Pullout of Inclined Flexible Fiber in Cementitious Composite
Pullout of Inclined Flexible Fiber in Cementitious Composite
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DOI：
10.1061/(asce)0733-9399(1997)123:3(239
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发表时间：
1997-03
期刊：
影响因子：
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通讯作者：
C. Leung;Numer V. Ybañez
中科院分区：
文献类型：
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作者：
C. Leung;Numer V. Ybañez
纤维增强复合材料的性能很大程度上取决于纤维的脱粘/拔出行为。在水泥基复合材料中，纤维通常以准随机的方式分布。因此，研究倾向于断裂的纤维的拔出是很重要的。对于柔性纤维，建立了一个简单的绳索通过摩擦滑轮的模型来描述纤维的倾斜拔出。现有的模型是基于从具有初始弯曲的纤维的试件中获得的实验结果。为了评估实验结果和模型的有效性，对聚丙烯纤维进行了拔出试验，使用(1)具有初始直纤维的试件；(2)具有初始弯曲纤维的试件。两组结果之间存在显著差异。由于初始直纤维的拔出行为更能代表实际复合材料的拔出行为，提出了一种新的柔性纤维拔出模型。通过考虑(1)界面摩擦力和缓冲系数随滑移的增加，以及(2)新模型中纤维出口处基质的剥落，可以得到与实验结果很好的拟合。
The performance of fiber-reinforced composites is strongly dependent on the debonding/pullout behavior of the fibers. In cementitious composites, fibers are usually distributed in a quasi-random manner. It is therefore important to study the pullout of fibers that are inclined to a crack. For flexible fibers, a simple model of a string passing over a frictional pulley has been developed to describe inclined fiber pullout. The existing model is based on experimental results obtained from specimens with initially bent fibers. To evaluate the validity of the experimental results and the model, pullout tests are carried out with polypropylene fibers using (1) specimens with initially straight fibers; and (2) specimens with initially bend fibers. Significant differences are found between the two set of results. Since the pullout behavior of initially straight fibers is more representative of that in real composites, a new model for flexible fiber pullout is developed. By considering (1) the increase of both interfacial friction and snubbing factor with sliding; and (2) spalling of matrix at fiber exit point in the new model, excellent fitting of the experimental results can be obtained.