Interface toughening high stiffness fiber metal propeller blade design method and application

Abstract

This invention provides a design method and application for interface-toughened high-stiffness fiber-metal propeller blades. The high-stiffness fiber-metal propeller blade is made of carbon fiber composite material and embedded titanium alloy sheet laminate. The titanium alloy sheet is embedded at the blade tip position and has a groove structure on its surface that is consistent with the fiber direction of the adjacent carbon fiber composite layer. The grooves on the surface of the titanium alloy allow the adjacent fiber bundles to be embedded to form a mechanical interlock, which improves the interlayer bonding strength of the heterogeneous interface. The surface grooves can coordinate the two materials with large differences in thermal expansion coefficients, reduce the residual stress after heating and pressurizing curing, and improve the stress state at the interface between the titanium alloy and the carbon fiber prepreg. Through reasonable component ratio, structural design and layup process, an interface-toughened high-stiffness fiber-metal propeller blade is formed.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding and marine engineering technology, and in particular to a design method and application of interface-toughened high-stiffness fiber-reinforced metal propeller blades. Background Technology

[0002] In the shipbuilding industry, traditional metal propellers are prone to cavitation corrosion and fatigue cracks, and the cost of processing complex metal materials is high. Fiber metal propellers have their own advantages, which can combine the excellent properties of metal and carbon fiber composite materials. However, under local stress, the blade tip deforms severely, which leads to a reduction in the overall stiffness of the blade. At the same time, the interface between heterogeneous materials is affected by the material properties, and is prone to metal / fiber interface delamination, fiber-resin matrix debonding, etc. Depending on the applied stress, its failure mode is also more complex.

[0003] This invention mainly studies the design method of toughening the interface of fiber-metal propeller blades to improve the overall stiffness of the blades. By toughening the titanium alloy material inside the fiber-metal propeller blades, the surface of the titanium alloy sheet contains a groove structure that is consistent with the direction of the adjacent fiber layer. The fiber and the groove structure form a mechanical interlock, which improves the interfacial bonding strength of the heterogeneous materials and reduces the damage modes inside the blade. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a design method for high-stiffness fiber-reinforced metal propeller blades with interface toughening. The technical means employed in this invention are as follows:

[0005] A design method for high-stiffness fiber-metal propeller blades with interface toughening is disclosed. The blades of the fiber-metal propeller are made of a carbon fiber composite layer and an embedded titanium alloy sheet. The titanium alloy sheet is embedded at the tip of the blade and the surface contains a groove structure that is consistent with the fiber direction of the adjacent carbon fiber composite layer. The overall stiffness of the fiber-metal propeller blade is related to the mechanical properties, component ratio, and shape structure of the two materials. By adjusting the mechanical properties, component ratio, and shape structure of the two materials, a fiber-metal propeller blade with a preset stiffness can be obtained.

[0006] Furthermore, the carbon fiber composite material layer includes a multilayer carbon fiber / epoxy resin composite prepreg, and the titanium alloy sheet structurally replaces the original carbon fiber composite propeller blade. The shape is consistent with the blade of the replaced layer and the length-to-thickness ratio is greater than 10:1. The surface of the titanium alloy sheet includes parallel straight groove structures with equal spacing and depth, and the groove orientation is consistent with the fiber direction of the adjacent carbon fiber composite material layer.

[0007] Furthermore, the groove is a linear structure with a length consistent with the blade structure, and its width and depth are both less than 1 / 2 of the thickness of the titanium alloy sheet. The spacing between the grooves is greater than the width of a single groove.

[0008] Furthermore, machining straight grooves on the surface of the titanium alloy sheet can increase the contact area between the titanium alloy and the fiber, allowing the fibers and resin of adjacent layers to be embedded in the grooves under the hot pressing load during the molding process, forming a mechanical interlock to improve the interface's resistance to shear failure.

[0009] Furthermore, after the titanium alloy sheet is processed, processing burrs are retained on the surface. These processing burrs can enhance fiber bonding and improve the interfacial shear strength and the interface's resistance to opening damage.

[0010] Furthermore, in addition to the relevant parameters of titanium alloy and carbon fiber composite materials, the overall stiffness of the propeller blade is also affected by the groove structure. The overall stiffness of the fiber-reinforced metal propeller blade is calculated using the following formula:

[0011]

[0012] in

[0013]

[0014] Where Q represents the stiffness of the titanium alloy or carbon fiber prepreg, Y represents the number of titanium alloy layers, m represents the minimum number of titanium alloy layers, n represents the number of carbon fiber prepreg layers, and h represents the thickness of the titanium alloy or carbon fiber prepreg. mTi Z represents the actual thickness of each titanium alloy sheet excluding the grooved portion, Z represents the number of grooves, and S represents the actual thickness of each layer of titanium alloy sheet excluding the grooved portion. g h represents the surface area of ​​the groove. g S represents the groove depth. Ti This represents the surface area of ​​each titanium alloy sheet. The subscript Ti represents titanium alloy, and the subscript c represents carbon fiber prepreg.

[0015] Furthermore, with the middle layer of the blade as the center of symmetry, titanium alloy sheets with grooved structures are embedded in the multi-layer blades near the back surface and the side of the blade that is splashing water. Through the component ratio of the symmetrical layered structure design, the embedded titanium alloy sheets are designed to have double-sided grooves. The groove direction is consistent with the direction of the adjacent fiber layer. The multi-layer carbon fiber composite material in contact with the grooves is tightly bonded to ensure no wrinkles or air bubbles.

[0016] Furthermore, based on the designed composite propeller blade layup sequence, carbon fiber composite material and grooved titanium alloy sheets are laid sequentially. After laying, the fiber-metal propeller blade is heated and pressurized using a hot press. The fluidity of the resin during the hot pressing process allows the fibers to be embedded in the grooves on the adjacent titanium alloy surface under pressure, forming a mechanical interlock between the fiber bundle and the titanium alloy. The processed grooves increase the bonding area between layers, and the burrs processed on the titanium alloy are embedded in the resin to form a micro-mechanical anchoring, thereby improving the heterogeneous interface bonding strength of the fiber-metal propeller blade and increasing its overall stiffness.

[0017] The present invention also discloses a fiber metal propeller blade manufactured using the above-mentioned interface toughening high stiffness fiber metal propeller blade design method.

[0018] The present invention has the following advantages:

[0019] 1. Fiber metal propeller blades made of carbon fiber / epoxy resin composite prepreg and titanium alloy sheets with groove structure have the advantages of being lightweight, deformable and designable, having high blade rigidity, and high interlayer bonding strength of heterogeneous materials.

[0020] 2. By embedding carbon fiber and resin into grooves on the surface of titanium alloy during hot pressing, the fiber can be embedded. The grooves increase the bonding area between dissimilar materials. At the same time, the burrs embedded in the resin can play a micro-mechanical anchoring role, which can improve the interlayer bonding strength of fiber metal propeller blades and ensure that their interlayer fracture toughness meets the requirements.

[0021] 3. The groove design in this invention combines the excellent properties of the two materials, reduces the residual stress generated between the heterogeneous materials after heating and pressurizing, and improves the overall performance of the fiber-metal propeller blade.

[0022] 4. Establish the relationship between the stiffness of fiber-reinforced metal propeller blades and the mechanical properties, component ratios, and groove structures of heterogeneous materials. Through reasonable structural design and symmetrical layup, and by fully combining the deformable design of fiber layers with the high stiffness advantage of titanium alloys, the problem of insufficient stiffness in traditional fiber-reinforced metal propellers is solved. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the internal components of the blade of the present invention.

[0025] Figure 2 This is a schematic diagram illustrating the principle of the original phase toughening method of this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 , Figure 2 As shown in the figure, this invention discloses a design method for a high-stiffness fiber-metal propeller blade with interface toughening. The blade of the fiber-metal propeller is made of a carbon fiber composite material layer and an embedded titanium alloy sheet. The titanium alloy sheet is embedded at the tip of the blade, and the surface contains a groove structure that is consistent with the fiber direction of the adjacent carbon fiber composite material layer. The overall stiffness of the fiber-metal propeller blade is related to the mechanical properties, component ratio, and shape structure of the two materials. By adjusting the mechanical properties, component ratio, and shape structure of the two materials, a fiber-metal propeller blade with a preset stiffness can be obtained. A reasonable structural design can achieve the optimal overall stiffness of the blade.

[0028] The carbon fiber composite material layer includes multiple layers of carbon fiber / epoxy resin composite prepreg. The titanium alloy sheet replaces the original carbon fiber composite propeller blade in structure. It is a titanium alloy sheet with the same shape as the blade being replaced and a length-to-thickness ratio greater than 10:1. The surface of the titanium alloy sheet contains parallel straight grooves of equal spacing and depth. The groove orientation is consistent with the fiber direction of the adjacent carbon fiber composite material layer.

[0029] The groove is a linear structure with a length consistent with the blade structure. Its width and depth are both less than 1 / 2 of the thickness of the titanium alloy sheet. The spacing between the grooves is greater than the width of a single groove. If the grooves are too deep, gaps will appear between the fibers and the grooves during the hot pressing process. If the spacing between the grooves is greater than the width of a single groove, too few grooves will reduce the bonding strength of the heterogeneous interface, while too many grooves will reduce the performance of the single-layer titanium alloy and affect the overall blade stiffness.

[0030] Processing straight grooves on the surface of titanium alloy sheets can increase the contact area between the titanium alloy and the fiber, allowing the fibers and resin of adjacent layers to be embedded in the grooves under hot pressure during the molding process, forming a mechanical interlock to improve the interface's resistance to shear failure.

[0031] After the titanium alloy sheet is processed, processing burrs are retained. These processing burrs can enhance fiber bonding and improve the interfacial shear strength and the interface's resistance to opening failure.

[0032] In addition to the relevant parameters of titanium alloy and carbon fiber composite materials, the overall stiffness of the propeller blade is also affected by the groove structure. The overall stiffness of the fiber-reinforced metal propeller blade is calculated using the following formula:

[0033]

[0034] in

[0035]

[0036] Where Q represents the stiffness of the titanium alloy or carbon fiber prepreg, Y represents the number of titanium alloy layers, m represents the minimum number of titanium alloy layers, n represents the number of carbon fiber prepreg layers, and h represents the thickness of the titanium alloy or carbon fiber prepreg. mTi Z represents the actual thickness of each titanium alloy sheet excluding the grooved portion, Z represents the number of grooves, and S represents the actual thickness of each layer of titanium alloy sheet excluding the grooved portion. g h represents the surface area of ​​the groove. g S represents the groove depth. Ti The subscript "Ti" represents the surface area of ​​each titanium alloy sheet, with "Ti" indicating titanium alloy and "c" indicating carbon fiber prepreg. Specifically, in this embodiment, a metal layer, i.e., an intermediate layer, is mainly laid in the area of ​​severe blade tip deformation. This improves the blade strength without adding excessive weight. The minimum number of titanium alloy layers is one, which can be adjusted according to actual conditions.

[0037] With the middle layer of the blade as the center of symmetry, titanium alloy sheets with grooved structures are embedded in the multi-layer blades near the back surface and the side that splashes water. Through the symmetrical layered structure design of the component ratio, the embedded titanium alloy sheets are designed to have double-sided grooves. The groove direction is consistent with the direction of the adjacent fiber layer. The multi-layer carbon fiber composite material in contact with the grooves is tightly bonded to ensure no wrinkles or air bubbles.

[0038] Based on the designed composite propeller blade layup sequence, carbon fiber composite material and grooved titanium alloy sheets are laid sequentially. After laying, the fiber-metal propeller blade is heated and pressurized using a hot press. The fluidity of the resin during the hot pressing process allows the fibers to be embedded in the grooves on the adjacent titanium alloy surface under pressure, forming a mechanical interlock between the fiber bundle and the titanium alloy. The processed grooves increase the bonding area between layers, and the fiber embedded in the groove structure forms a micro-mechanical anchor, thereby improving the heterogeneous interface bonding strength of the fiber-metal propeller blade and increasing its overall stiffness.

[0039] The present invention also discloses a fiber metal propeller blade manufactured using the above-mentioned interface toughening high stiffness fiber metal propeller blade design method.

[0040] Example 1

[0041] This embodiment provides a specific manufacturing process, specifically: the blades of the fiber metal propeller are made of a carbon fiber composite material layer and an embedded high-rigidity titanium alloy sheet laminate; the carbon fiber composite material is a T300 grade carbon fiber resin-based composite prepreg with a single layer thickness of 0.13mm to 0.2mm; the titanium alloy sheet material is TC4 titanium alloy with a thickness of 0.5mm to 2mm.

[0042] The titanium alloy sheet is a metal sheet with a length-to-thickness ratio greater than 10:1, cut into the shape of adjacent layer blades. The surface of the titanium alloy sheet contains parallel straight grooves of equal spacing and depth, and the orientation of the grooves is consistent with the fiber laying direction of the adjacent carbon fiber composite layer.

[0043] Specifically, the shape of the titanium alloy sheet is consistent with the shape of the adjacent blade layer. The thickness of the titanium alloy is determined based on a length-to-thickness ratio greater than 10:1. The surface of the titanium alloy sheet is grooved by wire cutting. The direction of the groove on the surface of the titanium alloy is consistent with the direction of the adjacent carbon fiber prepreg, so that the fiber bundles of the adjacent layer are embedded in the groove structure, thereby increasing their interlayer bonding strength.

[0044] The groove is a straight-line structure with the same length as the blade structure. Its width and depth are both less than 1 / 2 of the thickness of the metal sheet. The straight-line groove is machined on the surface of the titanium alloy sheet to increase the contact area between the titanium alloy and the fiber. This allows the fibers and resin of the adjacent layers to be embedded in the groove under the hot-press load during the molding process, forming a mechanical interlock and improving the interface's ability to resist shear failure.

[0045] Specifically, the titanium alloy surface is first pretreated by sanding the surfaces to be bonded with sandpaper. First, use 360-grit coarse sandpaper, then 600-grit, and finally 1000-grit sandpaper for fine sanding. Then, degrease the surface in acetone solution for 1-2 minutes and wipe the surfaces with anhydrous ethanol to remove grease, dirt, and dust. Next, grooves are machined on the titanium alloy surface using wire cutting. Depending on the thickness of the titanium alloy, the groove depth is 0.5-1 mm. The groove depth should not be too small to ensure that some fiber bundles can be embedded, increasing the interlayer bonding strength at the heterogeneous interface. The groove depth should also not be too large, as excessive depth will result in excessive residual stress between the carbon fiber composite and the titanium alloy during heating and pressurization, leading to severe deformation and reducing the overall strength of the composite propeller blade with embedded metal. The groove spacing is 1-2 mm.

[0046] After the surface of titanium alloy sheets is processed, the fiber connection can be enhanced, and the interfacial shear strength and the interfacial resistance to tensile failure can be improved.

[0047] Specifically, the processed titanium alloy is placed in an ultrasonic cleaner containing anhydrous ethanol solution to remove grease, dirt and dust remaining on the surface of the titanium alloy after processing.

[0048] Considering the grooved structure on the embedded metal surface, the overall stiffness of the blade, in addition to being related to the relevant parameters of the titanium alloy and carbon fiber prepreg, should also take into account the influence of the grooved structure on the blade stiffness. The overall stiffness of the fiber-reinforced metal propeller blade is calculated using the following formula:

[0049]

[0050] in

[0051]

[0052] Where Q represents the stiffness of the titanium alloy or carbon fiber prepreg, Y represents the number of titanium alloy layers, m represents the minimum number of titanium alloy layers, n represents the number of carbon fiber prepreg layers, and h represents the thickness of the titanium alloy or carbon fiber prepreg. mTi Z represents the actual thickness of each titanium alloy sheet excluding the grooved portion, Z represents the number of grooves, and S represents the actual thickness of each layer of titanium alloy sheet excluding the grooved portion. g h represents the surface area of ​​the groove. g S represents the groove depth. Ti This represents the surface area of ​​each titanium alloy sheet, with the subscript Ti indicating titanium alloy and the subscript c indicating carbon fiber prepreg.

[0053] With the middle layer of the blade as the center of symmetry, titanium alloy sheets with grooved structures are embedded in multiple blades near the back surface and the side of the blade that splashes water. Through the symmetrical layered structure design of the component ratio, the embedded titanium alloy sheets are designed to have double-sided grooves. The groove direction is consistent with the direction of the adjacent fiber layer. The multi-layer carbon fiber composite material in contact with the grooves is tightly bonded to ensure no wrinkles or air bubbles.

[0054] Specifically, the composite propeller blade model was established by using a laser cutter to cut unidirectional carbon fiber prepreg. Taking the middle layer of the blade as the center of symmetry, titanium alloy sheets with grooved structures were embedded in multiple layers of blades near the back surface and the side that splashes water. The titanium alloy sheets have a double-sided grooved structure, and the groove direction is consistent with the direction of the adjacent carbon fiber prepreg. The whole structure forms a symmetrical layup. On the surface-treated titanium alloy sheet, the multiple layers of carbon fiber prepreg are tightly bonded together. During the layup process, a vacuum is drawn every two layers of carbon fiber prepreg to ensure that there are no wrinkles or air bubbles.

[0055] Based on the designed composite propeller blade layup sequence, carbon fiber composite material and grooved titanium alloy sheets are laid sequentially. After laying, the fiber-metal propeller blade is heated and pressurized using a hot press. The fluidity of the resin during the hot pressing process allows the fibers to be embedded in the directional grooves on the adjacent titanium alloy surface under pressure, forming a mechanical interlock between the fiber bundle and the titanium alloy. The processed grooves increase the bonding area between layers, and the burrs processed on the titanium alloy are embedded in the resin to form a micro-mechanical anchoring, thereby improving the heterogeneous interface bonding strength of the fiber-metal propeller blade and increasing its overall stiffness.

[0056] Specifically, based on the designed composite material propeller blade model, a corresponding propeller mold is processed; a release agent is applied to the mold surface, and an air gun is used to accelerate the drying of the release agent. After the release agent dries, the laid-out layers are placed into the mold, and then the mold is closed; then the mold is placed in a hot press. In the first stage, the temperature is raised to 120℃, the temperature change time is 100s, the product pressure is 0.4Mpa, and the heating time is set to 30min; the second stage is the heat preservation stage, where the temperature is maintained at 120℃, the temperature change time is 800s, the product pressure is 1Mpa, and the heat preservation time is set to 120min; in the third stage, the temperature is naturally cooled to room temperature, the mold is opened, and the part is removed; after demolding, the edges are trimmed using machining to obtain interface-toughened high-rigidity fiber metal propeller blades.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of designing an interface-toughened high-stiffness fiber metal propeller blade, characterized by, The blades of the fiber-metal propeller are made of a composite layer of carbon fiber and an embedded titanium alloy sheet. The titanium alloy sheet is embedded at the tip of the blade and has a groove structure on the surface that is consistent with the fiber direction of the adjacent carbon fiber composite layer. The overall stiffness of the fiber-metal propeller blade is related to the mechanical properties, component ratio, and shape structure of the two materials. By adjusting the mechanical properties, component ratio, and shape structure of the two materials, a fiber-metal propeller blade with a preset stiffness can be obtained. The carbon fiber composite material layer includes multiple layers of carbon fiber / epoxy resin composite prepreg. The titanium alloy sheet structurally replaces the original carbon fiber composite propeller blade. Its shape is consistent with the blade of the replaced layer and its length-to-thickness ratio is greater than 10:

1. The surface of the titanium alloy sheet contains parallel straight grooves of equal spacing and depth. The length of the groove structure is the same as that of the blade structure, and the width and depth are both less than 1 / 2 of the thickness of the titanium alloy sheet. The spacing between the grooves is greater than the width of a single groove. In addition to the relevant parameters of titanium alloy and carbon fiber composite materials, the overall stiffness of the propeller blade is also affected by the groove structure. The overall stiffness of the fiber-reinforced metal propeller blade is calculated using the following formula: in Where Q represents the stiffness of the titanium alloy or carbon fiber prepreg, and Y represents the number of layers in the titanium alloy. m The minimum number of layers in a titanium alloy. n Represents the number of layers in carbon fiber prepreg. h This represents the thickness of the titanium alloy or carbon fiber prepreg. h mTi This represents the actual thickness of each titanium alloy sheet excluding the grooved portion. Z Represents the number of grooves. S g Represents the surface area of ​​the groove. h g Represents the depth of the groove. S Ti Represents the surface area of ​​each titanium alloy sheet, subscript Ti Represents titanium alloy, subscript c Represents carbon fiber prepreg; With the middle layer of the blade as the center of symmetry, titanium alloy sheets with grooved structures are embedded in multiple layers of blades near the back surface and the side that splashes water. Through the symmetrical layered structure design of the component ratio, the embedded titanium alloy sheets are designed to have double-sided grooves. The multi-layer carbon fiber composite material in contact with the grooves is tightly bonded to ensure no wrinkles or air bubbles.

2. The design method for high-stiffness fiber-reinforced metal propeller blades with interface toughening according to claim 1, characterized in that, Processing straight grooves on the surface of titanium alloy sheets can increase the contact area between the titanium alloy and the fiber, allowing the fibers and resin of adjacent layers to be embedded in the grooves under hot pressure during the molding process, forming a mechanical interlock to improve the interface's resistance to shear failure.

3. The design method for interface-toughened high-stiffness fiber-reinforced metal propeller blades according to claim 1, characterized in that, After the titanium alloy sheet is processed, processing burrs are retained. These processing burrs can enhance fiber bonding and improve the interfacial shear strength and the interface's resistance to opening failure.

4. The design method for interface-toughened high-stiffness fiber-reinforced metal propeller blades according to claim 1, characterized in that, Based on the designed composite propeller blade layup sequence, carbon fiber composite material and grooved titanium alloy sheets are laid sequentially. After laying, the fiber-metal propeller blade is heated and pressurized using a hot press. The fluidity of the resin during the hot pressing process allows the fibers to be embedded in the grooves on the adjacent titanium alloy surface under pressure, forming a mechanical interlock between the fiber bundle and the titanium alloy. The processed grooves increase the bonding area between layers, and the burrs processed on the titanium alloy are embedded in the resin to form a micro-mechanical anchoring, thereby improving the heterogeneous interface bonding strength of the fiber-metal propeller blade and increasing its overall stiffness.

5. A fiber metal propeller blade manufactured using the interface-toughened high-stiffness fiber metal propeller blade design method according to any one of claims 1 to 4.

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