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The focus of this study, using results obtained with hollow specimens of the alloy Al 2024 T3 (AlCuMg2 T3) with a one‐sided bore, was to determine if, under multiaxial loading, the fatigue strength in a notch with a uniaxial stress state can simply be assessed without the application of any multiaxial strength hypothesis. In the fatigue critical location, the bore edge, only a superimposition of normal stress components, resulting from axial loading or/and torsion, occurs. In the case of out‐of‐phase loading, the resulting local uniaxial stress is even lower than the stress under in‐phase loading and leads to an increase of fatigue life to crack initiation under the non‐proportional loading, which is not observed in the case of multiaxial stressing/straining of the material itself. As the local stress state in the crack initiation site is uniaxial, the application of a multiaxial strength hypothesis, for the failure criterion of crack initiation (l=0.2 mm), is not necessary. Furthermore, the benefit of non‐homogenous stress distributions, which allow locally higher stresses than the levels given by the Woehler‐line for unnotched specimens, was underlined by considering highly‐stressed, material‐volume‐related support factors. [ABSTRACT FROM AUTHOR]

Wheelset shafts are usually coated to protect them from mechanical and corrosive influences. However, damage during operation requires close inspection intervals to check permissible damage depths. The focus of this research is to investigate a possible increase in corrosion fatigue strength through inductive surface layer treatment for the wheelset shaft material EA4T (25CrMo4+quenched and tempered). For this purpose, process parameters for inductive surface hardening were identified and optimized in order to achieve a sufficiently high hardening depth and hardness of the surface layer on lightly notched test specimens. Subsequently, fatigue strength tests were carried out in air and in 5 % NaCl solution for the initial state and the hardened state. By comparing the fatigue strength results determined, the expected potential for increasing fatigue strength and corrosion fatigue strength was confirmed. In order to demonstrate stone chipping and corrosion stress, further tests were repeated with damage specifically introduced into the surface layer. The findings indicate the potential of surface layer hardening for significantly lower‐maintenance wheelset shafts in freight transport in the future. [ABSTRACT FROM AUTHOR]

Translation abstract: Zinc‐based corrosion protection systems provide the user with a favorable and long‐ lasting opportunity to protect steel components from corrosion. Therefore, these systems are used in many different variants and are state of the art. Investigations show that zinc‐based corrosion protection systems can have an influence on the fatigue strength during cyclic loading. This influence is not or only partly taken into account in current design regulations. In this paper, the influence on the fatigue strength and possibilities to consider the influence in the design against material fatigue is shown. [ABSTRACT FROM AUTHOR]

Analytical fatigue strength calculations based on the FKM guideline have been performed for hot tapered and stress-shot-peened high-strength leaf spring specimens subjected to three-point fatigue bending. The ultimate tensile strength of the decarburized specimens' surface has been approached by means of Rockwell-C hardness measurements, and used as input for the approximation of its fatigue limit and mean stress sensitivity. Surface roughness and residual stress measurements were performed to take account for the technological life influencing factors. Fatigue tests at a constant mean stress and various stress amplitude levels were performed to determine the specimens' S-N curve and validate the calculation's accuracy. Comparison of calculated with experimentally determined fatigue lives, though satisfactorily, pinpoints the necessity for more accurate implementation of the stress-shot-peening process within the FKM guideline. [ABSTRACT FROM AUTHOR]

In the present study, a local stress based concept for the fatigue assessment of weld ends in thin sheet structures under combined normal and shear loading is introduced. The notch stresses were calculated using the finite element method and submodel technique. An idealised weld end model was used in order to determine the stress state for such loading situations. Moreover, a numerical method was used to consider size effects, which combines both the geometrical and statistical size effects, to an integrated approach. Therewith and in connection with the cycles-to-failure from fatigue test results, a standardised S-N curve was derived. [ABSTRACT FROM AUTHOR]

For the desired energy and resource conservation in future lightweight concepts, detachable connections such as aluminium connections play an important role. Great potential in terms of reliability has been identified for aluminium bolts produced by equal-channel angular pressing (ECAP). Nevertheless, the mechanical properties of such bolts, required for a safe design of components, has not been adequately studied so far, especially not for dynamic load situations. Within this work, first results of fatigue tests of aluminium bolts of dimension M10x50 of aluminium alloy EN-AW 6082 and ECAP optimized EN-AW 6082 are presented and compared with properties of conventional bolts of the EN-AW 6056 series. Based on these findings, causes of failure are described and presented in the format of a fault tree analysis. [ABSTRACT FROM AUTHOR]