基于显微DIC的谐振疲劳短裂纹尖端变形场演化规律

doi:10.12382/bgxb.2022.0153

摘要/Abstract

摘要：

为研究疲劳短裂纹扩展机理,提出一种基于显微数字图像相关(DIC)的塑性金属材料谐振疲劳短裂纹尖端位移场、应变场和塑性区的测量方法,并对其演化规律进行研究。通过显微摄像系统采集疲劳裂纹扩展过程中谐振载荷最大点试件短裂纹图像;采用DIC方法获得裂纹尖端区域位移场和应变场的数据。通过虚拟引伸计技术结合位移场演化数据获得短裂纹扩展过程中裂纹尖端坐标,进而根据von Mises屈服准则和应变场数据确定裂纹尖端塑性区尺寸及演化规律并与Irwin模型的理论尺寸进行对比验证;采用电子背散射衍射(EBSD)技术测量典型塑性金属材料316不锈钢疲劳裂纹尖端的晶粒尺寸分布,进一步研究谐振载荷作用下疲劳短裂纹尖端区域沿晶粒尺度的位移和应变的演化规律。研究结果表明:提出的方法成功获取了短裂纹微米级变形场演化数据,为塑性金属材料疲劳短裂纹扩展特性的进一步研究和疲劳寿命预测提供了实验和理论支持。

关键词: 谐振疲劳扩展, 显微DIC, 短裂纹尖端, 变形场, 塑性区, 演变

Abstract:

To study the propagation mechanism of short fatigue cracks, a method is proposed to measure the displacement field, strain field, and plastic zone of the short crack tip of plastic metal materials under high-frequency resonant loading using microscope Digital Image Correlation (micro-DIC). And the evolution law of the displacement field, strain field, and plastic zone are studied. First, short crack images of the specimen under maximum resonant loading during fatigue crack growth (FCG) are collected by a microscope camera system. Second, data of the displacement field and strain field at the crack tip region are obtained using the DIC method. Third, the coordinates of the crack tip during short crack propagation are obtained by the virtual extensometer along with the displacement field evolution data. Then, based on the von Mises yield criterion and strain field data, evolution law of the size of the plastic zone is studied and compared with the Irwin model. Last, grain size distribution on the crack tip of 316 stainless steel, a typical plastic metal material, is measured by EBSD technology. The evolution law of displacement and strain along the grain scale in the short crack tip region under high-frequency resonant loading is further studied. The research results show that the proposed method can successfully obtain the micron-scale deformation field evolution data of short cracks, providing experimental and theoretical support for further examination of short fatigue cracks and fatigue life prediction of plastic metal materials under high-frequency resonant loading.

Key words: resonant fatigue growth, micro-DIC, short crack, deformation field, plastic zone, evolution

单晓锋, 高红俐, 黄心畏, 林志远, 赏鸿斌. 基于显微DIC的谐振疲劳短裂纹尖端变形场演化规律[J]. 兵工学报, 2023, 44(5): 1482-1492.

SHAN Xiaofeng, GAO Hongli, HUANG Xinwei, LIN Zhiyuan, SHANG Hongbin. Evolution Law of Deformation Field of Short Crack Tip under High-Frequency Resonant Loading Using a Microscope DIC System[J]. Acta Armamentarii, 2023, 44(5): 1482-1492.

图/表 21

图1 CT试件尺寸图

Fig.1 Dimensions of a CT specimen

图2 狗骨试件尺寸图

Fig.2 Dimensions of a dog-bone shaped specimen

表1 316材料参数

Table 1 Material parameters of 316 stainless steel

弹性模量/GPa	泊松比	屈服强度/MPa
195	0.3	335

图3 316取向分布图

Fig.3 Orientation distribution of stainless steel 316

图4 谐振疲劳短裂纹显微图像采集系统

Fig.4 Micro-image acquisition system of resonant fatigue short cracks

表2 主要硬件参数

Table 2 Main hardware parameters

硬件	型号	主要参数
相机	acA4112-30μm	分辨率:4096(H)×3000(V) 靶面尺寸:1.1″ 最大帧率:30帧/s 最短曝光时间:2μs 像元尺寸:3.45μm×3.45μm
镜头	Rodagon 5.6/105metal	焦距:105mm 最大成像圆直径:102mm 工作距离:292~1853mm

图5 DIC原理

Fig.5 Schematic diagram of DIC

图6 虚拟引伸计布置示意图

Fig.6 Setup of thevirtual extensometer

图7 拟合曲线求导示意图

Fig.7 Schematic diagram of fitting curve derivation

图8 裂纹尖端等效应变场及塑性区分布

Fig.8 Equivalent strain field and plastic zone distribution at the crack tip

图9 谐振疲劳短裂纹显微图像采集系统实物图

Fig.9 Micro-image acquisition system for capturing short fatigue cracks under resonant loading

图10 制备好的散斑试件

Fig.10 Prepared speckle specimen

图11 不同疲劳循环数时裂纹张开图像

Fig.11 Crack images under different fatigue cycles

图12 竖直方向位移云图

Fig.12 Vertical displacement nephogram

图13 不同位置引伸计张量曲线

Fig.13 Extensometer tensor curves at different positions

图14 裂尖垂线不同位移-位置曲线

Fig.14 Displacement curve at different positions of the vertical line of the crack tip

图15 裂纹尖端估计塑性区

Fig.15 Estimation of plastic zone at the crack tip

图16 等效应变场中裂纹尖端塑性区

Fig.16 Crack-tip plastic zone in the equivalent strain field

图17 裂纹尖端附近测量点布置图

Fig.17 Layout of measuring points near the crack tip

图18 测量点上位移曲线

Fig.18 Displacement curves at measuring points

图19 测量点上等效应变曲线

Fig.19 Equivalent strain curves at measuring points

参考文献 22

[1]	SURESH S, RITCHIE R O. Propagation of short fatigue cracks[J]. International Metals Reviews, 1984, 29(1):445-475. doi: 10.1179/imtr.1984.29.1.445 URL
[2]	张丽, 吴学仁. 基于小裂纹理论的GH4169高温合金的疲劳全寿命预测[J]. 航空材料学报, 2014, 34(6):75-83.
	ZHANG L, WU X R. Fatigue-life prediction method based on small-crack theory in GH4169 superalloy[J]. Journal of Aeronautical Materials, 2014, 34(6):75-83. (in Chinese)
[3]	MALITCKII E, REMES H, LEHTO P, et al. Strain accumulation during microstructurally small fatigue crack propagation in bcc Fe-Cr ferritic stainless steel[J]. Acta Materialia, 2018, 144:51-59. doi: 10.1016/j.actamat.2017.10.038 URL
[4]	LIU S D, ZHU M L, ZHOU H B, et al. Strain visualization of growing short fatigue cracks in the heat-affected zone of a Ni-Cr-Mo-V steel welded joint:Intergranular cracking and crack closure[J]. International Journal of Pressure Vessels and Piping, 2019, 178:103992. doi: 10.1016/j.ijpvp.2019.103992 URL
[5]	CHEN R, ZHU M L, XUAN F Z. Near-tip strain evolution and crack closure of growing fatigue crack under a single tensile overload[J]. International Journal of Fatigue, 2020, 134:1-11.
[6]	HOSDEZ J, LANGLOIS M, WITZ J F, et al. Plastic zone evolution during fatigue crack growth:digital image correlation coupled with finite elements method[J]. International Journal of Solids and Structures, 2019, 171:92-102. doi: 10.1016/j.ijsolstr.2019.04.032 URL
[7]	LORENZINO P, NAVARRO A. The variation of resonance frequency in fatigue tests as a tool for in-situ identification of crack initiation and propagation,and for the determination of cracked areas[J]. International Journal of Fatigue, 2015, 70:374-382. doi: 10.1016/j.ijfatigue.2014.08.002 URL
[8]	WITEK L. Simulation of crack growth in the compressor blade subjected to resonant vibration using hybrid method[J]. Engineering Failure Analysis, 2015, 49:57-66. doi: 10.1016/j.engfailanal.2014.12.004 URL
[9]	WALCKER A, WEYGAND D, KRAFT O. Inertial effects on dislocation damping under cyclic loading with ultra-high frequencies[J]. Materials Science and Engineering:A, 2005, 400:397-400.
[10]	AMIRKHIZI A V, TEHRANIAN A, NEMAT-NASSER S. Stress-wave energy management through material anisotropy[J]. Wave Motion, 2010, 47(8):519-536. doi: 10.1016/j.wavemoti.2010.03.005 URL
[11]	胡秀宏, 伍法权, 刘海燕. 全息干涉法测量Ⅰ型结构面技术路线[J]. 岩土力学, 2008, 29(11):3124-3127.
	HU X H, WU F Q, LIU H Y. Measure model-I crack stress intensity factor of rock-mass via laser holographic interferometry[J]. Rock and Soil Mechanics, 2008, 29(11):3124-3127. (in Chinese)
[12]	TANG M J, XIE H M, ZHU J G, et al. The failure mechanisms of TBC structure by moire interferometry[J]. Materials Science & Engineering A, 2013, 565:142-147.
[13]	DAI X J, PU Q, WANG L M, et al. Measurement on fracture process and prediction of the load capacity of steel fiber reinforced concrete by electronic speckle pattern interferometry[J]. Composites:Part B, 2011, 42:1181-1188. doi: 10.1016/j.compositesb.2011.03.003 URL
[14]	VASCO-OLMO J M, JAMES M N, CHRISTOPHER C J, et al. Assessment of crack tip plastic zone size and shape and its influence on crack tip shielding[J]. Fatigue & Fracture of Engineering Materials & Structures, 2016, 39(8):969-981.
[15]	ALSHAMMREI S, LIN B, TONG J. Full-field experimental and numerical characterisation of a growing fatigue crack in a stainless steel[J]. International Journal of Fatigue, 2020, 133:105449. doi: 10.1016/j.ijfatigue.2019.105449 URL
[16]	ZHANG W, CAI L, ZHOU D, et al. In-situ microscopy testing of plasticity variation ahead of fatigue crack tip in AL2024-T3[J]. International Journal of Fracture, 2019, 216(1):59-70. doi: 10.1007/s10704-018-00340-y
[17]	CARROLL J, EFSTATHIOU C, LAMBROS J, et al. Investigation of fatigue crack closure using multiscale image correlation experiments[J]. Engineering Fracture Mechanics, 2009, 76(15):2384-2398. doi: 10.1016/j.engfracmech.2009.08.002 URL
[18]	周金宇, 谢里阳, 朱福先, 等. 疲劳裂纹形核寿命的细观概率模型[J]. 兵工学报, 2016, 37(2):307-316. doi: 10.3969/j.issn.1000-1093.2016.02.017
	ZHOU J Y, XIE L Y, ZHU F X, et al. Meso-scale probabilistic model of fatigue crack nucleation life[J]. Acta Armamentarii, 2016, 37(2):307-316. (in Chinese)
[19]	GAO H L, ZHANG Z N, JIANG W, et al. Deformation fields measurement of crack tip under high-frequency resonant loading using a novel hybrid image processing method[J]. Shock and Vibration, 2018, 2018:1928926.
[20]	全国钢标准化技术委员会. GB/T 6398—2017,金属材料疲劳试验疲劳裂纹扩展方法[S]. 北京: 国家标准化管理委员会, 2017.
	The National Steel Standardization Technical Committee. GB/T 6398—2017,Metallic materials-Fatigue testing-Fatigue crack growth method[S]. Beijing: National Standardization Administration Committee, 2017. (in Chinese)
[21]	全国钢标准化技术委员会. GB/T 26077—2021,金属材料疲劳试验轴向应变控制方法[S]. 北京: 国家标准化管理委员会, 2021.
	The National Steel Standardization Technical Committee. BeGB/T 26077—2021,Metallic materials-Fatigue testing-Axial strain controlled methodijing[S]. Beijing: National Standardization Administration Committee, 2021. (in Chinese)
[22]	杨冰, JAMES M N, 基于CJP模型的疲劳裂纹扩展率曲线及应用方法[J]. 机械工程学报, 2018, 54(18):76-84. doi: 10.3901/JME.2018.18.076
	YANG B, JAMES M N. Fatigue crack growth rate curve based on the CJP model and its application method[J]. Journal of Mechanical Engineering, 2018, 54(18):76-84. (in Chinese) doi: 10.3901/JME.2018.18.076