scholarly journals On Creep Fatigue Interaction of Components at Elevated Temperature

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen ◽  
Yinghua Liu
Keyword(s):  
High Temperature ◽  
Mechanical Load ◽  
Direct Method ◽  
Bending Moment ◽  
Strain Range ◽  
Cyclic Plasticity ◽  
Element Analysis ◽  
Total Strain Range ◽  
Creep Fatigue ◽  
A Direct Method

The accurate assessment of creep–fatigue interaction is an important issue for industrial components operating with large cyclic thermal and mechanical loads. An extensive review of different aspects of creep fatigue interaction is proposed in this paper. The introduction of a high temperature creep dwell within the loading cycle has relevant impact on the structural behavior. Different mechanisms can occur, including the cyclically enhanced creep, the creep enhanced plasticity and creep ratchetting due to the creep fatigue interaction. A series of crucial parameters for crack initiation assessment can be identified, such as the start of dwell stress, the creep strain, and the total strain range. A comparison between the ASME NH and R5 is proposed, and the principal differences in calculating the aforementioned parameters are outlined. The linear matching method (LMM) framework is also presented and reviewed, as a direct method capable of calculating these parameters and assessing also the steady state cycle response due to creep and cyclic plasticity interaction. Two numerical examples are presented, the first one is a cruciform weldment subjected to cyclic bending moment and uniform high temperature with different dwell times. The second numerical example considers creep fatigue response on a long fiber reinforced metal matrix composite (MMC), which is subjected to a cycling uniform thermal field and a constant transverse mechanical load. All the results demonstrate that the LMM is capable of providing accurate solutions, and also relaxing the conservatisms of the design codes. Furthermore, as a direct method, it is more efficient than standard inelastic incremental finite element analysis.

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.

scholarly journals Probabilistic Life Models for Steel Structures Subject to Creep- Fatigue Damage

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Fatmagul Ibisoglu ◽  
Mohammad Modarres
Keyword(s):  
High Temperature ◽  
Fatigue Damage ◽  
Power Plants ◽  
Strain Range ◽  
Steel Structures ◽  
Software Tool ◽  
Bayesian Regression ◽  
Life Assessment ◽  
Total Strain Range ◽  
Creep Fatigue

When metal structures are subjected to long-term cyclic loading at high temperature, simultaneous creep and fatigue damage may occur. In this paper probabilistic life models, described by hold times in tension and total strain range at elevated temperature have been derived based on the creeprupture behavior of 316FR austenitic stainless steel, which is one of the candidate structural materials for fast reactors and future Generation IV nuclear power plants operating at high temperatures. The parameters of the proposed creepfatigue model were estimated using a standard Bayesian regression approach. This approach has been performed using the WinBUGS software tool, which is an open source Bayesian analysis software tool that uses the Markov Chain Monte Carlo sampling method. The results have shown a reasonable fit between the experimental data and the proposed probabilistic creep-fatigue life assessment models. The models are useful for predicting expended life of the critical structures in advanced high temperature reactors when performing structural health management.

Direct Method on Creep Fatigue Damage Assessment Considering Full Creep-Cyclic Plasticity Interaction

2017 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen ◽  
Weiling Luan
Keyword(s):  
High Temperature ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Direct Method ◽  
Creep Damage ◽  
Load Cycle ◽  
Cyclic Plasticity ◽  
Assessment Procedure ◽  
Creep Fatigue ◽  
The Uk

This paper introduces the latest research and development of the Linear Matching Method (LMM) on the creep fatigue damage assessment of components subjected to high temperature and cyclic load conditions. The method varies from existing rule-based approaches in both the ASME Boiler and Pressure Vessel Code (NH) and the UK R5 high temperature assessment procedure, where the creep behavior/creep damage and cyclic plastic response /fatigue damage are analyzed separately. In support to these the extended Direct Steady Cycle Analysis (eDSCA) has been proposed to provide a more accurate description of the potentially dangerous interaction between creep and cyclic plasticity during the load cycle, and hence is able to accurately address creep enhanced plasticity and cyclically enhanced creep. The applications of the LMM eDSCA method for creep fatigue damage assessment to three practical problems are then outlined to demonstrate that the proposed direct method is capable of predicting an accurate component life due to creep fatigue and creep ratcheting damages by modeling cyclic plasticity and creep interaction using this new simplified direct method, providing a degree of accuracy and convenience in creep fatigue assessment hitherto unavailable and without the restrictions inherent in other methodologies.

A Direct Method on the Evaluation of Cyclic Behaviour With Creep Effect

2012 ◽  
Author(s):  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Plastic Strain ◽  
Creep Strain ◽  
Fatigue Damage ◽  
Mechanical Load ◽  
Direct Method ◽  
Load Condition ◽  
Strain Range ◽  
Plastic Strain Range ◽  
Cyclic Behaviour ◽  
Creep Fatigue

This paper describes a new Linear Matching Method (LMM) technique for the direct evaluation of cyclic behaviour with creep effects of structures subjected to a general load condition in the steady cyclic state. The creep strain and plastic strain range for use in creep damage and fatigue assessments, respectively, are obtained. A benchmark example of a Bree cylinder subjected to cyclic thermal load and constant mechanical load is analysed to verify the applicability of the new LMM to deal with the creep fatigue damage. The cyclic responses for different loading conditions and dwell time periods within the Bree boundary are obtained. To demonstrate the efficiency and effectiveness of the method for more complex structures, a 3D holed plate subjected to cyclic thermal loads and constant axial tension is analysed. The results of both examples show that with the presence of creep the cyclic responses change significantly. The new LMM procedure provides a general purpose technique for the evaluation of cyclic behaviour, the plastic strain range and creep strain for the creep fatigue damage assessment with creep fatigue interaction.

Creep-Fatigue Interaction Effects On Pressure-Reducing Valve Under Cyclic Thermo-Mechanical Loadings Using Direct Cyclic Method

2021 ◽  
Author(s):  
Nak-Kyun Cho ◽  
Youngjae Choi ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Fatigue Failure ◽  
Material Properties ◽  
Structural Integrity ◽  
Direct Method ◽  
Element Model ◽  
Critical Loading ◽  
Creep Fatigue ◽  
Pressure Reducing Valve

Abstract Supercritical boiler system has been widely used to increase efficiency of electricity generation in power plant industries. However, the supercritical operating condition can seriously affect structural integrity of power plant components due to high temperature that causes degradation of material properties. Pressure reducing valve is an important component being employed within a main steam line of the supercritical boiler, which occasionally thermal-fatigue failure being reported. This research has investigated creep-cyclic plastic behaviour of the pressure reducing valve under combined thermo-mechanical loading using a numerical direct method known as extended Direct Steady Cyclic Analysis of the Linear Matching Method Framework (LMM eDSCA). Finite element model of the pressure-reducing valve is created based on a practical valve dimension and temperature-dependent material properties are applied for the numerical analysis. The simulation results demonstrate a critical loading component that attributes creep-fatigue failure of the valve. Parametric studies confirm the effects of magnitude of the critical loading component on creep deformation and total deformation per loading cycle. With these comprehensive numerical results, this research provides engineer with an insight into the failure mechanism of the pressure-reducing valve at high temperature.

scholarly journals Creep Fatigue Life Assessment of a Pipe Intersection with Dissimilar Material Joint by Linear Matching Method

2016 ◽  
Vol 853 ◽  
pp. 366-371
Author(s):  
Daniele Barbera ◽  
Hao Feng Chen ◽  
Ying Hua Liu
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Direct Method ◽  
Life Assessment ◽  
Dissimilar Material ◽  
Matching Method ◽  
Fatigue Life Assessment ◽  
Creep Fatigue ◽  
The Impact ◽  
Linear Matching Method

As the energy demand increases the power industry has to enhance both efficiency and environmental sustainability of power plants by increasing the operating temperature. The accurate creep fatigue life assessment is important for the safe operation and design of current and future power plant stations. This paper proposes a practical creep fatigue life assessment case of study by the Linear Matching Method (LMM) framework. The LMM for extended Direct Steady Cycle Analysis (eDSCA) has been adopted to calculate the creep fatigue responses due to the cyclic loading under high temperature conditions. A pipe intersection with dissimilar material joint, subjected to high cycling temperature and constant pressure steam, is used as an example. The closed end condition is considered at both ends of main and branch pipes. The impact of the material mismatch, transitional thermal load, and creep dwell on the failure mechanism and location within the intersection is investigated. All the results demonstrate the capability of the method, and how a direct method is able to support engineers in the assessment and design of high temperature component in a complex loading scenario.

A Viscoplastic Model for Alloy 617 for Use With the ASME Section III, Division 5 Design by Inelastic Analysis Rules

2021 ◽  
Author(s):  
M. C. Messner ◽  
T.-L. Sham
Keyword(s):  
High Temperature ◽  
Alloy 617 ◽  
Element Analysis ◽  
Material Models ◽  
Experimental Database ◽  
Viscoplastic Model ◽  
Analysis And Design ◽  
Inelastic Analysis ◽  
Wide Range ◽  
Creep Fatigue

Abstract The rules for the design of high temperature reactor components in Section III, Division 5, Subsection HB, Subpart B (HBB) of the ASME Boiler and Pressure Vessel Code contain two options for evaluating the deformation-controlled design limits on strain accumulation and creep-fatigue: design by elastic analysis and design by inelastic analysis. Of these options design by inelastic analysis tends to be less overconservative and produce more efficient designs. However, the HBB currently does not provide approved material models for use with the inelastic analysis rules, limiting their widespread use. A nonmandatory appendix has been developed to provide general guidance on appropriate material models and provide reference material models suitable for use with the design by inelastic analysis approach. This paper describes a viscoplastic model for Alloy 617 suitable for use with the HBB rules proposed for incorporation into the new appendix. The model represents the high temperature creep, creep-fatigue, and tensile response of Alloy 617 and accurately accounts for rate sensitivity across a wide range of temperatures. The focus in developing the model was on capturing key features of material deformation required for accurately executing the HBB rules and on developing a relatively simple model form that can be implemented in commercial finite element analysis software. The paper validates the model against an extensive experimental database collected as part of the Alloy 617 Code qualification effort as well as against specialized experimental tests examining the effect of elastic follow up on stress relaxation and creep deformation in the material.

An Evaluation of Creep-Fatigue Damage for the Prototype Process Heat Exchanger of the NHDD Plant

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Kee-Nam Song ◽  
Yong-Wan Kim ◽  
Sung-Deok Hong ◽  
Hong-Yune Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Fatigue Damage ◽  
Inlet Temperature ◽  
Alloy 617 ◽  
Element Analysis ◽  
Creep Fatigue ◽  
Process Heat ◽  
Very High

A process heat exchanger (PHE) transfers the heat generated from a nuclear reactor to a sulfur-iodine hydrogen production system in the Nuclear Hydrogen Development and Demonstration, and was subjected to very high temperature up to 950°C. An evaluation of creep-fatigue damage, for a prototype PHE, has been carried out from finite element analysis with the full three dimensional model of the PHE. The inlet temperature in the primary side of the PHE was 950°C with an internal pressure of 7 MPa, while the inlet temperature in the secondary side of the PHE is 500°C with internal pressure of 4 MPa. The candidate materials of the PHE were Alloy 617 and Hastelloy X. In this study, only the Alloy 617 was considered because the high temperature design code is available only for Alloy 617. Using the full 3D finite element analysis on the PHE model, creep-fatigue damage evaluation at very high temperature was carried out, according to the ASME Draft Code Case for Alloy 617, and technical issues in the Draft Code Case were raised.

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