高速クラックの動的様相に関する研究(第6報) : 張出型二重引張試験の動的解析

概要

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The arrestability of brittle crack of steel is probably associated very much with the formation of shear lips which are closely related to plastic deformation around crack tip. But the mechanism of initiation and growth of shear lips has not been clarified yet. For the purpose of studying the mechanism and role of shear lips, it is necessary to obtain experimental observation on a crack which runs fast and then comes to arrest in a test specimen with uniform temperature distribution. The conventional double tension test as a crack arrest test is not suitable for this purpose because the crack arrest is effected by gradient temperature distribution imposed on the crack propagation front of the specimen. In this paper, a modified test, that is, stress gradient type double tension specimen is used. The initial increase of crack extension force is followed by its decrease due to stress gradient which is effected by special configuration of crack propagation part of a specimen. The brittle crack propagation and arrest behavior in the above new type specimens are experimentally analyzed on the basis of dynamic fracture mechanics using finite-element technique. And the contribution of shear lips to crack arrestability is preliminarily considered with respect to dynamic fracture toughness K_D.
社団法人日本船舶海洋工学会の論文