Application of Life-Dependent Material Parameters to Fatigue Life Prediction under Multiaxial and Non-Zero Mean Loading

Limited Stress Surface Model for Bending and Torsion Fatigue Loading with the Mean Load Value

In this study, a linear model of the transformation of the stress amplitude due to the mean value was used. The coefficient of the material sensitivity to cycle asymmetry with consideration of the dependence of this coefficient on the number of fatigue loading cycles is also used. A three-parameter surface model of limited stresses is proposed in this paper. The model is verified using the results of fatigue tests for cyclic bending and torsion under mean loads. The tests are performed for two types of alloy steels—S355J0 and S355J2G1W. Comparison of the allowable stress amplitudes obtained experimentally with those predicted using the proposed model shows errors of no more than 18%, with the area of the surface with the largest error being relatively small.

Fatigue Prediction of Aluminum Alloys Considering Critical Plane Orientation under Complex Stress States

This publication is intended to present a new way of estimating the fatigue life of various construction materials. Carpinteri's proposal was modified by replacing the fatigue limits ratio with the value of the normal to shear stress ratio for a given number of cycles. In this study, the proposed criterion and calculation model was verified for the selected group of aluminium alloys. The purpose of the analysis of the experimental studies was to check the effectiveness of the proposed method of estimating fatigue life under the applied bending and torsional load conditions. The results of the fatigue calculations are presented in graphical form by means of diagrams showing the comparison of design and experimental strength. Before fatigue life was calculated, the critical plane orientation according to Carpinteri's model and the proposed model were determined. After analyzing the results of the comparison of design and experimental durability, it can be stated that the proposed fatigue life estimation algorithm gives satisfactory results for multiaxial cyclic loads.