An Investigation on the Effect of Creep Shakedown on the Creep Behavior of an Industrial Gas Turbine Blade

2015 ◽  
Author(s):  
Jun Zhao ◽  
Ashok K. Koul ◽  
Avisekh Banerjee
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Damage Accumulation ◽  
Creep Damage ◽  
Local Stress ◽  
Operating Conditions ◽  
Time Dependent ◽  
Strain Accumulation ◽  
Accumulation Process ◽  
Creep Life

The creep life computation of gas turbine hot section components using any damage modeling technique requires typical inputs of stress and temperature under actual engine operating conditions. The magnitude of these inputs is governed by the static or dynamic transient loading conditions that a component may be subjected to during service. The long term creep damage accumulation process in a hot section component leads to strain accumulation in the component with time. The rate of change of this strain accumulation in different regions of a component is controlled by the magnitude of the local stress, stress gradient and temperature. In some regions, the creep damage accumulation process may lead to a substantial change in the local stress distribution, also called the “Creep Shakedown”, and this time-dependent stress redistribution can have a substantial impact on the component creep life. The creep shakedown based creep life analysis of a GE Frame 7EA first stage turbine blade under off-design base-load engine operating conditions is studied. The evolution of the stress and strain in different regions of the blade with service time was analyzed using the finite element method. A user defined Garofalo model with hyperbolic sine creep rule was incorporated in the finite element analysis (FEA). The creep shakedown in the component is demonstrated to cause a local time-dependent stress redistribution effect in the FEA simulation. The significant stress variation and creep strain accumulation was observed in the creep critical regions where local stress raisers were present and/or a high temperature gradient due to internal cooling design existed. These effects are discussed in detail from a materials engineering perspective.

Assessing the Condition and Estimating the Remaining Lives of Pressure Components in a Methanol Plant Reformer: Part 2 — Engineering Evaluation

2016 ◽  
Author(s):  
Carl E. Jaske ◽  
Brian E. Shannon ◽  
Gustavo Miranda ◽  
Thomas J. Prewitt
Keyword(s):  
Finite Element ◽  
Creep Damage ◽  
General Purpose ◽  
Operating Conditions ◽  
Remaining Life ◽  
Creep Life ◽  
Service Failures ◽  
Finite Element Software ◽  
Creep Stress ◽  
Non Destructive

Statoil Tjelbergodden operates a 2,400 ton/day methanol plant in Norway. Part 1 of this paper described the advanced non-destructive examination (NDE) technologies that were applied to obtain data for engineering evaluation of radiant catalyst tubes, outlet pigtails, and outlet collection headers. The inspection results were compiled along with data on materials properties and plant operating conditions for use in a series of life prediction studies. This paper describes the assessment methodologies that were applied in evaluating the remaining life of the in-service components. The special purpose WinTUBE™ finite element software was applied to predict remaining catalyst tube creep life based on the computed creep stress-strain response and creep damage accumulation under simulated future operating conditions. Outlet headers and pigtails were modeled using general purpose finite element software to compute stresses and strains during operation. Following the methodology of API 579-1/ASME FFS-1 the computed stresses and strains were used to predict remaining creep life. Using the remaining life estimates to decrease the potential of in-service failures and increase the reliability of future reformer operations is discussed.

Marine Gas Turbine Performance Model for More Electric Ships

2011 ◽  
Author(s):  
George M. Koutsothanasis ◽  
Anestis I. Kalfas ◽  
Georgios Doulgeris
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Diesel Engines ◽  
Gas Turbines ◽  
Electric Propulsion ◽  
Operating Conditions ◽  
Prime Mover ◽  
Creep Life ◽  
Hull Fouling ◽  
Turbine Performance

This paper presents the benefits of the more electric vessels powered by hybrid engines and investigates the suitability of a particular prime-mover for a specific ship type using a simulation environment which can approach the actual operating conditions. The performance of a mega yacht (70m), powered by two 4.5MW recuperated gas turbines is examined in different voyage scenarios. The analysis is accomplished for a variety of weather and hull fouling conditions using a marine gas turbine performance software which is constituted by six modules based on analytical methods. In the present study, the marine simulation model is used to predict the fuel consumption and emission levels for various conditions of sea state, ambient and sea temperatures and hull fouling profiles. In addition, using the aforementioned parameters, the variation of engine and propeller efficiency can be estimated. Finally, the software is coupled to a creep life prediction tool, able to calculate the consumption of creep life of the high pressure turbine blading for the predefined missions. The results of the performance analysis show that a mega yacht powered by gas turbines can have comparable fuel consumption with the same vessel powered by high speed Diesel engines in the range of 10MW. In such Integrated Full Electric Propulsion (IFEP) environment the gas turbine provides a comprehensive candidate as a prime mover, mainly due to its compactness being highly valued in such application and its eco-friendly operation. The simulation of different voyage cases shows that cleaning the hull of the vessel, the fuel consumption reduces up to 16%. The benefit of the clean hull becomes even greater when adverse weather condition is considered. Additionally, the specific mega yacht when powered by two 4.2MW Diesel engines has a cruising speed of 15 knots with an average fuel consumption of 10.5 [tonne/day]. The same ship powered by two 4.5MW gas turbines has a cruising speed of 22 knots which means that a journey can be completed 31.8% faster, which reduces impressively the total steaming time. However the gas turbine powered yacht consumes 9 [tonne/day] more fuel. Considering the above, Gas Turbine looks to be the only solution which fulfills the next generation sophisticated high powered ship engine requirements.

Numerical Simulation of Stress Relaxation and Creep Response of X20 Steam Piping under Diverse Operating Conditions

2021 ◽  
Vol 57 ◽  
pp. 19-32
Author(s):  
Smith Salifu ◽  
Dawood A. Desai ◽  
Schalk Kok
Keyword(s):  
Steady State ◽  
Stress Relaxation ◽  
Damage Accumulation ◽  
Creep Behaviour ◽  
Creep Damage ◽  
Operating Conditions ◽  
Creep Model ◽  
Element Analysis ◽  
Peak Period ◽  
Creep Response

The creep response and stress relaxation of X20 CrMoV12-1 steam piping under diverse operating conditions were simulated using finite element analysis (FEA) code, Abaqus alongside fe-safe/Turbolife software. In the study, steady-state creep and creep analysis characterized by 24 hours daily cycle consisting of a total of 6 hours peak, 4 hours transient and 14 hours off-peak period was considered. Modified hyperbolic sine creep model used in the analysis was implemented in Abaqus via a special creep user-subroutine to compute the stress relaxation and creep behaviour, while the useful service life and creep damage was estimated using fe-safe/Turbolife. The optimum creep strain, stress, damage, and worst life were found at the intrados of the piping, with the steady-state analysis having a higher useful creep life and slower creep damage accumulation. Furthermore, slower stress relaxation with faster damage accumulation was observed in the analysis involving cycles. Finally, a good agreement was obtained between the analytical calculated and simulated rates of the piping.

A Damage Evaluation Model of Turbine Blade for Gas Turbine

2016 ◽  
Author(s):  
Dengji Zhou ◽  
Meishan Chen ◽  
Huisheng Zhang ◽  
Shilie Weng
Keyword(s):  
High Temperature ◽  
Real Time ◽  
Gas Turbine ◽  
Evaluation Model ◽  
Creep Damage ◽  
Operating Conditions ◽  
Damage Analysis ◽  
Damage Evaluation ◽  
Analysis Model ◽  
Estimation Model

Current maintenance, having a great impact on the safety, reliability and economics of gas turbine, becomes the major obstacle of the application of gas turbine in energy field. An effective solution is to process Condition based Maintenance (CBM) thoroughly for gas turbine. Maintenance of high temperature blade, accounting for most of the maintenance cost and time, is the crucial section of gas turbine maintenance. The suggested life of high temperature blade by Original Equipment Manufacturer (OEM) is based on several certain operating conditions, which is used for Time based Maintenance (TBM). Thus, for the requirement of gas turbine CBM, a damage evaluation model is demanded to estimate the life consumption in real time. A physics-based model is built, consisting of thermodynamic performance simulation model, mechanical stress estimation model, thermal estimation model, creep damage analysis model and fatigue damage analysis model. Unmeasured parameters are simulated by the thermodynamic performance simulation model, as the input of the mechanical stress estimation model and the thermal estimation model. Then the stress and temperature distribution of blades will be got as the input of the creep damage analysis model and the fatigue damage analysis model. The real-time damage of blades will be evaluated based on the creep and fatigue analysis results. To validate this physics-based model, it is used to calculate the lifes of high temperature blade under several certain operating conditions. And the results are compared to the suggestion value of OEM. An application case is designed to evaluate the application effect of this model. The result shows that the relative error of this model is less than 10.4% in selected cases. And it can cut overhaul costs and increase the availability of gas turbine significantly. Therefore, the physical-based damage evaluation model proposed in this paper, is found to be a useful tool to tracing the real-time life consumption of high temperature blade, to support the implementation of CBM for gas turbine, and to guarantee the reliability of gas turbine with lowest maintenance costs.

Deformation Modeling and Lifetime Prediction of Ni-Base Gas Turbine Blade Alloys Under TMF-Conditions

2014 ◽  
Author(s):  
Stefan Grützner ◽  
Bernard Fedelich ◽  
Birgit Rehmer ◽  
Maria Mosquera
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Creep Damage ◽  
Material Model ◽  
Lifetime Prediction ◽  
Strain Accumulation ◽  
Loading Conditions ◽  
Gas Turbine Blade ◽  
Thermomechanical Loading ◽  
Cyclic Thermomechanical Loading

Under cyclic thermomechanical loading conditions, various effects such as strain accumulation, creep damage, ageing, fatigue etc. may occur in the material of a gas turbine blade. Depending on the loading conditions, all these effects contribute to reduce the lifetime of the component. Subject of the present work is the development of a lifetime model able to discriminate between the different damage mechanisms, as well as the development of a material model to describe the mentioned effects and thus providing the input data for lifetime prediction.

Advanced Cyclic Plasticity Models in Simulating Ratcheting Responses of Straight and Elbow Piping Components, and Notched Plates

2005 ◽  
Author(s):  
Syed M. Rahman ◽  
Tasnim Hassan
Keyword(s):  
Damage Accumulation ◽  
Solid Mechanics ◽  
Fatigue Cracks ◽  
Constitutive Models ◽  
Local Stress ◽  
Weather Conditions ◽  
Operating Conditions ◽  
Cyclic Plasticity ◽  
Integration Schemes ◽  
Current State

Ratcheting is defined as the accumulation of strain or deformation in structures under cyclic loading. Damage accumulation due to ratcheting can cause failure of structures through fatigue cracks or plastic collapse. Ratcheting damage accumulation in structures may occur under repeated reversals of loading induced by earthquakes, extreme weather conditions, and mechanical and thermal operating conditions. A major challenge in structural and solid mechanics is the prediction of ratcheting responses of structures under any or combination of these loading conditions. Accurate prediction of ratcheting-fatigue and ratcheting-collapse is imperative in order to incorporate the ratcheting related failures into the ASME design Code in a rational manner. This would require predictions of both local (stress-strain) and global (load-deflection) responses simultaneously. In progressing towards this direction, a set of experimental ratcheting responses for straight and elbow piping components and notched plates is developed. Advanced cyclic plasticity models, such as, modified Chaboche, Ohno-Wang, and AbdelKarim-Ohno models, are implemented in ANSYS for simulation of these experimental responses. Various integration schemes for implementing the constitutive models into the structural analysis code ANSYS are studied. Results from the experimental and analytical studies are presented and discussed in order to demonstrate the current state of simulation modeling of structural ratcheting.

Prediction of Welding Residual Stresses, Crack Initiation and Creep Crack Driving Forces C(t) Within a Continuous Finite Element Solution

2010 ◽  
Author(s):  
D. P. Bray ◽  
R. J. Dennis ◽  
M. C. Smith
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Driving Forces ◽  
Welding Process ◽  
Creep Damage ◽  
Operating Conditions ◽  
Finite Element Solution ◽  
Element Solution ◽  
Element Analysis ◽  
Creep Crack

The work reported in this paper investigates the manufacture, through-life operation and cracked behaviour of an attachment weld in a UK AGR boiler. A structural assessment of the attachment weld was performed to demonstrate its integrity. This assessment made use of complex finite element analysis of both the welding process and postulated defects. A simulation of the welding process was performed in order to predict the residual stresses and hardened material state throughout the attachment weld. The welding simulation was performed in two stages since a butter weld was deposited prior to the attachment weld itself. The accumulation of creep damage was predicted during steady normal operating conditions for the lifetime of the component. A contour map of creep damage was used to postulate the location and size of hypothetical single and double edge surface cracks within the weld. These postulated cracks were then explicitly introduced into the finite element model. The crack tip stress parameter C(t) was evaluated in order to predict the creep crack driving forces. The results from a cracked body simulation suggested that the creep crack driving force C(t) reduces as the crack grows, due to relief of the dominant welding residual stresses. The residual stress, creep damage and cracked body simulations have been brought together into a novel continuous finite element solution. The results can be used to support a safety case for continued operation of existing plant.

scholarly journals Prediction and Analysis of Impact of Thermal Barrier Coating Oxidation on Gas Turbine Creep Life

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
E. A. Ogiriki ◽  
Y. G. Li ◽  
Th. Nikolaidis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Thermal Barrier ◽  
Creep Life ◽  
Premature Failure ◽  
Turbine Engine ◽  
Oxidation Rates ◽  
The Impact

Thermal barrier coatings (TBCs) have been widely used in the power generation industry to protect turbine blades from damage in hostile operating environment. This allows either a high turbine entry temperature (TET) to be employed or a low percentage of cooling air to be used, both of which will improve the performance and efficiency of gas turbine engines. However, with continuous increases in TET aimed at improving the performance and efficiency of gas turbines, TBCs have become more susceptible to oxidation. Such oxidation has been largely responsible for the premature failure of most TBCs. Nevertheless, existing creep life prediction models that give adequate considerations to the effects of TBC oxidation on creep life are rare. The implication is that the creep life of gas turbines may be estimated more accurately if TBC oxidation is considered. In this paper, a performance-based integrated creep life model has been introduced with the capability of assessing the impact of TBC oxidation on the creep life and performance of gas turbines. The model comprises of a thermal, stress, oxidation, performance, and life estimation models. High pressure turbine (HPT) blades are selected as the life limiting component of gas turbines. Therefore, the integrated model was employed to investigate the effect of several operating conditions on the HPT blades of a model gas turbine engine using a creep factor (CF) approach. The results show that different operating conditions can significantly affect the oxidation rates of TBCs which in turn affect the creep life of HPT blades. For instance, TBC oxidation can speed up the overall life usage of a gas turbine engine from 4.22% to 6.35% within a one-year operation. It is the objective of this research that the developed method may assist gas turbine users in selecting the best mission profile that will minimize maintenance and operating costs while giving the best engine availability.

Finite Element Analysis of History-Dependent Damage in Time-Dependent Fracture Mechanics

1993 ◽  
Vol 115 (4) ◽  
pp. 339-347 ◽  
Author(s):  
P. Krishnaswamy ◽  
F. W. Brust ◽  
N. D. Ghadiali
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Operating Conditions ◽  
Time Dependent ◽  
Element Analysis ◽  
Creep Crack ◽  
Numerical Predictions ◽  
Fracture Parameters ◽  
Growing Cracks

The demands for structural systems to perform reliably under both severe and changing operating conditions continue to increase. Under these conditions time-dependent straining and history-dependent damage become extremely important. This work focuses on studying creep crack growth using finite element (FE) analysis. Two important issues, namely, (i) the use of history-dependent constitutive laws, and (ii) the use of various fracture parameters in predicting creep crack growth, have both been addressed in this work. The constitutive model used here is the one developed by Murakami and Ohno and is based on the concept of a creep hardening surface. An implicit FE algorithm for this model was first developed and verified for simple geometries and loading configurations. The numerical methodology developed here has been used to model stationary and growing cracks in CT specimens. Various fracture parameters such as the C1, C*, T*, J were used to compare the numerical predictions with experimental results available in the literature. A comparison of the values of these parameters as a function of time has been made for both stationary and growing cracks. The merit of using each of these parameters has also been discussed.

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