A composite disc spring of a biomimetic spiral layup structure and a preparation method thereof

Abstract

The application provides a composite disc spring with a biomimetic spiral layup structure and a preparation method thereof, and belongs to the technical field of spring manufacturing. The disc spring is formed by stacking multiple layers of fiber reinforced composite prepreg along the thickness direction, the main direction of the fibers between adjacent layers is rotated around the center of the disc spring at a set angle layer by layer, forming a biomimetic spiral layup structure arranged periodically along the circumferential direction, which simulates the microstructure of the biological fiber layers in the chelate rod spiral area of mantis shrimps, and the SMA wires treated by a coupling agent are embedded in the inner ring and the middle ring of the fiber prepreg. The biomimetic spiral layup structure is constructed layer by layer in the thickness direction of the composite material, and the SMA wire is locally reinforced in the annular part, so that the disc spring realizes the synergistic improvement of the bearing capacity, energy absorption performance and interlayer failure resistance under the premise of lightweight, thereby improving the overall mechanical properties and service reliability.

Description

Technical Field

[0001] This invention relates to the field of spring manufacturing technology, and in particular to a biomimetic helical layup composite disc spring and its preparation method. Background Technology

[0002] With the rapid development of high-end equipment manufacturing, aerospace, and automotive engineering, the performance requirements for elastic components are constantly increasing, especially in terms of high load-bearing capacity, lightweight design, and resistance to complex service environments. Disc springs, as a typical axially loaded elastic component, have advantages such as compact structure, high load-bearing capacity, and flexible combination methods, and are widely used in applications such as damping, load adjustment, and structural preload. Traditional disc springs are usually made of metal materials such as spring steel. However, under the increasingly prominent application conditions of high specific strength requirements, corrosion resistance, and weight reduction, metal materials, due to their high density, limited environmental resistance, and fatigue life limited by intrinsic material properties, are gradually becoming unable to meet the development needs of engineering applications. Against this backdrop, composite material disc springs, as a lightweight innovation solution for automotive shock absorption and suspension systems, have stood out with their 40%-75% weight reduction advantage, 2-5 times improvement in fatigue life, and excellent damping and corrosion resistance, and have already achieved mass production application in a certain brand of vehicle. Utilizing fiber-reinforced composite materials to replace metal materials in the manufacture of disc springs has become an important development direction in this technological field.

[0003] In response to the aforementioned development trends, various structural designs and fabrication methods for composite disc springs have been disclosed in existing technologies. For example, publication number CN108506393A discloses a biomimetic composite disc spring part and its fabrication method. This technical solution introduces biomimetic concepts to construct a shell-like fiber-reinforced layer structure, and combines resin transfer molding technology and specific mold flow channel design to improve resin wetting effect and molding quality. Furthermore, in other published literature and engineering practices, composite disc springs typically use continuous fibers such as carbon fiber and glass fiber to form a laminated structure with a resin matrix, and are fabricated through processes such as hot pressing. The layup methods are mostly orthogonal layup, quasi-isotropic layup, or simple angle layup to meet basic mechanical performance and structural stability requirements. These existing technologies have made some progress in achieving weight reduction, corrosion resistance, and a certain degree of performance designability.

[0004] However, from an engineering application perspective, existing composite disc spring technology still has certain limitations. First, the layup methods commonly used in existing technologies offer limited control over fiber orientation, making it prone to stress concentration under complex stress conditions. This hinders the full utilization of the mechanical potential of fiber-reinforced materials, limiting the improvement of load-bearing capacity and energy absorption performance. Second, the interlaminar properties of composite laminates are relatively weak in the thickness direction. Under cyclic loading or large deformation conditions, delamination or localized damage is likely to occur, affecting the overall reliability and service life of the structure. Taking the technical solution in publication number CN108506393A as an example, its technical focus is mainly on the introduction of biomimetic layered structures and improvements in molding processes, while the control over the relationship between changes in the layup angle and mechanical properties within the composite material remains limited. Furthermore, existing technologies lack sufficient means to control the failure modes of composite disc springs. The structure often exhibits obvious brittle failure characteristics when approaching the ultimate load, making it difficult to simultaneously achieve high load-bearing capacity, good deformation capacity, and safe and reliable failure behavior. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a biomimetic spiral layup composite disc spring and its preparation method. By constructing a biomimetic spiral layup structure that rotates layer by layer in the thickness direction of the composite material, combined with SMA wire ring local reinforcement design, the disc spring can achieve a synergistic improvement in load-bearing capacity, energy absorption performance and interlayer failure resistance under the premise of lightweight, thereby improving its overall mechanical properties and service reliability.

[0006] To achieve the above objectives, the present invention provides the following solution: On one hand, the present invention provides a composite disc spring with a biomimetic helical layup structure. The disc spring is a conical annular elastic element, which is formed by stacking and curing multiple layers of fiber prepreg along the thickness direction. The fiber prepreg is a laminate composed of reinforcing fibers and matrix resin laid in a plane. The single layer of fiber prepreg is cut into an annular shape that matches the outer dimensions of the disc spring. When the multilayer fiber prepreg is stacked sequentially along the thickness direction, the main fiber direction of two adjacent fiber prepregs rotates around the center of the disc spring according to a set spiral layup angle, forming a biomimetic spiral layup structure arranged periodically along the circumference of the disc spring. The spiral layup angle between adjacent layers is 1°~45°. The biomimetic spiral layup structure simulates the microstructure of the mantis shrimp's spiral region of bio-fibers rotating and stacking layer by layer. The inner and middle rings of the fiber prepreg are circumferentially embedded with SMA filaments treated with coupling agent to reinforce the weak areas of the disc spring and synergistically improve the load-bearing capacity and energy absorption performance of the disc spring.

[0007] Preferably, the SMA filament has a diameter of 0.1~5mm and is embedded in a shallow groove in the fiber prepreg in a circular pattern of double inner rings and single middle rings; the width of the shallow groove is 0.05~0.1mm larger than the diameter of the SMA filament, and the depth is 1 / 3~1 / 2 of the thickness of the fiber prepreg.

[0008] Preferably, the reinforcing fibers in the fiber prepreg are unidirectional continuous fibers, and the reinforcing fibers include both single-material fibers and heterogeneous fiber blends; the reinforcing fiber material is one or more of carbon fiber, glass fiber, aramid fiber, basalt fiber, natural fiber, and shape memory alloy fiber; the resin matrix is ​​a thermosetting resin or a thermoplastic resin; the heterogeneous fiber blend is any one of carbon fiber-glass fiber blend, carbon fiber-aramid fiber blend, and basalt fiber-carbon fiber blend.

[0009] The aforementioned heterogeneous fiber blends utilize multiple fibers as reinforcements, bonded to a matrix in a specific manner. Due to their highly customizable composition and structure, fiber hybrid composites can fully leverage the advantages of various fibers at low cost. This invention employs carbon fiber-glass fiber blends, carbon fiber-aramid fiber blends, and basalt fiber-carbon fiber blends, with alternating carbon fiber and glass fiber layers balancing stiffness and cost. In the combination of carbon fiber and aramid fiber layers, carbon fiber provides high stiffness, while aramid contributes impact and fatigue resistance, making it suitable for high-end vehicle suspensions. The basalt and carbon fiber blend exhibits high temperature resistance and excellent thermal stability, making it suitable for suspension components near the engine.

[0010] Preferably, in the periodic spiral arrangement, the interlayer spiral angle gradually changes or changes in segments within the range of 1° to 45°, and the load-bearing capacity and energy absorption performance are synergistically improved through the optimized configuration of the interlayer spiral angle.

[0011] Preferably, the disc spring is composed of several composite material disc springs, and the combination method is any one of stacking combination, pairing combination, and composite combination; the stacking combination is several disc springs stacked in the same direction; the pairing combination is several disc springs arranged in pairs in opposite directions and stacked in sequence; the composite combination is several groups of stacked disc springs arranged in opposite directions stacked together.

[0012] On the other hand, the present invention also provides a method for preparing the above-mentioned biomimetic helical layup structure composite material disc spring, comprising the following steps: S1. Based on the geometric dimensions and design thickness of the target disc spring, determine the thickness and number of layers of the single-layer fiber prepreg. Cut the plate-shaped fiber prepreg into annular prepreg sheets that match the planar projection of the disc spring. Leave process allowances for the inner and outer diameters. Process the inner and middle rings of the prepreg sheets with arc-shaped shallow grooves that are adapted to SMA yarns. S2. After pre-treating the SMA filaments with a coupling agent, dry them at room temperature. Embed the pre-treated SMA filaments into the arc-shaped shallow grooves and fit them tightly. Then, rotate and stack the embedded circular prepreg sheets layer by layer at a spiral layup angle of 1°~45° to form a biomimetic spiral fiber reinforcement structure. S3. The fiber-reinforced structure is placed into the hot press mold cavity, pre-pressed and fixed, and then the mold is closed and sealed. S4. Maintain a weak vacuum atmosphere in the closed mold. First, apply low-pressure bonding and preheat to the initial gel temperature of the resin. Then, use pulsed intermittent pressure to cure. After curing, keep the mold closed and allow for gradual cooling. S5. After the mold cools to room temperature, the blank is removed from the mold. The inner and outer diameters of the blank are then polished and trimmed to the design dimensions to obtain the finished disc spring.

[0013] Preferably, in step S1, the inner and middle rings of the prepreg sheet are processed by laser micro-engraving, and the size of the shallow grooves is adapted to the SMA wire to be embedded.

[0014] Preferably, in step S2, the SMA filament is pretreated by soaking in silane coupling agent KH550 for 5-10 minutes and then drying at room temperature; after the SMA filament is embedded in the shallow groove, the prepreg sheet is gently pressed to achieve tight bonding.

[0015] Preferably, in step S4, the specific process parameters are as follows: during the preheating stage, the heating rate is 4~6℃ / min, with only low-pressure bonding and no continuous high pressure; during the curing stage, the pulse intermittent pressurization is applied for 3~5min per cycle, with pressure gradients of 2MPa, 4MPa, and 6MPa in sequence, and the pressure relief amplitude is 1~2MPa, with the holding time increasing with the temperature; during the slow cooling stage, the cooling rate is 3~5℃ / min, and the temperature is uniformly reduced to below 40℃.

[0016] Preferably, in step S5, the inner and outer diameters and end faces of the disc spring blank are trimmed using a CNC dry cutting process, and the dimensional tolerance of the finished product is controlled within ±0.08mm.

[0017] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) In this invention, adjacent lay-up fibers are rotated and stacked around the center of the disc spring in the thickness direction of the composite material disc spring at a set spiral angle to form a biomimetic spiral lay-up structure that changes periodically along the circumference. This structure simulates the microstructure of the biological fiber layers rotating and stacking in the spiral region of the mantis shrimp chelicerae. At the same time, it is reinforced with SMA filaments treated with coupling agent in the inner and middle rings of the fiber prepreg, so that the fiber orientation is continuously transitioned in space, improving the overall stress state of the disc spring, reducing local stress concentration, effectively reinforcing the weak stress area, and improving the structural cooperative load-bearing capacity.

[0018] (2) By limiting the interlayer spiral layup angle to the range of 1° to 45°, and by adopting a gradually changing or segmented layup method as needed, combined with the laminated structure design of continuous unidirectional reinforcing fiber and resin matrix, the load is transferred step by step between different layups, causing the crack to deflect and passivate during the propagation process. While maintaining the lightweight advantage of composite materials, the load-bearing capacity and energy absorption performance are synergistically improved.

[0019] (3) This invention uses continuous unidirectional reinforcing fibers (either single material or mixed fibers) to form a laminated structure with the resin matrix, and combines it with a biomimetic spiral layup design, which effectively improves the stress coordination and anti-delamination ability of the interlayer interface of the composite material, enhances the damage tolerance and service reliability of the disc spring under cyclic load or complex working conditions, and extends its service life.

[0020] (4) The hot pressing molding and pulse intermittent pressurization processes used in this invention can solve the industry pain points of insufficient resin impregnation, weak interlayer bonding and concentrated internal stress during curing, achieve uniform resin curing and dense and defect-free products, and ensure the quality of finished products through gradient slow cooling, CNC dry cutting and other processes, greatly improve production efficiency and meet the needs of high-efficiency mass production. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 An isometric view of the composite disc spring structure with a biomimetic helical layup structure provided by the present invention; Figure 2 This is a structural design view of the composite material disc spring single-layer prepreg provided by the present invention; Figure 3A flowchart illustrating the preparation method of the biomimetic helical layup composite disc spring provided by this invention; Figure 4 An isometric view of the spiral layup structure of the fiber prepreg in the preparation method provided by this invention; Figure 5 A modeling diagram of the composite disc spring layup structure of the biomimetic helical layup structure provided by this invention; Explanation of reference numerals in the attached figures: 1. Composite material disc spring; 2. Fiber prepreg; 3. Shallow groove; 4. Double-ring SMA yarn; 5. Single-ring SMA yarn. Detailed Implementation

[0023] 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, and 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.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, the present invention provides a biomimetic spiral layup composite disc spring, which is a conical annular elastic element, namely the composite disc spring 1. The composite disc spring 1 is formed by stacking and curing multiple layers of fiber prepreg 2 along the thickness direction, and SMA filaments are circumferentially embedded in the inner and middle rings of the fiber prepreg 2 to form a composite structure of biomimetic spiral layup and SMA filament reinforcement.

[0026] like Figure 4 As shown, the fiber prepreg 2 is a laminated sheet structure composed of reinforcing fibers and a resin matrix laid in a plane. Each single layer of fiber prepreg 2 is cut into a ring-shaped structure that matches the planar projection size of the composite disc spring 1. Figure 2 As shown, the prepreg sheet has shallow grooves 3, with double-ring SMA wires 4 embedded in parallel in the inner shallow groove 3, single-ring SMA wires 5 embedded in the middle shallow groove 3, and no SMA wires embedded in the outer ring, to adapt to the stress gradient distribution of the disc spring.

[0027] Specifically, the biofibers of the mantis shrimp claws are arranged in a periodic spiral pattern, with multiple cycles throughout the region. It can be observed that the biofibers of the claws overlap at different angles between layers, completing one cycle of spiral arrangement with a certain number of layers. Furthermore, this invention confirms that the interlayer spiral angle is a key factor in regulating the load-bearing capacity and energy absorption performance of the spiral layered structure. Changes in the interlayer spiral angle significantly reshape the stress state and distribution characteristics within and between single layers, thereby affecting the load-bearing limit, failure mode, load transfer efficiency of the laminated structure, and the spiral propagation behavior of interlayer cracks, ultimately determining the overall mechanical properties and energy absorption effect of the material.

[0028] Inspired by the microscopic helical regions of mantis shrimp claws, this invention simulates the single-layer bio-fiber of mantis shrimp claws and designs a disc spring component with a suitable interlayer helical angle. To obtain a suitable helical layup angle, this invention experimented with four helical angles: 12°, 24°, 45°, and 90°. When the experimental sample was unidirectional carbon fiber prepreg, the performance of composite materials with different helical angle layups was analyzed using finite element method software. The experiments revealed that, in terms of load-bearing capacity, the orthogonal layup sample had the lowest maximum load value, specifically 1355.6 N. As the interlayer helical angle gradually decreased, the load-bearing capacity of samples with different interlayer helical angles gradually increased. When the interlayer helical angle decreased to 12°, the load-bearing capacity of the sample reached a peak of 1715.65 N. From the perspective of energy absorption characteristics, the energy absorption value of the orthogonal layup sample is 3047.5 mJ. When the interlayer helix angle is 45°, the energy absorption decreases. Then, as the interlayer helix angle further decreases, the energy absorption gradually increases again. When the interlayer helix angle is 12°, the energy absorption reaches the maximum value of 3932.5 mJ.

[0029] Therefore, based on the above results, the node where the helical laminated structure first fails, the maximum load-bearing capacity, and the energy absorption are all closely related to the interlayer helical angle. Under bending loading, each basic unit of the helical laminated structure will undergo bending deformation, and internal stress will be generated in the fiber prepreg inside, with the stress distribution showing significant differences depending on the unit location. When the load reaches a critical value, the fiber prepreg will fracture, ultimately leading to the failure of the overall structure. Because the fiber prepreg is arranged in a unidirectional direction, its mechanical properties exhibit orthotropic characteristics: the load-bearing capacity along the fiber direction is the strongest, and the material will fail when the tensile and compressive stress reaches the threshold; the load-bearing capacity perpendicular to the carbon fiber direction is the weakest, and when the tensile stress reaches a critical value, it will trigger a failure mode dominated by fiber fracture, including fiber-matrix interface debonding and fiber self-fracture. Therefore, the intralayer failure modes of the basic unit are diverse. Changes in the interlayer helical angle will significantly affect the intralayer stress distribution of each basic unit, leading to significant changes in the types and numbers of various failure modes, ultimately having a key impact on the overall strength and toughness of the helical laminated structure material.

[0030] Furthermore, during the stacking process along the thickness direction, the main fiber direction of adjacent layers of fiber prepreg 2 rotates layer by layer relative to the center of the composite disc spring 1 of the previous layer at a set helical layup angle, thereby forming a biomimetic helical layup structure that changes periodically along the circumference. The helical layup angle between adjacent layers is controlled within the range of 1° to 45°, and a gradual or segmented layup method can be adopted according to design requirements. At the same time, the prepreg sheet embedded with SMA filaments is stacked synchronously with the helical layup, and the ring structure of the SMA filaments perfectly matches the circumferential periodic arrangement of the biomimetic helical layup, forming a synergistic force transmission system.

[0031] Furthermore, the biomimetic spiral layup structure simulates the microstructural characteristics of biological fibers rotating and stacking layer by layer in the spiral region of the mantis shrimp's chelicerae. Combined with the superelasticity and shape memory recovery force of SMA filaments, it precisely reinforces the weak stress areas such as the inner ring circumferential tension and the middle ring radial shear, thereby synergistically improving the load-bearing capacity, energy absorption performance and failure resistance of the composite disc spring 1.

[0032] The composite disc spring of this invention primarily utilizes natural fibers such as carbon fiber, glass fiber, aramid fiber, basalt fiber, and ramie, as well as shape memory alloy fibers. The reinforcing fibers in the fiber prepreg are unidirectionally arranged continuous fibers, and can be either single-material fibers or blends of dissimilar fibers. Furthermore, carbon fiber, with its extremely high specific strength and specific stiffness, is widely used in high-performance structural components; its low density and high tensile strength make it excellent in terms of lightweighting. Glass fiber offers advantages such as high specific strength, lightweight, weather and corrosion resistance, good insulation and chemical stability, controllable cost, and strong processing adaptability. Aramid fiber is renowned for its excellent impact toughness and high-temperature resistance, making it an ideal material for high-impact and high-temperature environments. Basalt fiber, made from natural basalt, is moderately priced and possesses good strength, high-temperature resistance, and corrosion resistance.

[0033] like Figure 3 As shown, the present invention also provides a method for preparing a biomimetic helical layup composite disc spring, comprising the following steps: S1. Based on the geometric dimensions and design thickness of the target disc spring, determine the thickness and number of layers of the single-layer fiber prepreg. Cut the sheet-like fiber prepreg into annular prepreg sheets that match the planar projection of the disc spring. Leave process allowances for the inner and outer diameters. Process the inner and middle rings of the prepreg sheets with arc-shaped shallow grooves that are adapted to SMA yarns.

[0034] Specifically, this step determines the thickness and number of layers of the single-layer fiber prepreg based on the geometric dimensions and design thickness of the target disc spring. Following equal-area projection and parametric dimensional relationships, the original sheet-like prepreg is cut into multiple annular prepreg sheets that match the planar projection shape of the disc spring, with process allowances reserved in the inner and outer diameter directions. A laser micro-engraving method is used to pre-reserve shallow arc-shaped grooves in the inner and middle rings of the prepreg sheets. The SMA filament diameter is 0.1~5mm, the groove width is 0.05~0.1mm larger than the SMA filament diameter, and the depth is 1 / 3~1 / 2 of the prepreg thickness, ensuring complete embedding of the SMA filament without damaging the overall structure of the prepreg sheet.

[0035] Furthermore, this step employs a supportless structure for subsequent prepreg cutting. Based on the concept of equal-area cutting, the original rectangular cross-section is projected onto a plane and transformed into an equivalent parallelogram. A circular ring shape is then uniformly selected as the cutting shape for the layup. This approach maintains the overall integrity of the blank, improves preparation efficiency, and also ensures ease of operation. Moreover, through optimization of subsequent molding process parameters, material accumulation and morphological deviations are effectively eliminated.

[0036] To further describe the aforementioned equal-area projection and parametric dimensional relationships, a parametric model of the disc spring's ply structure is presented below, and calculation formulas for key ply dimensional parameters are derived. For example... Figure 5 As shown, it illustrates the overall geometric profile and ply breakdown of the disc spring, highlighting key design parameters: free height H, deformation h under compression, profile length L, and inner and outer profile radii d / 2 and D / 2. The dashed lines on the sidewalls indicate the layered structure. This represents the actual number of layers.

[0037] The specific modeling and formula derivation are as follows: To ensure that the finished thickness of the sample matches the design thickness, the total layup thickness must meet the following conditions: ; in For the design thickness of disc spring products, This is a preliminary estimate of the number of prepreg layers to be laid. This refers to the finished thickness of a single-layer prepreg. For composite disc springs, the number of layups is a key process constraint. This represents the theoretical number of layers, which is generally a non-integer value. However, based on the actual process, an integer number of layers should be used. The remainder criterion is applied to determine the number of layers. Make corrections to obtain the actual number of layers. : ; ; in express The decimal part, the final actual thickness of the disc spring. It is evenly distributed in the thickness direction. Layer thickness, the average thickness of each layer is : ; The theoretical inner and outer diameters of each layer of the annular prepreg are determined by the following formula: (1) Inner diameter of the first layer of circular prepreg d 1.Outer diameter D 1 are respectively: ; (2) No. Inner diameter of layered ring prepreg d i , outer diameter D i They are respectively: ; ; In the above formula, the rounding threshold is set to 0.5. Its main purpose is to avoid resin overflow due to excessive compression of the prepreg during the molding process, and to prevent product performance degradation due to insufficient prepreg layers. At the same time, this value helps to control the compaction degree of each layer within a reasonable range, ensuring the quality consistency of the laminated structure.

[0038] Furthermore, considering the actual needs of centering and pressing during the installation process, an appropriate process allowance needs to be added to the actual prepreg sheets cut based on theoretical calculations. This allowance not only ensures that each layer can be fully matched and coordinated in deformation during the molding process to ultimately form the three-dimensional shape of the disc spring required by the design, but also improves the manufacturing tolerance, thereby maximizing the geometric accuracy and mechanical properties of the prototype.

[0039] Taking process allowances into account In this case, the inner and outer diameters of each layer of annular prepreg are determined by the following formula: (1) Inner diameter of the first layer of circular prepreg d 1.Outer diameter D 1 are respectively: ; (2) No. Inner diameter of layered ring prepreg d i , outer diameter D i They are respectively: ; ; Furthermore, the above formula describes the equal area projection and parameterized dimensional relationship. By establishing the mapping relationship from disc spring design parameters to prepreg layup dimensions, it not only provides a theoretical basis for the layup process, but also directly guides the design of molding dies and subsequent grinding dies.

[0040] S2. After pretreating the SMA filaments with a coupling agent, dry them at room temperature. Embed the pretreated SMA filaments into the arc-shaped shallow grooves and fit them tightly. Then, stack the embedded circular prepreg sheets layer by layer at a spiral layup angle of 1°~45° to form a biomimetic spiral fiber reinforcement structure.

[0041] Specifically, this step involves soaking the SMA filaments in silane coupling agent KH550 for 5-10 minutes and then drying them at room temperature to complete the pretreatment and improve the interfacial bonding between the SMA filaments and the resin matrix.

[0042] The pretreated SMA filaments are then embedded into shallow grooves in the prepreg sheet, with the inner ring of SMA filaments parallel to the main direction of the layup fibers to maximize the load-bearing circumferential tensile stress. After embedding, the prepreg sheet is gently pressed to ensure a tight fit between the SMA filaments and the grooves, preventing filament displacement during hot pressing. The annular fiber prepreg sheets containing the embedded SMA filaments are then stacked sequentially at the designed spiral layup angle to form a fiber reinforcement structure. The main direction of the fibers in adjacent layers of fiber prepreg rotates around the center of the disc spring at a spiral layup angle of 1° to 45°, forming a biomimetic spiral laminated structure.

[0043] The specific layup results are as follows Figure 4 As shown, when preparing samples with biomimetic spiral stacked structures, a protractor can also be used to guide the preparation of spiral stacked structure samples with different interlayer spiral angles.

[0044] S3. Place the fiber-reinforced structure into the hot press mold cavity, pre-press and fix it, and then close and seal the mold.

[0045] Specifically, the obtained fiber-reinforced structure is placed into the cavity of a hot-pressing mold, and the fiber-reinforced structure is pre-pressed and fixed using a movable block in the hot-pressing mold, followed by mold closing. This ensures that the layup structure with embedded SMA filaments does not shift during the hot-pressing process.

[0046] S4. Maintain a weak vacuum atmosphere in the closed mold. First, apply low-pressure bonding and preheat to the initial gel temperature of the resin. Then, use pulsed intermittent pressure to cure. After curing, keep the mold closed and allow for gradual cooling.

[0047] Specifically, after mold closing, maintain a weak vacuum atmosphere, start preheating, and quickly raise the temperature to the initial gel temperature of the resin. During this stage, do not apply continuous high pressure; only perform low-pressure bonding to prevent premature resin loss. Enter the gel curing stage, activate the pulsed intermittent pressurization mode, using a cyclical pulse pattern of "pressurization-holding-depressurization-repressurization" until curing is complete. After curing, keep the mold closed and implement a gradient slow cooling process. Demolding can be completed after cooling is finished.

[0048] Furthermore, the pulsed intermittent pressurization employed in this invention allows for thorough resin impregnation. The resin's impregnation flow within the fiber preform follows Darcy's law, a core formula describing fluid permeation within porous media and the core theoretical basis for pulsed pressure-optimized impregnation. Its 3D flow mathematical expression is: Q= Q—resin volumetric flow rate; K—fiber preform permeability; A—fluid flow cross-sectional area; ΔP—pressure gradient; L—resin flow distance.

[0049] During the pulse cycle, the instantaneous pressure gradient is Much greater than the traditional constant pressure gradient, the alternating pressure breaks down the resin stagnant layer between fiber bundles, reducing the effective viscosity. According to Darcy's law, dynamic... The resin flow rate Q is significantly increased, and even if the permeability K within the fiber bundle is extremely low, the resin can still overcome capillary resistance, penetrate into the fiber gaps, and eliminate flow dead zones.

[0050] The specific steps include the following process: First, preheat the resin to 80-100℃ at a uniform low temperature at a rate of 2-3℃ / min to soften it. Then, slowly increase the temperature to 130-150℃ in steps of 1-2℃ / min, while simultaneously activating a 3-5min cyclic pulse pressurization. Gradually increase the pressure from 2MPa to 4MPa to 6MPa, and then release the pressure slightly at 1-2MPa, using the dynamic pressure gradient to achieve deep resin impregnation. Next, increase the temperature very slowly at a rate of 1℃ / min to the corresponding resin curing peak temperature, then turn off the pulse and switch to constant high pressure for 25-35min to ensure complete resin cross-linking and curing. Finally, keep the mold closed and apply pressure, then cool down at a uniform rate of 3-5℃ / min to below 40℃ to release pressure and demold. This process releases internal stress and ensures the stability of the product's dimensions and performance.

[0051] Furthermore, the resin at its glass transition temperature T g To thermal decomposition temperature T d Within the specified range, the effect of temperature change on its viscosity and interfacial bonding state follows this pattern: when the temperature is within a certain range... T gWhen the temperature is near the surface, the resin viscosity is high, which is beneficial for maintaining the shape, but the interfacial fusion is insufficient and the interfacial bonding is poor; as the temperature increases... T d As the direction increases, the interface bonding gradually improves and forms a good interface bond; however, when the temperature approaches... T d At this time, the polymer is prone to thermal decomposition, and excessively low resin viscosity can lead to overflow or structural defects. This invention achieves full wetting within the optimal resin viscosity range through staged temperature control and pulsed pressurization, while controlling the maximum curing temperature to ≤200℃ to avoid the attenuation of the SMA filament shape memory effect.

[0052] S5. After the mold cools to room temperature, the blank is removed from the mold. The inner and outer diameters of the blank are then polished and trimmed to the design dimensions to obtain the finished disc spring.

[0053] Specifically, after the hot pressing mold cools to room temperature, the mold is opened and the blank is removed. The subsequent processing adopts CNC dry cutting technology to precisely trim the inner and outer diameters and end faces of the product. The processing is dust-free and tear-free, and the dimensional tolerance is controlled within ±0.08mm to ensure the smoothness and dimensional consistency of the finished product. Finally, a composite disc spring with a biomimetic spiral layup and SMA wire ring embedded composite structure is obtained.

[0054] Based on the above, this invention exhibits significantly superior load-bearing capacity and energy absorption in its helical layup, with performance far exceeding that of traditional layups when the layup angle is between 1° and 45°. Finite element analysis using unidirectional carbon fiber prepreg in this invention reveals that the load-bearing capacity of samples with different interlayer helical angles gradually increases as the interlayer helical angle decreases, with discontinuous fiber helical structures showing superior performance. Furthermore, the composite structure with embedded SMA filaments exhibits a 6% to 10% improvement in performance compared to a pure fiber helical structure.

[0055] In terms of damage mechanism, traditional orthogonal layup is prone to straight cross-shaped cracks and sudden failure. Helical layup forms helical or zigzag cracks as the angle decreases. The composite structure with embedded SMA wires can further delay crack propagation through the superelasticity of SMA wires. With the triple effect of progressive failure induced by tensile stress in the layers, helical progressive damage guided by interlaminar shear stress, and tensile energy absorption of SMA wires, the fracture surface is increased to absorb more energy.

[0056] In terms of stress distribution, traditional orthogonal layups show significant stress concentration, while pure fiber helical layups can disperse the stress within the layers. In contrast, composite structures with embedded SMA fibers can precisely offset the tensile stress in the inner rings and disperse the shear stress in the middle rings, further alleviating the concentration of interlayer shear stress and improving load transfer efficiency.

[0057] Therefore, the above-mentioned biomimetic spiral layup structure of composite disc spring and its preparation method, by constructing a biomimetic spiral layup structure that rotates layer by layer in the thickness direction of the composite material, combined with the differentiated SMA wire ring embedding design of the inner and middle rings, enables the disc spring to achieve a synergistic improvement in load-bearing capacity, energy absorption performance and interlayer failure resistance under the premise of lightweight, thereby improving its overall mechanical properties and service reliability.

[0058] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A composite disc spring with a biomimetic helical layup structure, characterized in that, The disc spring is a conical ring-shaped elastic element, which is formed by stacking and curing multiple layers of fiber prepreg along the thickness direction; the fiber prepreg is a laminate composed of reinforcing fibers and matrix resin laid in a plane, and the single layer of fiber prepreg is cut into a ring shape that matches the outer dimensions of the disc spring. When the multilayer fiber prepreg is stacked sequentially along the thickness direction, the main fiber direction of two adjacent fiber prepregs rotates around the center of the disc spring according to a set spiral layup angle, forming a biomimetic spiral layup structure arranged periodically along the circumference of the disc spring. The spiral layup angle between adjacent layers is 1°~45°. The biomimetic spiral layup structure simulates the microstructure of the mantis shrimp's spiral region of bio-fibers rotating and stacking layer by layer. The inner and middle rings of the fiber prepreg are circumferentially embedded with SMA filaments treated with coupling agent to reinforce the weak areas of the disc spring and synergistically improve the load-bearing capacity and energy absorption performance of the disc spring.

2. The composite material disc spring according to claim 1, characterized in that, The SMA filaments have a diameter of 0.1~5mm and are embedded in shallow grooves pre-set in the fiber prepreg according to the pattern of double inner rings and single middle rings. The width of the shallow grooves is 0.05~0.1mm larger than the diameter of the SMA filaments, and the depth is 1 / 3~1 / 2 of the thickness of the fiber prepreg.

3. The composite material disc spring according to claim 1, characterized in that, The reinforcing fibers in the fiber prepreg are unidirectional continuous fibers, and the reinforcing fibers can be either single-material fibers or heterogeneous fiber blends; the reinforcing fiber material is one or more of carbon fiber, glass fiber, aramid fiber, basalt fiber, natural fiber, and shape memory alloy fiber; the resin matrix is ​​a thermosetting resin or a thermoplastic resin; the heterogeneous fiber blends are any one of carbon fiber-glass fiber blends, carbon fiber-aramid fiber blends, and basalt fiber-carbon fiber blends.

4. The composite material disc spring according to claim 1, characterized in that, In the periodic spiral arrangement, the interlayer spiral angle gradually changes or varies in segments within the range of 1° to 45°.

5. The composite material disc spring according to claim 1, characterized in that, The disc spring is composed of several composite material disc springs, and the combination method is any one of the following: stacking combination, pairing combination, and composite combination; the stacking combination is several disc springs stacked in the same direction; the pairing combination is several disc springs arranged in pairs in opposite directions and stacked in sequence; the composite combination is several groups of stacked disc springs arranged facing each other.

6. A method for preparing a composite material disc spring as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Based on the geometric dimensions and design thickness of the target disc spring, determine the thickness and number of layers of the single-layer fiber prepreg. Cut the plate-shaped fiber prepreg into annular prepreg sheets that match the planar projection of the disc spring. Leave process allowances for the inner and outer diameters. Process the inner and middle rings of the prepreg sheets with arc-shaped shallow grooves that are adapted to SMA yarns. S2. After pre-treating the SMA filaments with a coupling agent, dry them at room temperature. Embed the pre-treated SMA filaments into the arc-shaped shallow grooves and fit them tightly. Then, rotate and stack the embedded circular prepreg sheets layer by layer at a spiral layup angle of 1°~45° to form a biomimetic spiral fiber reinforcement structure. S3. The fiber-reinforced structure is placed into the hot press mold cavity, pre-pressed and fixed, and then the mold is closed and sealed. S4. Maintain a weak vacuum atmosphere in the closed mold. First, apply low-pressure bonding and preheat to the initial gel temperature of the resin. Then, use pulsed intermittent pressure to cure. After curing, keep the mold closed and allow for gradual cooling. S5. After the mold cools to room temperature, the blank is removed from the mold. The inner and outer diameters of the blank are then polished and trimmed to the design dimensions to obtain the finished disc spring.

7. The method according to claim 6, characterized in that, In step S1, the inner and middle rings of the prepreg sheet are processed using laser micro-engraving. The size of the shallow grooves is adapted to the SMA wire to be embedded.

8. The method according to claim 6, characterized in that, In step S2, the SMA filaments are pretreated by soaking in silane coupling agent KH550 for 5-10 minutes and then drying at room temperature; after the SMA filaments are embedded in shallow grooves, the prepreg sheet is gently pressed to achieve tight bonding.

9. The method according to claim 6, characterized in that, In step S4, the specific process parameters are as follows: during the preheating stage, the heating rate is 4~6℃ / min, with only low-pressure bonding and no continuous high pressure; during the curing stage, the pulse intermittent pressure is applied for 3~5 minutes per cycle, with pressure gradients of 2MPa, 4MPa, and 6MPa respectively, and the pressure relief amplitude is 1~2MPa, with the holding time increasing with the temperature; during the slow cooling stage, the cooling rate is 3~5℃ / min, and the temperature is uniformly reduced to below 40℃.

10. The method according to claim 6, characterized in that, In step S5, the inner and outer diameters and end faces of the disc spring blank are trimmed using CNC dry cutting technology, and the dimensional tolerance of the finished product is controlled within ±0.08mm.

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