A Life Prediction Model for Single-Crystal Nickel-Base Alloys Under Low-Cycle Fatigue

2021 ◽  
Author(s):  
Firat Irmak ◽  
Ali Gordon ◽  
Taejun Yun ◽  
NAVINDRA WIJEYERATNE
Keyword(s):  
Prediction Model ◽  
Single Crystal ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Nickel Base ◽  
Life Prediction Model

Anisotropic Life Prediction for Single Crystal Nickel-Base Flat Plate with a Hole

2014 ◽  
Vol 891-892 ◽  
pp. 1033-1038
Author(s):  
Cheng Li Dong ◽  
Hui Chen Yu ◽  
Ying Li
Keyword(s):  
Single Crystal ◽  
Flat Plate ◽  
Life Prediction ◽  
Failure Strain ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
The Finite Element Method ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Elastoplastic Constitutive Model

The material properties of single crystal (SC) superalloys are orientation-dependent. To fully exploit the material capacity, the life modeling needs to consider the anisotropy. In the present study the life modeling of SC nickel-base superalloys is considered by employing the modified Mücker's anisotropic theory in which a Hill type function is utilized for describing the anisotropic failure. Strain-controlled low cycle fatigue (LCF) experiments of SC nickel-base superalloys at different crystallographic orientations (i.e.[00, [01 and [11) under high temperatures (i.e.760°C) are carried out to verify the modeling availability for the modified Mücker's anisotropic theory. Further, based on the stress-strain field obtained by the anisotropic elastoplastic constitutive model coupled with the finite element method (FEM), the modified Mücker's anisotropic theory is employed to predict the fatigue life for SC flat plate with a hole.

A Life Prediction Model for Single-Crystal Nickel-Base Alloys Under Low-Cycle Fatigue

2020 ◽  
Author(s):  
Firat Irmak ◽  
Navindra Wijeyeratne ◽  
Taejun Yun ◽  
Ali Gordon
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Deformation Model ◽  
Cycle Fatigue ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Prediction Approach

Abstract In the development and assessment of critical gas turbine components, simulations have a crucial role. An accurate life prediction approach is needed to estimate lifespan of these components. Nickel base superalloys remain the material of choice for gas turbine blades in the energy industry. These blades are required to withstand both fatigue and creep at extreme temperatures during their usage time. Nickel-base superalloys present an excellent heat resistance at high temperatures. Presence of chromium in the chemical composition makes these alloys highly resistant to corrosion, which is critical for turbine blades. This study presents a flexible approach to combine creep and fatigue damages for a single crystal Nickel-base superalloy. Stress and strain states are used to compute life calculations, which makes this approach applicable for component level. The cumulative damage approach is utilized in this study, where dominant damage modes are capturing primary microstructural mechanism associated with failure. The total damage is divided into two distinctive modules: fatigue and creep. Flexibility is imparted to the model through its ability to emphasize the dominant damage mechanism which may vary among alloys. Fatigue module is governed by a modified version of Coffin-Manson and Basquin model, which captures the orientation dependence of the candidate material. Additionally, Robinson’s creep rupture model is applied to predict creep damage in this study. A novel crystal visco-plasticity (CVP) model is used to simulate deformation of the alloy under several different types of loading. This model has capability to illustrate the temperature-, rate-, orientation-, and history-dependence of the material. A user defined material (usermat) is created to be used in ANSYS APDL 19.0, where the CVP model is applied by User Programmable Feature (UPF). This deformation model is constructed of a flow rule and internal state variables, where the kinematic hardening phenomena is captured by back stress. Octahedral, cubic and cross slip systems are included to perform simulations in different orientations. An implicit integration process that uses Newton-Raphson iteration scheme is utilized to calculate the desired solutions. Several tensile, low-cycle fatigue (LCF) and creep experiments were conducted to inform modeling parameters for the life prediction and the CVP models.

scholarly journals Low Cycle Fatigue Life Prediction Model of 800H Alloy Based on the Total Strain Energy Density Method

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 76 ◽  
Author(s):  
Wei Zhang ◽  
Tao Jiang ◽  
Liqiang Liu
Keyword(s):  
Prediction Model ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Total Strain Energy ◽  
Total Strain Energy Density ◽  
Life Prediction Model

In this paper, a high-temperature low-cycle fatigue life prediction model, based on the total strain energy density method, was established. Considering the influence of the Masing and non-Masing behavior of materials on life prediction, a new life prediction model was obtained by modifying the existing prediction model. With an 800H alloy of the heat transfer tube of a steam generator as the research object, the high-temperature and low-cycle fatigue test was carried out at two temperatures. The results show that the predicted and experimental results are in good agreement, proving the validity of the life prediction model.

A Life Prediction Model for Nickel-Base Single Crystal Superalloy DD3

2004 ◽  
Vol 261-263 ◽  
pp. 1123-1128 ◽  
Author(s):  
T. Li ◽  
Zhu Feng Yue
Keyword(s):  
Prediction Model ◽  
Single Crystal ◽  
Thermal Fatigue ◽  
Life Prediction ◽  
Hold Time ◽  
Turbine Blades ◽  
Single Crystal Superalloy ◽  
Main Factors ◽  
Nickel Base ◽  
Life Prediction Model

The possibility of the life prediction model for nickel-base single crystal blades has been studied. The fatigue-creep (FC) and thermal fatigue-creep (TMFC) as well as creep experiments have been carried out with different hold time of DD3. The hold time and the frequency as well as the temperature range are the main factors influencing on the life. An emphasis has been put on the micro mechanism of the rupture of creep, FC and TMFC. Two main factors are the voiding and degeneration of the material for the creep, FC and TMFC experiments. There are voids in the fracture surfaces, and size of the voids is dependent on the loading condition. Generally, the rupture mechanism is the same for creep, FC and TMFC. If the loading can be simplified to the working conditions of the turbine blades, i.e. the hold time is at the top temperature and maximum stress, a linear life model is satisfactory to the life prediction of nickel-base single crystal superalloy from the experimental study in this paper. The temperature and the stress level of the nickel-base single crystal (SC)blades are not uniform. To predict the life of SC blades, one should consider the cycles of the temperature and stress as well as the oxidation simultaneously. In the past 30 years, there are many works on the mechanical behavior and description, such as the inelastic constitutive relationships, plastic, fracture, isothermal creep and fatigue and thermal fatigue as well as oxidation[1-3]. There are also special software (program) to analyze the deformation and life of nickel-base single crystal structures, such as blades. In order to apply to the engineering more conveniently, there should be a life prediction model for the blades. The model should not be too complex, but take more influential factors as possible into consideration.

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