Experimental investigation on dynamic fracture toughness of offset crack material using caustic method
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摘要: 应用落锤冲击加载系统,对含偏置裂纹的半圆盘试件在冲击载荷作用下的动态断裂行为进行了实验研究.结果表明:随着预制裂纹偏置距离的增大,剪应力在裂纹尖端的作用增强,裂纹逐渐由I型向I-II复合型裂纹转变,裂纹起裂需要的时间也略有增加,裂纹在扩展过程中的曲裂程度显著增大;在动态载荷作用下,裂纹的扩展速度在起裂后迅速增大到某一值后呈现不断波动变化的特点,裂纹扩展的平均速度随偏置距离的增加逐渐减小,当裂纹扩展的归一化裂纹竖向长度λ>0.8时,由于冲击点处局部压应力场的影响,裂纹的扩展速度迅速降低;随着裂纹偏置距离的增大,材料的起裂韧性KIC减小、KIIC增大.随着裂纹的扩展,裂纹的扩展韧性有所增大.Abstract: The dynamic fracture behavior of notched semi-circular bending(NSCB)subjected to hammer impact loading was studied by using caustics experimental method.The results show that the shear stress at the crack tip increased with the offset distance increased,and correspondingly,the crack changed from mode I to mixed mode I-II,the time from impact force loaded to crack initiation also increased,moreover,the crack deflecting angle became more fluctuating with crack propagation;the crack velocity increased rapidly under dynamic load until it reached a certain value with continual fluctuation,with the ratio of crack vertical displacement to the total vertical length λ>0.8,the crack velocity sharply decreased because of the effect of the local compressive stress around the hammer;as the offset distance increased,the initial fracture toughness KIC decreased,whereas KIIC increased;while the dynamic propagation toughness increased gradually with crack propagation.
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Key words:
- offset crack /
- semi-circular specimen /
- caustics method /
- stress intensity factor /
- crack velocity
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[1] 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):59-62. [2] Krans R L.Semi-circular bending test:a practical crack growth test using asphalt concrete cores[C].International RILEM Conference on Reflective Cracking in Pavements,3rd,1996,Maastricht,The Netherlands,1996:123-132. [3] Dai F,Chen R,Xia K.A semi-circular bend technique for determining dynamic fracture toughness[J].Experimental Mechanics,2010,50(6):783-791. [4] Zhou Y X,Xia K,Li X B,et al.Suggested methods for determining the dynamic strength parameters and mode-I fracture toughness of rock materials[G]// The ISRM Suggested Methods for Rock Characterization,Testing and Monitoring:2007-2014.Springer International Publishing,2012:105-112. [5] 耿宁宁.静动态混凝土半圆弯拉实验的数值模拟[D].合肥:合肥工业大学,2013. [6] 刘帅华,李振兴.T应力对Ⅰ-Ⅱ复合型裂纹临界应力强度因子的影响[J].河南城建学院学报,2013,22(4):33-37. [7] Liu Shuaihua,Li Zhenxing.Effect of T stress on critical stress intensity factor of Ⅰ-Ⅱ mixed mode crack[J].Journal of Henan University of Urban Construction,2013,22(4):33-37. [8] 代树红,马胜利,潘一山.数字图像相关法测定岩石Ⅰ-Ⅱ复合型裂纹应力强度因子[J].岩土工程学报,2013,35(7):1362-1368. [9] Dai Shuhong,Ma Shengli,Pan Yishan.Evaluation of mixed-mode Ⅰ-Ⅱ stress intensity factors of rock utilizing digital image correlation method[J].Chinese Journal of Geotechnical Engineering,2013,35(7):1362-1368. [10] 陈静静.基于高速DIC方法的脆性材料动态力学性能研究[D].北京:北京理工大学,2014. [11] Ayatollahi M R,Aliha M R M,Hassani M M.Mixed mode brittle fracture in PMMA-An experimental study using SCB specimens[J].Materials Science and Engineering,2006,417(1):348-356. [12] Ayatollahi M R.An improvedsemi-circular bend specimen for investigating mixed mode brittle fracture[J].Engineering Fracture Mechanics,2011,78(1):110-123. [13] Papadopoulos G A.The experimental method of caustics and the det.-criterion of fracture[M].London:Springer-Verlag,1993. [14] Beinert J,Kalthoff J F.Experimental determination of dynamic stress intensity factors by shadow patterns[M].Netherlands:Springer,1981:281-330. [15] Kalthoff J F.The shadow optical method of caustics[M].Vienna:Springer,1987:407-522. [16] Gong K,Li Z.Caustics method in dynamic fracture problem of orthotropic materials[J].Optics & Lasers in Engineering,2008,46(8):614-619. [17] Gao G,Li Z,Xu J.Optical method of caustics applied in viscoelastic fracture analysis[J].Optics & Lasers in Engineering,2011,49(5):632-639. [18] Kutter H K,Fairhurst C.On the fracture process in blasting[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1971,8(3):181-202. [19] Rossmanith H P,Daehnke A,Nasmillner R E K,et al.Fracture mechanics applications to drilling and blasting[J].Fatigue & Fracture of Engineering Materials & Structures,2008,20(11):1617-1636. [20] Shimizu K,Suetsugu M,Nakamura T,et al.Evaluation of concentrated load by caustics and its application in the measurement of optical constant[J].Jsme International Journal,1998,41(1):134-141. [21] 樊金武,励争,王文彦.用焦散线方法测量集中载荷的误差分析[J].实验力学,2003,18(2):145-150. [22] Fan Jinwu,Li Zheng,Wang Wenyan.The measuring error for concentrated load by caustics[J].Journal of Experimental Mechanics,2003,18(2):145-150. [23] Kumar A.Study of fatigue crack-hole interaction and prediction of crack path[D].Rourkela:National Institute of Technology Rourkela,2015.
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