円筒と板の張出し変形における成形性

概要

論文の詳細を見る
The formability of tubes biaxially loaded in combined axial tension and internal pressure is known to differ from the formability of punched sheets, even if they are made of same materials. The fact suggests that uniform deformation continuing up to diffuse instability is very sensitive to the geometry of a specimen and loading conditions. Plastic instability is defined as the occurrence of the multiplicity in solution, and in general, it is thought not to be influenced directly by loading conditions. Then, the concept of load instability should be introduced for the appropriate evaluation of formability. At a formability test loading path is specified in advance irrespective of specimen strength prior to the test. Under the test the specimen is to meet the state that it cannot sustain the load acting on it. At the instance the loading system loses the control trying to make the loading path fit to the specified path. In this paper the occurrence of loading instability is examined in comparison with plastic instability. With respect to plastic instability the necessary and sufficient condition is proposed based on the concept of multiplicity. The instability appearing at sooner stage is real instability, and it decides the formability depending upon loading condition. The result shows good agreement with experimental formability published in literature.
一般社団法人日本機械学会の論文
1998-12-25