the motion of the hull in waves is unusual, a similar condition of unsteady flow is satisfied, i.e. equal Strouhal numbers:
where t is time.
The structural rigidity is similar, namely the structural deformation of the model is similar to that of a corresponding point of a real ship under the action of external force, and the model is also an advantageous characteristic of the continuous elastic model compared with a segmented keel beam type model. For the total longitudinal bending of the hull, the following conditions can be obtained, depending on the requirements that the relative deflection of the ship model is similar to that of a real ship:
wherein E is the elastic modulus and I is the bending moment of inertia of the section.
For the twisting of the hull, the following conditions can be obtained according to the requirement that the relative turning angle of the ship model is similar to that of a real ship:
wherein G is the shear modulus and J is the section torsion constant.
From the above similar conditions, it can be deduced that the similar relationships that need to be followed for the design of the simplified structural elastic model are shown in table 1.
TABLE 1 similarity of model and real ship
| Content providing method and apparatus | Unit of | Representing symbol | Coefficient of similarity | |
| Line scale | m | L | λ | |
| Discharge of water | kg | Δ | λ3 | |
| Time of day | s | t | λ1/2 | |
| Frequency of | rad/s | ω | λ-1/2 | |
| Angle of rotation | | θ | 1 | |
| Speed of rotation | m/s | V | λ1/2 | |
| Acceleration of a vehicle | m/s2 | a | 1 | |
| Force of | N | F | λ3 | |
| Moment of force | N·m | M | λ4 | |
| Flexural rigidity | N·m2 | EI | λ5 | |
| Torsional rigidity | N·m2 | GJ | λ5 |
(3) Modeling material selection
In order to satisfy the similar conditions of the bending rigidity and the torsional rigidity of the model and the real ship, the bending rigidity EI ratio of the model to the real ship is required to be lambda5The ratio of torsional rigidity GJ of the model to the real ship is also lambda5. Assuming that the model is still made of the same steel as the real ship and the elastic modulus E of the model and the real ship is equal, the bending moment of inertia I ratio of the model to the real ship is required to be lambda5. In fact, from dimensional analysis, it can be seen that the ratio of the bending moment of inertia I of the model to the real ship is about λ4Of the order of magnitude of (d). Therefore, it is required to reduce the elastic modulus of the ship model material so as to satisfy the rigidity similarity condition. In general pool model test, the selection range of the model scale ratio is lambda which is 1/100-1/30, so the elastic modulus of the model is about 1/100 of that of steel. However, most materials with an elastic modulus around 1/100, which is the elastic modulus of steel, have significant creep phenomena that interfere with the measurement of dynamic stress strain. Therefore, it can be concluded that the modeling material needs to satisfy the following requirements:
1) the elastic modulus E is far smaller than that of steel used for a real ship and is about 1 percent of the elastic modulus E;
2) the Poisson ratio mu is close to that of steel;
3) the elastic limit of the material is higher than the maximum stress of the model under the test working condition, namely the structural stress of the model is required to be ensured to be always in a linear elastic range;
4) no obvious creep phenomenon exists in the linear elasticity range;
5) isotropy;
6) the processing and forming are convenient, and the method can be applied to the 3D printing technology;
7) the surface can firmly adhere the strain gauge.
For comprehensive analysis, the ship model can be made of ABS engineering plastics (terpolymer of acrylonitrile, butadiene and styrene), PC plastics (polycarbonate), PVC plastics (polyvinyl chloride) and other materials. These materials meet the above requirements and are relatively low in cost.
(4) Design of internal structure of model
In the design process of simplifying the structural elastic model, on one hand, the complex structure of the real ship needs to be simplified, and on the other hand, the rigidity distribution of the model is ensured to be similar to that of the real ship as far as possible. Although the model and the real ship can not meet the complete similar conditions and can not take each local structure of the real ship into consideration, the overall and local stress distribution condition of the ship body can be well simulated by reasonably designing the model structure.
The geometric shapes of the plates such as the hull shell, the transverse bulkhead, the deck and the like are obtained by scaling according to the real ship geometric shape, and the plate thickness is not obtained by scaling according to the real ship plate thickness. This is because if the hull plate thickness is scaled according to the reduction ratio, the model plate thickness is very small, the strength is also weak, and the model is difficult to machine, which is not in accordance with actual conditions and test requirements. Thus, the ship template thickness should be greater than that obtained by scaling. In addition, the design can be simplified through the mode that reduces quantity, increase single aggregate size to vertical aggregate, also can change the form of aggregate as required, can select the aggregate of multiple forms such as angle steel, band steel, T section bar. In the design process, reasonable plate thickness of the ship body is selected, then the dimension of the aggregate is estimated, and the accurate adjustment of the section rigidity of the model is realized by adjusting the dimension of the aggregate, so that the section rigidity (including vertical bending rigidity, horizontal bending rigidity and torsional rigidity) of the ship model is similar to that of a real ship, and the height of a neutralization axis of the model is ensured to be similar to that of the real ship. Finite element modeling software such as MSC, Patran and the like can be adopted to directly measure the rigidity (including vertical bending rigidity, horizontal bending rigidity and torsional rigidity) of each section and the position of a neutral axis. The average value of the rigidity of the ship model section in the cabin section between the adjacent transverse bulkheads is equal to that of the real ship in the range, so that the design work can be simplified.
(5) Counterweight and ballast arrangement
The displacement and draft of the ship model are certain, while the weight of the model hull needs to be less than the displacement of the ship model. It is necessary to reserve about 1/3 weight for ballast weighting for the full displacement of the ship so that the displacement and draft of the ship model are equal to the design values. On the other hand, the ballast blocks need to be distributed in a reasonable arrangement so that the weight distribution, the gravity center position and the moment of inertia of the ship model are equal to the design values. The ballast weight can be composed of a plurality of small ballast iron blocks, and after the arrangement positions of the ballast blocks are calculated, the ballast blocks are fixed at corresponding positions in the ship shell through screws or adhesive. The calculation flow for determining the ballast block arrangement position is as follows:
1) according to the displacement of the ship model and the weight of the empty ship, the required total pressure carrying capacity can be obtained by difference;
2) according to the longitudinal distribution data of the weight of the ship, station positions are taken as units (the ship is usually divided into 20 theoretical station positions from bow to stern), the water displacement and the empty weight of each section between adjacent station positions are calculated, and the ballast weight required to be arranged in the hull of each section can be obtained by making a difference;
3) calculating and determining the arrangement positions of the ballast blocks in the ship shells of all the sections according to the data of the gravity center positions (including the longitudinal position, the transverse position and the vertical position) and the rolling inertia radius of all the sections of the ship body, so that the design value is equal to the target value;
4) according to the model hull and the configured ballast conditions of each section, calculating the gravity center position (including the longitudinal position, the transverse position and the vertical position) and the moment of inertia (including the pitching moment of inertia and the rolling moment of inertia) of the whole ship, and comparing the gravity center position and the moment of inertia with a target value;
5) and (4) further reasonably adjusting the ballast blocks in each section according to the comparison condition of the design value and the target value, and repeating the steps 3) to 4) until the design value is consistent with the target value.
(6) Model vibration natural frequency calculation
By means of the existing structural finite element analysis software, the vibration mode analysis of the hull structure can be conveniently realized. In order to reasonably consider the influence of local structure reinforcement on the vibration mode of the ship body, MSC.Patran software can be adopted to establish a three-dimensional finite element structure model of the ship model and carry out unit meshing. The plate unit is adopted to simulate the hull shell, the transverse bulkhead and the deck, the beam unit is adopted to simulate the longitudinal aggregate, and corresponding attribute parameters are given to each part of the structure. The weight of the counterweight ballast is processed by a concentrated mass method, namely mass units are built on corresponding nodes of the shell. Coarse mesh size modeling is used to improve computational efficiency, i.e., longitudinal and transverse bulkheads are used as boundaries for mesh partitioning. Then, the MSC.Patran modeling is led into an MSC.Nastran solver, the attached water mass is added through an MFLUID card method, and the wet mode of the ship body vibration is obtained through calculation and analysis. Based on the method, modal information (including natural frequency and natural mode shape of each order of vibration) of vertical bending vibration, horizontal bending vibration and torsional vibration of the model can be calculated. For simplicity, only the natural frequency of the first-order vibration of the corresponding mode is selected to be compared with the real ship target value.
(7) Strain gauge arrangement
The simplified structure elastic model can be used for measuring the overall load (such as vertical bending moment, horizontal bending moment, torque and the like) of the cross section of the ship body and measuring the local load (such as principal stress, direction angle and stress distribution). The following are several typical strain gage arrangements and measurement schemes:
1) and taking the cross section of the midship as a center, arranging a one-way strain gauge on a deck along the length direction of the ship, measuring the longitudinal load distribution, and calculating the longitudinal distribution of the total longitudinal bending moment along the length of the ship.
2) And (3) sticking unidirectional strain gauges at different widths on a deck of a midship section to measure the longitudinal stress distribution in the width direction of the ship.
3) And (3) sticking one-way strain gauges at different heights on a side board of a midship section, measuring the longitudinal stress distribution at different heights, and checking the position of a neutral axis.
4) Three-way strain patterns are pasted on the deck near the large opening area, and the magnitude and the direction of the main stress of the large opening area of the deck are measured.
5) Three-dimensional strain patterns are adhered to a hull and a deck of the bow outboard floating area, and the magnitude and the direction of the main stress of the bow area are measured when the hull is subjected to the outboard floating slamming.
The design key point of the simplified structure model design method for the ship water elasticity test is that the internal structure of the ship body is reasonably designed, so that on one hand, the complex real ship structure is simplified, and model processing and load measurement are convenient; on the other hand, the model needs to be ensured to reflect the rigidity distribution characteristic of the real ship structure to the maximum extent, and the elastic deformation effect of the whole and local structure of the real ship is fully simulated.
And designing a simplified hull model according to the design method, wherein the simplified hull model comprises a hull shell, transverse bulkheads, deck boards, longitudinal aggregates and ballast blocks. The shape of the hull shell is obtained by scaling the real ship-shaped line according to the geometric similarity relation, so that the similarity of the flow field around the outside of the hull to the actual condition is ensured. The position of the transverse bulkhead in the model is consistent with that of the transverse bulkhead of the solid ship, and the transverse bulkhead adopts uniform thin plates with equal thickness, so that the design and processing work can be simplified. The deck is arranged at the top of the hull shell, and a deck opening can be arranged on the deck according to actual conditions to simulate an entrance and an exit when goods in the cabin are loaded and unloaded. The deck can also be designed into one-layer or multi-layer structure according to the structure of the real ship. The longitudinal aggregate is arranged inside the model (comprising a bottom plate, a side plate and a deck) along the ship length direction and is used for simulating structures such as reinforcing ribs, longitudinal ribs and the like of a real ship. The longitudinal aggregates are arranged continuously and uniformly in the compartment sections between adjacent transverse bulkheads, so that the design work can be simplified. By reducing the number of longitudinal aggregates in the cross section and increasing the cross-sectional dimension of a single longitudinal aggregate, the rigidity of the cross section can be ensured to meet similar conditions, and the design work can be simplified.
The empty ship weight needs to be less than the displacement of the ship model, and 1/3 weight which is about the displacement of the whole ship is reserved for ballast weight. The ballast block is placed in the model, the hull shell is weighted, the water displacement and the draught of the model are enabled to be equal to the target values, and the weight distribution, the gravity center position and the rotational inertia of the model are enabled to be equal to the target values through reasonable arrangement of the ballast block positions. The components of the hull model are made of the same material. The hull model can be processed by means of a 3D printing technology, and the model is formed in one step, so that the model processing precision is guaranteed, and the model processing and manufacturing efficiency can be greatly improved.
As shown in fig. 2 and 3, the design scheme is a simplified structural model design scheme of a certain container ship. The typical cross section of the container ship real ship is shown in figure 4, and the simplified cross section is shown in figure 5, so that the simplified model and the design method thereof can simplify the complex hull structure, facilitate the design and processing of the model, and simultaneously simulate and reflect the rigidity characteristic of the real ship. By adopting the model and reasonably arranging the strain gauges, the stress distribution of the local structure shown in the figures 6, 7 and 8 can be measured, namely, the stress distribution conditions of the ship body shown in the figures 6, 7 and 8 can be obtained by adopting the model design method. Tests using conventional segmented keel beam models have failed to measure these local stress distributions.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A design method of a simplified structure model for a ship water elasticity test is characterized by comprising the following steps:
determining the geometric scaling ratio of the simplified structure model;
determining corresponding parameters of the model according to the parameter information of the real ship and the similar conversion relation;
selecting and determining a processing material of the model;
according to the structural form and the rigidity distribution of the real ship, simplifying and designing the thickness of the plate materials of the ship body of the model and the number, the size or the form of the longitudinal aggregate so as to enable the section rigidity distribution of the model to be as close to a target value as possible;
designing a counter weight and a ballast scheme of a model ballast block according to the gravity center position and the weight distribution of the real ship, so that the weight distribution, the gravity center position and the rotational inertia of the ship model are close to target values as much as possible;
and calculating the vibration natural frequency of the model, comparing the relation between the design value of the vibration natural frequency of the model and a target value, and if the difference exists, reasonably adjusting the internal structure size of the ship model and a counterweight ballast scheme until the vibration natural frequency of the model is equal to the target value.
2. The method as claimed in claim 1, wherein the parameter information of the real ship mainly includes geometric dimension, displacement, speed, weight distribution, center of gravity position, moment of inertia, longitudinal distribution of stiffness, and natural frequency of vibration.
3. The design method of the simplified structural model for the ship water elasticity test according to claim 2, wherein the gravity center position comprises a longitudinal position, a vertical position and a transverse position of the gravity center; the moment of inertia comprises a roll moment of inertia and a pitch moment of inertia; the stiffness longitudinal distribution comprises vertical bending stiffness longitudinal distribution, horizontal bending stiffness longitudinal distribution and torsional stiffness longitudinal distribution.
4. The design method of the simplified structural model for the ship water elasticity test according to claim 1, wherein the determination of the similarity criterion in the similarity conversion needs to consider geometric similarity, motion similarity, dynamic similarity and structural rigidity similarity.
5. The design method of the simplified structural model for the ship water elasticity test according to claim 1, characterized in that the processed material of the model meets the following requirements: the elastic modulus is far smaller than that of steel used for a real ship; the Poisson ratio is close to that of steel; the elastic limit of the material is higher than the maximum stress of the model under the test working condition; no obvious creep phenomenon exists in the linear elasticity range; isotropy; the processing and forming are convenient, and the method can be applied to the 3D printing technology; the surface can firmly adhere the strain gauge.
6. The design method of the simplified structural model for the ship water elasticity test according to claim 1, wherein the simplified design of the internal structure of the model comprises the following steps: firstly, selecting a reasonable ship plate thickness, wherein the plate thickness is larger than that of a plate obtained by scaling the actual ship plate thickness according to equal proportion; and then estimating the size of the longitudinal aggregates, and realizing the accurate adjustment of the section rigidity of the model by adjusting the size and the number of the longitudinal aggregates or replacing the aggregates, so that the section rigidity of the model is similar to that of a real ship, and the height of a neutralization axis of the model is ensured to be similar to that of the real ship.
7. The method of claim 1, wherein the cross-sectional stiffness of the model in the section between adjacent transverse bulkheads has an average value equal to that of a real ship in the range.
8. The design method of the simplified structural model for the ship hydro-elastic test is characterized in that the natural vibration frequencies comprise a vertical bending natural vibration frequency, a horizontal bending natural vibration frequency and a torsional natural vibration frequency; the natural frequency of the vertical bending vibration, the natural frequency of the horizontal bending vibration and the natural frequency of the torsional vibration are selected from the natural frequencies of the corresponding first-order vibration modes.
9. The method for designing the simplified structural model for the ship water elasticity test according to any one of claims 1 to 8, characterized in that after the natural frequency of vibration of the model is adjusted to be equal to a target value, the measurement content of the model wave load test is determined according to the ship type and the test purpose, and the corresponding arrangement scheme of the strain gauge is established.
10. A simplified structural model for a ship water elasticity test, manufactured by the design method according to any one of claims 1 to 9, comprising hull shells, transverse bulkheads, deck plates, longitudinal aggregates and ballast blocks, wherein the hull shell shapes are scaled from the solid ship-type lines according to geometric similarity, the positions of the transverse bulkheads in the model are consistent with the positions of the transverse bulkheads of the solid ships, the deck plates are arranged on the tops of the hull shells, and the longitudinal aggregates are arranged in the model along the ship length direction; the section rigidity of the model is similar to that of a real ship; the ballast block is placed in the model, and the hull shell is weighted, so that the water displacement and the draught of the model are equal to target values, and the weight distribution, the gravity center position and the rotational inertia of the model are equal to the target values.
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| CN112141290A (en) * | 2020-09-25 | 2020-12-29 | 哈尔滨工程大学 | Method for testing flow field or bubble field of ship model cross section |
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| CN111959708A (en) * | 2020-04-29 | 2020-11-20 | 中船第九设计研究院工程有限公司 | Ship draft simulation system |
| CN112141290A (en) * | 2020-09-25 | 2020-12-29 | 哈尔滨工程大学 | Method for testing flow field or bubble field of ship model cross section |
| CN112199780A (en) * | 2020-10-28 | 2021-01-08 | 中国舰船研究设计中心 | Design method of equal-thickness shrinkage ratio strength and fatigue combined test model of transition forging ring |
| CN112199780B (en) * | 2020-10-28 | 2022-04-15 | 中国舰船研究设计中心 | Design method of equal-thickness shrinkage ratio strength and fatigue combined test model of transition forging ring |
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| CN113722824A (en) * | 2021-08-30 | 2021-11-30 | 江南造船(集团)有限责任公司 | Ship plate structure simplification method and device suitable for finite element analysis |
| CN113715984B (en) * | 2021-09-18 | 2023-11-03 | 中国船舶工业集团公司第七0八研究所 | Simplified calculation method for total vibration of small waterplane area catamaran |
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| CN113788122B (en) * | 2021-10-28 | 2022-08-16 | 江南造船(集团)有限责任公司 | Finite element analysis pretreatment method for container ship body |
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| CN114323561B (en) * | 2021-12-30 | 2023-10-20 | 中国特种飞行器研究所 | Watertight hull test model device with gravity center inertia and high freedom degree adjustment |
| CN114323561A (en) * | 2021-12-30 | 2022-04-12 | 中国特种飞行器研究所 | Watertight hull test model device with high gravity inertia degree and high degree of freedom adjustment |
| CN114756962A (en) * | 2022-04-07 | 2022-07-15 | 武汉理工大学 | Ship structure nonlinear response similar distortion scaling model design method |
| CN116628838A (en) * | 2023-04-03 | 2023-08-22 | 中国船舶集团有限公司第七一九研究所 | Method and system for calculating weight center of gravity of open hole of ship body structure based on CAA development |
| CN116628838B (en) * | 2023-04-03 | 2024-01-09 | 中国船舶集团有限公司第七一九研究所 | Method and system for calculating weight center of gravity of open hole of ship body structure based on CAA development |
| CN116663192A (en) * | 2023-06-08 | 2023-08-29 | 武汉轻工大学 | Double-layer cylindrical shell vibration response simulation method and device |
| CN116663192B (en) * | 2023-06-08 | 2024-05-17 | 武汉轻工大学 | Double-layer cylindrical shell vibration response simulation method and device |
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