Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : December 22, 2018 - December 24, 2018
The double integrity is recently focused on to improve the structure integrity of the large container ships. In addition to material performance to arrest a propagating brittle crack, structural factors are expected to enhance the double integrity. Such structural design is called as crack arrester, and in large container ships, so called “structural crack arrest design” utilizing welded joint has been recently used as the crack arrester. Although such design is already applied to commercial ships, the mechanism of crack arrest in such design has not been clear because crack behavior in the joint is 3D and hard to measure by conventional methods. Therefore, in order to clarify crack arrest mechanism in structural crack arrest design, 3D rapid crack propagation and arrest behavior was observed in T-joint-like structures made of transparent elastic material by using high speed camera. The experiments were carried out for three kinds of specimen, whose flange thickness were different. The experiments showed that the crack was likely to be arrested in the thicker flange. The observation using high speed camera showed that the crack front shape was significantly important to consider crack arrest mechanism because the semi-elliptical-like crack front shape in flange plates caused reduction of SIF and crack arrest. Such crack front shape was easily kept in the thicker flange specimen, so the crack was arrested.
