Intelligent color-changing material based on force feedback and bolt

Abstract

The invention relates to the technical field of fixing components, and discloses an intelligent color-changing material based on force feedback and a bolt, the intelligent color-changing material comprises matrix resin, a curing agent, a composite force-induced color-changing system and a dispersing auxiliary agent, the composite force-induced color-changing system comprises two different types of force-induced color-changing compounds, and reinforcing fibers or nano reinforcing materials can be selectively added, so that the mechanochromic sensitivity, the color contrast and the corresponding stability of the material are remarkably improved. According to the bolt based on the material, the intelligent color-changing core column made of the intelligent color-changing material is fixed in the mounting hole for communicating the nut and the bolt, so that when the bolt is fastened, the color of the intelligent color-changing core column can be obviously changed along with the change of the pre-tightening force, and the fastening degree of the bolt can be visually judged only by directly looking at the color of the end face of the bolt with human eyes; the structure is simple and the modification cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fixing components, in particular to an intelligent color-changing material based on force feedback and a bolt. BACKGROUND

[0002] High-strength bolts are one of the most critical mechanical connecting components in the fields of steel structures, heavy machinery, aerospace and infrastructure. The reliability of the connection directly relates to the safety and service life of the overall structure. However, during the long-term service of the bolts, the pre-tightening force will decay or even loosen due to the effects of vibration, impact, creep, temperature cycling and corrosion, etc., thereby causing connection failure and possibly leading to catastrophic accidents. Therefore, it is crucial to effectively monitor the fastening state of the bolts.

[0003] At present, the bolt loosening monitoring methods mainly include the following categories: 1) direct detection methods, such as manual visual inspection, torque wrench re-tightening, ultrasonic detection, etc. These methods rely on manual operation, have strong subjectivity and low efficiency; 2) indirect sensing methods, such as technologies based on vibration analysis, acoustic emission, fiber Bragg grating sensors, etc. These methods require the installation of additional sensors on the bolts or structures, and have complex systems, high costs, and cumbersome wiring, and are easily affected by environmental electromagnetic interference and physical damage; 3) first-generation intelligent bolt / washer methods, such as electronic intelligent bolts integrated with piezoelectric ceramics and resistance strain gauges. Although these methods can provide electrical signal output, they usually require wiring for power supply and signal acquisition systems, and are complex to install, have long-term reliability affected by the aging and fatigue of electronic components, and have poor adaptability in harsh industrial environments.

[0004] In recent years, optical intelligent bolts based on the principle of force-induced color change have attracted attention as a new passive monitoring solution. The core idea is to integrate a special material on the surface or inside the bolt, which changes color when stressed, thereby converting mechanical information into an intuitive optical signal. For example, in the prior art, such as patent application publication CN120040912A, a composite material made of spiropyran and epoxy resin is filled in the bolt. Although the intelligent bolt made by this scheme is convenient to use and can determine the stress condition of the bolt without connecting to other electronic devices, it still has the following obvious limitations: first, its color development sensitivity and range are limited, it relies on a single force-induced color-changing molecule, the stress and color response curve of the material is single and cannot be adjusted, resulting in insufficient color contrast under different pre-tightening force levels, making it difficult to achieve fine differentiation of the bolt from loose to over-tight; second, its structure is complex, this scheme must additionally set a polarizer and a reflective material on the end of the bolt to form an optical assembly, which not only significantly increases the complexity and cost of the bolt structure, but more importantly, the user cannot directly observe and judge by the naked eye, and must observe through the polarizer at a specific angle, which weakens its intuitiveness; third, it is easy to cause monitoring distortion due to material mechanical mismatch, the pure resin-based composite material used has a large difference in mechanical properties compared with the metal bolt, and when stressed, different degrees of deformation may occur between the composite material core and the metal bolt body, resulting in low and uneven stress transmission efficiency, so that the color change cannot truly and synchronously reflect the actual stress state of the bolt shaft, and the accuracy of the monitoring result is questionable.

[0005] Therefore, it is necessary to provide an intelligent color-changing material based on force feedback and a bolt, aiming to solve the problems of low material response performance, monitoring accuracy, product practicability and industrial feasibility in the prior art. SUMMARY

[0006] In view of this, the present application provides an intelligent color-changing material based on force feedback and a bolt, aiming to solve the problems of low material response performance, monitoring accuracy, product practicability and industrial feasibility in the prior art.

[0007] The present application provides an intelligent color-changing material based on force feedback, comprising: a base resin, a curing agent, a composite force-induced color-changing system and a dispersing aid; wherein the mass percentage of each component is: the base resin is 60-75%, the curing agent is 20-30%, the composite force-induced color-changing system is 0.5-5%, and the dispersing aid is 0-10%; wherein, the sum of the mass percentages of the base resin, the curing agent, the composite force-induced color-changing system and the dispersing aid is 100%; The composite force-induced color change system comprises two different types of force-induced color change compounds, which are uniformly dispersed in a cured product network formed by the base resin and the curing agent.

[0008] Further, the composite force-induced color change system comprises a spiropyran compound and a spirothiopyran compound; wherein, The mass ratio of the spiropyran compound to the spirothiopyran compound is 10:1-1:10.

[0009] Further, the spiropyran compound is 1,3,3-trimethylindolinospirpyran, and the spirothiopyran compound is 1,3,3-trimethylindolinospirothiopyran.

[0010] Further, it further comprises reinforcing fibers accounting for 1-20% of the total mass of the smart color-changing material.

[0011] Further, the reinforcing fibers are at least one of chopped glass fibers, carbon fibers, or aramid fibers.

[0012] Further, the length of the reinforcing fibers is 50-1000 μm, and the diameter is 5-20 μm.

[0013] Further, it further comprises nano-reinforcing materials accounting for 0.1-5% of the total mass of the smart color-changing material.

[0014] Further, the nano-reinforcing materials are at least one of carbon nanotubes, graphene, or modified silica nanoparticles.

[0015] Further, the preparation method of the smart color-changing material comprises the following steps: S100, heating the base resin to a viscosity of 100-500 mPa·s to obtain a pretreated resin; S200, mixing the composite force-induced color change system with part of the pretreated resin or a special solvent, and forming a uniformly dispersed color change mother liquor by ultrasonic treatment; S300, mixing the color change mother liquor with the remaining pretreated resin, and performing first-stage stirring and defoaming treatment to obtain a uniform resin-color change agent mixture; S400, adding the curing agent and optionally reinforcing fibers or nano-reinforcing materials to the resin-color change agent mixture, and performing second-stage low-speed stirring and vacuum defoaming treatment; S500, injecting the mixture obtained in step S400 into a mold, and performing a stepwise curing program: first curing at 40-60°C for 1-3 hours, and then completely curing at 70-90°C for 2-6 hours.

[0016] In another aspect, the application also provides a bolt, comprising: a nut, a screw rod, an intelligent color-changing core column and a transparent protective layer; wherein, The intelligent color-changing core column is made of the force-feedback-based intelligent color-changing material according to any one of claims 1-9; An installation hole is formed in the center of the upper surface of the nut in the axial direction, the installation hole extends to the inside of the screw rod (200) and penetrates through one third of the length of the screw rod (200); The intelligent color-changing core column is arranged in the installation hole, and the bottom surface of the intelligent color-changing core column is fixedly connected with the bottom surface of the installation hole; The transparent protective layer covers and seals the installation hole, and the lower surface of the transparent protective layer is fixedly connected with the upper surface of the intelligent color-changing core column.

[0017] Compared with the prior art, the application has the following beneficial effects: I. High color development sensitivity: the composite force-induced color-changing system contains at least two different types of force-induced color-changing compounds, so that the intelligent color development material can produce continuous, stepwise and color-contrast bright changes in a wider stress range.

[0018] II. High reliability: the introduction of reinforcing fibers significantly improves the elastic modulus and toughness of the intelligent color development material, making its mechanical properties more matched with those of metal bolts, ensuring that the stress acting on the intelligent color development material can truly and synchronously reflect the actual stress state of the bolt, thereby greatly improving the accuracy and reliability of the monitoring.

[0019] III. Stress distribution visualization: the introduction of reinforcing fibers makes the intelligent color development material change from a transparent state to a translucent state, and when stressed, the stress is preferentially concentrated at the interface between the fibers and the resin and triggers color development, not only forming different color changes according to the stress size, but also forming a unique stress cloud pattern, the pattern of which can directly show the distribution of stress in the cross-section of the bolt. BRIEF DESCRIPTION OF DRAWINGS

[0020] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments, and are not meant to limit the present application. Moreover, the same reference numerals in the attached drawings indicate the same or similar components. In the drawings: Figure 1 The bolt structure schematic diagram provided for the embodiments of the application; DETAILED DESCRIPTION

[0021] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thoroughly and completely comprehended, and so that the scope of the present disclosure will be completely conveyed to those skilled in the art. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0022] In some embodiments of the present application, the present embodiment provides a force-feeding based intelligent color-changing material, comprising a base resin, a curing agent, a composite force-induced color-changing system, and a dispersing aid; wherein the mass percentage of each component is: The base resin is 60-75%, the curing agent is 20-30%, the composite force-induced color-changing system is 0.5-5%, and the dispersing aid is 0-10%; wherein, The sum of the mass percentages of the base resin, the curing agent, the composite force-induced color-changing system, and the dispersing aid is 100%; The composite force-induced color-changing system contains two different types of force-induced color-changing compounds, and the composite force-induced color-changing system is uniformly dispersed in the cured network formed by the base resin and the curing agent.

[0023] Specifically, as a preferred solution of the present application, the formula is as follows in terms of mass percentage: bisphenol A type epoxy resin 68%, modified amine curing agent 26%, composite force-induced color-changing system 3%, and silane coupling agent 3%, wherein the silane coupling agent is used as a dispersing aid.

[0024] Specifically, in terms of the mass percentage of each component selected above, the preparation process is as follows: first, preheat the epoxy resin at 65°C to reduce the viscosity, then mix the composite force-induced color-changing system with part of the preheated resin and the silane coupling agent, and form a uniform mother liquor by ultrasonic dispersion. Mix the mother liquor with the remaining resin and stir, and finally add the curing agent, vacuum degassing, and then pour into a mold, and cure at 80°C for 4 hours to obtain a cured product.

[0025] It can be understood that the present application establishes the basic component framework of the intelligent color-changing material. Each component synergistically acts under the above preferred ratio. The base resin and the curing agent form a strong and tough network skeleton. The composite force-induced color-changing system is used as the functional core. The dispersing aid ensures the uniform and stable dispersion of the functional components. The material prepared by this system has a significant and reliable force-induced color-changing response.

[0026] In some embodiments of the present application, the composite force-induced color-changing system includes spiropyran compounds and spirothiopyran compounds; wherein, The mass ratio of the spiropyran compound to the spirothiran compound is 10:1 to 1:10.

[0027] Specifically, the mass ratio of spiropyran compounds to spirothiran compounds is 8:2. Under stress, this composite system exhibits a continuous color transition from colorless to purplish-red. The color sensitivity in the low-stress region is mainly contributed by the spiropyran compounds, while the color depth and stability in the high-stress region are enhanced by the spirothiran compounds, achieving a wide-threshold stress response.

[0028] Understandably, the specific 8:2 formulation leverages the high sensitivity of spiropyran compounds in low-stress areas and the advantages of spirothiran compounds in improving color stability. This formulation enables the material to produce a smooth, wide-threshold color transition from colorless to purplish-red under stress, making it particularly suitable for applications requiring precise visual monitoring of the process from initial tightening to standard tightening.

[0029] Specifically, the mass ratio of spiropyran compounds to spirothiran compounds is 1:1. At this ratio, the two compounds exhibit the best synergistic response. The material displays the richest and most vivid color changes under stress, with a clear stepwise transition from pale yellow to orange and then to reddish-brown, demonstrating extremely high distinguishability between different levels of preload.

[0030] Understandably, the specific 1:1 blending ratio achieves optimal synergy and balance in the response characteristics of spiropyran and spirothiran compounds. This material exhibits a rich and contrasting gradient of colors under stress, maximizing the differentiation between different levels of preload. This provides operators with the clearest and most easily interpretable visual signals, significantly reducing the risk of misjudgment.

[0031] Specifically, the mass ratio of spiropyran compounds to spirothiran compounds is 2:8. At this ratio, the material exhibits a more stable blue-violet color under higher stress, and the color fades more slowly, making it suitable for scenarios requiring stress history preservation observation.

[0032] Understandably, the specific 2:8 compounding ratio is chosen to leverage the stable color development and slow fading of spirothiano compounds under high stress. The material exhibits and maintains a stable blue-purple color under high preload or overload conditions, providing a clear visual indication of whether bolts are overtightened or overloaded, and possesses a certain degree of stress history retention, facilitating subsequent inspection.

[0033] It is understandable that the mass ratio of spiropyran compounds to spirothiran compounds is adjusted to match the needs of different application scenarios.

[0034] In some embodiments of this application, the spiropyran compound is 1,3,3-trimethylindoline spiropyran, and the spirothiran compound is 1,3,3-trimethylindoline spirothiran.

[0035] Understandably, the spiropyran compounds selected are 1,3,3-trimethylindoline spiropyran, and the spirothiran compounds are 1,3,3-trimethylindoline spirothiran. These two compounds have similar spirocyclic structures but different heteroatoms, namely oxygen and sulfur, respectively. Furthermore, the ring-opening energy barriers and color development wavelengths of these two compounds differ. By blending these two compounds in a predetermined ratio, mechanochromic materials with excellent repeatability and high color contrast can be obtained.

[0036] In some embodiments of this application, the force-fed smart color-changing material further includes reinforcing fibers accounting for 1-20% of the total mass of the smart color-changing material.

[0037] Specifically, the mass percentages of each component are: 60-75% matrix resin, 20-30% curing agent, 0.5-5% composite mechanochromic system, 0-10% dispersing agent, and 1-20% reinforcing fiber.

[0038] Specifically, the reinforcing fiber is at least one of chopped glass fiber, carbon fiber, or aramid fiber. Chopped glass fiber is preferred.

[0039] Specifically, the reinforcing fibers have a length of 50-1000 μm and a diameter of 5-20 μm. The chopped glass fibers preferably have a length of 300 μm and a diameter of 12 μm.

[0040] Understandably, fibers of this size can effectively bear loads and improve modulus, without causing blockages or excessive internal defects due to excessive length and thickness.

[0041] Understandably, the addition of glass fiber is a revolutionary improvement. Although adding glass fiber changes the prepared material from a transparent to a translucent state, it offers significant advantages: First, it raises the tensile modulus of the composite material to a level closer to that of steel, resolving the mechanical mismatch between the material and metal bolts, making stress transfer more realistic and efficient, and significantly improving color accuracy. Second, the fiber causes the material to become translucent, forming unique colored stress stripes at the fiber ends and interfaces when under stress. This stress cloud map not only indicates the magnitude of the force but also visually displays the stress distribution, providing richer diagnostic information.

[0042] In some embodiments of this application, the force-fed smart color-changing material further includes nano-reinforcing materials accounting for 0.1-5% of the total mass of the smart color-changing material.

[0043] Specifically, the mass percentages of each component are as follows: 60-75% matrix resin, 20-30% curing agent, 0.5-5% composite mechanochromic system, 0-10% dispersant, 1-20% reinforcing fiber, and 0.1-5% nano-reinforcing material.

[0044] Specifically, the nano-reinforcing material is at least one of carbon nanotubes, graphene, or modified silica nanoparticles.

[0045] Understandably, adding nano-reinforcing materials can significantly improve the barrier and electromagnetic shielding properties of materials, making them more suitable for special environments. It can effectively reduce the curing shrinkage rate of resins, decrease internal stress, and improve dimensional stability and optical uniformity. This makes the technical solution of this application flexible and customizable to meet different needs.

[0046] In some embodiments of this application, the method for preparing the smart color-changing material includes the following steps: S100: Heat the matrix resin to a viscosity of 100-500 mPa·s to obtain a pretreated resin; S200. The composite mechanochromic system is mixed with a portion of the pretreated resin or special solvent, and ultrasonic treatment is used to form a uniformly dispersed color-changing mother liquor. S300. The color-changing mother liquor is mixed with the remaining pretreated resin, and a first stage of stirring and degassing is performed to obtain a uniform resin-color-changing agent mixture. S400: The curing agent and optional reinforcing fibers or nano-reinforcing materials are added to the resin-color changer mixture, and a second stage of low-speed stirring and vacuum degassing treatment is carried out. S500. Inject the mixture obtained in step S400 into the mold and perform a stepped curing process: first, cure at 40-60℃ for 1-3 hours, and then completely cure at 70-90℃ for 2-6 hours.

[0047] In another preferred embodiment based on the above embodiments, see [reference] Figure 1 As shown, this embodiment provides a bolt, including: a nut 100, a screw 200, a smart color-changing core 300, and a transparent protective layer 400; wherein, The intelligent color-changing core 300 is made of a force-fed intelligent color-changing material; The nut 100 has an axially oriented mounting hole at the center of its upper surface, which extends into the screw 200 and penetrates one-third of its length. The intelligent color-changing core 300 is disposed in the mounting hole, and its bottom surface is fixedly connected to the bottom surface of the mounting hole; The transparent protective layer 400 covers and seals the mounting hole, and its lower surface is fixedly connected to the upper surface of the smart color-changing core 300.

[0048] Specifically, the upper surface of the transparent protective layer 400 is flush with the upper surface of the nut 100. The transparent protective layer 400 is a transparent epoxy resin layer or a tempered glass sheet.

[0049] Understandably, when a preload is applied to the bolt, the bolt shank 200 will deform axially as the preload increases. The intelligent color-changing core 300 will also deform accordingly. Because glass fiber is incorporated into the manufacturing of the intelligent color-changing core 300, its stress deformation is more closely matched to that of the bolt shank 200. Furthermore, the intelligent color-changing core 300 will display different colors as the preload increases, and different stress cloud diagrams can be observed on its end face. On one hand, workers can observe whether the bolt is tightened based on the color displayed on the end face of the intelligent color-changing core 300; on the other hand, workers can determine the stress distribution within the bolt cross-section based on the stress cloud diagram.

[0050] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program goods. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program goods embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0051] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program goods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0052] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxesFigure 1 The function specified in one or more boxes.

[0053] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A force-feedback-based smart color-changing material, characterized in that, The composite force-induced color-changing system is uniformly dispersed in a cured product network formed by the base resin and the curing agent. The base resin 60-75%, the curing agent 20-30%, the composite force-induced color-changing system 0.5-5%, and the dispersing aid 0-10%; wherein, The sum of the mass percentages of the base resin, the curing agent, the composite force-induced color-changing system, and the dispersing aid is 100%. The composite force-induced color-changing system contains two different types of force-induced color-changing compounds, and the composite force-induced color-changing system is uniformly dispersed in a cured product network formed by the base resin and the curing agent.

2. The force-feedback based smart color-changing material of claim 1, wherein, The composite force-induced color-changing system includes a spiropyran compound and a spirothiopyran compound; wherein, The mass ratio of the spiropyran compound to the spirothiopyran compound is 10:1-1:

10.

3. The force-feedback based smart color-changing material of claim 2, wherein, The spiropyran compound is 1,3,3-trimethylindolinospirpyran, and the spirothiopyran compound is 1,3,3-trimethylindolinospirothiopyran.

4. The force-feedback based smart color-changing material of claim 3, wherein, It also includes reinforcing fibers accounting for 1-20% of the total mass of the intelligent color-changing material.

5. The force-feedback based smart color-changing material of claim 4, wherein, The reinforcing fibers are at least one of chopped glass fibers, carbon fibers, or aramid fibers. 6.The force-feedback based smart color-changing material of claim 5, wherein, The length of the reinforcing fibers is 50-1000 μm, and the diameter is 5-20 μm.

7. The force-feedback based smart color-changing material of claim 6, wherein, It also includes nano-enhancing materials accounting for 0.1-5% of the total mass of the intelligent color-changing material. 8.The force-feedback based smart color-changing material of claim 7, wherein, The nano-enhancing materials are at least one of carbon nanotubes, graphene, or modified silica nanoparticles. 9.The force-feedback based smart color-changing material of claim 8, wherein, The preparation method of the intelligent color-changing material includes the following steps: S100, heat the base resin to a viscosity of 100-500 mPa·s to obtain a pretreated resin; S200, mix the composite force-induced color-changing system with part of the pretreated resin or a special solvent, and form a uniformly dispersed color-changing mother liquor by ultrasonic treatment; S300, mix the color-changing mother liquor with the remaining pretreated resin, and perform first-stage stirring and defoaming treatment to obtain a uniform resin-color-changing agent mixture; S400, add the curing agent and optionally reinforcing fibers or nano-enhancing materials to the resin-color-changing agent mixture, and perform second-stage low-speed stirring and vacuum defoaming treatment; S500, inject the mixture obtained in step S400 into a mold, and perform a stepwise curing program: first, cure at 40-60°C for 1-3 hours, and then completely cure at 70-90°C for 2-6 hours.

10. A bolt, characterized by It includes: A nut (100), a screw rod (200), an intelligent color-changing core column (300), and a transparent protective layer (400); wherein, The intelligent color-changing core column (300) is made of the force-feeding-based intelligent color-changing material according to any one of claims 1-9; An installation hole is axially formed in the center of the upper surface of the nut (100), and the installation hole extends into the interior of the screw rod (200) and penetrates one-third of the length thereof; The intelligent color-changing core column (300) is arranged in the installation hole, and the bottom surface thereof is fixedly connected to the bottom surface of the installation hole; The transparent protective layer (400) covers and seals the installation hole, and the lower surface thereof is fixedly connected to the upper surface of the intelligent color-changing core column (300).

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