Investigation of Fatigue Strength Evaluation Method in Biaxial Stress State
Takanori KATO, Miyuki YAMAMOTO and Yoshinari YAMAMURA
Abstract:The practical stresses at the critical point of structures or components are often in multiaxial stress states due to the complexity of shapes and external loads. So, in order to evaluate the fatigue strength accurately, we must use an appropriate method considering the multiaxial stress state. In this report, we focused on railway wheel plates being in biaxial stress states by external loads. FEM analyses and uniaxial / biaxial fatigue tests of a wheel steel were carried out. Then we investigated applicability of various multiaxial fatigue strength evaluation methods. As a result, fatigue limits evaluated by uniaxial stresses in biaxial fatigue tests were different from those in uniaxial fatigue tests. And it was clarified that considering a critical plane and crack initiating direction, fatigue limits in biaxial fatigue tests were evaluated accurately by a method using the octahedral share stress. Key Words:Multiaxial stress, Railway, Fatigue limit, Critical plane, Octahedral shear stress