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Ductile cast irons are often used for turbocharged diesel engine components. These components are usually subjected to cyclic thermo-mechanical loading during their lifetime due to variable service conditions. A reliable damage assessment is required to guarantee service function, safety or light weight of the products. The first objective of this paper is to introduce the new test stand designed for uniaxial Low Cycle Fatigue (LCF) and Thermo-Mechanical Fatigue (TMF) tests. The second objective of the paper is to assess the lifetime of SiMo (Silicon Molybdenum) cast iron. Based on the experimental results, an appropriate energy-based fatigue criterion is proposed for predicting the LCF/TMF of complex engineering components. Reasonable correlation was achieved between the observed results and the predicted results. [ABSTRACT FROM AUTHOR]

This paper presents an assessment of the performance of a set of multi-axial high-cycle fatigue criteria on the basis of a series of fretting fatigue experiments. We carried out tests on a creep-resistant chromium steel material used for steam-turbine blades. The first type of experiment employed the classical cylinder-on-flat geometry with flat dog-bone specimens. The second set of experiments adopted dovetail geometry. Various loads were applied in order to capture a wide range of contact slip amplitudes. A set of eight plain multi-axial fatigue criteria was applied to the numerically simulated stress response in the contacts during a single load cycle. Methods, which originated in the so-called theory of critical distances, were used for correcting the results in order to take the stress gradient effect into account. A simple factor based on slip amplitudes is introduced in order to consider the surface damage and is calibrated for the McDiarmid method. This criterion provided the best estimates of the most probable cracking sites. [ABSTRACT FROM AUTHOR]

This paper describes and presents an experimental program of low-cycle fatigue tests of austenitic stainless steel 08Ch18N10T at room temperature. The low-cycle tests include uniaxial and torsional tests for various specimen geometries and for a vast range of strain amplitude. The experimental data was used to validate the proposed cyclic plasticity model for predicting the strain-range dependent behavior of austenitic steels. The proposed model uses a virtual back-stress variable corresponding to a cyclically stable material under strain control. This internal variable is defined by means of a memory surface introduced in the stress space. The linear isotropic hardening rule is also superposed. A modification is presented that enables the cyclic hardening response of 08Ch18N10T to be simulated correctly under torsional loading conditions. A comparison is made between the real experimental results and the numerical simulation results, demonstrating the robustness of the proposed cyclic plasticity model.