疲労亀裂進展の下限界条件ΔΚ_thおよび進展則に関する一考察

概要

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The phenomenon of ΔK_<th> and fatigue crack propagation in the ΔK_<th> region is investigated theoretically. When a difference between the binding energy of atoms and the strain energy of crystal lattice becomes nearly equal to that of thermal fluctuation, the separation of atoms may be regarded as a stochastic process. The ΔK_<th> is defined by the K value which gives such stochastic condition at a crack tip. Through this concept, the author proposed that a binding energy of atoms or Young's modulus is a most influensive physical property in determining ΔK_<th>. Moreover, standing on a view point that the crack tip opening displacement has a great influence on the crack propagation rate, he derived a second power rule for fatigue crack propagation in the region of slow fatigue crack growth. Consequently, it was concluded that the crack propagation rate is inversely proportional to the second power of Young's modulus. It is found that both theories proposed by the author yielded fair agreement with experimental results reported hitherto.
社団法人日本船舶海洋工学会の論文