Measurement of energy release rate and energy flux of rapidly bifurcating crack in Homalite 100 and Araldite B by high-speed holographic microscopy
Measurement of energy release rate and energy flux of rapidly bifurcating crack in Homalite 100 and Araldite B by high-speed holographic microscopy
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DOI：
10.1016/j.jmps.2006.12.007
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发表时间：
2007-07
影响因子：
5.3
通讯作者：
S. Suzuki;K. Sakaue;K. Iwanaga
中科院分区：
文献类型：
--
作者：
S. Suzuki;K. Sakaue;K. Iwanaga
应用高速全息显微术连续拍摄了Homalite 100和Araldite B中快速扩展裂纹分叉时刻的三张照片。Homalite 100的分叉处裂纹速度约为540 m/s，Araldite B的分叉处裂纹速度约为450 m/s。从这些照片中，得到了分叉前后的裂纹速度，发现在Homalite 100的情况下，在分叉时刻不存在裂纹速度的不连续变化，但在Araldite B的情况下，存在裂纹速度的不连续变化。从照片中，还测量了沿着裂纹的裂纹张开位移（COD），其作为距裂纹尖端的距离r的函数。测量结果表明，在分叉前，COD与Δ ε r成正比。分叉后，母裂纹的COD与σ r成正比，而分支裂纹的COD并不总是与σ r成正比。能量释放率是由实测COD得到的，发现无论是Homalite 100还是Araldite B，能量释放率在分叉点处都是连续的。还得到了能流，显示了能量流向裂纹尖端。
High-speed holographic microscopy is applied to take three successive photographs of fast propagating cracks in Homalite 100 or in Araldite B at the moment of bifurcation. Crack speed at bifurcation is about 540m/s on Homalite 100, and about 450m/s on Araldite B. From the photographs, crack speeds immediately before and after bifurcation are obtained, and it is found that discontinuous change of crack speed does not exist at the moment of bifurcation in the case of Homalite 100, but exists in the case of Araldite B. From the photographs, crack opening displacement (COD) is also measured along the cracks as a function of distance r from the crack tips. The measurement results show that the CODs are proportional to √r before bifurcation. After bifurcation, the CODs of mother cracks are proportional to √r, though the CODs of branch cracks are not always proportional to √r. The energy release rate is obtained from the measured CODs, and it is found that energy release rate is continuous at bifurcation point in both cases of Homalite 100 and Araldite B. Energy flux that shows the energy flow toward a crack tip is also obtained.