Design method of flexible energy-absorbing composite fender for air cushion vehicle

Abstract

The application discloses a design method of flexible energy-absorbing composite fender for hovercraft, which comprises the following steps: selecting the material of an outer cover layer and an inner energy-absorbing carrier to form a constraint structure; modeling the outer cover layer and the inner energy-absorbing carrier based on the differences between the physical properties and the mechanical properties of the outer cover layer and the inner energy-absorbing carrier and the complex coupling performance, and forming a constitutive model of the composite fender material; establishing a local rigid ship body model, coupling the composite fender material model with the ship body structure model, and forming an integrated fender material-rigid ship body simulation model; and forming a multi-specification outer cover layer and a multi-combination fender material design scheme of different material energy-absorbing foams. The application can provide a more accurate and effective fender material design method for hovercrafts with different full load displacements than the method based on experience. The application fully considers the adaptability between the main performance indexes of the fender material, such as energy-absorbing and deformation ratio, and the aluminum alloy ship body stiffness, and improves the anti-collision capability of the hovercraft during amphibious landing.

Description

TECHNICAL FIELD

[0001] The application relates to a design method of a light, large-flexibility and high-energy-absorption composite fender for a hovercraft, and belongs to the technical field of ship structures. BACKGROUND

[0002] The hovercraft is a new type of carrier between a conventional displacement ship and an airplane, mainly running on the water-air / land-air interface. The amphibious characteristics of the hovercraft determine that the use environment thereof is relatively complex. The fender material is arranged on the ship side and the bow and stern regions of the ship body and plays an important role in protecting the ship body structure under the use conditions of the hovercraft in the complex beach environment, berthing and towing.

[0003] At present, the fender material of the hovercraft generally adopts two schemes of a metal fender and a rubber fender. The metal fender is made of an aluminum alloy material which is the same as the material of the ship body. Since the anti-collision performance of the metal fender is poor, the design scheme of the fender has been gradually eliminated. The rubber fender is heavy, and the rigidity of the rubber fender is relatively large compared with the aluminum alloy ship body of the hovercraft. After the hovercraft is equipped with the rubber fender, the ship body structure of the hovercraft is damaged before the fender material.

[0004] In addition, the existing design method of the fender of the hovercraft is based on the design experience for the selection and design of the fender, and no design simulation calculation and test research are carried out. As a result, the fender material is heavy, and the effective anti-collision protection of the ship body structure cannot be realized. SUMMARY

[0005] The technical problem to be solved by the application is to provide a design method of a light, large-flexibility and high-energy-absorption composite fender material, which is used for the light fender design of different displacement hovercrafts.

[0006] In order to solve the above problems, the application provides a design method of a flexible energy-absorption composite fender for a hovercraft, characterized by comprising the following steps:

[0007] Step 1): selecting the materials of an outer cover layer and an inner energy-absorption carrier to form a constraint structure;

[0008] Step 2): based on the differences in the physical properties and the mechanical properties of the outer cover layer and the energy-absorption carrier and the complex characteristics of the coupling performance, the outer cover layer and the inner energy-absorption carrier are modeled to form a constitutive model of the composite fender material;

[0009] Step 3): a local rigid ship body model is established, the composite fender material model is coupled with the ship body structure model to form an integrated fender material-rigid ship body simulation model;

[0010] Step 4): considering the design requirements of lightness and high energy absorption, a multi-specification outer cover layer and a multi-combination fender material design scheme of different material energy-absorption foams are formed;

[0011] Step 5): determining the collision area; defining the collision speed of the integrated fender-rigid hull simulation model, and giving the initial speed of the integrated model;

[0012] Step 6): carrying out integrated fender-hull model impact simulation calculation of different schemes and different impact speeds, mastering the matching rules of the deformation ratio, energy absorption parameters of the fender material, and the stress and deformation of the rigid hull under different composite schemes and different impact speeds, and forming the design of light, large flexible and high energy absorption composite fender based on the safety usage boundary criterion of the rigid hull structure.

[0013] Preferably, in step 1), the material of the outer cover layer is polyurethane elastomer material.

[0014] Preferably, in step 1), the material of the inner energy absorption carrier is energy absorption foam material, and the fender structure with energy absorption foam material as the energy absorption and deformation carrier;

[0015] Preferably, in step 2), a three-order super-elastic model (Yeoh) is used to model the outer cover layer.

[0016] Preferably, in step 2), a low-density foam model (Low Density Foam) is used to model the inner energy absorption carrier.

[0017] Preferably, in step 2), after modeling, the performance parameters of the two materials are input for simulation trial calculation, and the above model is corrected by the test results of the performance of each material.

[0018] Preferably, in step 3), the method of binding constraint is used to couple the composite fender material model and the hull structure model to form an integrated fender material-rigid hull simulation model.

[0019] Preferably, in step 5), the master-slave surface contact search algorithm is used to define the contact search of two known interfaces to determine the collision area.

[0020] Preferably, in step 5), based on the principle of conservation of kinetic energy of the full load displacement of the actual ship and the integrated fender material-rigid hull simulation model, the collision speed of the integrated fender material-rigid hull simulation model is defined, and the initial speed of the integrated model is given by applying an acceleration field.

[0021] The application also provides a flexible energy absorption composite fender for air cushion ships, which comprises a polyurethane outer cover layer and an inner energy absorption carrier, the surface of the polyurethane outer cover layer is provided with a groove, the groove is provided with a pressing plate, and connecting bolts are sequentially connected with the pressing plate, the inner energy absorption carrier, the polyurethane outer cover layer, the side installation plate and the nut.

[0022] The present invention provides a design method for lightweight, highly flexible, and energy-absorbing composite fenders for hovercraft, offering a more accurate and effective fender design approach than empirical design for hovercraft with different full-load displacements. While prioritizing lightweight design, the invention fully considers the compatibility of key performance indicators such as energy absorption and deformation ratio of the fender with the stiffness of the aluminum alloy hull, proposing a design method for lightweight, highly flexible, and energy-absorbing composite fenders suitable for hovercraft, thereby improving the collision avoidance capabilities of hovercraft during amphibious landings. Attached Figure Description

[0023] Figure 1 A flowchart illustrating the design method of the flexible energy-absorbing composite material fender for air-cushioned ships provided by the present invention;

[0024] Figure 2 This is a schematic diagram of the composite material fender structure;

[0025] Figure 3 This is a schematic diagram of the ship's velocity field.

[0026] Figure 4 This is a schematic diagram of a local line collision. Detailed Implementation

[0027] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0028] Example

[0029] like Figure 1 As shown, this invention provides a design method for a flexible energy-absorbing composite material fender for hovercraft:

[0030] Step 1): Use polyurethane elastomer material as the outer layer of the fender material and energy-absorbing foam material as the inner energy-absorbing carrier to form a fender structure with polyurethane elastomer as the binding structure and energy-absorbing foam material as the energy absorption and deformation carrier, such as... Figure 2 As shown (including a polyurethane outer coating 1 and an inner energy-absorbing carrier 2, the surface of the polyurethane outer coating 1 is provided with a groove, and a pressure plate 3 is provided in the groove. The connecting bolt 4 passes through the pressure plate 3, the inner energy-absorbing carrier 2, the polyurethane outer coating 1, the side mounting plate 5 in sequence and is connected to the nut).

[0031] Step 2): Based on the differences in physical and mechanical properties and the complex coupling properties between the outer cladding and the energy absorber, a third-order hyperelastic model (Yeoh) is used to model the outer cladding, and a low-density foam model is used to model the inner energy absorber. The performance parameters of the two materials are input for simulation calculation, and the above models are corrected with the test results of the performance of each material to form a constitutive model of composite fender material.

[0032] Step 3): Establish a local rigid hull model, and use the binding constraint method to couple the composite fender model with the hull structure model to form an integrated fender-rigid hull simulation model;

[0033] Step 4): Considering the design requirements of light weight and high energy absorption, a multi-specification outer cover and different material energy-absorbing foam multi-combination fender design scheme is formed;

[0034] Step 5): The master-slave surface contact search algorithm is used to define two known interfaces for contact search to determine the collision area; based on the principle of kinetic energy conservation of the full load displacement of the actual ship and the integrated fender-rigid hull simulation model, the collision speed of the integrated fender-rigid hull simulation model is defined, and the initial speed of the integrated model is given by applying an acceleration field, as shown in Figure 3

[0035] Step 6): The integrated fender-hull model impact simulation calculation of different schemes and different impact speeds is carried out, as shown in Figure 4 , the matching law of the deformation ratio, energy absorption parameters of the composite material of different combination schemes and the stress and deformation of the rigid hull under different impact speeds is mastered, and the design of light weight, large flexibility and high energy absorption composite fender is formed based on the safety usage boundary criterion of the rigid hull structure.​

Claims

1. A method of designing a flexible energy-absorbing composite fender for a hovercraft, characterized in that, The method comprises the following steps: Step 1): selecting the material of the outer cover layer and the inner energy-absorbing carrier to form a constraint structure; Step 2): based on the differences in physical properties and mechanical properties of the outer cover layer and the energy-absorbing carrier, the coupling performance complex characteristics, modeling the outer cover layer and the inner energy-absorbing carrier to form a composite fender material constitutive model; Step 3): establishing a local rigid ship model, coupling the composite fender material model with the ship structure model to form an integrated fender material-rigid ship simulation model; Step 4): considering the design requirements of light weight and high energy absorption, forming a multi-specification outer cover layer and a multi-combination fender material design scheme of different material energy-absorbing foams; Step 5): determining the collision area; defining the collision speed of the integrated fender material-rigid ship simulation model and giving the initial speed of the integrated model; Step 6): carrying out impact simulation calculation of the integrated fender-ship model under different schemes and different impact speeds, mastering the matching rules of the deformation ratio, energy-absorbing parameters of the fender material under different combination schemes, different impact speeds, and the stress and deformation of the rigid ship, and forming the design of light weight, large flexibility and high energy-absorbing composite fender based on the safety usage boundary criterion of the rigid ship structure.

2. The method of designing a flexible energy-absorbing composite fender for a hovercraft as claimed in claim 1, wherein, In step 1), the material of the outer cover layer is polyurethane elastomer material.

3. The method of designing a flexible energy-absorbing composite fender for a hovercraft as claimed in claim 1, wherein, In step 1), the material of the inner energy-absorbing carrier is energy-absorbing foam material, and the fender structure with energy-absorbing foam material as the energy-absorbing and deformation carrier.

4. The method of designing a flexible energy-absorbing composite fender for a hovercraft as defined in claim 1, wherein In step 2), a third-order super-elastic model is used to model the outer cover layer.

5. The method of designing a flexible energy-absorbing composite fender for a hovercraft as defined in claim 1, wherein In step 2), a low-density foam model is used to model the inner energy-absorbing carrier.

6. The method of designing a flexible energy-absorbing composite material fender for an air cushion vehicle as claimed in claim 1, wherein, In step 2), after modeling, the performance parameters of the two materials are input for simulation trial calculation, and the above model is corrected by the test results of the material performance.

7. The method of designing a flexible energy-absorbing composite material fender for a hovercraft as claimed in claim 1, wherein, In step 3), the composite fender material model is coupled with the ship structure model by binding constraint to form an integrated fender material-rigid ship simulation model.

8. The method of designing a flexible energy-absorbing composite material fender for an air cushion vehicle as claimed in claim 1, wherein, In step 5), the master-slave surface contact search algorithm is used to define the contact search of two known interfaces to determine the collision area.

9. The method of designing a flexible energy-absorbing composite material fender for a hovercraft as claimed in claim 1, wherein, In step 5), based on the principle of conservation of kinetic energy of the full load displacement of the actual ship and the integrated fender material-rigid ship simulation model, the collision speed of the integrated fender material-rigid ship simulation model is defined, and the initial speed of the integrated model is given by applying an acceleration field.

10. A flexible energy-absorbing composite fender for a hovercraft, characterized in that The air cushion vehicle flexible energy-absorbing composite fender designed by the design method of any one of claims 1-9 comprises a polyurethane outer cover layer (1) and an inner energy-absorbing carrier (2), the polyurethane outer cover layer (1) is provided with a groove, a pressing plate (3) is arranged in the groove, and connecting bolts (4) are sequentially arranged through the pressing plate (3), the inner energy-absorbing carrier (2), the polyurethane outer cover layer (1), a side mounting plate (5) and a nut.

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