Crack initiation under thermal fatigue: An overview of CEA experiencePart II (of II): Application of various criteria to biaxial thermal fatigue tests and a first proposal to improve the estimation of the thermal fatigue damage

The primary purpose of this paper is to demonstrate the applicability of the three-stage Weibull equation to describe the fatigue damage process using flexural controlled deformation fatigue tests. A data set of 179 beam fatigue tests originally designed for exploring the fatigue performance of conventional dense graded asphalt concrete (DGAC) and asphalt–rubber hot-mix gap-graded (ARHM-GG) mixes was used to inspect the three-stage Weibull parameters that were estimated using a genetic algorithm. The tree-based regression–category models were then used to uncover the data structure of the estimated parameters as a function of material properties, conditioning methods, temperatures, compaction methods, and strain levels. In general, the three-stage Weibull equation provides satisfactory fitting results for the three-stage fatigue damage process occurring in a beam test. It was found that the tree-based models of three-stage Weibull parameters associated with the crack initiation stage were statistically adequate and reliable compared with the models of parameters related to the warm-up stage and the crack propagation stage. It might suggest that these crack initiation parameters are better indexes to assess the fatigue performance.

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Spectra Thermal Fatigue Tests Under Frequency Controlled Fluid Temperature Variation: Superposed Sinusoidal Temperature Fluctuation Tests

Volume 3: Design and Analysis ◽

10.1115/pvp2008-61225 ◽

2008 ◽

Cited By ~ 2

Author(s):

Nobuchika Kawasaki ◽

Hideki Takasho ◽

Sumio Kobayashi ◽

Shinichi Hasebe ◽

Naoto Kasahara

Keyword(s):

Fatigue Strength ◽

Crack Initiation ◽

Thermal Fatigue ◽

Test Piece ◽

Fatigue Tests ◽

Fluid Temperature ◽

Test Pieces ◽

Temperature Waves ◽

Temperature Ranges ◽

Sinusoidal Temperature

To clarify frequency-dependent attenuation effects of fluid temperature fluctuation on fatigue strength, thermal fatigue strength tests subjected to superposed sinusoidal temperature fluctuations were performed by the SPECTRA test facility. Fluid temperature waves were generated by superposition of sinusoidal waves, where frequencies were 0.05, 0.2, and 0.5Hz. Two types of superposed waves were selected for the tests, dual and triple ones. The dual one was obtained by superposing two sinusoidal waves whose temperature ranges and frequencies are respectively 200 centigrade and 0.05Hz and 60 centigrade and 0.5Hz at the inlet of test piece. The triple one was the superposition of three sinusoidal waves whose temperature ranges and frequencies are respectively, 150 centigrade and 0.2Hz, 75 centigrade and 0.05Hz and 50 centigrade and 0.5Hz at the inlet of test piece. The longest periods were 20 seconds for both types of waves and it is the fundamental cycle for the thermal fatigue tests. For the dual case, 73,810 cycles fatigue test was performed while for the triple one 116,640 cycles were performed. After these fatigue tests, cylindrical test pieces were cut away from the test loop, and cracks were observed on the inner surface of the test pieces. For the dual wave case, crack initiation occurred from 400 to 600mm position from the inlet of test piece. For the triple wave case, crack initiation occurred from 400 to 600mm position from the inlet of test piece. The corresponded fluid temperature range to crack initiation is from 205 to 220 centigrade for the dual one and from 195 to 215 centigrade for the triple one. Fatigue lives at crack initiation positions were evaluated based on the test conditions. Adopting power spectrum density functions and frequency transfer functions, fatigue lives were predicted within a factor 3 as predicted for single sinusoidal temperature waves in the other tests. To confirm advantages of these functions, fatigue life estimations were compared with those obtained without using these functions. Based on the compared results, these functions are necessary to predict accurate fatigue lives.

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Metallographic Study of Laser Thermal Fatigue Damage on Piston

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.2053 ◽

2011 ◽

Vol 415-417 ◽

pp. 2053-2061

Author(s):

Zhen Tao Liu ◽

Ming Pang ◽

Jian Song Tan ◽

Xiu Bo Liu

Keyword(s):

Fatigue Damage ◽

Thermal Fatigue ◽

Energy Dispersive Spectrometer ◽

Intermetallic Phase ◽

Fatigue Tests ◽

Power Laser ◽

Nonequilibrium Distribution ◽

Metallographic Study ◽

Thermal Fatigue Crack ◽

Cooling Method

The experiments of thermal fatigue damage on piston were conducted by shaped high power laser. Microstructure of thermal fatigue damaged specimen was characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The mechanical properties of thermal fatigue specimen were evaluated by microhardness and the corresponding damaged mechanisms were discussed. The results show that cracks originated from the interface of Al-matrix and intermetallic phase due to the thermal and mechanical mismatch between the brittle components of the microstructure and the surrounding ductile matrix. Oxides of thermal fatigue crack can accelerate the damage of piston. There exists a decline tendency in the microhardness of piston at all locations after thermal fatigue tests due to the comprehensive effects of nonequilibrium distribution of temperature and cooling method.

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Comparison of Fatigue Damage Criteria Applied to Multiaxial Fatigue

Volume 3: Design and Analysis ◽

10.1115/pvp2008-61735 ◽

2008 ◽

Author(s):

F. Curtit ◽

A. Le Pecheur ◽

J. M. Stephan

Keyword(s):

Fatigue Damage ◽

Thermal Fatigue ◽

Nuclear Power ◽

High Cycle Fatigue ◽

Fatigue Loading ◽

Fatigue Tests ◽

Multiaxial Fatigue ◽

304 Stainless Steel ◽

Cycle Fatigue ◽

Damage Criteria

The mixing tees of PWR nuclear power plant are submitted to complex cyclic thermal loadings that could lead to significant fatigue damage as observed on the RHR mixing area of Civaux 1 PWR in 1998. The characteristics of associated mechanical loading have been investigated by both experimental and numerical studies. A constant loading due to mean temperature and pressure is combined with equi-biaxial variable amplitude loading in the field of high cycle fatigue. This paper compares several fatigue damage criteria applied to both low and high cycle fatigue tests on 304 stainless steel specimens under several loading conditions according to mixing zone thermal fatigue loading amplitude. In order to focus the comparison on intrinsic qualities of the models, each criterion is evaluated directly with stress and strain measured on the specimen. The relevance of each criterion for high cycle thermal fatigue is discussed taking into considerations the precision of the results, and also the “usage cost” (including identification and complexity) and the adaptability to cumulative damage rules.

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Effect of Maximum Temperature on the Thermal Fatigue Behavior of Superalloy GH536

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.28 ◽

2016 ◽

Vol 853 ◽

pp. 28-32 ◽

Cited By ~ 1

Author(s):

Jing Chen ◽

Duo Qi Shi ◽

Guo Lei Miao ◽

Xiao Guang Yang

Keyword(s):

Crack Initiation ◽

Fatigue Test ◽

Thermal Fatigue ◽

Fatigue Behavior ◽

Fatigue Cracks ◽

Fatigue Crack Initiation ◽

Fatigue Tests ◽

Maximum Temperature ◽

Thermal Fatigue Crack ◽

Thermal Fatigue Test

Thermal fatigue tests of superalloy GH536 were carried out at different maximum temperature. Three-dimensional numerical finite element computations were performed to simulate thermal fatigue test process. The crack initiation, propagation and thermal fatigue failure mechanism of GH536 plate at different maximum temperatures were obtained by experiments and numerical methods. Result shows that the crack initiation life is shortened and the crack growth rate is accelerated with the increase of the maximum temperature of thermal fatigue test. The numbers of appearing 1 mm length cracks are 180, 74 and 37, respectively, when the maximum temperature is 800°C, 850°C and 900°C respectively. So the thermal fatigue performance decreases with the increase of the maximum temperature. But in the thermal fatigue tests of different maximum temperature, the thermal fatigue crack initiation is all caused by a single crack initiation source, and the thermal fatigue cracks initiate transgranularly, develop and propagate intergranularly.

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3D Characterization of Thermal Fatigue Damage in Monofilament Reinforced Copper for Heat Sink Applications in Fusion Reactor Systems

Practical Metallography ◽

10.3139/147.110139 ◽

2012 ◽

Vol 49 (5) ◽

pp. 278-289

Author(s):

M. Schöbel ◽

H.P. Degischer ◽

A. Brendel ◽

B. Harrer ◽

M. Di Michiel

Keyword(s):

Fatigue Damage ◽

Thermal Fatigue ◽

Heat Sink ◽

Fusion Reactor

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Induction of preset thermally stressed states in thermal fatigue tests: Choice of testing conditions and geometry of specimens

Strength of Materials ◽

10.1007/bf02767822 ◽

1997 ◽

Vol 29 (4) ◽

pp. 369-379

Author(s):

G. N. Tretyachenko ◽

B. S. Karpinos ◽

V. G. Barilo ◽

N. G. Solovyeva

Keyword(s):

Thermal Fatigue ◽

Fatigue Tests ◽

Testing Conditions ◽

Thermally Stressed

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Plastic Slip and Early Stage of Fatigue Damage in Polycrystals: Comparison between Experiments and Crystal Plasticity Finite Elements Simulations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.1711 ◽

2014 ◽

Vol 891-892 ◽

pp. 1711-1716 ◽

Cited By ~ 1

Author(s):

Loic Signor ◽

Emmanuel Lacoste ◽

Patrick Villechaise ◽

Thomas Ghidossi ◽

Stephan Courtin

Keyword(s):

Fatigue Crack ◽

Finite Elements ◽

Crack Initiation ◽

Fatigue Damage ◽

Crystal Plasticity ◽

Early Stage ◽

Low Cycle Fatigue ◽

Fatigue Cracks ◽

Fatigue Crack Initiation ◽

Plastic Slip

For conventional materials with solid solution, fatigue damage is often related to microplasticity and is largely sensitive to microstructure at different scales concerning dislocations, grains and textures. The present study focuses on slip bands activity and fatigue crack initiation with special attention on the influence of the size, the morphology and the crystal orientation of grains and their neighbours. The local configurations which favour - or prevent - crack initiation are not completely identified. In this work, the identification and the analysis of several crack initiation sites are performed using Scanning Electron Microscopy and Electron Back-Scattered Diffraction. Crystal plasticity finite elements simulation is employed to evaluate local microplasticity at the scale of the grains. One of the originality of this work is the creation of 3D meshes of polycrystalline aggregates corresponding to zones where fatigue cracks have been observed. 3D data obtained by serial-sectioning are used to reconstruct actual microstructure. The role of the plastic slip activity as a driving force for fatigue crack initiation is discussed according to the comparison between experimental observations and simulations. The approach is applied to 316L type austenitic stainless steels under low-cycle fatigue loading.

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Fatigue Damage of Al/SiC Composites - Macroscopic and Microscopic Analysis

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0016 ◽

2015 ◽

Vol 60 (1) ◽

pp. 101-105 ◽

Cited By ~ 2

Author(s):

A. Rutecka ◽

Z.L. Kowalewski ◽

K. Makowska ◽

K. Pietrzak ◽

L. Dietrich

Keyword(s):

Fatigue Damage ◽

Microscopic Analysis ◽

Inelastic Strain ◽

Damage Parameter ◽

Fatigue Tests ◽

Cyclic Plasticity ◽

Damage Mechanisms ◽

Before And After ◽

Fatigue Damage Parameter ◽

Sic Composites

Abstract The results of comparative examinations of mechanical behaviour during fatigue loads and microstructure assessment before and after fatigue tests were presented. Composites of aluminium matrix and SiC reinforcement manufactured using the KoBo method were investigated. The combinations of two kinds of fatigue damage mechanisms were observed. The first one governed by cyclic plasticity and related to inelastic strain amplitude changes and the second one expressed in a form of ratcheting based on changes in mean inelastic strain. The higher SiC content the less influence of the fatigue damage mechanisms on material behaviour was observed. Attempts have been made to evaluate an appropriate fatigue damage parameter. However, it still needs further improvements.

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Modeling of Fatigue Crack Propagation

Journal of Engineering Materials and Technology ◽

10.1115/1.1631026 ◽

2004 ◽

Vol 126 (1) ◽

pp. 77-86 ◽

Cited By ~ 53

Author(s):

Yanyao Jiang ◽

Miaolin Feng

Keyword(s):

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Initiation ◽

Crack Propagation ◽

Crack Growth ◽

Fatigue Damage ◽

Fatigue Crack Propagation ◽

Fatigue Crack Initiation ◽

Cyclic Plasticity ◽

R Ratio

Fatigue crack propagation was modeled by using the cyclic plasticity material properties and fatigue constants for crack initiation. The cyclic elastic-plastic stress-strain field near the crack tip was analyzed using the finite element method with the implementation of a robust cyclic plasticity theory. An incremental multiaxial fatigue criterion was employed to determine the fatigue damage. A straightforward method was developed to determine the fatigue crack growth rate. Crack propagation behavior of a material was obtained without any additional assumptions or fitting. Benchmark Mode I fatigue crack growth experiments were conducted using 1070 steel at room temperature. The approach developed was able to quantitatively capture all the important fatigue crack propagation behaviors including the overload and the R-ratio effects on crack propagation and threshold. The models provide a new perspective for the R-ratio effects. The results support the notion that the fatigue crack initiation and propagation behaviors are governed by the same fatigue damage mechanisms. Crack growth can be treated as a process of continuous crack nucleation.

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