超高韧性水泥基复合材料的层裂试验研究

层裂是材料遭受冲击、爆炸等高速荷载时的一种常见破坏方式。该文利用直径80 mm的霍普金森杆实验装置，研究了超高韧性水泥基复合材料UHTCC （Ultra High Toughness Cementitious Composites）中应力波的传播特性和材料的层裂强度。通过在试件表面粘贴5组应变片，获得了在0.2 MPa、0.3 MPa、0.4 MPa、0.5 MPa打击气压下，UHTCC中应力波的传播曲线。利用高速摄影机记录层裂试验，观测了UHTCC的层裂破坏过程。由试件表面应变片测得的应力波曲线，计算了材料中的应力波波速、动态弹性模量，分析了应力波在该材料中传播的衰减规律，并计算出不同打击气压下材料的层裂强度及应变率。试验结果显示: UHTCC的层裂过程相比混凝土具有更多的韧性特征； UHTCC中的应力波峰值在0 mm~500 mm范围内衰减迅速；在同等应变率下，UHTCC与静态抗拉强度相近的混凝土相比，层裂强度高出10 MPa左右，且UHTCC的层裂强度具有明显的应变率敏感性。

EXPERIMENTAL STUDY ON SPALL BEHAVIOR OF ULTRA-HIGH TOUGHNESS CEMENTITIOUS COMPOSITES

Spallation is a common failure mode of materials subjected to high-speed loads such as impact and explosion.The stress wave propagation and spall strength of UHTCC(Ultra High Toughness Cementitious Composites)has been studied experimentally using Φ80 mm Hopkinson bar.Firstly,stress wave curves in UHTCC under strike pressures of 0.2 MPa,0.3 MPa,0.4 MPa and 0.5 MPa were measured through 5 strain gauges attached on specimen surface,and the spallation process of UHTCC were recorded by high-speed camera.Secondly,the stress wave velocity and dynamic elastic modulus in the material were calculated from the stress wave curves.Finally,the attenuation law of the stress wave propagation in the material was analyzed,and the spall strength and strain rate of the material under different strike pressures were calculated.The experimental results show that the spallation process of UHTCC exhibits more toughness characteristics than concrete;the peak value of stress wave in UHTCC decays rapidly in the range of 0 mm^500 mm;at the same strain rate,the spalling strength of UHTCC is about 10 MPa higher than that of concrete with similar static tensile strength,and the spalling strength of UHTCC has a significant rate effect.