Effects of Loading Rate and Stress-State on Dimple Fracture

概要

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The influence of the specimen thickness on fracture have been investigated under static loading and interpreted in terms of stress conditions near a crack tip, namely crack tip plasticity under plane strain to plane stress condition. This work investigates the effect of stress conditions on dimple fracture produced by impulsive stress intensity of 20, 40 and 80 μs duration, experimentally and numerically. The fractographic observation shows that several voids nucleated at inclusions ahead of a crack tip coalescence with each others to form a large void, called a dominant void in this work, and that a size of the dominant void decrease as the pulse duration decreases from 40 μs to 20 μs, whereas the dominant void is nucleated at the constant distance from the crack tip. Finite element analysis shows that the hydrostatic stresses ahead of a crack tip can explain the experimental results that the dynamic fracture toughness of a 10 mm thich specimen is much smaller than that of a 3 mm thick specimen and that the void nucleation site is independent of the specimen thickness.
社団法人日本材料学会の論文
2000-06-15