scholarly journals Computational Methods for Lifetime Prediction of Metallic Components under High-Temperature Fatigue

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 390 ◽  
Author(s):  
Vitaliy Kindrachuk ◽  
Bernard Fedelich ◽  
Birgit Rehmer ◽  
Frauke Peter
Keyword(s):  
Life Prediction ◽  
Time Integration ◽  
Fatigue Loading ◽  
Parametric Models ◽  
Computational Techniques ◽  
Loading History ◽  
Integration Technique ◽  
Element Simulation ◽  
Austenitic Cast Iron ◽  
Viscoplastic Solid

The issue of service life prediction of hot metallic components subjected to cyclic loadings is addressed. Two classes of lifetime models are considered, namely, the incremental lifetime rules and the parametric models governed by the fracture mechanics concept. Examples of application to an austenitic cast iron are presented. In addition, computational techniques to accelerate the time integration of the incremental models throughout the fatigue loading history are discussed. They efficiently solve problems where a stabilized response of a component is not observed, for example due to the plastic strain which is no longer completely reversed and accumulates throughout the fatigue history. The performance of such an accelerated integration technique is demonstrated for a finite element simulation of a viscoplastic solid under repeating loading–unloading cycles.

scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

Direct Sensitivity Analysis of Multibody Systems: A Vehicle Dynamics Benchmark

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Alfonso Callejo ◽  
Daniel Dopico
Keyword(s):  
Sensitivity Analysis ◽  
Multibody Systems ◽  
Automatic Differentiation ◽  
Time Integration ◽  
General Purpose ◽  
Contact Forces ◽  
Design Parameters ◽  
Computational Techniques ◽  
Computationally Efficient ◽  
Integration Algorithm

Algorithms for the sensitivity analysis of multibody systems are quickly maturing as computational and software resources grow. Indeed, the area has made substantial progress since the first academic methods and examples were developed. Today, sensitivity analysis tools aimed at gradient-based design optimization are required to be as computationally efficient and scalable as possible. This paper presents extensive verification of one of the most popular sensitivity analysis techniques, namely the direct differentiation method (DDM). Usage of such method is recommended when the number of design parameters relative to the number of outputs is small and when the time integration algorithm is sensitive to accumulation errors. Verification is hereby accomplished through two radically different computational techniques, namely manual differentiation and automatic differentiation, which are used to compute the necessary partial derivatives. Experiments are conducted on an 18-degree-of-freedom, 366-dependent-coordinate bus model with realistic geometry and tire contact forces, which constitutes an unusually large system within general-purpose sensitivity analysis of multibody systems. The results are in good agreement; the manual technique provides shorter runtimes, whereas the automatic differentiation technique is easier to implement. The presented results highlight the potential of manual and automatic differentiation approaches within general-purpose simulation packages, and the importance of formulation benchmarking.

scholarly journals Life Prediction Method Under Creep-Fatigue Loading for Gas Turbine Combustion Transition Piece of Ni-Based Superalloy N263

1997 ◽  
Author(s):  
J. Kusumoto ◽  
H. Watanabe ◽  
A. Kanaya ◽  
K. Ichikawa ◽  
S. Sakurai
Keyword(s):  
Crack Length ◽  
Surface Crack ◽  
Life Prediction ◽  
Prediction Method ◽  
Fatigue Loading ◽  
Maximum Surface ◽  
Creep Fatigue ◽  
Loading Tests ◽  
Transition Piece ◽  
Life Fraction

In order to develop the life prediction method under creep-fatigue loading for gas turbine combustion transition piece, creep-fatigue tests were carried out on both as-received and aged Ni-based superalloy Nimonic 263. Crack initiation and propagation behaviors for the smooth specimen were observed. An unique relationship was obtained between life fraction and the maximum surface crack length under triangular wave shape loading tests, except the results for the trapezoidal wave loading tests. The latter results were due to the over estimation of the surface crack length at the crack initiation. These were caused from an oxide film break during straining. In the case of removing the oxide film before the measurement of surface crack, the relationship between life fraction and the maximum surface crack length obtained as unique relationship regardless of triangular and trapezoidal strain wave shapes. Using the life prediction method proposed, which is based on maximum surface crack length, the damage of combustion transition piece materials in service was evaluated.

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.

The Study on Airborne Equipments Life Prediction Based on the Finite Element Simulation under Comprehensive Stress

2013 ◽  
Vol 365-366 ◽  
pp. 224-228
Author(s):  
Tian Ma ◽  
Chuan Ri Li ◽  
Shuang Long Rong
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Life Prediction ◽  
Single Point ◽  
Simulation Method ◽  
Distribution Fitting ◽  
Kinetic Experiment ◽  
Element Simulation ◽  
Vibration Stress ◽  
Equipment Lifetime

To predict an airborne equipment lifetime with finite element simulation method, use ANSYS and Flothem, respectively, to analysis vibration stress and temperature stress, corrected by kinetic experiment; then import the results into the failure prediction software-CALCE PWA, set the intensity and duration of stress according to its mission profile, finally get the component failure life prediction results under comprehensive temperature and vibration stress; extract the Monte-Carlo simulation data, use the single point of failure distribution fitting, fault clustering and multipoint distribution fusion method to get the board and the whole machines lifetime and reliability prediction. The design refinement suggestion of the airborne equipment is given at the end of the conclusion.

Fatigue Loading and Life Prediction in Three Fretting Fatigue Fixtures

2008 ◽  
Vol 48 (3) ◽  
pp. 253-263 ◽  
Author(s):  
P. J. Golden ◽  
A. L. Hutson ◽  
B. B. Bartha ◽  
T. Nicholas
Keyword(s):  
Life Prediction ◽  
Fatigue Loading ◽  
Fretting Fatigue

NUMERICAL PREDICTION OF STIFFNESS DEGRADATION OF THIN-PLY CFRP LAMINATES UNDER FATIGUE LOADING

2021 ◽  
Author(s):  
RYOMA AOKI ◽  
RYO HIGUCHI ◽  
TOMOHIRO YOKOZEKI
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Crack Density ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Stiffness Degradation ◽  
Cfrp Laminates ◽  
Mechanics Model ◽  
Element Simulation ◽  
Proposed Model

This study aims to conduct a fatigue simulation for predicting the stiffness degradation of thin-ply composite laminates with several ply thicknesses. For the simulation, a fatigue evolution model of intra-laminar damage in thin-ply composite laminates considering the effect of ply thickness was proposed. The intra-laminar damage evolution was modeled using the continuum damage mechanics model and the static and fatigue evolution law were formulated by relating the transverse crack density to the damage variable. The finite element simulation using the proposed model was conducted to predict the stiffness degradation of the laminates as a function of the number of loading cycles. The simulation results show that the experimental data can be reproduced by using the proposed fatigue model.

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