動的き裂分岐現象の支配条件に関する基礎研究

概要

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Branched cracks are often observed in brittle materials and structures. However the mechanism of crack branching is not fully clarified. In this paper, first, dynamic crack branching phenomena in Homalite-911 and Homalite-100 were experimentally investigated. Caustic patterns during dynamic crack branching were recorded by an ultrahigh-speed camera. Next, on the basis of the dynamic J integral, energy concepts for dynamic crack branching are presented. Special attentions are focused on the energy flow into dynamically propagating crack tips. Then four possible fracture parameters associated with the dynamic J integral are proposed. The dynamic J integral values in a dynamic crack branching test are directly evaluated by the caustic patterns taken by the high-speed camera. The variations of four fracture parameters during dynamic crack propagation including at the instant of crack branching are presented. The experimental results reveal that the energy flux per a unit time into a propagating crack tip governs the crack branching.
社団法人日本機械学会の論文
1999-05-25