玄武岩纤维增强复合材料准脆性断裂行为与断裂参数预测

Quasi-brittle fracture behavior and fracture parameter prediction of basalt fiber-reinforced polymer

  • 摘要: 玄武岩纤维增强复合材料(Basalt fiber-reinforced polymer, BFRP)层合板在加工及服役过程中易产生表面划痕或浅缺口。在持续载荷作用下,这些初始缺陷可能扩展并诱发断裂失效。为探究BFRP层合板的准脆性断裂行为,对不同缺口深度的试样开展了三点弯曲(Three-point bending, 3-p-b)试验。基于边界效应模型(Boundary effect model, BEM),引入纤维织物单层厚度作为特征复合单元 C_\textch ,建立断裂参数计算方法,并结合载荷-位移曲线分析材料的断裂演化过程。采用正态分布对抗拉强度 f_\textt 和断裂韧性 K_\textIC 进行统计分析,并基于不同试样组的试验数据对断裂参数进行预测与验证。结果表明:BFRP层合板的断裂过程可分为线性、软化和失效三个阶段;抗拉强度 f_\textt =137.68 MPa,断裂韧性 K_\textIC =7.54 MPa·m1/2,与最小二乘法结果相比,相对误差为0.94%,且95%的试验数据位于置信区间内。此外,断裂参数随缝厚比 \alpha 的变化呈现非单调变化规律。各组试样断裂参数预测结果与试验结果吻合较好,相对误差均小于1%。

     

    Abstract: Basalt fiber-reinforced polymer (BFRP) laminates are prone to surface scratches and shallow notches during manufacturing and service. Under sustained loading, these initial defects may propagate and eventually lead to fracture failure. To investigate the quasi-brittle fracture behavior of BFRP laminates, three-point bending (3-p-b) tests were conducted on specimens with different notch depths. Based on the boundary effect model (BEM), the thickness of a single fiber fabric ply was introduced as the characteristic composite unit C_\textch to establish a fracture parameter calculation method. The fracture evolution process was further analyzed using load-displacement curves. A normal distribution was adopted to statistically analyze the tensile strength f_\textt and fracture toughness K_\textIC , and the fracture parameters were predicted and validated based on the experimental data of different specimen groups. The results show that the fracture process of BFRP laminates can be divided into three stages: linear deformation, softening, and failure. The tensile strength and fracture toughness were f_\textt =137.68 MPa and K_\textIC =7.54 MPa·m1/2, respectively. Compared with the least-squares fitting result, the relative error was 0.94%, and 95% of the experimental data fell within the confidence interval. In addition, the fracture parameters exhibited a non-monotonic variation with the crack-thickness ratio \alpha . The predicted fracture parameters agreed well with the experimental results for each specimen group, with relative errors below 1%.

     

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