Preparation method of a ski board core composite material

Abstract

The present invention discloses a preparation method of a ski board core composite material. Carbon fiber fabric and glass fiber fabric are selected as the panel materials of the ski board core. Then, a lower carbon-glass fiber panel, a foam sandwich layer, and an upper carbon-glass fiber panel are sequentially laid in layers to form a preform. Next, the stress condition of the ski board is simulated by finite element method, and different density and angle gradient stitching is performed on the preform according to the stress magnitude to increase the mechanical properties. Finally, the carbon fiber-glass fiber hybrid reinforced resin material and the sandwich material are tightly combined by the VARI process to form a fully-thickness stitched foam sandwich structure composite. The present invention uses a resin composite material reinforced by a mixture of carbon fiber and glass fiber as the outer shell material, combines the puncture stitching technology and the gradient stitching method to optimize the mechanical properties, load-bearing capacity and damage tolerance of the ski board core, effectively improves the core delamination, enhances the durability and damage tolerance of the ski board, and prolongs its service life.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and specifically to a preparation method of a composite material for a snowboard core. Background Art

[0002] With the progress of material science, the ice and snow industry has been promoted by leaps and bounds. The manufacturing materials of snowboards have been gradually optimized. Foam sandwich composite materials have been widely used in various fields such as aerospace, ships, automobiles, and sports equipment due to their excellent processability, isotropic properties, light weight, high strength, and simple molding.

[0003] At present, most snowboard cores use wood as the main material. Wood has disadvantages such as excessive weight, insufficient elasticity, and easy corrosion. Compared with wood materials, snowboard materials developed using fiber-reinforced resin-based composite materials can improve the quality of snowboards, have better controllability and damping performance, and extend their service life. The strength and stability of glass fiber materials enable snowboards to slide smoothly under different slopes and snow conditions, making glass fiber snowboards one of the mainstream materials for modern snowboards. The use of carbon fiber not only has the effect of light weight but also helps to accurately control the rigidity of snowboards, providing a better control experience for athletes.

[0004] However, using carbon fiber materials or glass fiber materials alone cannot overcome the defects of these materials themselves, and the combination of carbon fiber and resin is not very tight. All these defects affect the application of these materials and methods in snowboard cores. Moreover, the adhesives used in the preparation of composite snowboards contain harmful substances and are easy to volatilize, which is easy to cause environmental pollution and may also affect the skiing experience and use safety. Therefore, improving material quality, reducing board weight, improving the elasticity and durability of the board, and using environmentally friendly adhesives and preparation methods are one of the problems that need to be solved for current snowboards.

[0005] Currently, the "sandwich" sandwich structure is the mainstream structure of snowboards, and new composite materials are gradually replacing traditional single materials. Adding a sandwich layer to traditional composite material panels, the sandwich composite material not only has high specific strength, high specific stiffness, good corrosion resistance and fatigue resistance, but also is lighter than poplar wood. However, the sandwich composite material is prone to interface delamination, resulting in the failure of the sandwich composite material, thereby reducing the integrity and durability of the structure. Therefore, it is of great significance to design a composite method applied to snowboard cores to prepare foam sandwich composite materials. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a preparation method of a composite material for a snowboard core.

[0007] The technical solution for the present invention to solve the above-mentioned technical problems is to provide a method for preparing a composite material for a snowboard core, which is characterized in that the method comprises the following steps:

[0008] Step 1, material preparation: Select carbon fiber fabric and glass fiber fabric as the panel materials for the snowboard core; then cut the carbon fiber fabric, glass fiber fabric and foam sandwich into corresponding sizes of the snowboard core.

[0009] Step 2, preparation of preform: Lay the lower carbon-glass fiber panel, foam sandwich and upper carbon-glass fiber panel in sequence in the form of layers to form a preform.

[0010] Step 3, use finite element analysis software to simulate and analyze the stress condition of the snowboard when a person stands on it to obtain the stress nephogram of the snowboard; then design the stitching density and stitching angle of the preform in Step 2 according to the load distribution in the stress nephogram.

[0011] Step 4, preparation of fiber composite reinforcement: According to the stitching density and stitching angle of different stress regions of the preform obtained in Step 3, use stitching threads to stitch the preform in Step 2 through the stitch-through technique to stitch the lower carbon-glass fiber panel, foam sandwich and upper carbon-glass fiber panel together to obtain a fiber composite reinforcement.

[0012] Step 5, use the VARI molding process to cure and mold the fiber composite reinforcement in Step 4 to obtain a composite material for the snowboard core.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The present invention selects carbon fiber fabric and glass fiber fabric as the panel materials for the snowboard core; then lays the lower carbon-glass fiber panel, foam sandwich and upper carbon-glass fiber panel in sequence in the form of layers to form a preform; then uses finite element to simulate the stress condition of the snowboard, and performs gradient stitching with different densities and angles on the preform according to the stress magnitude to increase the mechanical properties. Finally, use the low-cost non-autoclave VARI process to tightly combine the carbon fiber-glass fiber hybrid reinforced resin material with the sandwich material to form a fully thickness stitched foam sandwich structure composite.

[0015] (2) The present invention uses a resin composite material reinforced with a mixture of carbon fiber and glass fiber as the outer shell material, combines the stitch-through technique and the gradient stitching method to optimize the mechanical properties, load-bearing capacity and damage tolerance of the snowboard core, effectively improves the delamination of the core, improves the durability and damage tolerance of the snowboard, and extends its service life.

[0016] (3) The present invention incorporates a gradient design on the basis of stitching, flexibly improving the stress state of the snowboard core, thereby enabling the stitching technique to exert its maximum advantage.

[0017] (4) The present invention prepares the panel material by alternately laminating carbon fiber fabric and glass fiber fabric in a ±45° manner, combined with PMI foam as the core material, ensuring the elasticity, mechanical properties, and lightweight characteristics of the snowboard core.

[0018] (5) The present invention adjusts the stitching density through finite element simulation of the stress on the snowboard, achieving a gradient distribution and improving the mechanical properties of the overall snowboard.

[0019] (6) The present invention adopts the low-cost and efficient VARI molding process, reducing production costs, improving production efficiency, ensuring product quality, enabling industrial production, and thus making the snowboard more competitive. This process has no dimensional requirements for the workpiece and is suitable for simple curved workpieces such as the snowboard core. The resin is always in the vacuum bag, which can reduce the release of volatiles during the curing process.

[0020] (7) The snowboard core prepared by the present invention has the advantages of light weight, high strength, high performance, and low cost, meeting the requirements for high-performance snowboards, improving the independent research and development and manufacturing level of the snowboard industry, promoting the development of the snowboard industry, and driving the development of the entire ice and snow industry chain. Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of the preform of the present invention;

[0022] Figure 2 is a schematic diagram showing the three-dimensional snowboard model, stress nephogram, and distribution of stitching density of Example 1 of the present invention;

[0023] Figure 3 is a schematic structural diagram of the fiber composite reinforcement of the present invention;

[0024] Figure 4 is a test result diagram of the shear strength and shear modulus of Example 1 of the present invention;

[0025] Figure 5 is a test result diagram of the flexural strength of Example 1 of the present invention;

[0026] Figure 6 is a test result diagram of the flexural modulus of Example 1 of the present invention;

[0027] Figure 7 is a test result diagram of the flexural stiffness of Example 1 of the present invention.

[0028] In the figure, the lower carbon-glass fiber panel 1, the foam sandwich 2, the upper carbon-glass fiber panel 3, and the stitching line 4. Detailed implementation manners

[0029] The following are specific embodiments of the present invention. The specific embodiments are only used for further elaborating the present invention in detail and do not limit the protection scope of the claims of the present invention.

[0030] The present invention provides a method for preparing a composite material for a snowboard core (hereinafter referred to as the method), which is characterized in that the method includes the following steps:

[0031] Step 1, material preparation: Select carbon fiber fabric and glass fiber fabric as the panel materials for the snowboard core; then cut the carbon fiber fabric, glass fiber fabric and foam sandwich 2 into the corresponding sizes of the snowboard core;

[0032] Preferably, in step 1, the carbon fiber fabric is a carbon fiber plain weave fabric; in this embodiment, the specification of the carbon fiber plain weave fabric is 3k and the linear density is 198 g / km.

[0033] Preferably, in step 1, the glass fiber fabric is a glass fiber plain weave fabric; in this embodiment, the specification of the glass fiber plain weave fabric is 300 tex and the linear density is 295 g / km.

[0034] Preferably, in step 1, the foam sandwich 2 is made of PMI (polymethacrylimide) foam; the PMI foam has light weight, high strength and excellent heat insulation performance, providing an ideal lightweight and strengthening effect for the core; the density of the PMI foam is 75 kg / m 3 .

[0035] Preferably, in step 1, taking an adult as an example, the cutting size is 160 cm × 110 cm.

[0036] Step 2, preparation of the preform: Lay the lower carbon-glass fiber panel 1, the foam sandwich 2 and the upper carbon-glass fiber panel 3 in sequence in the form of layers to form a preform;

[0037] The preparation of the lower carbon-glass fiber panel 1 is as follows: In the form of layers, lay the carbon fiber fabric in the +45° direction to form the first layer (which contacts the ground during use), then lay the glass fiber fabric in the -45° direction to form the second layer, and then lay the carbon fiber fabric and the glass fiber fabric alternately until the required laying thickness is reached, and the outermost layer is the glass fiber fabric (which contacts the lower surface of the foam sandwich 2);

[0038] The preparation of the upper carbon - glass fiber panel 3 is as follows: In the form of layers, the glass fiber fabric is laid in the +45° direction to form the first layer (which contacts the upper surface of the foam sandwich 2), then the carbon fiber fabric is laid in the -45° direction to form the second layer, and then the glass fiber fabric and the carbon fiber fabric are alternately laid at intervals until the required laying thickness is reached, and the top layer is the carbon fiber fabric (which contacts the human foot during use).

[0039] Preferably, in step 2, according to the ski board regulation standards, the thicknesses of both the lower carbon - glass fiber panel 1 and the upper carbon - glass fiber panel 3 are 1 mm; in this embodiment, according to the requirements and the thickness requirements of the fabric materials, both the lower carbon - glass fiber panel 1 and the upper carbon - glass fiber panel 3 are laid in 4 layers, that is, two layers of carbon fiber fabric and two layers of glass fiber fabric.

[0040] Preferably, in step 2, the laying angle is ±45°. This laying angle can enable the fabric to exhibit the optimal performance. The fabric laid at this laying angle can show the best mechanical properties and is not easily deformed.

[0041] Step 3: Use finite element analysis software to simulate and analyze the stress situation of the ski board when a person stands on it, and obtain the stress nephogram of the ski board; then design the stitching density and stitching angle of the preform in step 2 according to the load distribution in the stress nephogram to meet the requirements of the composite material for high performance and durability.

[0042] Preferably, step 3 is specifically as follows:

[0043] S1. Establish a three - dimensional ski board model: First, according to the geometric shape and size of the ski board, use drawing software to establish an accurate three - dimensional model of the ski board to obtain the three - dimensional ski board model; then import the three - dimensional ski board model into the finite element analysis software.

[0044] S2. Material property setting: In the finite element analysis software, specify the material properties for the three - dimensional ski board model.

[0045] Preferably, in step S2, set the Young's modulus to 850 GPa, the Poisson's ratio to 0.22, and the density to 2.54 g / cm 3 , and these parameters reflect the elastic and density characteristics of the ski board material.

[0046] S3. Analysis step module selection: In the analysis step module of the finite element analysis software, select the analysis type as dynamics, and simulate the stress situation of the ski board during the movement process through dynamic analysis.

[0047] Preferably, in step S3, set the interaction time between the ski board and the ground to 5 seconds to simulate a typical skiing process.

[0048] S4. Mesh Generation: Generate a mesh for the three-dimensional snowboard model;

[0049] Preferably, in step S4, select three-dimensional solid elements (C3D8R) to define the model, and set the mesh size to 0.8 mm.

[0050] Preferably, in step S4, the mesh generation needs to be detailed enough to capture the detailed features of the snowboard, while avoiding too many meshes that may lead to excessive computational effort. In this embodiment, a total of 60,000 meshes are generated, which is a result of balancing computational accuracy and efficiency.

[0051] S5. Boundary Condition Setting: To simulate the connection between the snowboard and the binding, use a tie constraint to fix the part of the bottom plate of the three-dimensional snowboard model connected to the binding, ensuring that the bottom plate does not displace or rotate when the snowboard is stressed;

[0052] S6. Load Application: Apply a downward load at the binding position to simulate the force exerted by the skier on the snowboard, and adjust the magnitude and direction of the load according to the actual situation;

[0053] Preferably, in step S6, the load is 1 kN.

[0054] S7. Stress and Strain Calculation: Submit a simulation job in the job module of the finite element analysis software, and the finite element analysis software calculates the three-dimensional snowboard model to obtain stress and strain results;

[0055] S8. Stress Contour Analysis: After the calculation is completed, view the stress contour in the visualization module of the finite element analysis software. The stress contour shows the stress distribution of each part of the snowboard when stressed in a color-coded manner; by analyzing the stress contour, obtain the stress distribution of each part of the snowboard when stressed;

[0056] S9. Design Optimization: According to the analysis results of the stress contour, optimize the stitching density and stitching angle of each stress area of the snowboard to increase the mechanical properties, determine the stitching density and stitching angle of each stress area of the snowboard, and then correspondingly design the stitching density and stitching angle of the preform in step 2.

[0057] Preferably, in step S9, in the stress contour, sequentially decrease the stitching density in the order of the red area, orange area, yellow area, green area, and blue area, where the stitching density in the red area is the largest and the stitching density in the blue area is the smallest; determine the amount of decrease in stitching density between stress areas based on experience.

[0058] Preferably, in step S9, sequentially decrease the stitching density in a gradient manner in the order of the red area, orange area, yellow area, green area, and blue area; the gradient decrease is in an arithmetic progression, expressed as: an = a1 + (n - 1)d, where a1 represents the maximum stitching density and d represents the reduction amount of the stitching density. In this embodiment, according to the area and stitching efficiency of the snowboard, the maximum stitching density a1 = 10mm × 10mm, and the stitching density is reduced in a gradient of d = 5mm × 5mm according to the force, and the stitching density gradient in other areas is reduced to 15mm × 15mm and 20mm × 20mm.

[0059] Preferably, in step S9, the strength of this area is increased by increasing the stitching density to enhance the stress dispersion effect; the ways to increase the stitching density are: (1) increasing the number of stitching threads in this area, thereby increasing the stitching density; (2) adjusting the position of the stitching threads and arranging the stitching threads on the path with greater stress, thereby increasing the stress resistance effect.

[0060] Preferably, in step 3 or S9, the stitching angle of the preform is adjusted according to the magnitude and direction of the stress: the stress direction is perpendicular to the surface of the snowboard, the stitching angle is parallel to the surface of the snowboard, and the stitching thread 4 can disperse the stress to the greatest extent.

[0061] Step 4, preparation of the fiber composite reinforcement: According to the stitching density and stitching angle of different stress areas of the preform obtained in step 3, use the stitching thread 4 to stitch the preform in step 2 through the puncture stitching technique, and stitch the lower carbon-glass fiber panel 1, the foam sandwich layer 2 and the upper carbon-glass fiber panel 3 together to obtain the fiber composite reinforcement;

[0062] Preferably, in step 4, the puncture stitching is different from the traditional stitching method. There is no bottom thread on the surface of the stitched preform, single-needle stitching is used, and there is no knotting between the surface stitches, so that both sides of the carbon-glass fiber panel are evenly loaded, effectively enhancing the interlayer performance of the composite material, improving its interlayer bonding strength, reducing the risk of delamination failure, and effectively reducing the influence of friction during stitching on the performance of the composite material. The puncture stitching technique uses a puncture stitching device; the puncture stitching device uses the sizing die of the carbon fiber box-shaped preform disclosed in 201510113258.7. This device is different from the chain stitching and lockstitch methods and can sew thick (the thickness is determined according to the length of the sewing needle) and hard sewing materials.

[0063] Preferably, in step 4, according to the limited range of the stitch pitch and row pitch of the puncture stitching device, the maximum value of the stitching density is 1mm × 1mm.

[0064] Preferably, step 4 is specifically as follows: During stitching, first clamp the preform obtained in step 2 with the fixture of the puncture stitching device and fix it on the frame of the puncture stitching device. Then, use the puncture head to drill holes in the preform, and insert a syringe needle at the drilled position of the preform. Then, place the sewing needle with the sewing thread 4 (a hand sewing needle is used in this embodiment) against the syringe needle. While the syringe needle is withdrawn, the sewing needle with the sewing thread 4 passes through the preform. The sewing thread 4 moves a distance of one needle pitch driven by the sewing needle. Then, the sewing needle is again placed against the syringe needle, the syringe needle is withdrawn, and the sewing needle passes through the preform along the drilled hole to complete one stitching action. Repeat the stitching action to complete the stitching of the entire preform and obtain the fiber composite reinforcement.

[0065] Preferably, in step 4, the diameter of the drilling needle is 1.2 mm, the diameter of the sewing needle is 1 mm, and the diameter of the drilling needle is slightly larger than that of the sewing needle.

[0066] Preferably, in step 4, the sewing thread 4 is made of carbon fiber with light weight, high strength, and good toughness; the specification of the carbon fiber is 3k, and two strands are used during stitching.

[0067] Step 5: Use the VARI (Vacuum Assisted Resin Infusion) molding process to cure and mold the fiber composite reinforcement obtained in step 4 to obtain the ski board core composite material.

[0068] Preferably, in step 5, the specific steps of the VARI molding process are as follows:

[0069] A1. Apply a release agent in the ski board core mold, lay the fiber composite reinforcement obtained in step 4 in the ski board core mold, then lay a release cloth on the fiber composite reinforcement, and place a flow guide tube at an appropriate position. Then, place the whole into a vacuum bag and seal it with sealant.

[0070] A2. Connect the flow guide tube to a resin tank containing resin. After checking the airtightness of the vacuum bag, start the vacuum pump, gradually reduce the pressure inside the vacuum bag to promote the resin to penetrate into the fiber composite reinforcement, fill the fiber gaps and infiltrate the fibers. Use a flat tool to scrape the resin inside the vacuum bag to promote the uniform distribution of the resin. Maintain a vacuum state for 15 min to remove air. After the resin is fully infiltrated, seal the vacuum bag.

[0071] Preferably, in step A2, the resin is 6349 epoxy resin, which is obtained by mixing 6439 resin A and 6439 resin B in a mass ratio of 2:1.

[0072] A3. According to the curing characteristics of the resin, put it into an oven, heat it from room temperature to 80 °C in 10 min, keep the curing process for 3 h, and maintaining the vacuum state helps to remove the volatiles and bubbles in the resin and ensure the quality of the prepared composite material.

[0073] A4. After curing is completed, stop the vacuum pump. After cooling, take out the product and trim the rough edges with scissors to obtain the composite material for the snowboard core.

[0074] Example 1

[0075] Step 1. Material preparation: Select carbon fiber plain weave fabric. In this example, the specification of the carbon fiber plain weave fabric is 3k and the linear density is 198 g / km.

[0076] Select fiberglass plain weave fabric. In this example, the specification of the fiberglass plain weave fabric is 300 tex and the linear density is 295 g / km.

[0077] The foam sandwich layer 2 uses PMI closed-cell foam, and the density of the PMI closed-cell foam is 75 kg / m 3 .

[0078] Step 2. Prepare the preform; the laying angle is ±45°.

[0079] In this example, according to the requirements and the thickness requirements of the fabric material, both the lower carbon-glass fiber panel 1 and the upper carbon-glass fiber panel 3 are laid in 4 layers:

[0080] The preparation of the lower carbon-glass fiber panel 1 is as follows: In the form of layers, lay the carbon fiber fabric in the +45° direction to form the first layer (which contacts the ground during use), then lay the fiberglass fabric in the -45° direction to form the second layer, then lay the carbon fiber fabric in the +45° direction to form the third layer, and then lay the fiberglass fabric in the -45° direction to form the fourth layer (which contacts the lower surface of the foam sandwich layer 2).

[0081] The preparation of the upper carbon-glass fiber panel 3 is as follows: In the form of layers, lay the fiberglass fabric in the +45° direction to form the first layer (which contacts the upper surface of the foam sandwich layer 2), then lay the carbon fiber fabric in the -45° direction to form the second layer, then lay the fiberglass fabric in the +45° direction to form the third layer; then lay the carbon fiber fabric in the -45° direction to form the fourth layer (which contacts the human foot during use).

[0082] In Step 3, the finite element analysis software uses ABAQUS. The drawing software uses AutoCAD.

[0083] Step 4. Prepare the fiber composite material reinforcement; as Figure 2 shown, the stitching densities are 20 mm × 20 mm, 15 mm × 15 mm, and 10 mm × 10 mm respectively.

[0084] Step 5. Use the VARI (vacuum assisted) molding process to cure and mold the fiber composite material reinforcement in Step 4 to obtain the composite material for the snowboard core.

[0085] The properties of the composite material were experimentally tested, including the mechanical properties of flat tensile, flat compression, side compression, shear, bending, and the compressive strength after impact. On the composite material of the snowboard core, three specimens with suture densities of 20mm×20mm, 15mm×15mm, and 10mm×10mm were taken respectively.

[0086] It can be seen from Figure 4 that the shear strengths of the specimens with suture densities of 20mm×20mm, 15mm×15mm, and 10mm×10mm were increased by 54%, 85%, and 187% respectively compared with the unsutured specimens, and the shear moduli were increased by 31.19%, 71.05%, and 117.17% respectively. Therefore, suturing can significantly improve the shear strength and shear modulus of the specimens, and with the increase of the suture density, the shear performance of the specimens increases accordingly, and there is a positive correlation between the suture density and the improvement amplitude of the shear strength. The improvement amplitudes of the shear strength and shear modulus of the specimen with a suture density of 10mm×10mm are the highest, the shear strength reaches 2.87MPa, and the shear modulus reaches 100.67MPa.

[0087] Under the shear load, in the unsutured specimen, the foam sandwich 2 is subjected to shear stress and a whole crack appears, and the foam bears the stress alone, so the shear strength and modulus are relatively low. However, due to the existence of the suture resin columns in the sutured foam sandwich 2, it can bear greater stress, and the fracture strength of the suture resin columns is much higher than that of the foam sandwich 2. Therefore, cracks first appear at the stress concentration points of the sutures in the foam sandwich 2, and with the increase of the load, the suture resin columns begin to fracture. So the sutured specimens have better shear performance. Among the tested suture densities, the shear performance of the specimens increases with the increase of the suture density, and the suture density of 10mm×10mm has the most significant improvement on the specimen performance, because the denser suture resin columns provide better mechanical support and stress distribution, thus enhancing the overall performance of the specimens.

[0088] It can be seen from Figures 5 - 7 that the flexural strengths of the specimens with suture densities of 20mm×20mm, 15mm×15mm, and 10mm×10mm were increased by 11.53%, 26.02%, and 38.21% respectively compared with the unsutured specimens, the flexural rigidities were increased by 15.09%, 33.19%, and 44.53% respectively, and the flexural moduli were increased by 15.2%, 33.33%, and 38.34% respectively. The flexural strength, flexural modulus, and flexural rigidity of the unsutured composite material are much smaller than those of the sutured ones. The flexural strengths, flexural moduli, and flexural rigidities of the composite materials with different suture densities are also different, and the one with a suture density of 10mm×10mm is the best.

[0089] The stitching density has a great influence on the bending properties of the specimen. The higher the stitching density, the better the bending properties of the specimen. The increase in stitching density significantly enhances the bending properties of the composite material because more stitches increase the connection points between the panel and the foam core 2, thus improving the overall stability and load-bearing capacity of the structure. This helps to disperse and transfer the applied bending force, reduce the risk of interlayer separation, and improve the energy absorption and dissipation capacity. At the same time, it increases the shear strength of the material. The combined effect improves the performance of the composite material under bending loads.

[0090] Therefore, through gradient stitching, the load-bearing capacity and damage tolerance are significantly improved compared to the composite material without stitched foam core 2, indicating that the snowboard core composite material of the present invention exhibits higher structural efficiency.

[0091] Matters not described in the present invention apply to the prior art.

Claims

1. A method for preparing a composite material for a snowboard core, characterized in that: The method comprises the following steps: Step 1, material preparation: selecting carbon fiber fabric and glass fiber fabric as the panel material of the snowboard core; then cutting the carbon fiber fabric, glass fiber fabric and foam interlayer (2) into the corresponding size of the snowboard core; Step 2, preparation of a preform: laying a lower carbon-glass fiber panel (1), a foam interlayer (2) and an upper carbon-glass fiber panel (3) in layers in sequence to form a preform; Step 3: Use finite element analysis software to simulate and analyze the stress of the ski when a person stands, and obtain a stress cloud map of the ski; then optimize the stitching density and stitching angle of each stress area of ​​the ski according to the load distribution in the stress cloud map to increase the mechanical properties, determine the stitching density and stitching angle of each stress area of ​​the ski, and then design the stitching density and stitching angle of the preform in step 2 accordingly; The stitching density is gradually reduced in the order of red area, orange area, yellow area, green area and blue area; the gradient is reduced in an arithmetic progression, expressed as: a n =a1+(n-1)d, a1 represents the maximum stitching density, d represents the reduction of stitching density; Step 4, preparation of a fiber composite material reinforcement: according to the stitching density and stitching angle of different stress regions of the preform obtained in step 3, the preform obtained in step 2 is stitched using a stitching thread (4) through a puncture stitching technique, and the lower carbon-glass fiber panel (1), the foam interlayer (2) and the upper carbon-glass fiber panel (3) are stitched together to obtain a fiber composite material reinforcement; Step 5: Use VARI molding process to solidify and mold the fiber composite reinforcement of step 4 to obtain a snowboard core composite material.

2. The method for preparing the composite material for the core of a snowboard according to claim 1, characterized in that: In step 1, the carbon fiber fabric is carbon fiber plain fabric; the glass fiber fabric is glass fiber plain fabric; and the foam interlayer (2) is PMI foam.

3. The method for preparing the composite material for the core of a snowboard according to claim 1, characterized in that: In step 2, the lower carbon-glass fiber panel (1) is prepared by laying the carbon fiber fabric in a +45° direction to form a first layer, and then laying the glass fiber fabric in a -45° direction to form a second layer, and then laying the carbon fiber fabric and the glass fiber fabric alternately until the laying thickness requirement is reached, and the uppermost layer is the glass fiber fabric; The upper carbon-glass fiber panel (3) is prepared by laying the glass fiber fabric in a +45° direction to form a first layer, and then laying the carbon fiber fabric in a -45° direction to form a second layer, and then laying the glass fiber fabric and the carbon fiber fabric alternately until the laying thickness requirement is reached, and the uppermost layer is the carbon fiber fabric.

4. The method for preparing the composite material for the core of a snowboard according to claim 1, characterized in that: Step 3 specifically is: S1. Establishing a three-dimensional snowboard model: firstly establishing a three-dimensional snowboard model according to the geometric shape and size of the snowboard to obtain a three-dimensional snowboard model; then importing the three-dimensional snowboard model into the finite element analysis software; S2. Material property setting: In the finite element analysis software, specify material properties for the three-dimensional snowboard model; S3. Analysis step module selection: In the analysis step module of the finite element analysis software, select the analysis type as dynamics, and simulate the force of the ski during the movement through dynamic analysis; S4. Meshing: Meshing the three-dimensional snowboard model; S5. Boundary condition setting: In order to simulate the connection between the snowboard and the binding, the binding constraint is used to fix the part where the base plate of the 3D snowboard model is connected to the binding to ensure that the base plate will not be displaced or rotated when the snowboard is subjected to force; S6. Apply load: Apply a downward load at the binding position to simulate the force applied by the skier on the skis. The size and direction of the load are adjusted according to the actual situation. S7, stress and strain calculation: submit the simulation job in the job module of the finite element analysis software, and the finite element analysis software calculates the three-dimensional snowboard model to obtain stress and strain results; S8. Stress cloud map analysis: After the calculation is completed, the stress cloud map is viewed in the visualization module of the finite element analysis software. The stress cloud map displays the stress distribution of each part of the ski board when it is subjected to force in a color-coded manner; by analyzing the stress cloud map, the stress distribution of each part of the ski board when it is subjected to force is obtained; S9. Design optimization.

5. The method for preparing the composite material for the core of a snowboard according to claim 4, characterized in that: In step S2, the Young's modulus is set to 850 GPa, the Poisson's ratio is set to 0.22, and the density is set to 2.54 g / cm 3 ; In step S3, the interaction time between the ski board and the ground is set to 5 seconds to simulate a skiing process; In step S4, a three-dimensional solid unit is selected to define the model, and the mesh size is set to 0.8 mm; a total of 60,000 meshes are divided; In step S6, the load is 1 kN; In step S9, the reduction amount of stitching density between stress regions is determined empirically.

6. The method for preparing the composite material for the core of a snowboard according to claim 1 or 4, characterized in that: In step 3, the stitching angle of the preform is adjusted according to the magnitude and direction of the stress: the stress direction is perpendicular to the surface of the snowboard, the stitching angle is parallel to the surface of the snowboard, and the stitching line (4) can disperse the stress to the maximum extent.

7. The method for preparing the composite material for the core of a snowboard according to claim 1, characterized in that: Step 4 specifically comprises: when suturing, firstly clamp the preform obtained in step 2 with a clamp of a puncture and suturing device and fix it on the frame of the puncture and suturing device, then use the puncture head to drill a hole on the preform, and then insert a needle tube at the drilling position of the preform; then, a suturing needle with a suture thread (4) is pressed against the needle tube, and the needle tube is withdrawn while the suturing needle with a suture thread (4) passes through the preform, and the suture thread (4) moves a distance of a needle pitch under the drive of the suturing needle, and then the suturing needle is pressed against the needle tube again, the needle tube is withdrawn, and the suturing needle passes through the preform along the drilled hole, completing one suturing action; repeating the suturing action to complete the suturing of the entire preform, and obtaining a fiber composite material reinforcement; The suture (4) is made of carbon fiber; the specification of the carbon fiber is 3k, and double strands are used for suture.

8. The method for preparing the composite material for the core of a snowboard according to claim 1, characterized in that: In step 5, the specific steps of the VARI molding process are as follows: A1. Apply a release agent in the snowboard core mold, lay the fiber composite reinforcement of step 4 in the snowboard core mold, lay a release cloth on the fiber composite reinforcement, and place a guide tube at an appropriate position; then put the whole into a vacuum bag and seal it with a sealant; A2. Connect the guide tube to the resin tank containing the resin, check the air tightness of the vacuum bag and start the vacuum pump to gradually reduce the pressure in the vacuum bag to promote the resin to penetrate into the fiber composite reinforcement, fill the fiber gaps and infiltrate the fibers; scrape the resin in the vacuum bag to promote uniform distribution of the resin; maintain the vacuum state for 15 minutes to remove the air, and close the vacuum bag after the resin is fully infiltrated; A3. According to the curing characteristics of the resin, put it in an oven and heat it from room temperature to 80°C in 10 minutes. The curing process is maintained for 3 hours. Maintaining a vacuum state helps to discharge volatiles and bubbles in the resin. A4. After curing is completed, stop the vacuum pump, take it out after cooling, trim the burrs, and obtain the snowboard core composite material.

9. The method for preparing the composite material for the core of a snowboard according to claim 8, characterized in that: In step A2, the resin used is 6349 epoxy resin, which is obtained by mixing 6439 resin A and 6439 resin B in a mass ratio of 2:1.

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