Rain erosion resistant protection method for rigid composite material part

Abstract

The invention discloses a rain-erosion-resistant protection method for a rigid composite material part, and belongs to the technical field of composite material protection. In order to solve the problem that a rigid composite part is easily impacted and damaged by liquid drops in a rain erosion scene, a method of removing a preset thickness of a rigid layer and laying a fiber-reinforced flexible composite material as a flexible layer is mainly adopted, and the flexible layer and the rigid layer are connected through in-situ curing of flexible resin, so that the overall protection performance is improved. According to the method, the synergistic effect that the rigid part bears the structural load and the flexible part absorbs impact energy can be achieved, and the rain erosion resistance, sand erosion resistance and impact resistance of a workpiece are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material protection, and in particular relates to a rain erosion resistance protection method for rigid composite material parts. Background Art

[0002] At present, in order to achieve the goals of wave transmission / stealth / lightweight, equipment such as aircraft wave-transmitting cabins, aerodynamic leading edges, and leading edges of wind turbine blades use a large number of quartz / glass fiber composite materials, carbon fiber composite materials, etc. With the further increase in tip speed and the increase in the demand for all-weather use, the defect of composite products that are not resistant to rain erosion is further exposed. When the aircraft penetrates rain or clouds or the rotor parts rotate at high speed in droplets, they are eroded by rain, and the matrix in the composite material will break, the fibers will break, and even the structure will be damaged. This is an important reason for the damage of composite materials during service in high-speed scenarios.

[0003] At present, in order to improve the rain erosion resistance of components in high-speed scene composite products, there are two main technical paths: one is to apply a flexible coating on the surface of the component, and the other is to lay a flexible film. The systems adopted by the flexible coating include chloroprene rubber, polyurethane, fluororubber and other coatings, which are suitable for different temperature conditions. However, since the coating is applied in situ on the surface of the component and the coating system usually has no reinforcement, the fracture strength and elongation of the coating material are poor and heavily dependent on the coating process; the laying of flexible film usually adopts polyurethane film bonded with pressure-sensitive adhesive or hot-melt adhesive. Since the polyurethane film is prepared separately, it can be strengthened by high pressure or biaxial stretching. Its fracture strength and elongation can exceed the coating material by 100% to 150%, but the bonding interface strength of the pressure-sensitive adhesive or hot-melt adhesive is poor. Under rain erosion conditions, the interface is first damaged, resulting in bubbling or peeling between the rain erosion protection film and the substrate. Summary of the invention

[0004] The purpose of the present invention is to provide a method for rain erosion protection of rigid composite parts. By designing and adding a flexible layer on the rigid composite parts, the rain erosion protection performance of the rigid composite parts can be greatly improved.

[0005] The technical solution adopted by the present invention to achieve its purpose is as follows:

[0006] A method for protecting a rigid composite material from rain erosion comprises the following steps:

[0007] Determine the area to be protected of the rigid composite material part, and remove the rigid layer of the area with a preset thickness;

[0008] The fiber-reinforced flexible composite material is laid on the area to be protected as a flexible layer, and a flexible resin is used to in-situ cure and connect it to the rigid layer to achieve rain erosion protection.

[0009] Furthermore, if the rigid layer of the rigid composite product originally contains a rain erosion protection layer, the fiber-reinforced flexible composite material is laid between the rain erosion protection layer and the rigid layer with a preset thickness removed, so that the formed flexible layer serves as an intermediate interlayer.

[0010] Furthermore, the rigid composite material product is a wave-transmitting structure, a load-bearing structure, a rectifying structure, a rotor-type structure, an impact-resistant structure or an explosion-resistant structure for use in rain erosion scenarios.

[0011] Furthermore, the fiber-reinforced flexible composite material includes one of a quartz fiber-reinforced polyurethane composite material, a carbon fiber-reinforced polyurea composite material, a glass fiber-reinforced polyurea composite material, a quartz fiber-reinforced polyurea composite material, a carbon fiber-reinforced silicone rubber composite material, and a carbon fiber-reinforced polysiloxane composite material.

[0012] Furthermore, if the rigid layer of the rigid composite material part is made of quartz fiber reinforced cyanate ester composite material, the flexible layer is made of quartz fiber reinforced polyurethane composite material.

[0013] Furthermore, if the rigid layer of the rigid composite material part is made of carbon fiber reinforced epoxy resin composite material, the flexible layer is made of carbon fiber reinforced polyurea composite material.

[0014] Furthermore, if the rigid layer of the rigid composite material part adopts aramid / carbon fiber mixed braided fabric reinforced epoxy resin composite material, the flexible layer adopts carbon fiber reinforced silicone rubber composite material.

[0015] The beneficial effects achieved by the present invention are as follows:

[0016] 1. The present invention greatly improves the rain erosion resistance of the rigid composite material part by designing and adding a fiber-reinforced flexible layer on the surface of the part, and can effectively absorb the impact energy of droplets and buffer stress.

[0017] 2. The present invention adopts an in-situ curing process of a flexible resin, so that the bonding force between the flexible layer and the rigid layer is strong, and the structural stability and protective effect are significantly enhanced.

[0018] 3. The present invention optimizes the materials of the flexible layer and the rigid layer, thereby realizing the design of different material systems in the thickness direction of the product, and obtaining a multifunctional structural layer with different stiffness and impact resistance.

[0019] 4. The present invention is suitable for a variety of harsh application scenarios, such as rain erosion, sand erosion, bullet-proof fragment impact or blasting and other complex working conditions, and meets various requirements such as wave-transmitting structure, load-bearing structure, and impact-resistant structure.

[0020] 5. The present invention makes full use of the designability of composite materials, optimizes the balance between structural load-bearing and rain erosion / sand erosion / impact resistance, and expands the potential application of composite materials in complex environments such as aircraft.

[0021] 6. The present invention provides customized solutions for various specific scenarios through the rational combination of different materials, such as quartz fiber reinforced cyanate ester and polyurethane, carbon fiber reinforced epoxy resin and polyurea, etc., showing strong adaptability and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the improvement of the rain erosion protection of the leading edge of the aircraft fairing in Example 1.

[0023] Figure 2 It is a schematic diagram of the improved rain erosion protection of the leading edge of the tail wing of the fixed-wing UAV in Example 2.

[0024] Figure 3 It is a schematic diagram of the improved rain erosion protection of the UAV antenna cover in Example 3.

[0025] Figure 4 It is a schematic diagram of the improved rain erosion protection of the leading edge of a wind turbine blade in Example 4. DETAILED DESCRIPTION

[0026] In order to make the various technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below with reference to the accompanying drawings.

[0027] Example 1

[0028] The fairing of a certain civil aircraft adopts a single-layer structure of glass fiber reinforced epoxy resin composite material. Its leading edge is damaged by rain erosion / sand erosion during service, and the standard rain erosion resistance life of the structure is 35 minutes. The method of the present invention is used to improve it, and 1 / 3 of the total thickness of the glass fiber reinforced epoxy resin composite material (i.e., the rigid layer) at the leading edge is replaced with a glass fiber reinforced polyurea composite material as a flexible layer to form a gradient composite material structure. Figure 1 .

[0029] Glass fiber reinforced polyurea composite materials have dielectric properties close to those of glass fiber reinforced epoxy composite materials, so they have almost no effect on the wave transmission characteristics. The improved gradient composite material structure was subjected to rain erosion test. Under the same rainfall and flight speed, the rain erosion life of the improved structure reached 140 minutes. At the same time, the improved gradient composite material structure was subjected to vibration, impact, bird strike, aerodynamic load and other assessments. Due to the damping effect of the flexible layer, the structure responded less under dynamic loads such as vibration and impact. The simulated deformation under aerodynamic load increased by 20% relative to the original state, and the simulated maximum stress increased by 25% relative to the original state, both of which were within the safe range. The improved gradient composite material structure was subjected to actual strength tests. The maximum deformation of the product under the limiting load increased by 22% relative to the original state, and the maximum stress of the sampling point test increased by 24% relative to the original state, both of which were within a safe state.

[0030] Example 2

[0031] The leading edge of the tail wing of a certain civilian fixed-wing UAV adopts a 3.0mm thick carbon fiber reinforced epoxy resin composite material structure (i.e., the rigid layer). A 0.36mm flexible polyurethane film was originally attached to the surface as a rain erosion protection layer for improvement. Tests found that after about 90 minutes of standard rain erosion test, delamination between the polyurethane film and the substrate appeared in the improved structure. The method of the present invention is used to improve the original structure, and the 3.0mm thick carbon fiber reinforced epoxy resin composite rigid layer thickness of the leading edge part is reduced to 2.7mm, and a 0.5mm thick carbon fiber reinforced polysiloxane composite material is added as a flexible layer. A 0.36mm flexible polyurethane film rain erosion protection layer is attached to the surface (not shown) to form a gradient composite material structure. Figure 2 .

[0032] Since a flexible layer is added as a transition between the flexible polyurethane film and the rigid layer, it provides load buffering during impact load. The improved gradient composite material structure was subjected to a standard rain erosion test. After 240 minutes, pitting corrosion occurred in the flexible polyurethane film and began to expand damage, while the interface was never damaged. At the same time, structural strength, fatigue and vibration impact assessments were carried out, and the structural safety and fatigue characteristics met the design requirements.

[0033] Example 3

[0034] The antenna cover of a certain civilian UAV adopts a honeycomb sandwich structure, and the outer skin is a 1mm thick quartz fiber reinforced epoxy resin composite material structure. During the test flight, it was found that after 5-7 takeoffs and landings in rainy weather, the outer skin began to be seriously damaged and could not continue to serve. The method of the present invention is used to improve it, and the outer skin is optimized to a 0.7mm thick quartz fiber reinforced epoxy resin composite material structure (i.e., rigid layer) and a 0.4mm thick quartz fiber reinforced polyurea composite material structure (i.e., flexible layer), forming a gradient composite material structure, which can maintain the original structural strength and rigidity. Figure 3 .

[0035] The improved gradient composite material structure has been tested in flight. After 13-15 takeoffs and landings in rainy weather, the rigid layer of the outer skin is intact, but cracks appear in the flexible layer. However, the flexible layer of quartz fiber reinforced polyurea composite material can be re-prepared after in-situ grinding and painted to continue to serve, which can continue to prevent damage to the rigid layer of the outer skin. The electrical properties, structural strength and stiffness, and rain erosion resistance of the repaired product are all no different from the original state.

[0036] Example 4

[0037] The blade working radius of a certain type of wind power equipment is 60 meters, the maximum rotation speed is 38r / min, the maximum tip speed is 120m / s, the main structure of the blade is a foam core layer and a glass fiber epoxy resin composite skin structure (i.e., a rigid layer), the skin structure thickness is 8mm, and the surface is coated with a coating with a thickness of 1.2mm as a rain erosion protection layer. Under the meteorological conditions of the installation location, under the combined effects of environmental conditions such as rain erosion / sand erosion / sunlight, the maintenance cycle is 1.5 years. The method of the present invention is used to improve the thickness of the skin structure, keep the thickness unchanged, form a glass fiber reinforced polyurea composite material with a thickness of 0.5mm thereon as a flexible layer structure, and apply a rain erosion protection layer with a thickness of 0.7mm on the flexible layer structure to form a gradient composite material, see Figure 4 .

[0038] The total structural thickness of the improved gradient composite material remains unchanged, and the increase in thickness echelons has an impact on the weight of the entire structure of no more than 2%. Within the design tolerance range, after equivalent tests and actual installation assessments, the environmental corrosion resistance has been significantly improved, and the maintenance cycle has been increased to 2.5-3 years, which has significantly increased the continuous operation time of the equipment and reduced the equipment maintenance cost.

[0039] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A method for protecting a rigid composite material from rain erosion, characterized in that: The following steps are involved: Determine the area to be protected of the rigid composite material part, and remove the rigid layer of the area with a preset thickness; The fiber-reinforced flexible composite material is laid on the area to be protected as a flexible layer, and a flexible resin is used to in-situ cure and connect it to the rigid layer to achieve rain erosion protection.

2. The method according to claim 1, characterized in that If the rigid layer of the rigid composite product originally contains a rain erosion protection layer, the fiber-reinforced flexible composite material is laid between the rain erosion protection layer and the rigid layer with a preset thickness removed, so that the formed flexible layer serves as an intermediate layer.

3. The method according to claim 1, characterized in that The rigid composite material product is a wave-transmitting structure, a load-bearing structure, a rectifying structure, a rotor-type structure, an impact-resistant structure or an explosion-resistant structure used in rain erosion scenarios.

4. The method according to claim 1, characterized in that The fiber-reinforced flexible composite material includes one of a quartz fiber-reinforced polyurethane composite material, a carbon fiber-reinforced polyurea composite material, a glass fiber-reinforced polyurea composite material, a quartz fiber-reinforced polyurea composite material, a carbon fiber-reinforced silicone rubber composite material, and a carbon fiber-reinforced polysiloxane composite material.

5. The method according to claim 4, characterized in that If the rigid layer of the rigid composite material part is made of quartz fiber reinforced cyanate ester composite material, the flexible layer is made of quartz fiber reinforced polyurethane composite material.

6. The method according to claim 4, characterized in that If the rigid layer of the rigid composite material part is made of carbon fiber reinforced epoxy resin composite material, the flexible layer is made of carbon fiber reinforced polyurea composite material.

7. The method according to claim 4, characterized in that If the rigid layer of the rigid composite material part adopts aramid / carbon fiber mixed woven fabric reinforced epoxy resin composite material, the flexible layer adopts carbon fiber reinforced silicone rubber composite material.

Images