界面要素を用いたFEMによる溶接高温割れに関する理論的研究(第二報) : 温度依存型界面要素の定量的モデル化

抄録

In the previous report, a finite element method(FEM)using temperature dependent interface element is proposed for the occurrence and propagation of hot cracking under welding. The appropriateness of proposed method is investigated, and it is found that the computed results agree with the phenomena generally observed in experiments. In this report, the potential usefulness of the proposed method for clarifying the mechanism of hot cracking is demonstrated using the Fish Bone type hot cracking test. There are two types of Fish Bone test depending on the choice of the welding direction. In case of the originally proposed test, the welding starts from the wider side. The test with welding in the opposite direction is also commonly employed. But clear deference between the two methods is not given. After brief discussion on the analysis of Fish Bone test, the acceptability of the computed results by the proposed method is closely examined. Especially, effects of the BTR(Brittleness Temperature Range), the strength ratio between yield stress σ_Y and interfacial bonding strength in BTR σ_<cr>, the scale parameter γ_0 involved in the interface potential @φ@ and the size of the mesh are investigated. Through this study, it is found that the hot cracking simulated by the proposed method is basically determined by the BTR and the scale parameter γ_0. This agrees with the concept proposed by Matsuda through high temperature ductility curve. Finally, the possible procedure to determine these parameters used in the proposed method is discussed.