Creep Fatigue Damage Assessment of V-Butt Weld Pipe With an Extended Direct Steady Cycle Analysis

2018 ◽  
Author(s):  
Manu Puliyaneth ◽  
Haofeng Chen ◽  
Weiling Luan
Keyword(s):  
Fatigue Damage ◽  
Power Plants ◽  
Mechanical Load ◽  
Axial Stress ◽  
Load Level ◽  
Cyclic Plasticity ◽  
Butt Weld ◽  
Creep Fatigue ◽  
Welded Pipe ◽  
The Impact

One of the methods to increase the efficiency of power plants is by increasing their operating temperature, this can lead to various damage mechanisms due to creep-cyclic plasticity interactions such as creep ratcheting, cyclically enhanced creep and creep enhanced plasticity. In the presence of welds, their assessments are complicated due to the presence of different material zones, namely parent metal, weld metal and heat affected zone which exhibit different properties. This paper aims at investigating the creep-fatigue damage of a V-butt welded pipe under a constant mechanical load and a cyclic temperature load, considering full interaction between creep and cyclic plasticity using the extended Direct Steady Cycle Analysis (eDSCA) within the Linear Matching Method Framework (LMMF). The impact of applied load level and creep dwell on the failure mechanism and location is investigated. Influence of hoop to axial stress ratio and groove angle is studied comprehensively by choosing ranges covering majority of common pipe configurations. Further validation of results is carried out by using detailed step-by-step inelastic analyses in ABAQUS, thereby demonstrating the accuracy and efficiency of LMM eDSCA in predicating the remaining life of multi-material components such as a welded pipe, combining with appropriate creep and fatigue damage models.

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.

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.

Structural Evaluation With Elastic and Inelastic Analysis Methods on a High Temperature Storage Tank Subjected to Static and Dynamic Loadings

2020 ◽  
Author(s):  
Wen Wang ◽  
Xiaochun Zhang ◽  
Xiaoyan Wang ◽  
Maoyuan Cai
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Molten Salt ◽  
Fatigue Damage ◽  
Storage Tank ◽  
Power Plants ◽  
Elastic Analysis ◽  
Inelastic Analysis ◽  
Analysis Methods ◽  
Creep Fatigue

Abstract The structural integrity of reactor components is very essential for the reliable operation of all types of power plants, especially for components operating at elevated temperature where creep effects are significant and where components are subjected to high-temperature alteration and seismic transient loading conditions. In this article, a molten salt storage tank in high temperature thorium molten salt reactor (TMSR) is evaluated according to ASME-III-5-HBB high temperature reactor code. The evaluation based on 3D finite element analyses includes the load-controlled stress, the effects of ratcheting, and the interaction of creep and fatigue. The thermal and structural analysis and the application procedures of ASME-HBB rules are described in detail. Some structural modifications have been made on this molten salt storage tank to enhance the strength and reduce thermal stress. The effects of ratcheting and creep-fatigue damage under elevated temperature are investigated using elastic analysis and inelastic analysis methods for a defined representative load cycle. In addition, the strain range and the stress relaxation history calculated by elastic and inelastic methods are compared and discussed. The numerical results indicate that the elastic analysis is conservative for design and a full inelastic analysis method for estimating input for creep-fatigue damage evaluation need to be developed.

Findings on Creep-Fatigue Damage in Pressure Parts of Long-Term Service-Exposed Thermal Power Plants

1985 ◽  
Vol 107 (3) ◽  
pp. 260-270 ◽  
Author(s):  
F. Masuyama ◽  
K. Setoguchi ◽  
H. Haneda ◽  
F. Nanjo
Keyword(s):  
Fatigue Damage ◽  
Power Plants ◽  
Thermal Power ◽  
Field Experiences ◽  
Creep Damage ◽  
Thermal Power Plants ◽  
Damage Analysis ◽  
Creep Fatigue ◽  
Fatigue Damage Analysis

The increase of long-term service exposure to thermal power plants, the tendency toward intermediate and cyclic operation to meet the change in electric power demand and supply situation, and the requirement to develop higher-temperature and higher-pressure plants have led to increasing attention towards the reliability improvement. This paper presents findings from field experiences of cracking or failure and two types of damage analyses—(1) creep-fatigue damage analysis based on the life fraction rule and (2) metallurgical damage analysis—of boiler pressure parts that have been exposed to long-term elevated temperature service. The field experiences are (1) cracking or failure of thick-walled Type 316 stainless steel pressure parts in the main steam line of an ultra-supercritical thermal power plant and (2) dissimilar metal weld joints for boiler tubing. The creep-fatigue damage analysis of these pressure parts showed a reasonable correspondence with the field experience. According to the creep-fatigue damage analysis and the metallurgical damage analysis, most of damage was restrained creep mode phenomenon without deformation. The creep damage was composed of metallurgical damage and mechanical damage such as microvoids and structural defects. One method of simulating field experienced creep damage was proposed and performed. As a result, the process of creep voids being generated and growing into cracks without deformation was successfully observed. Also a review of the current status of nondestructive detecting methods of creep damage suggests that detecting the creep voids metallurgically is more practical at the present time than doing so analyzing the changes in physical properties of the material. It is also suggested that, in the metallurgical approach, detecting the creep voids and cracks by replica method and anlayzing precipitates for evaluation of material deterioration by precipitate extraction method will make it possible to successfully address the problem of plant equipment creep damage evaluation and life prediction.

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.

Creep-Fatigue Damage Evaluation of Grade 91 Steel Using Interrupt Creep Fatigue Test

2018 ◽  
Author(s):  
Uijeong Ro ◽  
Jeong Hwan Kim ◽  
Hoomin Lee ◽  
Seok Jun Kang ◽  
Moon Ki Kim
Keyword(s):  
Fatigue Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fatigue Behavior ◽  
Fe Model ◽  
Testing Method ◽  
Creep Fatigue ◽  
Grade 91 ◽  
Grade 91 Steel

The Sodium Fast-cooled Reactor (SFR), are generation IV nuclear power plants, have a target operating temperature of 550°C which makes creep-fatigue behavior more critical than a generation III nuclear power plants. So it is important to understand the nature of creep-fatigue behavior of the piping material, Grade 91 steel. The creep-fatigue damage diagram of Grade 91 steel used in ASME-NH was derived using a conventional time-fraction testing method which was originally developed for type 300 stainless steels. Multiple studies indicate that the creep-fatigue damage diagram of Grade 91 steel developed using this testing method has excessive conservatism in it. Therefore, an alternative testing method was suggested by separating creep and fatigue using interrupted creep tests. The suggested method makes it possible to control creep life consumption freely which was difficult with the previous method. It also makes it easier to observe the interaction between creep and fatigue mechanisms and microstructural evolution. In conclusion, an alternative creep-fatigue damage diagram for Grade 91 steel at 550°C was developed using an interrupt creep fatigue testing method and FE model simulation.

Evaluation of Creep-Fatigue Life Using Backscattering of Rayleigh Surface Wave

2005 ◽  
Vol 297-300 ◽  
pp. 415-420 ◽  
Author(s):  
Byeong Soo Lim ◽  
Bum Joon Kim ◽  
Sung Jin Song ◽  
Young H. Kim
Keyword(s):  
Fatigue Life ◽  
Surface Wave ◽  
Fatigue Damage ◽  
Power Plants ◽  
Fatigue Behavior ◽  
Hold Time ◽  
Rayleigh Surface Wave ◽  
P92 Steel ◽  
Creep Fatigue ◽  
Main Steam

The application of nondestructive evaluation to creep-fatigue damage was examined in this paper. Generally, as the hold time of static load increases, the degradation of material becomes more rapid and the creep-fatigue life decreases. Therefore, in the evaluation of creep-fatigue strength and life of high-pressure vessel such as main steam pipe at high temperature is very important in power plants. In this study, the creep-fatigue behavior of P92 steel was evaluated nondestructively by the backscattered ultrasound using the creep-fatigue specimens. The results obtained by Rayleigh surface wave of backscattered ultrasound were compared and analyzed with the experimental parameters. Also, the relation between the SDA (slope of degraded area) and creep-fatigue life was examined. From the result of nondestructive test, we suggest that SDA would be used as the new parameter for the evaluation of creep-fatigue damage. As the degradation increased, the SDA decreased and also the creep-fatigue life decreased.

A Procedure to Include the Additional Fatigue Effects of Thermal Gradients in a B31.1 Butt Weld of Dissimilar Metals and Welding End Transition of Similar Metals for Design and Plant Life Extension

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
David H. Creates
Keyword(s):  
Power Plant ◽  
Fatigue Damage ◽  
Power Plants ◽  
Pressure Vessels ◽  
Life Extension ◽  
Dissimilar Metals ◽  
Thermal Gradients ◽  
Plant Design ◽  
Butt Weld ◽  
Plant Life

Fatigue evaluation in B31.1-2007 is currently done in accordance with para. 102.3.2 and generally considers only the stresses due to displacement load ranges and other cyclic loads. Yet fatigue damage is also occurring due to thermal gradients which are not considered. To exacerbate and complicate this additional type of fatigue damage, power plant design pressures and temperatures are rising, new materials are being introduced, pipes and attached components are becoming increasingly thick, and owners are requiring power plants to heat-up and cool-down at faster rates. Also, power plant owners are more and more interested in extending the life of power plants beyond their original design life. Although the fatigue design of ASME nuclear Class 1 piping components has long required thermal gradients to be considered, no attempt has been made to incorporate this knowledge into the B31.1 Power Piping Code (other than Creates, D. H., 2009, “A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension,” PVP2009-77148, Proceedings of the ASME 2009 Pressure Vessels and Piping Conference, Volume 3, Design and Analysis, A. Segall, ed., ASME, New York, PVP-Vol. 3, pp. 101–110). To address this pressing need in today’s power plant environment this paper now provides a fully comprehensive methodology for assessing an “as-welded” Butt weld of dissimilar metals and a Welding End Transition (B31.1-2007, Fig. 127.4.2) of similar metals to include the additional fatigue effects of thermal gradients calculated in accordance with ASME Section III-2007 Subarticle NB-3600. The disadvantage of this approach is that the conservatism in these calculations may produce unacceptable results. In that case, this assessment is a warning that something else needs to be done by way of monitoring, modifying the design or the thermal operation, or performing a more rigorous evaluation. The advantage of this methodology is that it maintains the traditional B31.1 approach to fatigue with the same limit of SA except that there is now an additional term, STG, to account for the fatigue contribution due to thermal gradients. Considering the effects of thermal gradients in this way will further help to preserve the integrity of the piping pressure boundary and consequently, the safety of personnel in today’s power plants and into the future.

Creep-Fatigue Damage Evaluation of Modified Grade 91 Headers Using Damage Coupled Unified Viscoplastic Model

2017 ◽  
Author(s):  
Nazrul Islam ◽  
David J. Dewees ◽  
Michael Cooch ◽  
Tasnim Hassan
Keyword(s):  
Fatigue Damage ◽  
Power Plants ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Creep Damage ◽  
Combined Cycle ◽  
Damage Evaluation ◽  
Operation Condition ◽  
Creep Fatigue ◽  
Grade 91

A case study for life prediction of Grade 91 heat recovery steam generator (HRSG) superheater outlet header of typical combined cycle power plants (CCPP) is presented in this paper. The effect of high cycling and fast startup along with elevated design temperature and pressure on the creep life is studied. A consistent material model based on MPC Omega is used to evaluate the creep damage of HRSG header components. In addition, a robust unified constitutive model (UCM) based on continuum damage mechanics (CDM) (see [1]) is used for creep-fatigue damage evaluation of the header components. The performance of the UCM is compared against creep and damage focused models in predicting the life of HRSG header components subjected to steady operation condition with low cycle fatigue scenario.

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.

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