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| A method measuring dynamic fracture toughness of rock using VB-SCSC specimens#br# |
| WANG Xiaomeng1，2，ZHU Zheming1，2，SHI Zebing1，2，FAN Yong1，2，KANG Jiming1，2 |
| (1. Key Laboratory of Energy Engineering Safety and Disaster Mechanics，Sichuan University，Chengdu，Sichuan 610065，China；2. School of Architecture and Environment，Sichuan University，Chengdu，Sichuan 610065，China) |
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Abstract In order to arrest the extending cracks，the specimen with SCSC configuration has been improved，and a new type of specimen with VB-SCSC configuration having a V-shaped boundary was thus proposed in this paper. Under the impacting loads，the compressive stress waves propagate towards the crack tips，and the compressive stress waves restrain the propagating of cracks. The experiments were performed by using the impact load of low & medium speed and the crack propagation time and propagation speed were measured with the propagation gauges(CPGs). The VB-SCSC specimens with three angles of V-shaped bottoms 120°，150° and 180°(straight bottom) were tested，and the former two specimens have the arrest function on the propagating cracks. The finite difference code AUTODYN was applied in the simulation of crack propagation behavior，and the results agree well with the test results. The finite element code ABAQUS was applied in the calculation of stress intensity factors，and Freund?s function was applied in the correction of stress intensity factors. Finally，the dynamic fracture toughness was determined by using the crack initiation time and propagation time. The results show that the 120° VB-SCSC specimens arrest the propagating cracks well and are recommended for the future experimental study. The dynamic fracture toughness is inversely proportional to the crack propagation speed.
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[1] AWAJI H，SATO S. Combined mode fracture toughness measurement by disk test[J]. Journal of Engineering Materials and Technology Transactions of the ASME，1978，100(2)：175–182.
[2] AYATOLLAHI M R，ALIHA M R M. Wide range data for crack tip parameters in two disc-type specimens under mixed mode loading[J]. Computational Materials Science，2007，38(4)：660–670.
[3] CHONG K P，KURUPPU M D. New specimen for fracture toughness determination for rock and other materials[J]. International Journal of Fracture，1984，26(2)：R59–R62.
[4] 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.(in Chinese))
[5] GRÉGOIRE D，MAIGRE H，COMBESCURE A. New experimental and numerical techniques to study the arrest and the restart of a crack under impact in transparent materials[J]. International Journal of Solids and Structures，2009，46(18/19)：3 480–3 491.
[6] 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)：2 474–2 485.(WANG Meng，ZHU Zheming，XIE Jun. Experimental and numerical studies of the mixed-mode I and II crack propagation under dynamic loading using SPHB[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(12)：2 474–2 485.(in Chinese))
[7] 李银平，王元汉. 压荷载下类岩石材料中的锯齿形裂纹分析[J]. 固体力学学报，2003，24(4)：456–462.(LI Yinping，WANG Yuanhan. Analysis of zigzag cracks in rock-like materials under compression[J]. Chinese Journal of Solid Mechanics，2003，24(4)：456–462.(in Chinese))
[8] 周绍青，郭少华，李显方. T应力对岩石断裂韧度及扩展路径的影响[J]. 中南大学学报：自然科学版，2009，40(3)：797–802.(ZHOU Shaoqing，GUO Shaohua，LI Xianfang. T-stress?s impact on rock?s fracture toughness and propagation path[J]. Journal of Central South University：Science and Technology，2009，40(3)：797–802.(in Chinese))
[9] 张振亚，周风华. 脆性PMMA带板中的动态裂纹传播实验[J]. 实验力学，2012，27(4)：401–407.(ZHANG Zhenya，ZHOU Fenghua. Experiment of dynamic crack propagation in brittle PMMA strip[J]. Journal of Experimental Mechanics，2012，27(4)：401–407.(in Chinese))
[10] 王 蒙，朱哲明，胡 荣. 基于SCSCC试样的岩石复合型裂纹动态扩展特征研究[J]. 四川大学学报：工程科学版，2016，(2)：57–65.(WANG Meng，ZHU Zheming，HU Rong. Rock experiments study of crack propagation under I and II mixed-mode dynamic loading using SCSCC specimens[J]. Journal of Sichuan University：Engineering Science Edition，2016，(2)：57–65.(in Chinese))
[11] 王 蒙，朱哲明，王 雄. 冲击荷载作用下的I/II复合型裂纹扩展规律研究[J]. 岩石力学与工程学报，2016，35(7)：1 323–1 332. (WANG Meng，ZHU Zheming，WANG Xiong. The growth of mixed-mode I/II under impacting loads[J]. Chinese Journal of Rock Mechanics and Engineering，2016，35(7)：1 323–1 332.(in Chinese))
[12] 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 and Mining Sciences，2013，60(8)：423–439.
[13] ZHANG Q B，ZHAO J. Effect of loading rate on fracture toughness and failure micro mechanisms in marble[J]. Engineering Fracture Mechanics，2013，102(2)：288–309.
[14] 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2)：3 948– 3 955.(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(Supp.2)：3 948–3 955. (in Chinese))
[15] WANG Q Z，FENG F，NI M，et al. Measurement of mode I and mode II rock dynamic fracture toughness with cracked straight through flattened Brazilian disc impacted by split Hopkinson pressure bar[J]. Engineering Fracture Mechanics，2011，78(12)：2 455–2 469.
[16] 倪 敏，汪 坤，王启智. SHPB冲击加载下四种岩石的复合型动态断裂实验研究[J]. 应用力学学报，2010，27(4)：697–702.(NI Min，WANG Kun，WANG Qizhi. Experimental study on mixed-mode dynamic fracture of four rocks under impact loading using split Hopkinson pressure bar[J]. Chinese Journal of Applied Mechanics，2010，27(4)：697–702.(in Chinese))
[17] 倪 敏，苟小平，王启智. 霍普金森杆冲击压缩单裂纹圆孔板的岩石动态断裂韧度试验方法[J]. 工程力学，2013，30(1)：365–372.(NI Min，GOU Xiaoping，WANG Qizhi. Test method for rock dynamic fracture toughness using single cleavage drilled compression specimen impacted by split Hopkinson pressure bar[J]. Engineering Mechanics，2013，30(1)：365–372.(in Chinese))
[18] MAHMOUD H N，DEXTER R J. Propagation rate of large cracks in stiffened panels under tension loading[J]. Marine Structures，2005，18(3)：265–288.
[19] ALIHA M R M，HOSSEINPOUR G R，AYATOLLAHI M R. Application of cracked triangular specimen subjected to three-point bending for investigating fracture behavior of rock materials[J]. Rock Mechanics and Rock Engineering，2013，46(5)：1 023–1 034.
[20] JIANG F，VECCHIO K S. Hopkinson bar loaded fracture experimental technique：a critical review of dynamic fracture toughness tests[J]. Applied Mechanics Reviews，2009，62(6)：1 469–1 474.
[21] LEE D，TIPPUR H，BOGERT P. Dynamic fracture of graphite/epoxy composites stiffened by buffer strips：An experimental study[J]. Composite Structures，2012，94(94)：3 538–3 545.
[22] ZHU Z M，MOHANTY B，XIE H P. 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 Z M，XIE H P，MOHANTY B. Numerical investigation of blasting-induced damage in cylindrical rocks[J]. International Journal of Rock Mechanics and Mining Sciences，2008，45(2)：111–121.
[24] ZHU Z M. Numerical prediction of crater blasting and bench blasting[J]. International Journal of Rock Mechanics and Mining Sciences，2009，46(9)：1 088–1 096.
[25] ZHU Z M，WANG C，KANG J M，et al. Study on the mechanism of zonal disintegration around an excavation[J]. International Journal of Rock Mechanics and Mining Sciences，2014，67(4)：88–95.
[26] FREUND L B，HUTCHINSON J W. Dynamic fracture mechanics[J]. Cambridge Monographs on Mechanics and Applied Mathematics，1992，59(1)：245–251.
[27] WANG Q Z，YANG J R，ZHANG C G，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. |
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2018, Vol. 37 
