scholarly journals Status report on improved understanding of creep-fatigue damage in advanced materials.

2012 ◽  
Author(s):  
M. Li ◽  
S. Majumdar ◽  
W.K. Soppet ◽  
D. Rink ◽  
K. Natesan
Keyword(s):  
Fatigue Damage ◽  
Advanced Materials ◽  
Status Report ◽  
Creep Fatigue

Creep-fatigue interaction on estimation of lifetime and fatigue damage of F82H

2021 ◽  
Vol 173 ◽  
pp. 112830
Author(s):  
Wenhai Guan ◽  
Hyoseong Gwon ◽  
Takanori Hirose ◽  
Hisashi Tanigawa ◽  
Yoshinori Kawamura ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Creep Fatigue

Management of Complex Loading Histories for Use in Probabilistic Creep-Fatigue Damage Assessments

2018 ◽  
Author(s):  
N. A. Zentuti ◽  
J. D. Booker ◽  
R. A. W. Bradford ◽  
C. E. Truman
Keyword(s):  
Fatigue Damage ◽  
Input Parameter ◽  
Three Dimensional ◽  
Complex Loading ◽  
Fe Model ◽  
Plant Component ◽  
Fatigue Lifetime ◽  
Wide Range ◽  
Stress Components ◽  
Creep Fatigue

An approach is outlined for the treatment of stresses in complex three-dimensional components for the purpose of conducting probabilistic creep-fatigue lifetime assessments. For conventional deterministic assessments, the stress state in a plant component is found using thermal and mechanical (elastic) finite element (FE) models. Key inputs are typically steam temperatures and pressures, with the three principal stress components (PSCs) at the assessment location(s) being the outputs. This paper presents an approach which was developed based on application experience with a tube-plate ligament (TPL) component, for which historical data was available. Though both transient as well as steady-state conditions can have large contributions towards the creep-fatigue damage, this work is mainly concerned with the latter. In a probabilistic assessment, the aim of this approach is to replace time intensive FE runs with a predictive model to approximate stresses at various assessment locations. This is achieved by firstly modelling a wide range of typical loading conditions using FE models to obtain the desire stresses. Based on the results from these FE runs, a probability map is produced and input(s)-output(s) functions are fitted (either using a Response Surface Method or Linear Regression). These models are thereafter used to predict stresses as functions of the input parameter(s) directly. This mitigates running an FE model for every probabilistic trial (of which there typically may be more than 104), an approach which would be computationally prohibitive.

A Direct Method on the Evaluation of Cyclic Steady State of Structures With Creep Effect

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Fatigue Damage ◽  
Mechanical Load ◽  
Direct Method ◽  
Load Condition ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Cyclic Behavior ◽  
Direct Evaluation ◽  
Plastic Strain Range ◽  
Creep Fatigue

This paper describes a new extension of the linear matching method (LMM) for the direct evaluation of cyclic behavior with creep effects of structures subjected to a general load condition in the steady cyclic state, with the new implementation of the cyclic hardening model and time hardening creep constitutive model. A benchmark example of a Bree cylinder and a more complicated three-dimensional (3D) plate with a center hole subjected to cyclic thermal load and constant mechanical load are analyzed to verify the applicability of the new LMM to deal with the creep fatigue damage. For both examples, the stabilized cyclic responses for different loading conditions and dwell time periods are obtained and validated. The effects of creep behavior on the cyclic responses are investigated. The new LMM procedure provides a general purpose technique, which is able to generate both the closed and nonclosed hysteresis loops depending upon the applied load condition, providing details of creep strain and plastic strain range for creep and fatigue damage assessments with creep fatigue interaction.

Estimation of Creep-Fatigue Damage Through Indentation Test Method

2011 ◽  
Author(s):  
Raghu V. Prakash
Keyword(s):  
Tensile Properties ◽  
Fatigue Damage ◽  
Indentation Test ◽  
Creep Damage ◽  
Test Method ◽  
Specimen Preparation ◽  
Creep Fatigue ◽  
Critical Components ◽  
The Cost

Creep, creep-fatigue damage is often estimated through in-situ metallography, tensile testing of specimens. However, these methods require specimen preparation which includes specimen extraction from critical components. Automated ball indentation testing has been used as an effective tool to determine the mechanical properties of metallic materials. In this work, the tensile properties of materials subjected to controlled levels of damage in creep, creep-fatigue is studied. It is found that the tensile properties such as yield strength and UTS deteriorates with creep damage, whereas the same specimens show an improved UTS values (at the cost of ductility) when subjected to creep-fatigue interactions.

Creep-Fatigue Damage and Crack Initiation for a Mod 9Cr-1Mo Structure With Weldments

2007 ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Se-Hwan Lee ◽  
Jong-Bum Kim ◽  
Jae-Han Lee
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Damage ◽  
Hold Time ◽  
Fatigue Crack Initiation ◽  
Creep Damage ◽  
Steel Specimen ◽  
Structural Test ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

A structural test and evaluation on creep-fatigue damage, and creep-fatigue crack initiation have been carried out for a Mod. 9Cr-1Mo steel structural specimen with weldments. The conservatisms of the design codes of ASME Section III subsection and NH and RCC-MR codes were quantified at the welded joints of Mod.9Cr-1Mo steel and 316L stainless steel with the observed images from the structural test. In creep damage evaluation using the RCC-MR code, isochronous curve has been used rather than directly using the creep law as the RCC-MR specifies. A y-shaped steel specimen of a diameter 500mm, height 440mm and thickness 6.35mm is subjected to creep-fatigue loads with two hours of a hold time at 600°C and a primary nominal stress of 30MPa. The defect assessment procedures of RCC-MR A16 guide do not provide a procedure for Mod.9Cr-1Mo steel yet. In this study application of σd method for the assessment of creep-fatigue crack initiation has been examined for a Mod. 9Cr-1Mo steel structure.

Analysis of Multi-Axial Creep–Fatigue Damage on an Outer Cylinder of a 1000 MW Supercritical Steam Turbine

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Weizhe Wang
Keyword(s):  
Steam Turbine ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Hydrostatic Stress ◽  
Fatigue Behavior ◽  
Axial Stress ◽  
Outer Cylinder ◽  
Continuum Damage Mechanics ◽  
Transfer Coefficients ◽  
Creep Fatigue

A multi-axial continuum damage mechanics (CDM) model was proposed to calculate the multi-axial creep–fatigue damage of a high temperature component. A specific outer cylinder of a 1000 MW supercritical steam turbine was used in this study, and the interaction of the creep and fatigue behavior of the outer cylinder was numerically investigated under a startup–running–shutdown process. To this end, the multi-axial stress–strain behavior of the outer cylinder was numerically studied using Abaqus. The in-site measured temperatures were provided to validate the heat transfer coefficients, which were used to calculate the temperature field of the outer cylinder. The multi-axial mechanics behavior of the outer cylinder was investigated in detail, with regard to the temperature, Mises stress, hydrostatic stress, multi-axial toughness factor, multi-axial creep strain, and damage. The results demonstrated that multi-axial mechanics behavior reduced the total damage.

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