【作者】 陈江平；

【导师】 张亚芳；

【作者基本信息】 广州大学 ， 工程力学， 2010， 硕士

【摘要】 水泥基材料是目前最大宗的、拥有优良特性的人造建筑材料,但随着建筑材料越来越向高强高性能化方向发展,其固有的一些弱点也愈益突出。将材料复合化是提高水泥基材性能的主要途径之一,采用纤维增强是其核心。近年来,增强纤维中的钢纤维、聚丙烯纤维和玻璃纤维增强水泥基材料发展较快,与此同时,工程实践要求纤维增强水泥基材料的基础理论研究进一步深化。纤维增强水泥基材料损伤与断裂过程中的裂纹扩展以及损伤与断裂等基本理论问题,是该领域的一个前沿课题。本文应用大连理工大学唐春安教授拥有自主版权的数值分析软件RFPA2D(Realistic Failure Process Analysis)对水泥基复合材料的受弯性能进行模拟。采用Weibull随机分布函数描述水泥基材料的细观非均匀性,实现了纤维增强水泥基试件微裂纹萌生、扩展直至贯通全过程的模拟。利用模拟结果深入分析不同掺量的纤维增强水泥基复合材料在弯曲条件下的破坏规律和基本力学性能,对其破坏机理进行研究,为水泥基材料的强韧化设计提供理论上的指导。本研究的主要内容包括:1、针对工程实践中常用的纤维增强水泥复合材料(包括玻璃纤维增强水泥、聚丙烯纤维增强水泥和钢纤维增强水泥),了解其应用范围和优缺点,对其进行数值模拟,并将数值模拟结果与已有的物理试验相比较,通过分析他们的破坏形态、声发射特征、弯曲韧性、强度变化等来研究其破坏机理。通过分析得出,无论掺钢纤维、玻璃纤维还是聚丙烯纤维,都能明显改善水泥基体的韧性性能;此外,由于钢纤维和玻璃纤维的抗拉强度较高,其对强度的改善也较明显。2、搜集工程中应用较多的纤维增强混凝土(包括钢纤维混凝土、玻璃纤维混凝土和聚丙烯纤维混凝土)复合材料,对其发展和应用现状进行总结,建立不同掺量纤维混凝土的细观数值模型,通过模拟结果分析其破坏过程中裂纹扩展的规律,裂纹的最终形态,荷载—位移曲线图的走势,声发射时空分布规律,弯曲韧性及抗弯强度的大小等来揭示纤维增强混凝土的破坏规律及强韧化机理。研究表明掺钢纤维和玻璃纤维能改善混凝土基体的抗弯强度,掺聚丙烯纤维则对强度提高影响不大;三种纤维均能明显增强混凝土的韧性,从而使试件的破坏由脆性逐步转变为延性。3、特别针对应用潜力较大、性价比较优的局部高掺量钢纤维混凝土(PHPSFRC)进行数值研究,从其破坏过程中的裂纹扩展、声发射特征、中部区域从上到下选取单元进行应力分析、不同掺量试件荷载—位移曲线和韧性比较等来探讨PHPSFRC的破坏机理。与全局掺钢纤维相比较,相同数量的纤维在PHPFRC试件中能更好的发挥增强增韧作用。相对于SIFCON而言,又极大地降低了成本,简化了施工难度。钢纤维在混凝土中的性价比得到了极大提高。更多还原

【Abstract】 Cement-based materials is the largest, and has excellent characteristics man-made building materials, but as more and more construction materials developed in the direction of high strength and high performance, its inherent weaknesses also become increasingly prominent. The composite material is one of the main substrate to improve the performance of cement-based materials , and using fiber-reinforced is the core. In recent years, steel fiber, polypropylene fiber and glass fiber reinforced cement-based materials developed rapidly, at the same time, engineering practice requires fiber reinforced cement-based materials to further deepen the basis of theoretical research.. Some basic theoretical issues such as crack propagation in the damage and fracture process and damage and fracture of fiber reinforced cement-based material , is a leading project in this area.In this paper, using numerical analysis software RFPA2D (Realistic Failure Process Analysis) owned its copyright by Professor Tang Chunan in Dalian University of Technology to simulate the flexural performance of the cement-based composites . Using Weibull random distribution function to describe the mesoscopic heterogeneity of cement-based materials,on this basis,elastic damage constitutive model of unit cells has been established, by incorporating stiffness degradation in material failure process to deal with initiation and development of crack ,in order to achieve the whole process simulation include micro-crack initiation, extending until through of fiber-reinforced cement-based specimen. Recycling the simulation results analyze failure law and the basic mechanical properties of different volume fiber reinforced cementitious composites in bending,to study the mechanism of its destruction, for providing theoretical guidance for the strengthening and toughening design to cement-based materials. This study include: 1 To the fiber reinforced cement composite materials(including glass fiber reinforced cement, polypropylene fiber reinforced cement and steel fiber reinforced cement)commonly used in engineering practice, understanding of their application, advantages and disadvantages, carrying on numerical simulation to them,and comparing numerical simulation results and the physical tests, by analyzing their failure modes, acoustic emission characteristics, flexural toughness, strength changes to study the failure mechanism. Analysis indicates that, regardless of steel fiber, glass fiber or polypropylene fiber, can significantly improve the toughness properties of cement matrix; Moreover, steel fiber and glass fiber of high tensile strength, its strength also improved more significantly.2 Collection of fiber reinforced concrete composite materials(including steel fiber reinforced concrete, glass fiber reinforced concrete and polypropylene fiber reinforced concrete)having more application in engineering,suming up their development and application, establishing of numerical Model of different content fiber concrete,through the simulation results analysing the law of crack growth in the failure process, the final crack patterns,the trend of the load-displacement curve, temporal and spatial distribution of acoustic emission, bending toughness and the measurement of bending strength to reveal the failure law and the strengthening and thoughening mechanism of fiber reinforced concrete. Studies show that the steel fiber and glass fiber can improve the flexural strength of concrete matrix, polypropylene fiber is a little effect on the strength increased; three kinds of fiber can significantly enhance the toughness of concrete, so that the destruction of the specimen gradually changes from brittle the ductility3 In special,numerical study on Partially High-Percentage Steel Fiber Reinforced Concrete(PHPSRFC)wih great potential for application and good value for money have been executed,the failure mechanism of PHPSFRC has been probed from crack propagation in failure process, acoustic emission characteristics, selecting the unit from top to bottom at the central area to analyse stress, comparison at the load-displacement curve and toughness with different contents specimen.comparison with full-doped steel fiber concrete specimens, the same number of fiber samples in PHPFRC better play in reinforcing and toughening effects. Relative to SIFCON, also greatly reduces costs, simplifies the construction difficult. Steel fibers in concrete cost has been greatly enhanced更多还原