Determination of Strain and Stress Ranges under Cyclic Proportional and Non-Proportional Multiaxial Loading
Takamoto ITOH, Masao SAKANE and Tomohiko OZAKI
Abstract:Von Mises equivalent strain and stress have no negative values so that they have a difficulty to express strain and stress ranges even in a simple push-pull loading. Tresca equivalent values, on the other hand, have negative values but they also have a difficulty to put a sign to the shear strain and stress in cyclic loading. In non-proportional multiaxial fatigue, principal directions of strains and stresses change during a cycle. In such a case, strain and stress ranges and mean strain and stress cannot be easily determined. Developing an appropriate method of determining the ranges and mean values are needed for the design of pressure vessels and so on. This study proposes a simple method of defining the maximum strain and stress ranges and the mean strain and stress under proportional and non-proportional loading. Key Words:Multiaxial stress state, Non-proportional loading, Stress and strain, Fatigue, Design criteria