混杂纤维增强水泥基复合材料抗冲击性能
High Impact Resistance of Hybrid Fiber Reinforced Engineered Cementitious Composite
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摘要: 为了进一步提高工程水泥基复合材料(engineered cementitious composite,ECC)抗冲击性能,通过落锤冲击试验研究不同弹性模量、长度的非金属纤维和钢纤维(steel fiber,SF)增强ECC的抗冲击性能。结果表明:ECC的破坏冲击次数随着纤维模量和纤维长度的增加而增加,在相同非金属纤维体积率下,长度12 mm聚乙烯(polyethylene,PE)纤维增强ECC的破坏冲击次数分别是长度12 mm玻璃纤维(glass fiber,GF)、36 mm玻璃纤维增强ECC破坏冲击次数的2.92、1.43倍;无纤维增强ECC的破坏模式为碎裂成几块,而混杂纤维增强ECC只在冲击部位发生局部冲切破坏,试件保持较好的完整性。建立基于双参数威布尔分布的冲击损伤演化方程和寿命预测模型。对比机器学习方法k近邻算法(k-nearest neighbors,KNN)、粒子群优化随机森林算法(particle swarm optimization random forest,PSO-RF)、粒子群优化k近邻算法(particle swarm optimization k-nearest neighbors,PSOKNN)与传统拟合模型的预测精度,PSO-KNN模型具有最好的拟合效果。研究结果将为工程应用甄选纤维和利用机器学习方法预测ECC抗冲击性能提供参考。Abstract: To further enhance the impact resistance of engineered cementitious composites (ECC), this study investigates the impact resistance of ECC reinforced with non-metallic fibers and steel fibers (SF) of varying elastic moduli and lengths through drop-weight impact tests. The results indicate that the number of impact failures of ECC increases with increasing fiber modulus and fiber length. Under the same volume fraction of non-metallic fibers, the number of impact failures for ECC reinforced with 12 mm polyethylene (PE) fibers is 2. 92 times and 1. 43 times that of ECC reinforced with 12 mm glass fibers (GF) and 36 mm glass fibers, respectively. The failure mode of ECC without fiber reinforcement is fragmentation into several pieces, whereas hybrid fiber-reinforced ECC only experiences local punching shear failure at the impact site, maintaining high integrity of the specimen. An impact damage evolution equation and a life prediction model based on the two-parameter weibull distribution were established. Comparing the prediction accuracy of machine learning methods such as k-nearest neighbors (KNN), particle swarm optimization random forest (PSO-RF), and particle swarm optimization k-nearest neighbors (PSO-KNN) with traditional fitting models, the PSO-KNN model demonstrates the best fit. The findings of this study provide a reference for selecting fibers in engineering applications and utilizing machine learning methods to predict the impact resistance of ECC.
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