A microstructure synergistic strengthening fiber reinforced resin matrix composite efficient bonding method based on linear beam laser pretreatment

Abstract

This invention discloses a highly efficient bonding method for fiber-reinforced resin matrix composites based on microstructure synergistic reinforcement using line-beam laser pretreatment. The method first shapes a Gaussian beam into a line beam and selectively removes the surface resin of the fiber-reinforced resin matrix composite in a patterned manner, exposing the reinforcing fibers and simultaneously inducing the formation of laser-induced periodic surface structures (LIPSS). Then, the treated material is placed in an oxidizing acid-modified solution for chemical-ultrasonic synergistic cleaning, and finally, bonding is completed under ultrasonic assistance. This invention achieves large-area, high-efficiency surface resin removal through line-beam shaping, and combined with the microstructure synergistic reinforcement effect and multi-scale mechanical interlocking, significantly improves the pretreatment efficiency and joint strength of the bonding interface of fiber-reinforced resin matrix composites.

Description

Technical Field

[0001] This invention belongs to the field of laser-processed fiber-reinforced composite materials technology, specifically relating to an efficient bonding method for microstructure-synergistically reinforced fiber-reinforced resin matrix composite materials based on line-beam laser pretreatment. Background Technology

[0002] Fiber-reinforced resin matrix composites, especially carbon fiber reinforced resin matrix composites (CFRP), are seeing their usage in high-end equipment manufacturing fields such as aerospace increase steadily due to their high specific strength, high specific modulus, and excellent fatigue resistance, as the trend towards lightweight structures deepens. In the assembly process of composite structural components, adhesive bonding technology has become an important alternative to traditional mechanical connections due to its advantages such as uniform stress distribution, no drilling stress concentration, good sealing, and ability to connect irregularly shaped structures. However, the reliability of the adhesive interface is highly dependent on the quality of surface pretreatment. Currently used industrial surface treatment methods, such as mechanical grinding and sandblasting, while increasing surface roughness to improve the mechanical interlocking effect, generally suffer from poor controllability, easy damage to the reinforcing fiber matrix, and limited improvement in interfacial chemical activity. While mechanical connection methods are intuitive to operate, drilling cuts continuous reinforcing fibers, causing severe stress concentration and delamination damage, while also introducing additional fastener weight, contradicting the original design goal of lightweight structures.

[0003] In recent years, laser processing technology has been gradually introduced into the field of composite material surface pretreatment due to its non-contact, high precision, and high controllability. By selectively removing surface resin and exposing underlying reinforcing fibers with lasers, a microscopic mechanical anchoring structure can be formed at the interface, introducing active functional groups and thus improving bond strength to some extent. However, existing laser pretreatment methods mostly employ point-by-point scanning with a circular Gaussian spot. Their processing efficiency is limited by the small spot area and dense scanning path, making it difficult to meet the high-efficiency processing requirements of large-sized components. Simultaneously, the Gaussian spot energy is distributed with a central peak, easily leading to heat accumulation in the overlapping scanning area, causing excessive resin ablation and even thermal damage to the reinforcing fibers, thus restricting further improvement in bond strength. Furthermore, the molten and resolidified debris remaining on the surface after laser ablation is chemically inert, difficult to completely remove with conventional cleaning, and cannot effectively improve surface chemical activity and wettability, limiting the full potential of interfacial adhesion. In subsequent bonding processes, traditional static application of adhesive is prone to uneven adhesive layer distribution due to insufficient wetting, leaving bubbles and voids at the interface.

[0004] Therefore, how to simultaneously achieve high-efficiency, low-damage surface pretreatment and synergistically enhance cleaning and bonding processes has become a key issue that urgently needs to be addressed in the field of fiber-reinforced resin matrix composite bonding technology. To address these shortcomings, this invention proposes a microstructure-based synergistic reinforcement method for high-efficiency bonding of fiber-reinforced resin matrix composites based on line-beam laser pretreatment. This method achieves large-area uniform processing through line-beam shaping, and combines chemical-ultrasonic synergistic cleaning with ultrasonic-assisted bonding, significantly improving the pretreatment efficiency of the bonding interface and the mechanical properties of the joint. Summary of the Invention

[0005] (a) Purpose of the invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a highly efficient bonding method for microstructure-synergistically reinforced fiber-reinforced resin matrix composites based on line-beam laser pretreatment. The method aims to achieve large-area uniform processing through line-beam shaping, enhance surface activity by combining chemical-ultrasonic synergistic cleaning, and promote uniform distribution of adhesive layers and suppression of interface defects by utilizing ultrasonic-assisted bonding, thereby simultaneously improving the bonding interface pretreatment efficiency and connection strength.

[0007] (II) Technical Solution

[0008] This invention is achieved through the following technical solution:

[0009] A highly efficient bonding method for microstructure-synergistically reinforced fiber-reinforced resin matrix composites based on line-beam laser pretreatment includes the following steps:

[0010] S1. The Gaussian beam is shaped into a line beam by a beam shaping element.

[0011] S2. Using preset laser parameters, the surface of the fiber-reinforced resin matrix composite material is scanned with the line beam to selectively remove the surface resin, expose the reinforcing fibers, and induce the formation of laser-induced periodic surface structures (LIPSS) on the exposed reinforcing fiber surface, while forming a surface with a preset pattern.

[0012] S3. The patterned fiber-reinforced resin matrix composite material is placed in an oxidizing acidic modified solution for ultrasonic cleaning, and then dried.

[0013] S4. Using preset ultrasonic vibration platform parameters, apply adhesive to the surface of the dried fiber-reinforced resin composite material under ultrasonic assistance and cure it to complete the bonding.

[0014] Furthermore, the fiber-reinforced resin matrix composite material is one of carbon fiber reinforced resin matrix composite material (CFRP), glass fiber reinforced resin matrix composite material (GFRP), or aramid fiber reinforced resin matrix composite material (KFRP).

[0015] Furthermore, the beam shaping element mentioned in step S1 is one of a cylindrical array mirror, a Powell prism, or a diffractive optical element (DOE).

[0016] Furthermore, the line beam shaped in step S1 is a flat-top line beam with uniform energy distribution, with a length of 1 mm to 50 mm and a width of 10 μm to 2 mm.

[0017] Furthermore, the preset laser parameters in step S2 include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, and number of scans, with values ​​set to 10 fs~1000 fs, 300 nm~1100 nm, 0.01 W~20 W, 1 kHz~10 MHz, 1 mm / s~5000 mm / s, and 1 scan~20 scans, respectively.

[0018] Furthermore, the stripe direction of the LIPSS formed in step S2 is perpendicular to the direction of the principal shear stress on the adhesive joint.

[0019] Furthermore, the preset pattern in step S2 includes one or more of honeycomb, feather, or spider web patterns, the line width of the preset pattern is 0.05 mm to 10 mm, and the coverage area of ​​the preset pattern accounts for 20% to 70% of the total area of ​​the adhesive area.

[0020] Further, the oxidizing acidic modification solution mentioned in step S3 is one of nitric acid solution, a mixed solution of nitric acid and hydrogen peroxide, or a mixed acid solution of nitric acid and sulfuric acid.

[0021] Furthermore, the preset ultrasonic vibration platform parameters mentioned in step S4 include ultrasonic frequency, ultrasonic power, amplitude, and time, with values ​​set to 1 kHz~100 kHz, 5 W~50 W, 5 μm~30 μm, and 5 min~60 min, respectively.

[0022] Further, the concentration of the nitric acid solution is 60 vol%~70 vol%; or the concentration of nitric acid in the mixed solution of nitric acid and hydrogen peroxide is 1 vol%~10 vol% and the concentration of hydrogen peroxide is 1 vol%~10 vol%; or the concentration of nitric acid in the mixed acid solution of nitric acid and sulfuric acid is 10 vol%~30 vol% and the concentration of sulfuric acid is 10 vol%~30 vol%.

[0023] (III) Beneficial Effects

[0024] The above-described technical solution of the present invention has the following beneficial technical effects:

[0025] (1) By shaping the Gaussian beam into a line beam, a large area can be covered in a single scan, greatly reducing the processing time and improving the efficiency of surface pretreatment of fiber-reinforced resin matrix composites.

[0026] (2) The energy distribution of the flat-top line beam after shaping is uniform. Combined with the cold processing characteristics of femtosecond laser, it effectively suppresses the heat accumulation in the scanning overlap area and avoids excessive resin ablation and thermal damage to the reinforcing fiber.

[0027] (3) The oxidizing acidic modification liquid and ultrasonic cleaning are used in synergistic treatment to introduce polar functional groups on the surface of the reinforcing fiber while efficiently removing laser ablation inert debris, thereby improving surface chemical activity and wettability.

[0028] (4) Ultrasonic-assisted bonding promotes the adhesive to fully impregnate and remove air bubbles, making the adhesive layer uniform and dense. Combined with the macroscopic mechanical interlocking of LIPSS stripe direction control and preset honeycomb, feather or spider web patterns, the multi-scale synergistic enhancement of interface load transfer capability from submicron LIPSS to millimeter pattern improves the strength and reliability of the bonded joint. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the bonding process for the fiber-reinforced resin matrix composite material of the present invention.

[0030] Figure 2 This is a schematic diagram of the preset pattern in this invention.

[0031] Figure 3 This is a comparison chart of the processing efficiency of line beam laser preprocessing according to the present invention.

[0032] Figure 4 This is a comparison diagram of the shear strength of the adhesive joint after laser pretreatment according to the present invention.

[0033] Explanation of reference numerals in the attached figures: 201 - grid pattern; 202 - honeycomb pattern; 203 - feather pattern; 204 - spider web pattern. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention.

[0035] Example 1:

[0036] A highly efficient bonding method for microstructure-synergistically reinforced fiber-reinforced resin matrix composites based on line-beam laser pretreatment, using carbon fiber reinforced resin matrix composites (CFRP) as the material to be processed, includes the following steps:

[0037] S1. The Gaussian beam is shaped into a line beam by a Powell prism. The shaped line beam is a flat-topped line beam with uniform energy distribution. The length of the line beam is 0.5 mm and the width is 50 μm.

[0038] S2. Using preset laser parameters (laser pulse width 217 fs, laser wavelength 342 nm, laser power 0.5 W, pulse frequency 100 kHz, scanning speed 50 mm / s, number of scans 1), the line beam is used to scan the CFRP surface, selectively removing the surface resin to expose the carbon fibers, and inducing the formation of LIPSS on the exposed carbon fiber surface. The direction of the LIPSS stripes is perpendicular to the direction of the principal shear stress on the adhesive joint; simultaneously forming… Figure 2 The feather-shaped pattern 203 shown has a line width of 0.5 mm and covers 50% of the total area of ​​the adhesive area.

[0039] S3. The patterned CFRP was placed in a 60 vol% nitric acid solution for ultrasonic cleaning at a frequency of 20 kHz for 30 min. After cleaning, it was rinsed with deionized water and dried.

[0040] S4. Using preset ultrasonic vibration platform parameters (ultrasonic frequency 20 kHz, ultrasonic power 20 W, amplitude 10 μm, time 30 min), apply epoxy resin adhesive to the dried CFRP surface under ultrasonic assistance and cure it to complete the bonding.

[0041] Example 2:

[0042] The only difference between this embodiment and Embodiment 1 is that in step S2, a process is formed with... Figure 2 The surface of the honeycomb pattern 202 shown has a line width of 0.5 mm and covers 50% of the total area of ​​the adhesive bonding region. The remaining steps and parameters are the same as in Example 1.

[0043] Example 3:

[0044] The only difference between this embodiment and Embodiment 1 is that in step S2, a process is formed with... Figure 2 The surface of the spider web pattern 204 shown has a line width of 0.5 mm and covers 50% of the total area of ​​the adhesive bonding region. The remaining steps and parameters are the same as in Example 1.

[0045] Example 4

[0046] The only difference between this embodiment and Embodiment 1 is that the object to be processed is replaced with glass fiber reinforced resin matrix composite (GFRP). All other steps and parameters are the same as in Embodiment 1.

[0047] Example 5

[0048] The only difference between this embodiment and Embodiment 1 is that the material to be processed is replaced with aramid fiber reinforced resin matrix composite (KFRP). All other steps and parameters are the same as in Embodiment 1.

[0049] Comparative Example 1:

[0050] The difference between this comparative example and Example 1 is that the beam in step S1 is an unshaped circular Gaussian beam (spot diameter approximately 50 μm). In step (2), the same laser parameters as in Example 1 are used, and the Gaussian beam is used to scan the CFRP surface. By setting the fill line spacing to 20 μm, multiple scan lines are arranged side by side to form a feather-like pattern 203 with a line width of 0.5 mm, which covers 50% of the total area of ​​the adhesive bonding region. The remaining steps and parameters are the same as in Example 1.

[0051] Comparative Example 2:

[0052] The only difference between this comparative example and Example 1 is that in step S2, a product with... Figure 2 The surface of the grid pattern 201 shown has a line width of 0.5 mm and covers 50% of the total area of ​​the adhesive bonding region. The remaining steps and parameters are the same as in Example 1.

[0053] Comparative Example 3:

[0054] This comparative example does not undergo laser pretreatment, ultrasonic cleaning with oxidizing acidic modification solution, and is cured under static conditions.

[0055] Comparison results:

[0056] Figure 3 This is a comparison of the processing efficiency between Example 1 and Comparative Example 1. Within a 25.4 mm × 25.4 mm bonding area, Example 1 can form a pattern with a line width of 0.5 mm in a single scan using a line beam, while Comparative Example 1, using a Gaussian beam with a spot diameter of approximately 50 μm, requires multiple scan lines to fill the area side-by-side to achieve the same line width. The results show that the shaped line beam can significantly improve preprocessing efficiency.

[0057] Figure 4The comparison results of the shear strength of the adhesive joints in Examples 1-3 and Comparative Examples 2-3 are shown. It can be found that after selectively removing the surface resin using feather-like, honeycomb-like, and spiderweb-like biomimetic patterns, the shear strength of the adhesive joints is significantly improved compared to the mesh-like pattern and the untreated samples. The feather-like pattern of this invention is derived from the branching structure of bird feathers, which can effectively inhibit crack propagation; the honeycomb pattern is derived from the hexagonal structure of a honeycomb, possessing excellent specific strength and energy absorption characteristics; the spiderweb pattern is derived from the radial stress dispersion mechanism of a spider web, which is beneficial for the uniform transfer of load. All of the above biomimetic patterns can achieve significantly improved adhesive strength compared to the comparative examples and should fall within the protection scope of this invention.

[0058] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A highly efficient bonding method for microstructure-synergistically reinforced fiber-reinforced resin matrix composites based on line-beam laser pretreatment, characterized in that... Includes the following steps: S1. The Gaussian beam is shaped into a line beam using a beam shaping element; S2. Using preset laser parameters, the surface of the fiber-reinforced resin matrix composite material is scanned with the line beam to selectively remove the surface resin, expose the reinforcing fibers, and induce the formation of laser-induced periodic surface structures (LIPSS) on the exposed reinforcing fiber surface, while forming a surface with a preset pattern. S3. The patterned fiber-reinforced resin matrix composite material is placed in an oxidizing acidic modified solution for ultrasonic cleaning, and then dried. S4. Using preset ultrasonic vibration platform parameters, apply adhesive to the surface of the fiber-reinforced resin matrix composite material under ultrasonic assistance and cure it to complete the bonding.

2. The method according to claim 1, characterized in that, The fiber-reinforced resin matrix composite material is one of carbon fiber reinforced resin matrix composite material (CFRP), glass fiber reinforced resin matrix composite material (GFRP), or aramid fiber reinforced resin matrix composite material (KFRP).

3. The method according to claim 1, characterized in that, The beam shaping element mentioned in step S1 is one of a cylindrical array mirror, a Powell prism, or a diffractive optical element (DOE).

4. The method according to claim 1, characterized in that, The line beam after shaping in step S1 is a flat-top line beam with uniform energy distribution, with a length of 1 mm to 50 mm and a width of 10 μm to 2 mm.

5. The method according to claim 1, characterized in that, The preset laser parameters in step S2 include laser pulse width, laser wavelength, laser power, pulse frequency, scanning speed, and number of scans, with values ​​set to 10 fs~1000 fs, 300nm~1100 nm, 0.01 W~20 W, 1 kHz~10 MHz, 1 mm / s~5000 mm / s, and 1 scan~20 scans, respectively.

6. The method according to claim 1, characterized in that, The direction of the LIPSS stripes formed in step S2 is perpendicular to the direction of the principal shear stress on the adhesive joint.

7. The method according to claim 1, characterized in that, The preset pattern mentioned in step S2 includes one or more of honeycomb, feather, or spider web patterns. The line width of the preset pattern is 0.05 mm to 10 mm, and the coverage area of ​​the preset pattern accounts for 20% to 70% of the total area of ​​the adhesive area.

8. The method according to claim 1, characterized in that, The oxidizing acidic modification solution mentioned in step S3 is one of the following: nitric acid solution, a mixed solution of nitric acid and hydrogen peroxide, or a mixed acid solution of nitric acid and sulfuric acid.

9. The method according to claim 1, characterized in that, The preset ultrasonic vibration platform parameters mentioned in step S4 include ultrasonic frequency, ultrasonic power, amplitude and time, with values ​​set to 1 kHz~100 kHz, 5 W~50 W, 5 μm~30 μm and 5 min~60 min, respectively.

10. The method according to claim 8, characterized in that, The concentration of the nitric acid solution is 60 vol%~70 vol; or the concentration of nitric acid in the mixed solution of nitric acid and hydrogen peroxide is 1 vol%~10 vol% and the concentration of hydrogen peroxide is 1 vol%~10 vol%; or the concentration of nitric acid in the mixed acid solution of nitric acid and sulfuric acid is 10 vol%~30 vol% and the concentration of sulfuric acid is 10 vol%~30 vol%.

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