Experimental and Numerical Study on the Unstable ModeII Crack Growth with Image Analysis

为了研究压缩载荷下裂纹的不稳定扩展机理，进行了单轴压缩下二维裂纹扩展实验、三维内裂纹扩展实验和数值模拟。利用超高速摄影图像分析技术研究了准静态单轴压缩下二维裂纹失稳扩展过程。利用光弹性技术对裂纹尖端应力场进行可视化，以250，000 fps的帧率拍摄裂纹扩展图像和应力场图像。结果表明，裂纹扩展受应力波的影响。利用超高速摄像机对三维内裂纹扩展过程进行了图像分析，成功地实现了三维内裂纹扩展过程的可视化。应用PDS-FEM技术对三维内裂纹扩展进行了数值分析，结果与实验结果吻合较好。

To study the unstable crack growth mechanism under compressive loading, the experiment of two dimensional crack growth under uni-axial compression, the experiment and numerical simulation of three dimensional inner crack growth has been performed. Image analysis with ultra-high-speed camera is applied to the two dimensional unstable crack growth under quasi-static uniaxial compression. Stress field around the moving crack tip is visualized by means of photo-elastic technique and images of growing cracks and the stress field are captured with the frame rate of 250,000 fps. As a result, it is revealed that the crack growth is affected by the stress wave travelling the specimen. Image analysis with ultra-high speed camera is also applied to the three dimensional inner crack growth, and the growth is visualized successfully. Numerical analysis with PDS-FEM technique is applied to the three dimensional inner crack growth, and the result shows a good agreement with the experimental result.