A rear support arm for use in a hovercraft duct assembly

Abstract

The present application relates to air cushion ship structure design technical field, especially to a kind of rear support arm for air cushion ship duct combination device, including support middle section and respectively with the inner joint and outer joint of two ends of support middle section are connected, the inner joint is used to be connected with the shaft sleeve in duct combination device;The outer joint includes the convex part and flange plate connected, and first chamfer area is formed at the junction of the convex part and flange plate;Two pieces of reinforcing sheet are riveted on the outside of the outer joint, and the shape formed by the two pieces of reinforcing sheet is matched with the shape of outer joint, second chamfer area is formed on the reinforcing sheet, and the radius of first chamfer area is less than the radius of second chamfer area.The stress concentration of outer joint chamfer leading edge can be reduced by the rear support arm, and then the fatigue strength of outer joint is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hovercraft structure design, in particular to a rear support arm used in a duct combination device of a hovercraft. BACKGROUND

[0002] Unlike conventional displacement ships, a hovercraft usually adopts a ducted air propeller as a propulsion system. The flow guide device of the air propeller is called a duct, and the duct, as a special structure of the hovercraft, has its unique importance: it can improve the static thrust of the propeller, reduce noise, and provide safety protection for passengers. The high-speed airflow of the air propeller causes a pressure field on the inner wall of the duct, and the integral of the axial component forms the duct thrust, which is usually about 30% to 50% of the total thrust of the ducted air propeller. Therefore, the design of the duct combination structure is an important part of the structure design of the hovercraft.

[0003] As a thrust device of a hovercraft, the duct combination device adopts various support structures to maintain the stiffness of the duct cylinder due to the need to support the duct cylinder. According to the structural requirements of the model, the support structure in the duct combination device needs to maintain the stiffness of the duct cylinder and bear complex loads, especially vibration loads.

[0004] In actual use, the chamfered front edge of the outer joint of the rear support arm is prone to cracks, which affects the usability of the duct and further affects the navigation and safety of the hovercraft. SUMMARY

[0005] To solve the above technical problems, the present application provides a rear support arm used in a duct combination device of a hovercraft, which can reduce the stress concentration of the chamfered front edge of the outer joint and further improve the fatigue strength of the outer joint.

[0006] The present application is achieved by adopting the following technical solutions:

[0007] A rear support arm used in a duct combination device of a hovercraft, characterized in that it comprises a support middle section and an inner joint and an outer joint connected to both ends of the support middle section, the inner joint is used to connect with a shaft sleeve in the duct combination device; the outer joint comprises a protruding part and a flange plate connected to each other, a first chamfered area is formed at the connection between the protruding part and the flange plate; two reinforcing sheets are riveted to the outer side of the outer joint, the shape enclosed by the two reinforcing sheets matches the shape of the outer joint, a second chamfered area is formed on the reinforcing sheet, and the radius of the first chamfered area is smaller than the radius of the second chamfered area.

[0008] The radius of the first chamfered area is 5mm, and the radius of the second chamfered area is 10mm.

[0009] The support middle section comprises a skin, a front beam, a rear beam and several partitions; the partitions are arranged along the axial direction of the duct assembly device, and are connected with the front beam and the rear beam at two ends respectively.

[0010] The protruding part is formed with a groove; one end of the front beam is riveted with an inner joint, and the other end is inserted into the groove and riveted with an outer joint; the two ends of the rear beam are fixedly connected with the inner joint and the outer joint respectively.

[0011] The outer joint is integrally formed, and the thickness of the flange plate is greater than that of the protruding part.

[0012] The thickness of the flange plate is 4 mm.

[0013] The rear support arm is made of aluminum alloy material.

[0014] The gaps between the two reinforcing sheets and between the reinforcing sheet and the outer joint are sealed by sealing glue.

[0015] The inner structure of the rear support arm is sprayed with two layers of 75 mu m wear-resistant aluminum powder pure epoxy primer, and the outer structure of the rear support arm is sprayed with a protective layer, which comprises two layers of 75 mu m wear-resistant aluminum powder pure epoxy primer, one layer of 75 mu m epoxy connecting paint and two layers of 40 mu m polyurethane topcoat.

[0016] Compared with the prior art, the beneficial effects of the present application are as follows:

[0017] 1. The duct has high flow guiding performance requirements, the structure of the reinforcing sheet is set, the aerodynamic performance is fully considered, and the surface of the outer joint is tightly attached, so that the local fatigue strength is improved while the flow guiding performance is ensured. Further, even if the outer joint fails, the reinforcing sheet still has a certain degree of bearing capacity. At the same time, the design of the reinforcing sheet considers the repair performance in the field, so that the repair and replacement can be quickly carried out even if the failure occurs in the field.

[0018] 2. The radius of the first chamfer area is 5 mm, and the radius of the second chamfer area is 10 mm. The increase of the chamfer area radius causes stress concentration in the chamfer area, thereby improving the local strength of the outer joint.

[0019] 3. The partitions are arranged, on the one hand, to reduce the force arm of the skin shear flow caused by the aerodynamic load of the duct inner wall, increase the stiffness of the rear support skin and improve the deformation resistance. On the other hand, the partitions have a wing type, and the support middle section composed of the front beam, the skin and the rear beam has good flow guiding effect. Moreover, the partitions can accommodate clamps and pipe clamps, which can fix the pipeline and other system equipment, and can reduce the vibration caused by the suspended shaking of the pipeline.

[0020] 4. The thickness of the flange is greater than the thickness of the protrusion, thereby reducing stress concentration at the chamfered front edge of the outer joint.

[0021] 5. The rear support arm is made of aluminum alloy material, which can meet the lightweight requirement of the air cushion vehicle and enable the air cushion vehicle to have high-speed attack capability.

[0022] 6. The sealing is realized by sealing glue, which can avoid seawater from flowing in and metal structure corrosion caused by seawater vapor.

[0023] 7. The inner structure and the outer structure of the rear support arm adopt different paint spraying processes, and the thickness of the paint layer is specially set, so that the process economy can be improved while meeting the corrosion resistance requirement. BRIEF DESCRIPTION OF DRAWINGS

[0024] The application will be further described in detail below in combination with the drawings and specific embodiments, in which:

[0025] Figure 1 Fig. 1 is a schematic diagram of the overall structure of the application;

[0026] Figure 2 Fig. 2 is a schematic diagram of the internal structure of the overall structure of the application;

[0027] Figure 3 Fig. 3 is a schematic diagram of the structure of the outer joint in the application, in which R represents the radius of the first chamfered area;

[0028] Figure 4 Fig. 4 is a schematic diagram of the structure of the reinforcing sheet in the application;

[0029] Markings in the drawings:

[0030] 1. inner joint, 2. support middle section, 3. outer joint, 4. reinforcing sheet, 5. front beam, 6. partition plate, 7. skin, 8. rear beam. DETAILED DESCRIPTION

[0031] Example 1

[0032] As a basic embodiment of the application, the application comprises a rear support arm used in a duct combination device of an air cushion vehicle, which comprises a support middle section 2 and an inner joint 1 and an outer joint 3 connected to the two ends of the support middle section 2 respectively. The inner joint 1 is used to be connected to a shaft sleeve in the duct combination device. The outer joint 3 comprises a protrusion and a flange connected to each other, and a first chamfered area is formed at the connection between the protrusion and the flange. Two reinforcing sheets 4 are riveted to the outer side of the outer joint 3, and the shape enclosed by the two reinforcing sheets 4 matches the shape of the outer joint 3. A second chamfered area is formed on the reinforcing sheet 4, and the radius of the first chamfered area is smaller than the radius of the second chamfered area.

[0033] Example 2

[0034] As a preferred embodiment of the present application, the present application comprises a rear support arm for a hovercraft duct assembly, comprising a support middle section 2 and an inner joint 1 and an outer joint 3 connected to the two ends of the support middle section 2 respectively. The inner joint 1 is used to connect with the shaft sleeve in the duct assembly. The outer joint 3 comprises a convex part and a flange connected to each other, and a first chamfer area is formed at the joint of the convex part and the flange. Two reinforcing sheets 4 are riveted to the outer side of the outer joint 3, and the shape enclosed by the two reinforcing sheets 4 matches the shape of the outer joint 3. A second chamfer area is formed on the reinforcing sheet 4, and the radius of the first chamfer area is smaller than the radius of the second chamfer area.

[0035] The inner joint 1, the support section, the outer joint 3 and the reinforcing sheet 4 are all made of aluminum alloy. The rear support arm is installed in the radial direction of the duct. The support middle section 2 comprises a skin 7, a front beam 5, a rear beam 8 and a plurality of partitions 6. The partitions 6 are provided in N number, arranged in the axial direction of the duct assembly, and divide the skin 7 into N+1 separate areas. N is a natural number. The inner joint 1, the outer joint 3, the partitions 6 and the front beam 5 are riveted to the skin 7 respectively. The front beam 5 is riveted to the inner joint 1 and the outer joint 3 respectively, and the rear beam 8 is welded to the inner joint 1 and the outer joint 3 respectively.

[0036] Example 3

[0037] As another preferred embodiment of the present application, the present application comprises a rear support arm for a hovercraft duct assembly, comprising a support middle section 2 and an inner joint 1 and an outer joint 3 connected to the two ends of the support middle section 2 respectively. The inner joint 1 is used to connect with the shaft sleeve in the duct assembly. The outer joint 3 comprises a convex part and a flange connected to each other, and a first chamfer area is formed at the joint of the convex part and the flange. Two reinforcing sheets 4 are riveted to the outer side of the outer joint 3, and the shape enclosed by the two reinforcing sheets 4 matches the shape of the outer joint 3. A second chamfer area is formed on the reinforcing sheet 4, and the radius of the first chamfer area is smaller than the radius of the second chamfer area.

[0038] In order to reduce the stress concentration of the chamfered front edge of the outer joint 3, the thickness of the flange can be increased, and the thickness of the flange is set to 4mm. At the same time, the radius of the first chamfer area is increased, and the radius of the first chamfer area is set to 5mm, and the radius of the second chamfer area is 10mm.

[0039] During the assembly of the rear support arm, the inner and outer structures are also coated with glue and sprayed with protective paint to ensure corrosion resistance and economic conditions to extend the service life of the structure in the marine environment.

[0040] Example 4

[0041] As the best embodiment of the present application, the drawings attached to the specification Figure 1The present application relates to a kind of rear support arm for air cushion vehicle duct assembly, comprising support midsection 2 and inner joint 1 and outer joint 3 connected with the two ends of support midsection 2 respectively.

[0042] Referring to the drawings Figure 2 Support midsection 2 belongs to thin-walled structure, similar to the structure of aircraft wing.The support midsection 2 includes skin 7, front beam 5, rear beam 8 and two radial direction of duct axial direction of baffle 6.The rear beam 8 is solid structure, not conducive to riveting operation, so that rear beam 8 and inner joint 1 and outer joint 3 are welded.

[0043] Baffle 6 divides skin 7 into three separate areas.On the one hand, it can reduce the force arm of skin 7 shear flow caused by duct inner wall aerodynamic load, increase the stiffness of rear support skin 7, improve the resistance to deformation capacity.On the other hand, baffle 6 has airfoil, and the support midsection 2 composed of front beam 5, skin 7 and rear beam 8 has good flow guide effect.And, baffle 6 can be placed with pipe clamp and pipe clamp, which can fix pipe and other system equipment, and can reduce the vibration caused by pipe hanging and shaking.Baffle 6 and skin 7 are riveted.

[0044] Therefore, skin 7 is connected with inner joint 1, front beam 5 and outer joint 3.Specifically, skin 7 and front beam 5 are riveted;Skin 7, outer joint 3 and reinforcing sheet 4 are riveted;Skin 7 and inner joint 1 are riveted.

[0045] Referring to the drawings Figure 3 Outer joint 3 includes a flange plate and a protruding part connected integrally.The protruding part is formed with a groove.The one end of front beam 5 is riveted with inner joint 1, and the other end is inserted into the groove and riveted with outer joint 3.The outer joint 3 is a machined part, and the flange plate on the side of the duct is thickened by 1mm, becoming 4mm.Structure strengthening usually increases the overall thickness at the same time, but the protruding part of outer joint 3 is limited by internal pipeline and other system equipment, and cannot be increased in thickness and length upward;Due to the limitation of the shape of rear support skin 7, the thickness cannot be increased outward.Taking into account the coordination of the structure, the thickness of the flange plate and the protruding part of outer joint 3 is different, which will cause the connecting chamfer area to become a weak point, so only the thickness of the flange plate can be increased from 3mm to 4mm.The connecting part of the protruding part and the flange plate is formed with a first chamfer area.

[0046] Increasing the radius R of the first chamfer region can effectively reduce the local stress concentration. In view of the structural characteristics of the outer joint 3, while increasing the chamfer, the margin requirement of the rivet must be considered. The larger the chamfer of the outer joint 3, the smaller the skin 7 connection area connected with the riveted connection of the outer joint 3, so the radius of the chamfer region of the outer joint 3 can be increased from 3mm to 5mm, which is used for the stress concentration of the first chamfer region, and improves the local strength of the outer joint 3.

[0047] Referring to the drawings Figure 4 The shape enclosed by the two pieces of reinforcing sheet 4 matches the shape of the outer joint 3, and the second chamfer region is formed on the reinforcing sheet 4, and the radius of the first chamfer region is smaller than the radius of the second chamfer region. The reinforcing sheet 4 is also a machined part, with a thickness of 3mm, and the radius of the second chamfer region can be 10mm. The duct has high flow guiding performance requirements, and the shape of the reinforcing sheet 4 fully considers the aerodynamic performance and closely fits the surface of the outer joint 3, which improves the local fatigue strength while ensuring that the flow guiding performance is not affected. Selecting materials with good fatigue performance is the simplest and most effective way to improve the fatigue strength of the structure. However, the marine environment can exacerbate the electrochemical corrosion between dissimilar metals, so the reinforcing sheet 4 is made of the same aluminum alloy as the outer joint 3 and the skin 7.

[0048] Even if the outer joint 3 fails, the reinforcing sheet 4 still has a certain degree of load-bearing capacity. At the same time, the design of the reinforcing sheet 4 considers the repair performance in the field, so that even if there is a failure in the field, repair and replacement can be quickly carried out.

[0049] The middle gap of the two reinforcing sheets 4 on the left and right sides and the close-fitting gap with the outer joint 3 are sealed with sealant to prevent seawater from flowing in and seawater vapor from causing metal structure corrosion.

[0050] The marine environment is highly corrosive, so the rear arm must have high corrosion resistance. Conventional ships usually use stainless steel materials, which have strong corrosion resistance, while hovercrafts need to have high-speed attack capabilities, so aluminum alloy materials are used for lightweight requirements, which have poor corrosion resistance, so it is necessary to improve their corrosion resistance by painting.

[0051] The paint protection process is carried out at room temperature of 12-35 degrees Celsius and humidity of 70%. Each paint layer needs to be placed for 12-24 hours to make the paint layer fully dry, and the paint layer is tested by using 3M 250 adhesive tape to observe whether the adhesive tape can stick and peel the paint layer. According to the environment and process economy of the rear support structure, different paint spraying processes are used inside and outside the structure. The inside of the structure is not directly in contact with the marine environment, and the process economy is improved to meet the requirement of corrosion resistance, so only two 75μm wear-resistant aluminum powder pure epoxy primer is sprayed. The outside of the structure is directly in contact with seawater and marine environment, and has high corrosion resistance requirement, so two 75μm wear-resistant aluminum powder pure epoxy primer, one 75μm epoxy connecting paint and two 40μm polyurethane topcoat are used for protection. If the thickness of the paint layer is too thin, the corrosion resistance of the structure will be reduced; if the thickness of the paint layer is too thick, the adhesion between the paint layers will be reduced, so the lower limit of the thickness of the sprayed paint layer should not be less than 90% of the specified value, and the upper limit should not exceed 120% of the specified value, and the upper limit of the part not easy to spray can be appropriately widened.

[0052] In summary, after reading the present application document, the ordinary skilled in the art can make various corresponding transformation schemes according to the technical solutions and technical concepts of the present application without creative mental labor, which all belong to the protection scope of the present application.

Claims

1. A rear strut arm for use in a hovercraft duct assembly, characterised in that: The support middle section (2) is connected with the inner joint (1) and the outer joint (3) at both ends of the support middle section (2), the inner joint (1) is used to be connected with the shaft sleeve in the catheter combination device, the outer joint (3) comprises a convex part and a flange plate connected with each other, a first chamfer area is formed at the connection of the convex part and the flange plate, two reinforcing sheets (4) are riveted on the outer side of the outer joint (3), the shape enclosed by the two reinforcing sheets (4) matches the shape of the outer joint (3), a second chamfer area is formed on the reinforcing sheet (4), the radius of the first chamfer area is smaller than the radius of the second chamfer area, and the gap between the two reinforcing sheets (4) and the gap between the reinforcing sheet (4) and the outer joint (3) are sealed by sealing glue.

2. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 1, characterised in that: The radius of the first chamfer area is 5mm, and the radius of the second chamfer area is 10mm.

3. A rear strut arm for use in a combination of ducts for a hovercraft as claimed in claim 1 or claim 2, wherein: The support middle section (2) comprises a skin (7), a front beam (5), a rear beam (8) and a plurality of partitions (6), the partitions (6) are arranged along the axial direction of the catheter combination device, and the two ends are connected with the front beam (5) and the rear beam (8) respectively.

4. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 3, wherein: A groove is formed on the convex part, one end of the front beam (5) is riveted with the inner joint (1), the other end is inserted into the groove and riveted with the outer joint (3), and the two ends of the rear beam (8) are fixedly connected with the inner joint (1) and the outer joint (3) respectively.

5. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 4, wherein: The outer joint (3) is integrally formed, and the thickness of the flange plate is greater than the thickness of the convex part.

6. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 5, wherein: The thickness of the flange plate is 4mm.

7. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 1, characterised in that: The rear support arm is made of aluminum alloy material.

8. A rear strut arm for use in a duct assembly for a hovercraft as claimed in claim 1, characterised in that: The internal structure of the rear support arm is sprayed with 2 layers of 75μm wear-resistant aluminum powder pure epoxy primer, and a protective layer is sprayed on the external structure of the rear support arm, the protective layer comprises 2 layers of 75μm wear-resistant aluminum powder pure epoxy primer, 1 layer of 75μm epoxy connecting paint and 2 layers of 40μm polyurethane topcoat.

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