Methods of Computational Determination of Growth Rates of Fatigue, Creep, and Thermal Fatigue Cracks in Poly- and Monocrystalline Blades of Gas Turbine Units

During operation of transport and maneuverable gas-turbine units, there are crack formation in turbine disc rims what exerted by thermomechanical cycling loads. For in-depth study of these problems we have to use theories of plasticity and creep which form the basis for determining the complex stress-strain state in the stress concentration zone for disc rims, and a modern failure criterion which can predict lifetime under conditions of simultaneous plastic and creep strain accumulation. There is a finite-element method (FEM) that allows us to evaluate the stress-strain state in a stress concentration zone for a non-elastic material behavior. With plasticity and creep theories, it is possible to determine local strain quiet reliable by FEM.

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“…5. The further improvement of the disc lifetime prediction can be performed with taking into account a crack propagation stage [20].…”

Section: Results Of Fem Modeling Of Stress Strain Behavior Of Turbine...mentioning

confidence: 99%

Thermal-Fatigue Analysis of Turbine Discs under Complex Thermo-Mechanical Loading with Account of Plasticity and Creep Effects

Ignatovich

Семенов

Semenov

et al. 2015

AMM

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“…As soon as cracks can appear due to various kinds of deformation, the nature of cracks origination owing to creep and thermal fatigue on the example of turbine disks and blades via the method of finite element analysis [11,12]. Assessment methods of stress state of disks, turbine blade and interlocks of turbine equipment are considered in the researches [13,14].…”

Section: Introductionmentioning

confidence: 99%

Optimal distribution of capsules with active substance for the crack detection system in a turbine blade body

Andrianov,

Chepurnova

2023

cisisr

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This research is devoted to optimization of the detection system for damages of blades of a gas turbine engine in non-stationary conditions. The system is based on the approach on the method, when capsules with active substance are placed in a steel blade body, then a capsule is bursting due to difference of pressures during the process of crack propagation; as a result, ejected active substance is registered. The problem of this research is connected with optimal distribution of capsules, which contain active substance, in a turbine blade body. The research technique was developed for a modeling problem, when a steel turbine blade with constant cross section, having tensile crack and subjected to the action of extension centrifugal force, was observed. Development of the model with optimal distribution of capsules was based on assessment of pre-critical crack growth: it was required to distribute the capsules along the median line of blade cross section in such way, that it would be possible to detect the crack of pre-critical growth. Analysis of ultimate state of a blade with crack was carried out on the base of stress intensity coefficient, which allows to take into account the feature of crack location and to determine its critical length when its accelerated growth takes place. Variation of the pressure inside a capsule, required for its bursting depending on opening of crack sides. The suggested model takes into account location of the capsule with active substance relating to crack opening sides. Calculation of minimal number of capsules in blade bode depending on pressure inside the capsule and rotating speed of blades was conducted on the example of the steel turbine blade R-5530 B. The obtained dependences allow us to find the optimal combination between the geometric and physical characteristics of the crack detection system and the minimal number of capsules. The application of the proposed approach to the optimal distribution of capsules along the median line of the blade cross section will increase the efficiency of use of the damage detection system in turbine blades in non-stationary conditions, thereby ensuring the safety of operation of gas turbine engines in aviation technology.

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“…When manufactured products largely retain their strength and are used in similar environments, the remaining service life can be predicted by referring to past service history and experimental results. Numerical simulation can also be an effective tool when the physical phenomena are relatively simple and the mechanical and geometric boundary conditions are known: for example, (Semenov et al, 2012). However, in practice, the strength of the products varies because of variations in the construction process and individual differences in the materials themselves, such as microdefects and inclusions.…”

Section: Introductionmentioning

confidence: 99%

Non-destructive estimation of three-dimensional inelastic strain via nonlinear inverse analysis using displacement

FUJII,

OGAWA,

HIRABAYASHI

2023

Mechanical Engineering Journal

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The service life of mechanical structures is influenced by the inelastic strain generated during manufacturing and operation. Therefore, non-destructive estimation of three-dimensional inelastic strain is essential to ensure structure safety even during operation. Accordingly, an inverse problem method was proposed to estimate the inelastic strain over the entire component based on the eigenstrain theory using non-destructively measured surface displacement. However, this method assumes micro-deformation, in which the causal inelastic strain and resulting displacement are linearly related. In practice, the value of inelastic strain is large, which results in large deformation and a nonlinear effect on displacement determined by the magnitude of the inelastic strain. This study considers the inverse problem of estimating the creep strain in a turbine blade for power generation from the displacement caused by the creep strain and proposes a method to derive the exact solution even for large deformation problems. Numerical simulations using a simplified turbine model show that the estimates converge to the correct solution value with relatively high accuracy in the absence of measurement errors. Moreover, the result of the iterative calculations used in the proposed method converge around the correct value, even in the presence of measurement errors in the displacement by the laser displacement meter.

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Methods of Computational Determination of Growth Rates of Fatigue, Creep, and Thermal Fatigue Cracks in Poly- and Monocrystalline Blades of Gas Turbine Units

Cited by 12 publications

References 28 publications

Thermal-Fatigue Analysis of Turbine Discs under Complex Thermo-Mechanical Loading with Account of Plasticity and Creep Effects

Thermal-Fatigue Analysis of Turbine Discs under Complex Thermo-Mechanical Loading with Account of Plasticity and Creep Effects

Optimal distribution of capsules with active substance for the crack detection system in a turbine blade body

Non-destructive estimation of three-dimensional inelastic strain via nonlinear inverse analysis using displacement

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