Fatigue Life Modeling and Experimental Validation of Additively Manufactured Turbine Blade with Respect to Defect Size and Location

2022 ◽  
Author(s):  
Daniel Miller ◽  
Ryan Kemnitz ◽  
Ramana V. Grandhi ◽  
Luke C. Sheridan
Keyword(s):  
Fatigue Life ◽  
Turbine Blade ◽  
Experimental Validation ◽  
Defect Size

Life Prediction Method of CC and DS Ni Base Superalloys Under High Temperature Biaxial Fatigue Loading

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Takashi Ogata
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Life Prediction ◽  
Compressive Strain ◽  
Prediction Method ◽  
Strain Range ◽  
Fatigue Loading ◽  
Normal Strain ◽  
Biaxial Fatigue

Polycrystalline conventional casting (CC) and directionally solidified (DS) Ni base superalloys are widely used as gas turbine blade materials. It was reported that the surface of a gas turbine blade is subjected to a biaxial tensile-compressive fatigue loading during a start-stop operation, based on finite element stress analysis results. It is necessary to establish the life prediction method of these superalloys under biaxial fatigue loading for reliable operations. In this study, the in-plane biaxial fatigue tests with different phases of x and y directional strain cycles were conducted on both CC and DS Ni base superalloys (IN738LC and GTD111DS) at high temperatures. The strain ratio ϕ was defined as the ratio between the x and y directional strains at 1/4 cycle and was varied from 1 to −1. In ϕ=1 and −1. The main cracks propagated in both the x and y directions in the CC superalloy. On the other hand, the main cracks of the DS superalloy propagated only in the x direction, indicating that the failure resistance in the solidified direction is weaker than that in the direction normal to the solidified direction. Although the biaxial fatigue life of the CC superalloy was correlated with the conventional Mises equivalent strain range, that of the DS superalloy depended on ϕ. The new biaxial fatigue life criterion, equivalent normal strain range for the DS superalloy was derived from the iso-fatigue life curve on a principal strain plane defined in this study. Fatigue life of the DS superalloy was correlated with the equivalent normal strain range. Fatigue life of the DS superalloy under equibiaxial fatigue loading was significantly reduced by introducing compressive strain hold dwell. Life prediction under equibiaxial fatigue loading with the compressive strain hold was successfully made by the nonlinear damage accumulation model. This suggests that the proposed method can be applied to life prediction of the gas turbine DS blades, which are subjected to biaxial fatigue loading during operation.

Improving turbine blade fatigue life

1988 ◽  
Author(s):  
H. BUDDENBOHM
Keyword(s):  
Fatigue Life ◽  
Turbine Blade

Novel and Applicable Method to Determine Equivalent Strain Range and Equivalent Strain Direction Under Multiaxial Non-Proportional Loading

2019 ◽  
Author(s):  
Charles R. Krouse ◽  
Grant O. Musgrove ◽  
Taewoan Kim ◽  
Seungmin Lee ◽  
Muhyoung Lee
Keyword(s):  
Fatigue Life ◽  
Turbine Blade ◽  
Low Cycle Fatigue ◽  
Dimensional Space ◽  
Strain Range ◽  
Element Model ◽  
Equivalent Strain ◽  
Loading Conditions ◽  
Proportional Loading ◽  
Strain Direction

Abstract When considering mechanical components that are subjected to complex loading conditions, it is difficult to achieve accurate predictions of low-cycle fatigue life. For multiaxial and non-proportional loads, the principal strain directions vary in three-dimensional space with time. The commonly accepted methods to determine fatigue life under such loading conditions are based on a critical plane approach, and they rely heavily on accurate strain range estimates. However, there is no singly accepted method to determine the critical plane, equivalent strain magnitude, or equivalent strain direction. Furthermore, current suggestions are computationally intensive and challenging to implement. This paper offers a novel and concise method to accurately determine equivalent strain range and equivalent strain direction under multiaxial, non-proportional loading in three-dimensional space. A practical approach is provided for implementing the method, and an example of an application using a finite element model of a first stage turbine blade is discussed. To demonstrate the approach, ANSYS Mechanical was used to simulate a turbine blade under transient loading conditions and to determine the resulting strains. Equivalent strain range results were applied to a Coffin-Manson relation to determine the low-cycle fatigue life of every node within the finite element model of the first stage turbine blade. The post-processing of the strain predictions, which yielded the equivalent strain range and equivalent strain direction, is discussed in detail.

A Synthetical Numerical Model for Evaluating the Reliability of Turbine Blade

2002 ◽  
Author(s):  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Fatigue Life ◽  
Numerical Model ◽  
Steam Turbine ◽  
Turbine Blade ◽  
Power Plants ◽  
Dynamic Stress ◽  
Turbine Blades ◽  
Dynamic Stress Analysis ◽  
Steam Turbine Blades ◽  
Blade Failure

Reliability of turbines is very important for power plants, and the most common blade failure normally result from forced vibration which lead to fatigue failure of blades. In this study, a synthetical numerical model has been developed to obtain more precise evaluation of the reliability of blades. At first, the model used to analyze the dynamic stress of steam turbine blades is investigated, base on the results of dynamic stress analysis, a model to evaluate the fatigue life of turbine blade has been developed, many factors such as manufacturing technology of blades and erosion operating environment are considered to get more accurate results for the fatigue life prediction of blades. At last, a 323 mm blade in a 75MW steam turbine is analyzed by the model developed in this paper, it is shown clearly that the model can provide some significant data to evaluate the reliability of blade.

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