Spiral fiber layup structure, super-spiral composite material and design method

Abstract

The present invention discloses a ply structure of spirally laid fibers, a super-helical composite material, and a design method, comprising a plurality of fiber plies of different areas formed by different fiber lengths, wherein the fiber layers are periodically spirally arranged along the ply direction to form a forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180]; a regular hexagonal frame is nested outside each ply, and the laying angle of the externally nested fiber frame layer is 180°-θ, forming a reverse spiral unit [180 / 180-θ / ... / 2θ / θ / 0]. Due to the different areas of the fiber plies and the differences in the ply angles between the fiber layers, when the composite material of the present invention is subjected to external loads, the bending deformation between different fiber plies, the friction between the layers, the rotation between the fiber plies, the stretching of the fibers in the fiber plies, the pulling out of the fibers, and the delamination absorb part of the energy, while reducing the shear stress concentration between the layers, thereby forming a continuous transition in mechanical properties. By optimizing the ply structure, the delamination phenomenon is reduced, thereby improving its mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a fiber spirally laid layer structure, a super-spiral composite material and a design method. Background Art

[0002] Fiber-reinforced resin-based composites (FRCs) have found widespread application in defense, aviation, and other fields due to their numerous advantages, including high specific strength, large specific modulus, highly customizable material properties, corrosion resistance, and excellent durability. CFRPs also offer advantages such as lightweight, high strength, fatigue resistance, corrosion resistance, flexible design possibilities, and excellent impact resistance. These advantages have made FRCs indispensable in modern science and technology, significantly improving performance, durability, and affordability while also meeting the demands of various sectors and driving technological innovation and development.

[0003] Traditional composite laminates often utilize uniform layups or simple angled stacking designs, which present several challenges: high risk of delamination, concentrated interlaminar shear stresses that can easily lead to interfacial delamination, limited structural stiffness, difficulty adapting uniformly sized honeycomb or laminated structures to complex load distributions, poor process compatibility, and difficulty performing secondary processing after thick panels are formed. While prior research has explored gradient spiral structures, optimizing interlaminar stresses by combining the dimensional gradient of a regular hexagon with a multi-angle spiral arrangement has yet to be achieved. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the prior art and provide a fiber spirally laid layer structure, super spiral composite material and design method to overcome the problem that traditional fiber reinforced composite materials are difficult to simultaneously meet high strength and high toughness, and are prone to debonding of the resin interface between layers and stratification failure when subjected to load.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, a spirally laid fiber ply structure is provided, comprising a plurality of fiber plies having different fiber lengths and areas, the plurality of fiber plies being arranged along a central axis, the plurality of fiber plies increasing in size from the center toward the edges and becoming gradually thinner near the free boundaries;

[0007] The fiber plies are arranged in a periodic spiral along the ply direction, and adjacent fiber plies have a periodically changing spiral angle. Assuming the spiral angle is θ, the spiral angles of several fiber plies form a forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180].

[0008] The fiber spirally laid ply structure improves the structure of each ply so that the areas of each fiber ply and the ply angles between the fiber layers are different. When the material is subjected to external loads, the bending deformation between different fiber plies, the friction between the layers, the rotation between the fiber plies, the stretching of the fibers within the fiber plies, the pulling out of the fibers, and the delamination can all absorb energy, thereby reducing the shear stress concentration between the layers and forming a continuous transition of mechanical properties. By optimizing the ply structure, the delamination phenomenon is reduced, thereby improving its mechanical properties.

[0009] Furthermore, a fiber frame layer is nested on the periphery of each layer of the fiber ply, and the total area of ​​each layer of the fiber ply and the fiber frame layer is the same.

[0010] Furthermore, the helical angle of the fiber frame layer is 180°-θ, and the helical angles of several layers of the fiber frame layer form a reverse helical unit [180 / 180-θ / ... / 2θ / θ / 0].

[0011] By nesting a fiber frame on the periphery of the fiber ply, the outer contour area of ​​each layer is made basically the same. This super-helical composite ply structure, which is nested inside and outside and spirally formed layer by layer, has excellent mechanical properties, can effectively weaken the anisotropy within the composite layer, and reduce interface delamination damage; when the material is subjected to impact load, the crack expands along the spiral fiber interface, forming a three-dimensional spiral path, increasing the surface area for crack expansion and dissipating energy. The crack mainly expands in a spiral shape between the chitin fibers, avoiding fatal damage through the entire structure, while reducing the shear stress concentration between layers and forming a continuous transition of mechanical properties.

[0012] Furthermore, the spiral angle θ ranges from 0° to 90°, and the spiral period is an integer multiple of 180°.

[0013] Furthermore, a stagger angle α is provided between the fiber ply and the fiber frame layer, and the reverse spiral unit of the fiber frame layer is [180+α / 180-θ+α / ... / 2θ+α / θ+α / 0+α].

[0014] Furthermore, the fiber ply and the fiber frame layer are both regular polygonal structures.

[0015] Furthermore, the fibers of the laminate structure are one or more combinations of carbon fibers, glass fibers, basalt fibers, and aramid fibers.

[0016] According to a second aspect, a superhelical composite material with spirally arranged fibers is provided, wherein the superhelical composite material comprises a plurality of fiber layers stacked in parallel with each other, each fiber layer being deflected at an angle relative to the next layer, and the constant angle difference between adjacent fiber layers forms a rotation period of 180°; the fiber layer comprises an embedded regular polygonal fiber layer and an externally nested regular polygonal fiber frame layer.

[0017] Cracks in these superhelical composites propagate along the interfaces of the helical fibers, forming a three-dimensional helical path. This increases the surface area for crack propagation and dissipates energy. Cracks primarily propagate in a helical pattern between fibers, avoiding penetration throughout the entire structure. This reduces interlaminar shear stress concentration and creates a continuous transition in mechanical properties. These superhelical composites are suitable for applications in aerospace, defense, automotive, and other fields requiring lightweight, high-strength, and high-toughness materials.

[0018] Furthermore, it also includes a composite material laminate made from a plurality of the super-helical composite materials.

[0019] In a third aspect, a method for designing a super-helical composite material layup structure with spirally laid fibers is provided, the method comprising the following steps:

[0020] Constructing a plurality of fiber plies with different areas formed by fibers of different lengths, wherein the fiber plies are regular polygons;

[0021] Arrange the fiber layers in a periodic spiral along the ply direction, with an initial angle of 0°, and deflect each layer by an angle of θ;

[0022] A regular polygonal fiber frame layer is nested outside each regular polygonal fiber ply so that the total area of ​​each ply is the same. The laying angle of the externally nested fiber frame layer is 180°-θ to form the ply structure.

[0023] This design method is based on the lightweight and high-strength characteristics of the periodic regional fiber arrangement structure inside the mantis shrimp knuckles. It integrates the bionic design concept into the layup design of traditional composite laminates, providing a design method that can not only improve the out-of-plane mechanical properties of composite laminates, but also effectively weaken the in-plane anisotropy of composite laminates and reduce interface delamination damage.

[0024] Compared with the prior art, the beneficial effects of the present invention are: 1. The fiber spirally laid ply structure improves the structure of each ply and reduces the stratification phenomenon by optimizing the ply structure, thereby improving its mechanical properties. The areas of each fiber ply and the ply angles between the fiber layers are different. When the material is subjected to external loads, the bending deformation between different fiber plies, the friction between layers, the rotation between fiber plies, the fiber stretching in the fiber ply, the fiber pulling out and stratification can all absorb energy, reducing the shear stress concentration between layers and forming a continuous transition of mechanical properties; 2. The super-helical composite material ply structure formed by nesting the fiber frame on the periphery of the fiber ply has excellent mechanical properties, can effectively weaken the anisotropy within the composite material layer, and reduce interface stratification damage; when the material is subjected to impact loads, the cracks extend along the spiral fiber interface. , forming a three-dimensional spiral path, increasing the surface area for crack expansion, dissipating energy, and the cracks mainly expand in a spiral shape between the chitin fibers to avoid penetrating the entire structure and causing fatal damage; 3. The superhelical composite material crack expands along the spiral fiber interface, forming a three-dimensional spiral path, increasing the surface area for crack expansion, and dissipating energy; the cracks mainly expand in a spiral shape between the fibers to avoid penetrating the entire structure, reducing the concentration of interlaminar shear stress, and forming a continuous transition of mechanical properties; 4. This design method is based on the lightweight and high-strength characteristics of the periodic regional fiber arrangement structure inside the mantis shrimp knuckle stick, and incorporates the bionic design concept into the traditional laminate design of composite material laminates, providing a design method that not only improves the out-of-plane mechanical properties of composite laminates, but also effectively weakens the in-plane anisotropy of composite laminates and reduces interface delamination damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of the hexagonal fiber spiral unit embedded in the fiber spirally laid layer structure of the present invention;

[0026] Figure 2 This is a front view of the regular hexagonal fiber spiral unit embedded in the ply structure of the present invention;

[0027] Figure 3 A top view of a regular hexagonal fiber spiral unit embedded in the ply structure of the present invention;

[0028] Figure 4 This is a schematic structural diagram of the regular hexagonal framework fiber spiral unit nested outside the ply structure of the present invention;

[0029] Figure 5 This is a front view of the regular hexagonal frame fiber spiral unit nested outside the ply structure of the present invention;

[0030] Figure 6 A top view of the regular hexagonal framework fiber spiral units nested outside the ply structure of the present invention;

[0031] Figure 7 A bottom view of the regular hexagonal frame fiber spiral unit nested outside the ply structure of the present invention;

[0032] Figure 8 A schematic diagram of a supercoiled composite structure is provided for Example 2 of the present invention;

[0033] Figure 9 A front view of a supercoiled composite structure is provided for Example 2 of the present invention;

[0034] Figure 10 A top view of a superhelical composite structure is provided for Example 2 of the present invention;

[0035] Figure 11 A bottom view of a superhelical composite structure is provided for Example 2 of the present invention;

[0036] Figure 12 A diagram showing the relationship between the misalignment angles α of the forward spiral group and the reverse spiral group provided in an embodiment of the present invention;

[0037] In the figure: 1. Fiber layup; 2. Fiber frame layer; 3. Super-helical composite material. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," etc., etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Example 1

[0040] A fiber spirally laid ply structure is provided, such as Figures 1 to 3 As shown, it comprises a plurality of fiber layers 1 with different fiber lengths and areas, the plurality of fiber layers 1 being arranged along a central axis, the sizes of the plurality of fiber layers 1 increasing layer by layer from the center to the edge, and the thickness gradually becoming thinner near the free boundary;

[0041] The fiber plies 1 are arranged in a periodic spiral along the ply direction, and adjacent fiber plies 1 have a periodically changing spiral angle. Assuming the spiral angle is θ, the spiral angles of several fiber plies form a forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180].

[0042] The fiber spirally laid ply structure improves the structure of each ply so that the areas of each fiber ply and the ply angles between the fiber layers are different. When the material is subjected to external loads, the bending deformation between different fiber plies, the friction between the layers, the rotation between the fiber plies, the stretching of the fibers within the fiber plies, the pulling out of the fibers, and the delamination can all absorb energy, thereby reducing the shear stress concentration between the layers and forming a continuous transition of mechanical properties. By optimizing the ply structure, the delamination phenomenon is reduced, thereby improving its mechanical properties.

[0043] The fiber layers of the ply structure are different from conventional fiber layered structures. The fiber lengths used in each layer of the fiber ply are different, and the area of ​​the layer is also different, forming a Figure 2 The layered structure with gradually increasing area (medium perspective) has a thinner thickness closer to the edge for the entire laminate structure.

[0044] These fiber layers stacked layer by layer have a common central axis, and are rotated layer by layer around the central axis, so that each layer is deflected by a fixed angle relative to the next layer, thereby forming a spiral layout structure that deflects layer by layer from bottom to top and has a varying area.

[0045] Further, combined Figures 4 to 7 As shown, a fiber frame layer 2 is nested on the periphery of each fiber ply 1 , and the total area of ​​each fiber ply 1 and the fiber frame layer 2 is the same.

[0046] By nesting a fiber frame on the periphery of the fiber ply 1, the outer contour area of ​​each layer is made basically the same. This super-helical composite ply structure that is nested inside and outside and spirally formed layer by layer has excellent mechanical properties, can effectively weaken the anisotropy within the composite material layer, and reduce interface delamination damage; when the material is subjected to impact load, the crack expands along the spiral fiber interface to form a three-dimensional spiral path, which increases the surface area for crack expansion and dissipates energy. The crack mainly expands in a spiral shape between the chitin fibers, avoiding penetrating the entire structure and causing fatal damage, while reducing the shear stress concentration between layers and forming a continuous transition of mechanical properties.

[0047] In addition to the advantages mentioned above, this laminate structure with an internal fiber layer 1 and an external embedded fiber frame layer 2 also solves the complex operational problems of the current technology for improving the mechanical properties of composite laminates, providing a constructive basis and effective suggestions for the design and manufacture of composite laminates.

[0048] In this spirally laid fiber structure, each layer is tilted (deflected) at a certain angle relative to the next layer. This constant angle difference between adjacent layers eventually forms a rotation period of 180°, thereby forming a characteristic wavelength and a superhelical layer; wherein the laying directions of each fiber ply are different, and the fiber layers with the same layer sequence in each of the fiber ply groups are periodically spirally laid along the laying direction.

[0049] Specifically, the spiral angle between adjacent fiber plies is θ, and the spiral angles of several fiber plies form a forward spiral unit (or a forward spiral group) [0 / θ / 2θ / ... / 180-θ / 180]; the spiral angle of the fiber frame layer is 180°-θ, and the spiral angles of several layers of the fiber frame layers form a reverse spiral unit (or a reverse spiral group) [180 / 180-θ / ... / 2θ / θ / 0].

[0050] Through this regular stacking and rotation, a periodic super-helical arrangement structure can be formed. This periodic regional fiber arrangement structure has the characteristics of light weight and high strength. It can overcome the problem that traditional fiber-reinforced composite materials are difficult to meet the requirements of high strength and high toughness at the same time, as well as the problem of debonding and stratification damage at the resin interface between layers when subjected to load. It can be widely used in the field of engineering technology.

[0051] Furthermore, the spiral angle θ ranges from 0° to 90°, and the spiral period is an integer multiple of 180°.

[0052] Furthermore, an offset angle α is provided between the fiber layup and the fiber framework layer, and the reverse spiral unit of the fiber framework layer is [180+α / 180-θ+α / ... / 2θ+α / θ+α / 0+α]. In other words, by varying the offset angle α between the fiber layup and the fiber framework layer, different reverse spiral units can be obtained. This adjustment can also improve the flexibility and versatility of the composite layup structure, allowing the deduction and production of composite materials with different layered spirals.

[0053] Furthermore, the fiber ply and the fiber frame layer are both regular polygonal structures. In this embodiment, a regular hexagonal structure is preferred, wherein the fiber ply is a regular hexagonal fiber ply and the fiber frame layer is a regular hexagonal frame, and the two are nested with each other.

[0054] Furthermore, the fibers used in the fiber layer and the fiber frame layer can be one or more combinations of carbon fiber, glass fiber, basalt fiber, and aramid fiber. Example 2

[0055] This embodiment provides a super-helical composite material with spirally laid fibers, combined with Figures 8 to 11 As shown, the superhelical composite material 3 is based on the fiber spirally laid layer structure described in Example 1, and the superhelical composite material 3 includes a number of fiber layers stacked in parallel with each other, each fiber layer is deflected at an angle relative to the next layer, and this constant angle difference between adjacent fiber layers forms a rotation period of 180°; the fiber layer includes an embedded regular polygonal fiber layer 1 and an externally nested regular polygonal fiber frame layer 2.

[0056] Superhelical composites with this structure exhibit the following properties: cracks propagate along the helical fiber interfaces, forming a three-dimensional helical path that increases the crack propagation surface area and dissipates energy. Cracks primarily propagate in a helical pattern between fibers, avoiding penetration throughout the entire structure. This reduces interlaminar shear stress concentration and creates a continuous transition in mechanical properties. These superhelical composites are suitable for applications in aerospace, defense, automotive, and other fields requiring lightweight, high-strength, and high-toughness materials.

[0057] Furthermore, this type of super-helical composite material can be used to make composite laminates, which optimizes shear stress, has a lower risk of delamination, is not easy to peel at the interface, is not limited by structural stiffness, and has good process compatibility, thereby reducing the difficulty of making the composite laminates and allowing secondary processing after the plates are formed.

[0058] Furthermore, the resin matrix of the supercoiled composite material is a thermosetting resin or a thermoplastic resin. Example 3

[0059] This embodiment provides a design method for a super-helical composite material layup structure with spirally laid fibers.

[0060] Traditional composite laminates often employ uniform layups or simple angled stacking designs, which present significant challenges, including high risk of delamination, concentrated shear stress between layers that can easily lead to interfacial delamination, limited structural stiffness, difficulty adapting uniformly sized honeycomb or laminated structures to complex load distributions, poor process compatibility, and difficulty performing secondary processing after thick plates are formed. While prior research has explored gradient spiral structures, the combination of the dimensional gradient of a regular hexagon and a multi-angle spiral arrangement has yet to achieve optimized interlaminar stress.

[0061] Mantis shrimps are capable of generating impact forces of up to 700N in a very short period of time. This force not only shatters the exoskeleton of their prey but also generates cavitation bubbles, which, when collapsed, generate high-frequency stress waves. However, the mantis shrimp knuckles can withstand thousands of impacts without catastrophic failure. The mantis shrimp's knuckles' remarkable damage resistance stems from their complex, multi-level structure, comprising a highly mineralized surface, helically arranged biofibers, and gradient-varying periodic regions. The helical structure of the mantis shrimp's periodic regions is a highly ordered microstructure with a layered, helical arrangement. Chitin fibers form thin layers with a protein matrix, each layer rotated at a fixed angle relative to the adjacent layers. Layer by layer, they form a helical gradient, resulting in a continuous spiral arrangement resembling a "spiral staircase," with up to hundreds of layers. This design approach, based on the study and analysis of this mantis shrimp structure, results in a superhelical design by varying the laying angle of the fiber sheets and the area of ​​the hexagonal faces of each fiber sheet.

[0062] The design method comprises the following steps:

[0063] Constructing a plurality of fiber plies with different areas formed by fibers of different lengths, wherein the fiber plies are regular hexagons;

[0064] Arrange the fiber plies in a periodic spiral along the ply direction, with an initial angle of 0°. Each ply rotates clockwise or counterclockwise about the central axis of the regular hexagon, deflecting by an angle θ in sequence. The angle between the sides of adjacent regular hexagonal fiber plies is θ; thus, a forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180] is obtained.

[0065] A regular polygonal fiber frame layer is nested outside each regular polygonal fiber layer to make the total area of ​​each layer the same. The laying angle of the outer nested fiber frame layer is 180°-θ, resulting in an inverse spiral unit [180 / 180-θ / ... / 2θ / θ / 0];

[0066] The laminate structure is obtained by nesting the internal forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180] with the external reverse spiral unit [180 / 180-θ / ... / 2θ / θ / 0]. The design of this optimized laminate structure can greatly reduce the delamination phenomenon and thus improve its mechanical properties.

[0067] This design approach, based on the lightweight and high-strength properties of the periodic fiber arrangement within the mantis shrimp's knuckles, incorporates biomimetic design concepts into the layup design of traditional composite laminates. This approach provides a method that not only improves the out-of-plane mechanical properties of composite laminates, but also effectively weakens the in-plane anisotropy of composite laminates, mitigating interfacial delamination damage. When the material is subjected to impact loads, cracks propagate along the spiral fiber interface, forming a three-dimensional spiral path. This increases the surface area for crack propagation and dissipates energy. The cracks primarily propagate in a spiral pattern between the chitin fibers, avoiding penetrating the entire structure and causing fatal damage. This also reduces shear stress concentration between layers, resulting in a continuous transition in mechanical properties.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. The fiber spirally laid layer structure is characterized by: The fiber layers include a plurality of fiber layers with different fiber lengths and areas, the plurality of fiber layers are arranged along a central axis, the size of the plurality of fiber layers increases from the center to the edge, and the thickness gradually becomes thinner near the free boundary; The fiber plies are arranged in a periodic spiral along the ply direction, and adjacent fiber plies have a periodically varying spiral angle. Assuming the spiral angle is θ, the spiral angles of several fiber plies form a forward spiral unit [0 / θ / 2θ / ... / 180-θ / 180]. A fiber frame layer is nested on the periphery of each layer of the fiber ply, and the total area of ​​each layer of the fiber ply is the same as that of the fiber frame layer, so that the total area of ​​each layer of the ply is the same; the spiral angle of the fiber frame layer is 180°-θ, and the spiral angles of several layers of the fiber frame layers form a reverse spiral unit [180 / 180-θ / ... / 2θ / θ / 0].

2. The fiber spirally laid ply structure according to claim 1, characterized in that: The spiral angle θ ranges from 0° to 90°, and the spiral period is an integer multiple of 180°.

3. The fiber spirally laid ply structure according to claim 1, characterized in that: There is a stagger angle α between the fiber laying layer and the fiber frame layer, and the reverse spiral unit of the fiber frame layer is [180+α / 180-θ+α / ... / 2θ+α / θ+α / 0+α].

4. The spirally laid fiber ply structure according to claim 1, characterized in that: The fiber layer and the fiber frame layer are both regular polygonal structures.

5. The spirally laid fiber ply structure according to claim 1, characterized in that: The fibers of the laminate structure are one or more combinations of carbon fibers, glass fibers, basalt fibers, and aramid fibers.

6. A supercoiled composite material with spirally arranged fibers, characterized in that: The supercoiled composite material is based on a fiber spirally laid ply structure as described in any one of claims 1 to 5, and the supercoiled composite material includes a plurality of fiber layers stacked in parallel with each other, each fiber layer is deflected at an angle relative to the next layer, and this constant angle difference between adjacent fiber layers forms a rotation period of 180°; the fiber layer includes an embedded regular polygonal fiber ply and an external nested regular polygonal fiber frame layer.

7. The supercoiled composite material with spirally laid fibers according to claim 6, characterized in that: Also included is a composite laminate made from a plurality of the super-helical composite materials.

8. The method for designing a spirally laid fiber ply structure according to any one of claims 1 to 5, characterized in that: The design method comprises the following steps: Constructing a plurality of fiber plies with different areas formed by fibers of different lengths, wherein the fiber plies are regular polygons; Arrange the fiber layers in a periodic spiral along the ply direction, with an initial angle of 0°, and deflect each layer by an angle of θ; A regular polygonal fiber frame layer is nested outside each regular polygonal fiber ply so that the total area of ​​each ply is the same. The laying angle of the externally nested fiber frame layer is 180°-θ to form the ply structure.

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