UHMWPE复合材料的冲击损伤特性研究

发布时间：2018-05-17 07:07

本文选题：动态冲击 + 动态特性　；参考：《湖南科技大学》2015年硕士论文

【摘要】：含沙流导致的过流件冲蚀是水电工程中存在的主要技术问题,研究表明它是粒子流对材料表面连续冲击损伤的结果。上世纪80年代,研究人员开始进行聚合物材料抗冲蚀的应用试验,结果表明,在中低水头的高含沙环境中,以超高分子量聚乙烯(UHMWPE)为代表的聚合物基复合材料显示出比普通碳钢材料更优良的抗冲蚀性能。根据接触动力学理论,材料的动态力学特性对材料冲击破坏有着重要影响,随着聚合物复合材料在冲蚀环境中的推广应用,开展聚合物复合材料动态冲击特性的研究,对于揭示聚合物材料冲蚀损伤机理,完善抗冲蚀聚合物复合材料的组分设计,改进抗冲蚀聚合物复合材料制备方法,进一步提高其抗冲蚀综合性能有着重要的科学与应用意义。本文选择两种材料的填充粒子,采用压制烧结工艺制备了UHMWPE复合材料,应用霍普金森压杆实验技术研究了复合材料的动态冲击性能,并通过数据处理分析了材料在冲击过程中的吸能特性;通过冲蚀磨损实验考察了复合材料的抗粒子流冲击损伤(冲蚀)性能;结合实验结果分析讨论了材料损伤与本身静、动态特性及材料微观结构的相关性,主要结论如下:1.填充粒子可提高UHMWPE复合材料的表面硬度、屈服应力,但填充粒子后的复合材料比纯UHMWPE的冲击韧性降低。相同填充量时,云母/UHMWPE复合材料的冲击韧性值高于碳酸钙/UHMWPE复合材料。2.填充粒子能有效提高UHMWPE复合材料的动态屈服应力值,在相同应变率下,UHMWPE复合材料的动态屈服应力值随粒子填充量的加大而提高,且填充碳酸钙粒子比云母粒子更明显。UHMWPE复合材料的动态屈服应力随应变率的增大而提高,具有显著的应变率强化效应。3.根据动态实验数据,采用吸能效率评价了UHMWPE复合材料的动态吸能特性,结果表明,在应变率3200/s以下范围内,UHMWPE复合材料的吸能效率随应变率的增加而提高。粒子填充量在5%~15%范围内,复合材料吸能效率相对UHMWPE提高15%左右。填充量相同时,填充云母粒子比碳酸钙粒子更能提高UHMWPE复合材料的吸能效率,相差在8%左右。4.冲蚀实验表明,UHMWPE复合材料具有优良的抗冲蚀性能,相同工况下,UHMWPE复合材料的冲蚀磨损量仅为45#钢的0.08倍。5%云母填充量的UHMWPE复合材料的抗冲蚀性能比纯UHMWPE高10%左右。5.UHMWPE复合材料的抗冲蚀性能与其硬度、静态屈服应力等静态性能相关性不高,而与其冲击韧性和动态屈服应力乘积、吸能效率等动态性能有良好的正对应关系。UHMWPE复合材料优良的抗冲击损伤性能从能量角度可解释为聚合物内部分子链的伸缩与球晶结构的扭转有效耗散了冲击能量;填充粒子减少微剪切带的形成,起到增强作用。
[Abstract]:The main technical problem in hydropower engineering is the erosion of overflowing parts caused by sand flow. The research shows that it is the result of continuous impact damage caused by particle flow on the surface of materials. In the 1980s, researchers began to test the erosion resistance of polymer materials, and the results showed that in high-sand environments with low and low water head, The polymer matrix composites, represented by UHMWPE, show better erosion resistance than ordinary carbon steel materials. According to the contact dynamics theory, the dynamic mechanical properties of the materials have an important effect on the impact failure of the materials. With the popularization and application of polymer composites in the erosion environment, the dynamic impact characteristics of polymer composites are studied. It is of great scientific and practical significance to reveal the erosion damage mechanism of polymer materials, improve the composition design of erosion-resistant polymer composites, improve the preparation method of anti-erosion polymer composites, and further improve their comprehensive anti-erosion properties. In this paper, UHMWPE composites were prepared by pressing sintering process, and the dynamic impact properties of the composites were studied by using Hopkinson compression bar test technique. The energy absorption characteristics of the materials during impact are analyzed by data processing, the impact damage (erosion) properties of the composites are investigated by erosion wear experiments, and the damage and static properties of the composites are discussed by combining the experimental results. The main conclusions are as follows: 1. The surface hardness and yield stress of UHMWPE composites can be improved by filling particles, but the impact toughness of the composites filled with particles is lower than that of pure UHMWPE. The impact toughness of mica / UHMWPE composite is higher than that of calcium carbonate / UHMWPE composite. The dynamic yield stress of UHMWPE composites can be improved by filling particles, and the dynamic yield stress of UHMWPE composites increases with the increase of particle filling at the same strain rate. The dynamic yield stress of UHMWPE composites increases with the increase of strain rate, and it has a significant strain rate strengthening effect .3.The results show that the dynamic yield stress of UHMWPE composites is more obvious than that of mica particles, and the dynamic yield stress increases with the increase of strain rate. According to the dynamic experimental data, the dynamic energy absorption characteristics of UHMWPE composites are evaluated by energy absorption efficiency. The results show that the energy absorption efficiency of UHMWPE composites increases with the increase of strain rate in the range of 3 200 / s. The energy absorption efficiency of the composite is about 15% higher than that of UHMWPE in the range of 5% particle filling. When the filling amount is the same, filling mica particles can improve the energy absorption efficiency of UHMWPE composites better than calcium carbonate particles, and the difference is about 8%. 4. The erosion test shows that the UHMWPE composite has excellent erosion resistance. Under the same condition, the erosion resistance and hardness of the UHMWPE composite with only 0.08 times the amount of mica filled with 4 steel is about 10% higher than that of the pure UHMWPE under the same condition. 5. The erosion resistance and hardness of the UHMWPE composite is about 10% higher than that of the pure UHMWPE composite, and the erosion resistance of the UHMWPE composite is only 0.08% of that of the pure UHMWPE composite. The static properties, such as static yield stress, are not highly correlated with their impact toughness and dynamic yield stress. The excellent impact damage resistance of UHMWPE composites can be explained from the energy point of view as the molecular chain stretching inside the polymer and the torsion of spherulite structure effectively dissipating the impact energy. Filling particles reduce the formation of microshear bands and play an enhanced role.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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