中低速冲击载荷作用下SCT岩石试样Ⅰ型裂纹的动态扩展行为
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摘要
为研究侧开单裂纹三角形(SCT)岩石试样的动态扩展行为和断裂韧度,采用落锤冲击实验系统进行动态加载,通过裂纹扩展计(CPG)得到裂纹的断裂时间和扩展速度;用有限差分软件AUTODYN进行数值模拟,验证实验结果的可靠性;将实验测量的载荷条件代入有限元软件ABAQUS建立的数值模型中,得到动态应力强度因子时程曲线,通过普适函数修正后,利用断裂时间得到动态断裂韧度。研究结果表明:SCT试件构型能够较好地应用于岩石动态扩展行为的研究;砂岩的扩展韧度与裂纹扩展速度呈负相关;数值模拟得到的裂纹扩展路径与实验结果基本一致,裂纹扩展速度不为常数;岩石裂纹动态扩展过程中可能存在止裂现象,止裂韧度大于扩展韧度,但与起裂韧度相差不大。
In order to study crack dynamic propagation behavior and rock fracture toughness, single cleavage triangle(SCT) specimens were used. By using these specimens and a drop weight test system, impact experiments were performed, and the crack propagation velocity and the fracture time were measured by crack propagation gauges(CPG).In order to examine the effectiveness of the experiment results, finite difference numerical models were established by using AUTODYN. Finite element code ABAQUS was used to calculate crack dynamic stress intensity factors(SIF) based on numerical models and the measured loading curves, and the curve of crack dynamic SIF versus time was obtained.The fracture toughness was determined according to the correction universal function and the fracture time measured by CPG. The results show that the SCT specimen is suitable for the study of crack dynamic propagation behavior and fracture toughness. Propagation toughness decreases with the increase of the crack propagation velocity. The crack propagation paths obtained from numerical simulation are basically the same with those of the test results, and the crack propagation speed is not a constant. In the process of crack propagation, crack arrest may happen, in which arrest toughness is higher than crack propagation toughness, and the difference between the initiation toughness and arrest toughness is slight.
In order to study crack dynamic propagation behavior and rock fracture toughness, single cleavage triangle(SCT) specimens were used. By using these specimens and a drop weight test system, impact experiments were performed, and the crack propagation velocity and the fracture time were measured by crack propagation gauges(CPG).In order to examine the effectiveness of the experiment results, finite difference numerical models were established by using AUTODYN. Finite element code ABAQUS was used to calculate crack dynamic stress intensity factors(SIF) based on numerical models and the measured loading curves, and the curve of crack dynamic SIF versus time was obtained.The fracture toughness was determined according to the correction universal function and the fracture time measured by CPG. The results show that the SCT specimen is suitable for the study of crack dynamic propagation behavior and fracture toughness. Propagation toughness decreases with the increase of the crack propagation velocity. The crack propagation paths obtained from numerical simulation are basically the same with those of the test results, and the crack propagation speed is not a constant. In the process of crack propagation, crack arrest may happen, in which arrest toughness is higher than crack propagation toughness, and the difference between the initiation toughness and arrest toughness is slight.
引文
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[18]王蒙,朱哲明,谢军.岩石Ⅰ-Ⅱ复合型裂纹动态扩展SHPB实验及数值模拟研究[J].岩石力学与工程学报, 2015, 34(12):2474-2485.WANG Meng, ZHU Zheming, XIE Jun. Experimental and numerical studies of the mixed-modeⅠandⅡcrack propagation under dynamic loading using SPHB[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(12):2474-2485.
[19] WANG Xiaomeng, ZHU Zheming, WANG Meng et.al. Study of rock dynamic fracture toughness by using VB-SCSC specimens under medium-low speed impacts[J]. Engineering Fracture Mechanics, 2017, 181:52-64.
[20] RAVI-CHANDAR K, KNAUSS W G. An experimental investigation into dynamic fracture:Ⅰ. Crack initiation and arrest[J]. International Journal of Fracture, 1984, 25(4):247-262.
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[22] ZHU Zheming, Mohanty B, XIE Heping. Numerical investigation of blasting-induced crack initiation and propagation in rocks[J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(3):412-424.
[23] ZHU Zheming, XIE Heping, MOHANTY B. Numerical investigation of blasting-induced damage in cylindrical rocks[J].International Journal of Rock Mechanics&Mining Sciences,2008, 45(2):111-121.
[24] ZHU Zheming. Numerical prediction of crater blasting and bench blasting[J]. International Journal of Rock Mechanics&Mining Sciences, 2009, 46(6):1088-1096.
[25] ZHU Zheming, WANG Chao, KANG Jiming, et al. Study on the mechanism of zonal disintegration around an excavation[J].International Journal of Rock Mechanics&Mining Sciences,2014, 67:88-95.
[26] FREUND L B, HUTCHINSON J W. Dynamic fracture mechanics[J]. Journal of Applied Mechanics, 1992, 59(1):245.
[27] RAVI-CHANDAR K. Dynamic fracture[M]. London, UK:Elsevier, 2004:49-69.
[2] CHAKRABORTY T, MISHRA S, LOUKUS J, et al.Characterization of three Himalayan rocks using a split Hopkinson pressure bar[J]. International Journal of Rock Mechanics&Mining Sciences, 2016, 85:112-118.
[3] JIANG Fengchun, VECCHIO K S. Hopkinson bar loaded fracture experimental technique:a critical review of dynamic fracture toughness tests[J]. Applied Mechanics Reviews, 2009,62(6):1469-1474.
[4] ZHANG Qianbing, ZHAO Jian. A Review of dynamic experimental techniques and mechanical behaviour of rock materials[J]. Rock Mechanics&Rock Engineering, 2014, 47(4):1411-1478.
[5] WANG Qizhi, YANG Jingrui, ZHANG Caigui, et al. Sequential determination of dynamic initiation and propagation toughness of rock using an experimental–numerical–analytical method[J].Engineering Fracture Mechanics, 2015, 141:78-94.
[6] HAERI H, SHAHRIAR K, MARJI M F, et al. Experimental and numerical study of crack propagation and coalescence in pre-cracked rock-like disks[J]. International Journal of Rock Mechanics&Mining Sciences, 2014, 67(4):20-28.
[7] BERTRAM A, KALTHOFF J F. Crack propagation toughness of rock for the range of low to very high crack speeds[J]. Key Engineering Materials, 2003, 251/252:423-430.
[8] ZHANG Q B, ZHAO J. Determination of mechanical properties and full-field strain measurements of rock material under dynamic loads[J]. International Journal of Rock Mechanics&Mining Sciences, 2013, 60:423-439.
[9] LEE D, TIPPUR H, BOGERT P. Dynamic fracture of graphite/epoxy composites stiffened by buffer strips:An experimental study[J]. Composite Structures, 2012, 94(12):3538-3545.
[10] AVACHAT S, ZHOU Min. High-speed digital imaging and computational modeling of dynamic failure in composite structures subjected to underwater impulsive loads[J].International Journal of Impact Engineering, 2015, 77:147-165.
[11]汪坤,王启智.中心直裂纹平台巴西圆盘复合型动态断裂实验研究[J].实验力学, 2008, 23(5):417-426.WANG Kun, WANG Qizhi. Experimental study of mixed mode dynamic fracture for cracked straight through flattened brazilian disc[J]. Journal of Experimental Mechanics, 2008, 23(5):417-426.
[12] CHEN Rong, XIA Kaiwen, DAI Feng, et al. Determination of dynamic fracture parameters using a semi-circular bend technique in split Hopkinson pressure bar testing[J]. Engineering Fracture Mechanics, 2009, 76(9):1268-1276.
[13]潘峰,党发宁,焦凯,等.冲击荷载作用下不均匀脆性材料动态弯拉强度提高机制研究[J].岩石力学与工程学报, 2015,34(增刊2):3948-3955.PAN Feng, DANG Faning, JIAO Kai, et al. Mechanism on enhancement of dynamic flexural tensile strength for nonuniform brittle materials under impact loading[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(Suppl.2):3948-3955.
[14]宋义敏,何爱军,王泽军,等.冲击载荷作用下岩石动态断裂试验研究[J].岩土力学, 2015, 36(4):965-970.SONG Yimin, HE Aijun, WANG Zejun, et al. Experiment study of the dynamic fractures of rock under impact loading[J]. Rock and Soil Mechanics, 2015, 36(4):965-970.
[15]杨井瑞,张财贵,周妍,等.用SCDC试样测试岩石动态断裂韧度的新方法[J].岩石力学与工程学报, 2015, 34(2):279-292.YANG Jingrui, ZHANG Caigui, ZHOU Yan, et al. A new method for determing dynamic fracture toughness of rock using SCDC specimens[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(2):279-292.
[16]张财贵,曹富,李炼,等.采用压缩单裂纹圆孔板确定岩石动态起裂、扩展和止裂韧度[J].力学学报, 2016, 48(3):624-635.ZHANG Caigui, CAO Fu, LI Lian, et al. Determination of dynamic fracture initiation, propagation, and arrest toughness of rock using SCDC specimen[J]. Chinese Journal of Theoretical and Applied Mechanics, 2016, 48(3):624-635.
[17] WANG Meng, ZHU Zheming, DONG Yuqing, et al. Study of mixed-modeⅠ/Ⅱfractures using single cleavage semicircle compression specimens under impacting loads[J]. Engineering Fracture Mechanics, 2017, 177:33-44.
[18]王蒙,朱哲明,谢军.岩石Ⅰ-Ⅱ复合型裂纹动态扩展SHPB实验及数值模拟研究[J].岩石力学与工程学报, 2015, 34(12):2474-2485.WANG Meng, ZHU Zheming, XIE Jun. Experimental and numerical studies of the mixed-modeⅠandⅡcrack propagation under dynamic loading using SPHB[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(12):2474-2485.
[19] WANG Xiaomeng, ZHU Zheming, WANG Meng et.al. Study of rock dynamic fracture toughness by using VB-SCSC specimens under medium-low speed impacts[J]. Engineering Fracture Mechanics, 2017, 181:52-64.
[20] RAVI-CHANDAR K, KNAUSS W G. An experimental investigation into dynamic fracture:Ⅰ. Crack initiation and arrest[J]. International Journal of Fracture, 1984, 25(4):247-262.
[21]刘德顺,李夕兵.冲击机械系统动力学[M].北京:科学出版社, 1999:40-42.LIU Deshun, LI Xibing. Mechanical impact dynamics[M].Beijing:Science Press, 1999:40-42.
[22] ZHU Zheming, Mohanty B, XIE Heping. Numerical investigation of blasting-induced crack initiation and propagation in rocks[J]. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(3):412-424.
[23] ZHU Zheming, XIE Heping, MOHANTY B. Numerical investigation of blasting-induced damage in cylindrical rocks[J].International Journal of Rock Mechanics&Mining Sciences,2008, 45(2):111-121.
[24] ZHU Zheming. Numerical prediction of crater blasting and bench blasting[J]. International Journal of Rock Mechanics&Mining Sciences, 2009, 46(6):1088-1096.
[25] ZHU Zheming, WANG Chao, KANG Jiming, et al. Study on the mechanism of zonal disintegration around an excavation[J].International Journal of Rock Mechanics&Mining Sciences,2014, 67:88-95.
[26] FREUND L B, HUTCHINSON J W. Dynamic fracture mechanics[J]. Journal of Applied Mechanics, 1992, 59(1):245.
[27] RAVI-CHANDAR K. Dynamic fracture[M]. London, UK:Elsevier, 2004:49-69.