The paper compares various methods for computing the equivalent stress amplitude cycles of non-zero mean value in stress-life fatigue prediction. A set 11 calculation is evaluated. In addition to formulations based on common static or properties, Walker formula and generalized Linear are included investigation. These two use an optimization routine find material parameters. final response compared discussed. method provides a better solution. produces inferior results, i.e. linear fit...

The paper presents a comparison of six recently introduced multiaxial fatigue strength estimation criteria to four methods, the large-scope validation which has already been published. results obtained for each newer method are analyzed and discussed. From only criterion by Böhme reaches an quality similar best performing criteria. was performed on FatLim data sets, but primary focus is set analyzing smaller AMSD25 derived from it. shows that application practice allows users reduce number...

Abstract This paper describes the way in which a specialized validation set intended for quick of new multiaxial fatigue strength estimation models high‐cycle regime was prepared. The rules established accepting various data sets into complete FatLim database are briefly described. final contained 282 items at moment this written. how has been reduced to smaller set, marked as AMSD25. criteria used small‐scale test based on evaluating mean and standard deviation index errors obtained each...

This paper discusses the phase shift effect occurring between two and more load channels of multiaxially loaded specimens. The discussion concludes that there is an extreme shortage good experimental data would prove existence trend in high-cycle fatigue region. It no wonder are so many strength estimation criteria use quite different computational concepts, because response to base often hidden a conglomeration other interacting effects. presents results sensitivity study compares for...

Abstract This paper presents an assessment of the performance a set multi‐axial high‐cycle fatigue criteria on basis series fretting experiments. We carried out tests creep‐resistant chromium steel material used for steam‐turbine blades. The first type experiment employed classical cylinder‐on‐flat geometry with flat dog‐bone specimens. second experiments adopted dovetail geometry. Various loads were applied in order to capture wide range contact slip amplitudes. A eight plain was...

The influence of critical volume on fatigue strength is assessed based experiments six specimen types (both unnotched and notched) manufactured from 42CrMo4+QT steel. Three size effect models are evaluated. To deal with them, additional coinciding influencing factors, such as surface roughness, had to be analyzed a data set comprised both notched specimens.

The increasing demands on the flexibility of steam turbines due to use renewable energy sources substantially alters fatigue strength requirements components these devices. This paper presents Thermo-Mechanical Fatigue (TMF) design calculations for turbine shaft. shaft is exposed complex thermo-mechanical loading conditions during operating cycle turbine. An elastic-plastic structural Finite Element Analysis (FEA) performed basis calculated temperature fields obtained in a previous transient...

With increasing share of renewable energy sources in the electricity production strict demands are placed on thermal power plants that have to cover shortages more frequently. Increasing number steam turbine (ST) start-ups and shutdowns, as well requirements higher ramping operating conditions, has detrimental effect overall lifetime ST components. In design process, this situation be dealt by applying advanced prediction methodologies handling thermo-mechanical fatigue mechanism, for...

Increasing demands on the flexibility of steam turbines due to use renewable energy sources substantially alters fatigue strength requirements components these devices. Rapid start-ups as well increased number load cycles applied must be handled by design methodologies. The goal work presented in this paper was provide a computational framework applicable thermo-mechanical (TMF) prediction turbine shafts. so-called Damage Operator Approach Nagode et al. has been implemented software codes...

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The increasing demands on the flexibility of steam turbines due to use renewable energy sources substantially alters fatigue strength requirements components these facilities. work summarized hereafter was initiated by effort develop methodology prediction thermo-mechanical turbine rotors. A significant put into local stress-strain response modelling in shaft material. An FE model structure assuming 2D axisymmetry idealisation developed and verified. In-house codes based a variety approaches...

The paper is an overview of the work conducted in order to investigate thermo-mechanical fatigue (TMF) performance a CrMo steel applicable steam turbine shaft design. Uniaxial TMF tests tubular specimens under various temperature ranges and phase shifts were carried out. Damage Operator Approach (DOA) proposed by Nagode et al. (2009) was calibrated low-cycle experiments its quality prediction verified tests. obtained results show that DOA predicts with higher range temperatures (100-600 °C)...

Fatigue strength prediction methods of blades a high pressure steam turbine are the main topic this article. Experimental approaches, as well use experimental results for verification finite element method (FEM) and fatigue models, were performed on two basic levels. First, by tests smooth notched cylindrical specimens under room service conditions was performed. Second, real blade limit conducted. These carried out using special test stand typical combined loading. Appropriate uniaxial...

Growth of share renewables in the field electric power supplier and a lack mechanism to cover shortage, force standard energy stabilize electrical grid. This situation is then demonstrated by increase hot-start cold-starts. But there for robust tool qualitative assessment residual life turbine shaft design such component. The goal this paper present influence holding period on low-cycle fatigue (LCF), thermo-mechanical (TMF) so called Damage Operator Approach (DOA) Nagode, which were used as...

Abstract Increasing share of renewable energy sources in the electricity production results a pressure on thermal power plants to cover fluctuation very frequently. The increasing number start-ups and shutdowns as well requirements for prompt ramping higher operation temperature has cardinal influence lifetime steam turbine. This all brings new challenges designing process turbines analysis currently operated ones. paper aims present experimental work, basic material parameters such tensile...