用压缩单裂纹半圆孔板(SCSDC)研究砂岩动态起裂、扩展和止裂的全过程
首发时间:2017-08-08
摘要:首次提出压缩单裂纹半圆孔板(SCSDC)试样构型,分析了SCSDC用于断裂实验时不需要支座的优点,以及端面接触摩擦力对试样起裂的影响。利用大直径分离式霍普金森压杆动态冲击SCSDC砂岩试样,探究了砂岩I型动态起裂、扩展及止裂的全过程。采用两片首尾相接粘贴在预制裂纹前方的裂纹扩展计监测裂纹动态起裂、扩展和止裂等时间特征参数,测得裂纹扩展过程中的速度变化;用实验-数值-解析法得到了砂岩的动态起裂、扩展和止裂韧度。研究发现:在较宽裂纹速度范围内(0.1~0.5cR),裂纹动态扩展韧度随着裂纹速度增加而增大,在排除了材料变化、速度测量误差及试样构型因素后,得到了砂岩动态扩展韧度与裂纹速度唯一的关系曲线。
关键词: 压缩单裂纹半圆孔板(SCSDC) 砂岩 动态断裂全过程 KICd-a(o)关系
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Investigation of the whole process of dynamic initiation, propagation and arrest using sandstone single cleavage semi-drilled compression (SCSDC) specimen
Abstract:We first introduce the single cleavage semi-drilled compression (SCSDC) specimen, then analyze advantages of the SCSDC configuration for fracture experiments and the influence of friction at contact end on initiation of crack. Sandstone SCSDC specimens were dynamically impacted by using large diameter split Hopkinson pressure bar, to investigate the whole process of crack initiation, propagation and arrest of mode I crack. Two pieces of crack propagation gauge, pasted ahead of the pre-crack,were needed to monitor the characteristic parameters of time at the crack dynamic initiate, propagate and arrest, respectively. We successfully got the changes of crack velocity during the process of crack grow. The dynamic initiation toughness, dynamic propagation toughness and dynamic arrest toughness were obtained by using the experiment-numerical-analytical method. Our conclusions are as follows: In the wide crack speed range of (0.1 ~ 0.5) cR, the dynamic propagation toughness would increase with increasing the speed; Excluding the influence of material variation, speed measurement error and specimen configuration, there would be only one relationship between the dynamic propagation toughness and crack speed of sandstone.
Keywords: single cleavage semi-drilled compression (SCSDC) sandstone the whole dynamic fracture process the relationship between KICd and a(o)
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用压缩单裂纹半圆孔板(SCSDC)研究砂岩动态起裂、扩展和止裂的全过程
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