Advancement of Experimental Methods and Cailletaud Material Model for Life Prediction of Gas Turbine Blades Exposed to Combined Cycle Fatigue

2012 ◽  
Author(s):  
Marcus Thiele ◽  
Swen Weser ◽  
Uwe Gampe ◽  
Roland Parchem ◽  
Samuel Forest
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Life Prediction ◽  
Kinematic Hardening ◽  
Turbine Blades ◽  
Material Model ◽  
Combined Cycle ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Gas Turbine Blades

The European project PREMECCY has been conducted to enhance predictive methods for combined cycle fatigue (CCF) of gas turbine blades, i.e. interaction of low cycle fatigue (LCF) and high cycle fatigue (HCF). While design of CCF feature tests, comprising specimen and test rig design, has already been reported, this paper presents experimental HCF/ CCF test results and progress in life prediction. Besides standard lab specimen tests for characterization of single crystal and conventional cast material, also advanced specimens representing critical rotor blade features were tested in a hot gas rig. Based on these experimental data an extended Cailletaud material model for stress-strain analysis has been calibrated and combined with a modified ONERA damage model for creep-fatigue interaction to estimate the lifetime of the advanced test specimens. The model extensions address the effect of ratcheting, which is typical for CMSX-4 at asymmetric cyclic loading at elevated temperature. Caused by limitations of the Armstrong-Frederick kinematic hardening rule regarding ratcheting, three models for improved ratcheting simulation of isotropic material were adopted to anisotropic material. In addition multiple Norton-flow rules for the viscous part of the model are combined with time recovery terms in the kinematic hardening evolution to represent the behaviour of single crystal material in high temperature environment at a wide range of strain rates. Hence, an improved model for stress-strain and lifetime prediction for single crystals has been developed.

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.

Probability-based service safety life prediction approach of raw and treated turbine blades regarding combined cycle fatigue

2021 ◽  
Vol 110 ◽  
pp. 106513
Author(s):  
Lei Han ◽  
Cao Chen ◽  
Tongyue Guo ◽  
Cheng Lu ◽  
Chengwei Fei ◽  
...  
Keyword(s):  
Life Prediction ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Cycle Fatigue ◽  
Prediction Approach

Innovative Casting Methods for Single Crystal Turbine Blades

2021 ◽  
Vol 1032 ◽  
pp. 178-185
Author(s):  
Wan Qiu Ding
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Operation System ◽  
Gas Turbine Blades ◽  
Bridgman Process

This report outlines a succinct analysis of the contemporary casting methods in single-crystal turbine blades. Furthermore, this paper also provides an examination of the solidification procedure in mixed turbine blades. The couple cooling and heating operation system was advanced to obtain identical thermal positions for single crystal (SC) solidification in the blade group, thereby significantly diminishing the associated flaws in the contemporary Bridgman process. The chemistry science of Nickel based alloys planed for single crystal (SC) gas turbine blades has been notably improved upon, especially when considering the initial production of alloys. The second and third production within the total operation has been enhanced by the introduction of rhenium (Re). Surged density, grain flaws, and microstructural stableness have presented themselves as significant issues within this process. Additionally, it is imperative to minimize the concentrations of the different alloying components.

scholarly journals Single crystal casting of gas turbine blades using superior ceramic core

2020 ◽  
Vol 9 (3) ◽  
pp. 3348-3356
Author(s):  
Eun-Hee Kim ◽  
Hye Yeong Park ◽  
Cho-long Lee ◽  
Jong Bum Park ◽  
SeungCheol Yang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Ceramic Core ◽  
Gas Turbine Blades

scholarly journals Stress-strain response in gears tooth root due to low cycle fatigue

2019 ◽  
Vol 287 ◽  
pp. 02002
Author(s):  
Marina Franulovic ◽  
Kristina Markovic ◽  
Zdravko Herceg
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Material Model ◽  
Strain Response ◽  
Tooth Root ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Main Research ◽  
Damage Initiation

Gears are mechanical components which experience high dynamic loading during their exploitation period. Therefore, their load carrying capacity together with life expectancy are often the main research interest in various studies. The research presented in this paper is focused on the materials response in spur gears tooth root, with the attention given to the repeated overloads during gears operation. In order to simulate low cycle fatigue by using numerical modeling of stress - strain relationship within material, the material model which takes into account isotropic and kinematic hardening is used here. Material response of specimens produced out of steel 42CrMo4 in different loading conditions is used for the calibration of material model, which is then applied to simulate damage initiation and materials stress - strain response in gears tooth root. The results show that materials response to the given loading conditions non-linearly change through the loading cycles.

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