Search results for "Equivalent stress"
showing 4 items of 4 documents
Assessment of multiaxial fatigue behaviour of welded joints under combined bending and torsion by application of a fictitious notch radius
2004
Abstract A major problem in the assessment of the multiaxial fatigue behaviour in welded joints is the determination of local notch stresses, since the real local radii in most cases are not known. This can be circumvented by introducing a fictitious notch radius, according to Neuber and Radaj. The calculations of local equivalent stress amplitudes for welded joints (tube–tube and flange–tube) under pure bending, pure torsion and combined in- and out-of-phase bending with torsion can then be carried out by stress-based and strain energy density-based criteria. Among the investigated methods, the most reliable results are obtained with the effective equivalent stress hypothesis, an integral …
Comparison of Variance and Damage Indicator Methods for Prediction of the Fracture Plane Orientation in Multiaxial Fatigue
1999
ABSTRACT Two methods that enable prediction of the fracture plane orientation are presented and compared in this paper. The first one is a statistical approach, which is based on the variance of an equivalent stress. It is assumed that the fracture plane is the one where the variance of a linear combination of the shear and normal stresses acting on this plane is maximum. The second one uses the so-called damage indicator of a multiaxial fatigue criterion, which is based on the research of the critical plane. The formulation of the criterion involves shear and normal stress amplitudes and mean normal stress. The fracture plane is the critical plane; That is to say the one where the damage i…
Fatigue fracture plane under Multiaxial Random Loadings - prediction by variance of equivalent stress based on the maximum shear and normal stresses
1992
It is assumed that the plane in which the maximum variance of the equivalent stress appears is critical for a material and the fatigue fracture should be expected in this plane. The equivalent stress is calculated according to the fatigue criterion of maximum shear and normal stresses in the fracture plane. It was demonstrated that for each stationary random stress state there is one or more critical planes where the fatigue fracture plane can be expected. The variance method together with the discussed fatigue criterion give good results for three analysed types of carbon steels under multiaxial cyclic loadings.
ESTIMATED AND EXPERIMENTAL FATIGUE LIVES OF 30CrNiMo8 STEEL UNDER IN-AND OUT-OF-PHASE COMBINED BENDING AND TORSION WITH VARIABLE AMPLITUDES
2007
Abstract— Calculated fatigue lives, based on three criteria for multiaxial random fatigue, were compared with lives obtained from tests on cylindrical specimens of 30CrNiMo8 steel subjected to in- and out-of-phase bending and torsion at variable amplitudes. In the chosen fatigue criteria the expected position of the fracture plane, determined from a variance method for the equivalent stress, were taken into account. The equivalent stress history was related to the rain flow method and fatigue damage was evaluated from the Palmgren–Miner hypothesis. It has been shown that the expected fatigue fracture planes agree with those determined by experiments. The most realistic estimations of fatigu…