PP/CF增强珊瑚砂水泥基复合材料冲击压缩力学性能研究

在人工海水制备珊瑚砂水泥基复合材料中混杂加入碳纤维和聚丙烯纤维，得到4种不同纤维掺量的碳-聚丙烯混杂纤维增强珊瑚砂水泥基复合材料。采用直径100 mm的分离式Hopkinson压杆，对材料进行5种应变率下的冲击压缩试验，采用LS-DYNA进行相应的冲击压缩数值模拟。结果表明:(1) 试验应变率临界值为200 s?1，当试验应变率大于200 s?1时，混杂碳纤维和聚丙烯纤维所形成的纤维网络对试块的增韧效果加强；(2) 碳-聚丙烯混杂纤维增强珊瑚砂水泥基复合材料峰值应力具有明显的应变率效应，且动态增强因子对应变率的敏感程度较高；(3) 使用珊瑚砂细骨料导致试块内微裂纹和微空洞等缺陷较多，在珊瑚砂水泥基复合材料内混杂掺加碳纤维和聚丙烯纤维后，试块冲击抗压强度的提升有限，但珊瑚砂水泥基复合材料的抗冲击韧性显著提升；(4) 通过试验数据和参数调试确定了HJC模型的参数，试块峰值应力的模拟结果与试验结果的误差在5.97 %以内。

A study on impact compression mechanical properties of PP/CF reinforced coral sand cement-based composites

Four kinds of carbon-polypropylene hybrid fiber reinforced coral sand cement-based composites with different fiber content were obtained by mixing carbon fiber and polypropylene fiber into coral sand cement-based composites prepared by artificial seawater. Impact compression tests of this material under five strain rates were carried out with a 100-mm diameter split Hopkinson pressure bar. The parameters of Holmquist-Johnson-Cook model are determined by experimental data and parameter debugging. Based on Holmquist-Johnson-Cook model, LS-DYNA is used to simulate the impact compression of this material. By analyzing the failure mode, stress-strain curve and energy dissipation of the test blocks, the impact compression mechanical properties of carbon-polypropylene hybrid fiber reinforced coral sand cement-based composites are studied. The results are as follows. (1) The critical value of test strain rate is 200 s?1; when the test strain rate is greater than 200 s?1, the fiber network formed by hybrid carbon fiber and polypropylene fiber strengthens the toughening effect of the test block. (2) The peak stress of carbon-polypropylene hybrid fiber reinforced coral sand cement-based composites exhibits obvious strain rate effect, and the dynamic increase factor is highly sensitive to the strain rate. (3) The use of fine aggregate of coral sand results in more defects such as micro-cracks and micro-voids in the test block; after mixing carbon fiber and polypropylene fiber into the coral sand cement-based composites, the improvement of the impact compressive strength of the test block is limited, but the impact toughness of the coral sand cement-based composites is significantly enhanced. (4) LS-DYNA is used to numerically simulate the impact compression test process of hybrid carbon fiber (15.75 kg/m3) and polypropylene fiber (1.82 kg/m3), while the error between the simulation results of peak stress and the test results is within 5.97 %. The study is of great significance for the preparation of high performance coral sand cement-based composites and the emergency repair of offshore islands and reefs.