基于数字图像相关的J积分测量方法
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摘要
J积分是定量描述裂纹尖端区域应力应变场强度的重要断裂参量,J积分的快速准确测量对于评估机械装备上裂纹的稳定性和扩展性有重要意义。从J积分的原始理论公式出发,结合数字图像相关技术,提出了一种J积分测量新方法。该方法首先通过数字图像相关技术,在不同载荷下对含裂纹缺陷的紧凑拉伸试样的表面位移场和应变场进行测算;然后选取围绕裂纹尖端的矩形积分路径,用离散化的方法对积分路径进行处理,并编写Matlab程序计算J积分;最后将该方法的计算结果与美国电力研究院(EPRI)工程估算法和有限元法获得的J积分进行对比。结果表明,由本文提出的方法获得的结果与其它计算方法获得的结果相近,并且在实验测量J积分方面具有非接触、高精度、光路简单、受环境影响小等优点。方法为裂纹断裂参数J积分的实验测量提供了一种方法,并可用于大型在役机械装备上表面裂纹的安全评估。
J-integral is an important fracture parameter which quantitatively describes the stress and strain fields near a crack tip. Accurate and efficient measurement of J-integral is of great significance for the evaluation of crack stability and propagation in mechanical equipment. This paper proposes a new method for J-integral measurement by using digital image correlation technique. The displacement and strain fields on the surface of a pre-cracked compact tension specimen were firstly measured and calculated by digital image correlation technique under different loads. A MATLAB program was then developed to calculate the J-integral by selecting a rectangular integral path around the crack tip. The calculated results were compared with those obtained from the US Electric Power Research Institute( EPRI) estimation method and finite element method. The proposed method can produce similar results compared with other methods. It also has advantages of non-contact,high-precision,simple optical path,and less sensitive to the environment. The proposed method for J-integral measurement has potential to be applied to the crack evaluation for large in service mechanical equipment.
J-integral is an important fracture parameter which quantitatively describes the stress and strain fields near a crack tip. Accurate and efficient measurement of J-integral is of great significance for the evaluation of crack stability and propagation in mechanical equipment. This paper proposes a new method for J-integral measurement by using digital image correlation technique. The displacement and strain fields on the surface of a pre-cracked compact tension specimen were firstly measured and calculated by digital image correlation technique under different loads. A MATLAB program was then developed to calculate the J-integral by selecting a rectangular integral path around the crack tip. The calculated results were compared with those obtained from the US Electric Power Research Institute( EPRI) estimation method and finite element method. The proposed method can produce similar results compared with other methods. It also has advantages of non-contact,high-precision,simple optical path,and less sensitive to the environment. The proposed method for J-integral measurement has potential to be applied to the crack evaluation for large in service mechanical equipment.
引文
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[18]孙亮,李培宁,刘长军.任意应力应变关系材料J积分估算的等效原场应力法[J].机械强度,2003,25(4):450-455.SUN Liang,LI Pei Ning,LIU Chang Jun.Equivalent remote stress method of J-integral evaluation for any stress-strain relationship materials[J].Journal of Mechanical Strength.2003,25(4):450-455(In Chinese).
[19]Zahoor A.Fracture of Circumferentially Cracked Pipes[J].Journal of Pressure Vessel Technology,1986,108(4):529-531.
[20]Zahoor A.Evaluation of J-integral estimation scheme for flawed through-wall pipes[J].Nuclear Engineering&Design,1987,100(1):1-9.
[21]Zahoor A.J-Integral Analysis for Notched Round Bar in Tension[J].Journal of Pressure Vessel Technology,1987,109(1):155-158.
[22]杜国强.斜接弯管内侧裂纹断裂参数研究[D].大连:大连理工大学,2009:23-25.DU Guo Qiang.The Study of Fracture Parameters of the inboard Crack on Mitered Elbow[D].Dalian:Dalian University of Technology,2009:23-25(In Chinese).
[23]谢奇,吕运冰,徐兆雄.Ramberg-Osgood形幂硬化材料的硬化系数及硬化指数的确定[J].武汉交通科技大学学报,1996,20(3):319-322.XIE Qi,LV Yun Bing,XU Zhao Xiong.The determining of Ramberg-Osgood-shaped power hardening material’s hardening factor and hardening exponent[J].Journal of Wuhan Transportation University,1996,20(3):319-322(In Chinese).
[2]Rice J R.Plane strain deformation dear a crack tip in a power-law hardening material[J].Journal of the Mechanics of Solids,1968(16):1.
[3]Dally J W,Sanford R J.Strain gage methods for measuring the opening-mode stress intensity factor[J].Experimental Mechanics,1987(27):381-388.
[4]Bonestell R M,Piper D E,Davinroy A T.Compliance and calibration of double cantilever beam(DCB)specimens[J].Engineering Fracture Mechanics,1978(10):425-428.
[5]Wang W C,Hwang C H.Experimental analysis of vibration characteristics of an edge-cracked composite plate by ESPI method[J].International Journal of Fracture,1998,91(4):311-321.
[6]王依兵.电测法测量J—积分的实验方法研究[J].科技创新导报,2011(26):7-8.WANG Yi Bing.The experimental method study of measuring Jintegral by electrical measuring method[J].Science and Technology Innovation Herald,2011(26):7-8.(In Chinese)
[7]张蕊,贺玲凤.数字图像相关法测量聚碳酸酯板应力强度因子[J].工程力学,2012,29(12):22-27.ZHANG Rui,HE Ling Feng.Evaluating stress intensity factor of polycarbonate using digital image correlation[J].Engineering Mechanics,29(12),2012:22-27(In Chinese).
[8]Peters W H,Ranson W F.Digital imaging techniques in experimental stress analysis[J].Optics and Precision Engineering.1982,21(3):427-431.
[9]Chu T C,Ranson W F,Sutton M A,et al.Applications of digital image correlation techniques to experimental mechanics[J].Experimental Mechanics,1985,25(3):232-245.
[10]白晓红.数字图像相关(DIC)测量方法在材料变形研究中的应用[D].沈阳:东北大学,2011:1-11.BAI Xiao Hong.Application of Digital Image Correlation Method in Study of Material Deformation[D].Shenyang:Northeastern University,2011:1-11(In Chinese).
[11]胡浩,梁晋,唐正宗,等.数字图像相关法测量金属薄板焊接的全场变形[J].光学精密工程.2012,20(7):1636-1643.HU Hao,LIANG Jin,TANG Zheng Zong,et al.Measurement of full-field deformations in metal sheet welding processes by image correlation method[J].Optics and Precision Engineering,2012,20(7):1636-1643(In Chinese).
[12]Ziegel E R.Applied Statistics for Engineers and Scientists(2nd ed.)[M]//Applied statistics for engineers and scientists/.Prentice Hall,1999:767-767.
[13]Irwin G R.Analysis of stresses and strains near the end of a crack traversing a Plate[J].Journal of Applied Mechanics,1957(24):361-364.
[14]中国航空研究院.应力强度因子手册[M].北京:科学出版社,1984:150-151.China Aviation Institute.Stress intensity factor handbook[M].Beijing:Science Press,1984:150-151(In Chinese).
[15]Wang W Q,Li A J,Li P N,et al.An engineering approach for notch elastic-plastic fracture analysis[J].International Journal of Pressure Vessels&Piping,1994,60(1):1-16.
[16]Kumar V,German M D,Wilkening W W.清华大学工程力学研究所译.EPRI NP-3607弹塑性断裂分析进展[M].北京:清华大学出版社,1984:48-64.Kumar V,German M D,Wilkening W W.Translated by Institute of Engineering Mechanics,Tsinghua University.The progress of EPRI NP-3607 plastic fracture analysis[M].Beijing,Tsinghua University Press,1984:48-64(In Chinese).
[17]Zikry M.Ductile Fracture[J].Handbook of Materials Modeling,2005(25):1171-1181.
[18]孙亮,李培宁,刘长军.任意应力应变关系材料J积分估算的等效原场应力法[J].机械强度,2003,25(4):450-455.SUN Liang,LI Pei Ning,LIU Chang Jun.Equivalent remote stress method of J-integral evaluation for any stress-strain relationship materials[J].Journal of Mechanical Strength.2003,25(4):450-455(In Chinese).
[19]Zahoor A.Fracture of Circumferentially Cracked Pipes[J].Journal of Pressure Vessel Technology,1986,108(4):529-531.
[20]Zahoor A.Evaluation of J-integral estimation scheme for flawed through-wall pipes[J].Nuclear Engineering&Design,1987,100(1):1-9.
[21]Zahoor A.J-Integral Analysis for Notched Round Bar in Tension[J].Journal of Pressure Vessel Technology,1987,109(1):155-158.
[22]杜国强.斜接弯管内侧裂纹断裂参数研究[D].大连:大连理工大学,2009:23-25.DU Guo Qiang.The Study of Fracture Parameters of the inboard Crack on Mitered Elbow[D].Dalian:Dalian University of Technology,2009:23-25(In Chinese).
[23]谢奇,吕运冰,徐兆雄.Ramberg-Osgood形幂硬化材料的硬化系数及硬化指数的确定[J].武汉交通科技大学学报,1996,20(3):319-322.XIE Qi,LV Yun Bing,XU Zhao Xiong.The determining of Ramberg-Osgood-shaped power hardening material’s hardening factor and hardening exponent[J].Journal of Wuhan Transportation University,1996,20(3):319-322(In Chinese).