S031023 エルボ配管の低サイクル疲労挙動に及ぼす繰返し過大予荷重の影響([S03102]低サイクル疲労とその応用(2))

概要

論文の詳細を見る
Low cycle fatigue tests were conducted using sound elbows made of carbon steel (STPT410). The elbows were subjected to cyclic in-plane bending under displacement control with internal pressure of 9 MPa. Initially, fatigue tests were conducted under constant cyclic displacements. Then, two step fatigue tests were carried out to investigate the influence of cyclic pre-overload on low cycle behavior of elbow on the basis of the previous test results. The fatigue test results were evaluated by using the total usage factor UF_<total> (=UF_1+UF_2), where the UF_1 and UF_2 correspond to usage factor for δ_1 andδ_2, respectively. The residual fatigue life overloaded pipe in UF_1=0.6 was evaluated on non-conservative side by the cumulative fatigue damage rule. On the other hand, the residual fatigue lives in the range of UF_1≦0.4 can be estimated based on the cumulative fatigue damage rule generally. In addition, three-dimensional elastic-plastic analyses were carried out using the finite element method. The crack penetration area and the crack growth direction were successfully predicted by the analyses.
2011-09-11