Crack observation methods, their application and simulation of curved fatigue crack growth
Crack observation methods, their application and simulation of curved fatigue crack growth
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DOI：
10.1016/j.engfracmech.2010.04.013
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发表时间：
2010-07
影响因子：
5.4
通讯作者：
S. Henkel;D. Holländer;M. Wünsche;H. Theilig-;P. Hübner;H. Biermann;S. Mehringer
中科院分区：
文献类型：
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作者：
S. Henkel;D. Holländer;M. Wünsche;H. Theilig-;P. Hübner;H. Biermann;S. Mehringer
观察弯曲裂纹路径的裂纹必须用光学方法进行。结果表明，改进的商用平板扫描仪和10,000×10,000像素的高分辨率扫描仪摄像系统与远心透镜相结合，适合于210 mm×290 mm的样品区域上多个裂纹端面的高分辨率(高达8μm/像素)光学记录。高分辨率照片适合于裂纹长度的测定。还可以通过图像相关来观察裂纹路径或几何裂纹尖端参数和应变场。用该方法测定了中心裂纹拉伸试件和双向十字形试件的静态抗裂性能和循环裂纹扩展曲线。在此基础上，本文提出了一种改进的有限元方法，用于模拟双向平面应力载荷作用下多个任意预裂纹板的弯曲疲劳裂纹扩展。为此，扩展了PCCS-2D程序，在全自动模拟中分析了裂纹扩展和每个裂纹扩展步骤的塑性极限载荷。该算法将失效评定图法与裂纹路径数值模拟相结合，为缺陷评定提供了有力的工具。最后，对仿真结果进行了实验验证。
The observation of cracks with curved crack path has to be done optically. It is shown that a modified commercial flat bed scanner and a combination of a high-resolution scanner camera system with 10,000×10,000 pixels with a telecentric lens are appropriate for high-resolution (up to 8μm/pixel) optical recording of multiple crack ends on sample areas up to 210mm×290mm. The high-resolution photographs are suitable for determination of crack lengths. It is also possible to observe crack paths or geometrical crack tip parameters and strain fields by image correlation. The method is used to determine static crack resistance and cyclic crack growth curves on center crack tension and biaxial cruciform samples. Furthermore, the paper presents an improved finite element technique for the simulation of curved fatigue crack growth in a multiple arbitrarily pre-cracked isotropic sheet under biaxial plane stress loading applying a predictor–corrector procedure in combination with the modified virtual crack closure integral (MVCCI) method including the consideration of the plastic limit loads. For this, the program PCCS-2D was extended to analyse the crack growth and the plastic limit load for each crack propagation step in a fully automatic simulation. The proposed solution algorithm provides a powerful tool for flaw assessment with the failure assessment diagram procedure in combination with a numerical crack path simulation. Finally, the simulation is verified experimentally.