523 モアレ干渉法による分岐切欠の開口変位と応力拡大係数の測定(OS9-3 光計測法,OS9 実験力学における新たな試み)

概要

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Static experiments are performed to confirm the COD method that is the only method to measure the energy release rate of fast propagating cracks just after bifurcation. The crack opening displacement (COD) of the mother cracks of bifurcated cracks is measured in static condition by Moire interferometry. Thin notches are used instead of cracks. The bifurcation angle is 13.5 degrees that is the same as the angle of bifurcation of fast propagating cracks in PMMA. The measured CODs are proportional to the square root of the distance from the nominal tip of the mother crack. Stress intensity factor of the bifurcated crack is obtained from the measured CODs through the formula of the COD of single crack. The experimental results say that the stress intensity factor of a bifurcated crack has the same value as that of the single crack whose length is the same as that of the bifurcated crack. This is caused by the small bifurcation angle of 13.5 degrees. It is concluded that the COD method is correct to measure the energy release rate of rapidly bifurcating cracks.
一般社団法人日本機械学会の論文
2007-10-24