石墨烯涂层-镀铜钢纤维协同增强水泥基复合材料的自感知机制及智能损伤评估

Synergistic self-sensing mechanism and intelligent damage assessment of cement-based composites enhanced by graphene coating and copper-coated steel fibers

  • 摘要: 水泥基结构健康监测材料在土木工程领域具有重要应用价值。目前,水泥基自感知复合材料普遍存在导电性与力学性能难以兼顾、损伤监测灵敏度不足等问题。为解决上述难题,本研究提出了一种石墨烯导电涂层与镀铜钢纤维协同增强的水泥基自感知材料体系,通过丝网印刷工艺制备了不同配比的试件。三点弯曲加载试验结果显示,在最优配比(钢纤维含量2.5%、石墨烯涂层厚度0.5 mm)下,主裂缝扩展阶段材料电阻变化率达到181%,峰值抗弯强度为3.57 kN,表现出优异的力-电协同响应能力。构建了耦合主裂缝长度与最大挠度的无量纲损伤指标 \varPsi ,该指标实现了对结构损伤状态的连续量化与安全分级,为工程应用提供了明确的损伤评估依据。引入“多层感知机”(Multilayer Perceptron, MLP)机器学习回归模型,实现了电阻与损伤指标的高精度非线性映射,模型测试集判定系数R2为0.961。研究结果表明,该复合体系有效提升了损伤监测的灵敏度和准确性,为水泥基结构健康状态的智能评估提供了新的技术路径。

     

    Abstract: Cement-based structural health monitoring materials have important application value in the field of civil engineering. At present, cement-based self-sensing composites generally face problems such as the difficulty in balancing electrical conductivity and mechanical properties, as well as insufficient sensitivity for damage monitoring. To address the above challenges, this study innovatively proposes a cement-based self-sensing material system synergistically reinforced by graphene conductive coatings and copper-coated steel fibers, and prepares specimens with different proportions through screen printing technology. The results of three-point bending loading tests show that under the optimal proportion (steel fiber content of 2.5% and graphene coating thickness of 0.5 mm), the resistance change rate of the material reaches 181% during the main crack propagation stage, and the peak flexural strength is 3.57 kN, demonstrating excellent force-electricity collaborative response capability. By using the main crack length and maximum deflection, a dimensionless damage index \varPsi is constructed. This index realizes continuous quantification of structural damage states and safety grading by coupling the main crack length and maximum deflection, providing a clear basis for damage assessment in engineering applications. Additionally, a Multilayer Perceptron (MLP) machine learning regression model is introduced to achieve high-precision nonlinear mapping between resistance and the damage index, with the determination coefficient R2 of the model's test set reaching 0.961. The research results show that this composite system effectively improves the sensitivity and accuracy of damage monitoring, providing a new technical path for the intelligent assessment of the health status of cement-based structures.

     

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