Design method of flexible energy-absorbing composite fender for hovercraft

Abstract

The invention discloses a design method of a flexible energy-absorbing composite fender for a hovercraft. The design method comprises the following steps: selecting materials of an outer coating and an inner energy-absorbing carrier to form a constraint structure; based on the characteristics that physical properties and mechanical properties of an outer coating and an energy absorption carrier are different and coupling performance is complex, modeling is conducted on the outer coating and an inner-layer energy absorption carrier, and a composite material fender constitutive model is formed; establishing a local rigid hull model, and coupling the composite fender material model with the hull structure model to form an integrated fender material-rigid hull simulation model; and a multi-combination fender material design scheme with multi-specification outer coatings and energy-absorbing foams made of different materials is formed. According to the method, a fender material design means which is more accurate and effective than that designed according to experience can be provided for hovercraft with different full-load displacement. The adaptability of main performance indexes such as energy absorption and deformation ratio of the fender and the rigidity of the aluminum alloy hull is fully considered, and the anti-collision capacity of amphibious landing of the hovercraft is improved.

Description

Technical Field

[0001] The invention relates to a design method for a lightweight, highly flexible, high-energy-absorbing composite material fender for an air cushion ship, and belongs to the technical field of ship structures. Background Art

[0002] A hovercraft is a new type of vehicle between conventional displacement ships and aircraft. It mainly operates at the water-air / land-air interface. The amphibious characteristics of a hovercraft determine that its operating environment is relatively complex. The fender, as a protective structure arranged on the side and bow and stern areas of the hull, shoulders the important task of protecting the hull structure when the hovercraft is sailing, berthing and towing in complex shore environments.

[0003] At present, hovercraft fenders generally adopt two schemes: metal fenders and rubber fenders. Metal fenders are made of aluminum alloy, the same material as the hull. Due to its poor anti-collision performance, hovercraft has gradually eliminated this fender design scheme. Rubber fenders are heavy and have greater rigidity than the aluminum alloy hull of the hovercraft. After installation, the hull structure of the hovercraft will be damaged before the fenders.

[0004] In addition, the existing hovercraft fender design methods are all based on design experience to select and design fenders, and no design simulation calculations and experimental research have been carried out, resulting in heavy fender materials and inability to achieve effective anti-collision protection of the hull structure. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a design method for a lightweight, highly flexible, high-energy-absorbing composite material fender material, which is used for the design of lightweight fenders for hovercrafts with different displacements.

[0006] In order to solve the above problems, the present invention provides a design method of a flexible energy-absorbing composite material fender for an air cushion craft, which is characterized by comprising the following steps:

[0007] Step 1): Select the materials of the outer covering layer and the inner energy absorbing carrier to form a restraining structure;

[0008] Step 2): Based on the differences in physical and mechanical properties of the outer layer and the energy absorbing carrier and the complex coupling properties, the outer layer and the inner layer energy absorbing carrier are modeled to form a constitutive model of the composite fender;

[0009] Step 3): Establish a local rigid hull model, couple the composite fender model with the hull structure model, and form an integrated fender-rigid hull simulation model;

[0010] Step 4): Considering the design requirements of lightweight and high energy absorption, a multi-combination fender design scheme with multiple specifications of outer covering layers and energy-absorbing foams of different materials is formed;

[0011] Step 5): Determine the collision area; define the collision speed of the integrated fender-rigid hull simulation model, and assign the initial velocity to the integrated model;

[0012] Step 6): Carry out impact simulation calculations of integrated fender-hull models with different schemes and impact speeds, master the deformation ratio of composite materials in different combination schemes, the matching rules of energy absorption parameters and rigid hull stress and deformation of fender materials under different impact speeds, and form a design of lightweight, highly flexible and high energy absorption composite fender based on the safe use boundary criteria of rigid hull structure.

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

[0014] Preferably, in step 1), the material of the inner layer energy absorbing carrier is an energy absorbing foam material, and the fender structure uses the energy absorbing foam material as the energy absorbing and deformation carrier;

[0015] Preferably, in step 2), a third-order hyperelastic model (Yeoh) is used to model the outer covering layer.

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

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

[0018] Preferably, in step 3), the composite fender model is coupled with the hull structure model by using a binding constraint method to form an integrated fender-rigid hull simulation model.

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

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

[0021] The present invention also provides a flexible energy-absorbing composite material fender for an air cushion vessel, which includes a polyurethane outer covering layer and an inner energy-absorbing carrier. A groove is provided on the surface of the polyurethane outer covering layer, a pressure plate is provided in the groove, and connecting bolts pass through the pressure plate, the inner energy-absorbing carrier, the polyurethane outer covering layer, the side mounting plate and the nut in sequence.

[0022] The method for designing a lightweight, highly flexible, high-energy-absorbing composite fender for a hovercraft provided by the present invention can provide a more accurate and effective means for designing fenders for hovercrafts with different full load displacements than designing based on experience. Under the premise of taking into account lightweight design, the present invention fully considers the adaptability of the main performance indicators such as fender energy absorption and deformation ratio with the stiffness of the aluminum alloy hull, and proposes a method for designing a lightweight, highly flexible, high-energy-absorbing composite fender suitable for a hovercraft, thereby improving the anti-collision capability of the hovercraft for amphibious landing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flow chart of a design method for a flexible energy-absorbing composite material fender for an air cushion craft provided by the present invention;

[0024] Figure 2 It is a structural schematic diagram of a composite material fender;

[0025] Figure 3 is the schematic diagram of the hull velocity field;

[0026] Figure 4 Schematic diagram of local line collision. DETAILED DESCRIPTION

[0027] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0028] Example

[0029] like Figure 1 As shown, a design method for a flexible energy-absorbing composite material fender for an air cushion craft provided by the present invention is as follows:

[0030] Step 1): Use polyurethane elastomer material as the outer covering 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 restraining structure and energy absorbing foam material as the energy absorbing and deformation carrier, such as Figure 2 As shown (comprising a polyurethane outer coating 1 and an inner energy absorbing carrier 2, a groove is provided on the surface of the polyurethane outer coating 1, a pressing plate 3 is provided in the groove, and a connecting bolt 4 passes through the pressing plate 3, the inner energy absorbing carrier 2, the polyurethane outer coating 1, the side mounting plate 5 and is connected with a nut in sequence);

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

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

[0033] Step 4): Considering the design requirements of lightweight and high energy absorption, a multi-combination fender design scheme with multiple specifications of outer covering layers and energy-absorbing foams of different materials is formed;

[0034] Step 5): Using the master-slave contact search algorithm, define two known interfaces for contact search and determine the collision area; based on the full load displacement of the actual ship and the kinetic energy conservation principle of the integrated fender-rigid hull simulation model, define the collision velocity of the integrated fender-rigid hull simulation model, and give the integrated model an initial velocity by applying a velocity field, such as Figure 3 As shown;

[0035] Step 6): Carry out the integrated fender-hull model impact simulation calculation with different schemes and different impact speeds, see Figure 4 , master the deformation ratio of composite materials in different combination schemes, fender materials under different impact speeds, the matching rules of energy absorption parameters and rigid hull stress and deformation, and form the design of lightweight, highly flexible and high energy absorption composite fender based on the safe use boundary criteria of rigid hull structure.

Claims

1. A design method for a flexible energy-absorbing composite material fender for an air cushion craft, characterized in that: The following steps are involved: Step 1): Select the materials of the outer covering layer and the inner energy absorbing carrier to form a restraining structure; Step 2): Based on the differences in physical and mechanical properties of the outer layer and the energy absorbing carrier and the complex coupling properties, the outer layer and the inner layer energy absorbing carrier are modeled to form a constitutive model of the composite fender; Step 3): Establish a local rigid hull model, couple the composite fender model with the hull structure model, and form an integrated fender-rigid hull simulation model; Step 4): Considering the design requirements of lightweight and high energy absorption, a multi-combination fender design scheme with multiple specifications of outer covering layers and energy-absorbing foams of different materials is formed; Step 5): Determine the collision area; define the collision speed of the integrated fender-rigid hull simulation model, and assign the initial velocity to the integrated model; Step 6): Carry out impact simulation calculations of integrated fender-hull models with different schemes and impact speeds, master the deformation ratio of composite materials in different combination schemes, the matching rules of energy absorption parameters and rigid hull stress and deformation of fender materials under different impact speeds, and form a design of lightweight, highly flexible and high energy absorption composite fender based on the safe use boundary criteria of rigid hull structure.

2. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 1), the outer coating layer is made of polyurethane elastomer material.

3. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 1), the material of the inner layer energy absorbing carrier is energy absorbing foam material, and the fender structure uses the energy absorbing foam material as the energy absorbing and deformation carrier.

4. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 2), the outer covering layer is modeled using a third-order hyperelastic model.

5. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 2), a low-density foam model is used to model the inner energy absorbing carrier.

6. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 2), after modeling, two material performance parameters are input for simulation calculation, and the above model is corrected using the test results of each material performance.

7. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 3), the composite fender model is coupled with the hull structure model by using the binding constraint method to form an integrated fender-rigid hull simulation model.

8. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 5), a master-slave surface contact search algorithm is used to define two known interfaces for contact search and determine the collision area.

9. The design method of the flexible energy-absorbing composite material fender for air cushion craft according to claim 1, characterized in that: In step 5), based on the full load displacement of the actual ship and the kinetic energy conservation principle of the integrated fender-rigid hull simulation model, the collision velocity of the integrated fender-rigid hull simulation model is defined, and the initial velocity of the integrated model is given by applying a velocity field.

10. A flexible energy-absorbing composite material fender for an air cushion craft, characterized in that: The invention comprises 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, a pressure plate (3) is provided in the groove, and a 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) and is connected with a nut in sequence.

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