| 摘要: |
| 采用超声波脉冲法研究了单轴受压条件下钢聚乙烯醇(PVA)纤维混杂增强延性水泥基材料(以下简称混杂纤维延性材料)的破坏机理.结果表明:混杂纤维延性材料加载前的初始波速主要受制于基材,波速与弹性模量、抗压强度均具有良好相关性;加载过程中,纵波波速受应力应变发展的影响不显著,而横波波速的变化较为明显;单掺PVA纤维体系进入应力下降段后横波波速出现陡降,而混杂纤维体系的横波波速表现为平稳的渐退式下降;单掺纤维延性材料主要产生劈裂破坏,主裂缝平行于轴压方向,而混杂纤维延性材料的主裂缝倾斜于轴向,裂缝迂曲度明显增大,材料塑性变形能力显著提升.另外，采用超声脉冲法检测混杂纤维延性材料受压破坏过程的有效性在试验过程中得到了验证. |
| 关键词: 混杂纤维 轴压 超声波 韧性 |
| DOI：103969/j.issn.1007 9629201901021 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目(51808545,51622404);北京市自然科学基金资助项目(8184083);中央高校基本科研业务费项目(2017QL01);中国矿业大学(北京)越崎杰出学者奖励计划项目 |
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| Ultrasonic Velocity Characteristics of Hybrid Fiber Ductile Cementitious Composites under Uniaxial Compression |
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WANG Zhenbo, ZUO Jianping, ZHANG Xiaoyan, LIU Chang, ZHANG Zishan
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School of Mechanics and Civil Engineering, China University of Mining and TechnologyBeijing, Beijing 100083, China
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| Abstract: |
| Failure mechanism of steel fiber polyvinyl alcohol fiber hybrid reinforced cementitious composites under uniaxial compression was investigated by ultrasonic pulse method. The experimental results show that the initial wave velocity in hybrid fiber composites prior to loading is mainly controlled by the matrices. Good correlation exists between wave velocity and elastic modulus or compressive strength. During loading, the velocity of primary wave stays almost unchanged while shear wave velocity shows an obvious variation. The shear wave velocity in polyvinyl alcohol fiber reinforced system experiences a sudden drop after entering stress drop stage. However, the shear wave velocity in hybrid fiber reinforced system exhibits a steady decline. The failure mode of mono fiber reinforced system displayes splitting failure with major crack parallel to axial direction. By contrast, the major crack in hybrid fiber reinforced system turns out to be inclined to axial direction, with increased tortuosity that yields larger plastic deformation capacity. The effectiveness of ultrasonic pulse method in detecting the compressive failure of hybrid fiber composites is validated. |
| Key words: hybrid fiber uniaxial compression ultrasonic pulse toughness |
