The Method of Accounting for Loading Cycle Asymmetry in Gas Turbine Engine Components’ Cyclic Durability Analysis

2006 ◽  
Author(s):  
R. H. Muratov
Keyword(s):  
Strain Range ◽  
Cyclic Strain ◽  
Mean Stress ◽  
Turbine Engine ◽  
Transient Strain ◽  
High Durability ◽  
Durability Analysis ◽  
Cyclic Durability ◽  
Engine Components ◽  
The Impact

The proposed method has been demonstrated on the universal slopes equation (Manson 1965) and the modified universal slopes equation (Muralidharan & Manson 1998). New equations take into account independence of the transient strain range from the cycle mean stress, define more precisely the impact of the cycle mean stress upon the durability, take into account the impact of cycle mean strain plastic component upon the durability. The resulted equations have been validated with finite element analyses of smooth samples and full-scale parts, for which the results of cyclic tests in the conditions of asymmetric loading are available. The analyses have been performed employing an elastic-plastic approach using cyclic strain curves taken from original durability equations. The use of new equations ensured a good match between design and experimental durability values. Also, the new equations were used to plot Smith and Hay diagrams for low, mean and high durability. The resulted analytical diagrams represent a high quality illustration of the experimental diagrams found in the publications. The presented approach to the accounting for cycle mean stress and strain will also apply when using experimental cyclic durability curves specific for the material.

The Method of Accounting for Loading Cycle Asymmetry in Cyclic Durability Analysis

2009 ◽  
Author(s):  
R. H. Muratov ◽  
M. A. Kornilova
Keyword(s):  
Strain Range ◽  
Cyclic Strain ◽  
Average Stress ◽  
Stress And Strain ◽  
Transient Strain ◽  
Asymmetric Loading ◽  
High Durability ◽  
Durability Analysis ◽  
Cyclic Durability ◽  
The Impact

The proposed method has been demonstrated on the universal slopes equation (Manson 1965) and the modified universal slopes equation (Muralidharan & Manson 1998). New equations take into account independence of the transient strain range from the cycle average stress, define more precisely the impact of the cycle average stress upon the durability, take into account the impact of cycle average strain plastic constituent upon the durability. The resulted equations have been validated with finite element analyses of non-notched samples and full-scale parts, for which the results of cyclic tests in the conditions of asymmetric loading are available. The analyses have been performed employing an elastic-plastic approach using cyclic strain curves taken from original durability equations. The use of new equations ensured a good match between design and experimental durability values. Also, the new equations were used to plot Smith, Hay and Wo¨hler diagrams for low, mean and high durability. The resulted analytical diagrams represent a high quality illustration of the experimental diagrams found in the publications. The presented approach to the accounting for cycle average stress and strain will also apply when using experimental cyclic durability curves specific for the material.

Experimental and Numerical Correlation of Impact of Spherical Projectile for Damage Analysis of Aero Engine Component

2016 ◽  
Vol 66 (2) ◽  
pp. 193 ◽  
Author(s):  
Anuradha Nayak Majila ◽  
Rajeev Jain ◽  
Chandru Fernando D. ◽  
S. Ramachandra
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Metallographic Analysis ◽  
Damage Analysis ◽  
Alloy Plate ◽  
Turbine Engine ◽  
Aero Engine ◽  
Engine Components ◽  
The Impact

<p>Studies the impact response of flat Titanium alloy plate against spherical projectile for damage analysis of aero engine components using experimental and finite element techniques. Compressed gas gun has been used to impart speed to spherical projectile at various impact velocities for damage studies. Crater dimensions (diameter and depth) obtained due to impact have been compared with finite element results using commercially available explicit finite element method code LS-DYNA. Strain hardening, high strain rate and thermal softening effect along with damage parameters have been considered using modified Johnson-Cook material model of LS-DYNA. Metallographic analysis has been performed on the indented specimen. This analysis is useful to study failure analysis of gas turbine engine components subjected to domestic object damage of gas turbine engine. </p><p> </p>

Engine Component Life Prediction Methodology for Conceptual Design Investigations

1986 ◽  
Author(s):  
John D. Cyrus
Keyword(s):  
Life Prediction ◽  
Preliminary Design ◽  
Design Decisions ◽  
Turbine Engine ◽  
Detailed Consideration ◽  
Engine Design ◽  
Engine Component ◽  
Fundamental Understanding ◽  
Engine Components ◽  
The Impact

The increasing emphasis on engine durability requires that an analytical capability be acquired to assess engine component lives during the conceptual/preliminary design phases. A generalized methodology has been developed to provide a fundamental understanding of the impact of engine design decisions, material selections, and a detailed consideration of engine usage for critical gas turbine engine components.

Limits on Morrow Mean Stress Correction of Manson-Coffin Life Prediction Models

2011 ◽  
Author(s):  
W. David Day
Keyword(s):  
Life Prediction ◽  
Prediction Models ◽  
Negative Impact ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
The Impact ◽  
Very High ◽  
Mean Stresses

Accurate prediction of crack initiation life is of critical importance in designing turbo-machinery. To improve this accuracy, more sophisticated prediction techniques are required. A large number of materials have shown a correlation between low cycle fatigue initiation life and strain range, as represented by the well-known Manson-Coffin equation. Testing has shown that tensile mean stress has a negative impact on life. This effect has been noted for many years when applied to high-cycle fatigue, resulting in the use of Goodman or Haigh diagrams to account for the impact of both stress range (and therefore strain range) and mean stress. Morrow proposed a methodology for accounting for mean stress in low cycle fatigue. Noting that as plasticity increases, the effect of mean stress decreases, the correction was applied only to the elastic strain versus life line. Use of the Morrow mean stress corrections improves the accuracy of life predictions, but there are limitations. The most significant of these limitations are situations in which the correction may be non conservative for high compressive mean stresses or very high tensile mean stresses. While a benefit from compressive mean stress is to be expected, at some point further increasing the compressive mean stress should have a negative impact on life. At very high tensile mean stresses near the material yield, the calculated impact of mean stress on life is non conservative. To overcome these limitations, the analyst may place limits on the acceptable range of R-ratios used based on actual test data, but this would do little more than highlight when the user is outside of his database limits. Alternatively a life system may be made in which mean stresses are conservatively expected to be tensile. Neither of these methods are useful for calculating different lives in compressive or tensile regimes. This difficulty is especially seen in bolted joints, which are subjected to high mean stresses and small stress amplitudes. A technique is proposed here in-which limits are placed on the mean stress correction, directly analogous to those used in the creation of so-called modified Goodman diagrams. This technique has been successfully applied at PSM to improve the accuracy of life prediction without increasing the risk of non conservatism. A review of some literature is made to show examples where this effect may be taking place. A small number of tests provide additional validation.

Size- and Temperature-Dependent Collision and Deposition Model for Micron-Sized Sand Particles

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Kuahai Yu ◽  
Danesh Tafti
Keyword(s):  
Gas Turbine ◽  
Recovery Process ◽  
Recovery Stage ◽  
Turbine Engine ◽  
Collision Model ◽  
Size Dependent ◽  
Plastic Stage ◽  
Sand Particles ◽  
Engine Components ◽  
The Impact

Sand ingestion and deposition in gas turbine engine components can lead to several operational hazards. This paper discusses a physics-based model for modeling the impact, deposition, and sticking of sand particles to surfaces. The collision model includes both normal and tangential components of impact. The normal collision model divides the impact process into three stages, the elastic stage, the elastic–plastic stage, and full plastic stage, and the recovery process is assumed to be fully elastic. The adhesion loss in the recovery stage is described using Timoshenko's model and Tsai's model, and shows that the two models are consistent under certain conditions. Plastic deformation losses of surface asperities are also considered for particle–wall collisions. The normal impact model is supplemented by an impulse-based tangential model, which includes both sliding and rolling frictions. Sand properties are characterized by size and temperature dependencies. The predicted coefficient of restitution (COR) of micron-sized sand particles is in very good agreement with experimental data at room temperature and at higher temperatures from 1073 K to 1340 K. The predicted COR decreases rapidly at temperatures above 1340 K. There is a strong interplay between the size-dependent properties of micron sand particles and the temperature dependency of yield stress on the collision and deposition characteristics. This is the first physics-based high temperature model including translation and rotation of micron-sized sand particles with sliding and rolling modes in the gas turbine literature.

Flexible manufacturing in repair of gas turbine engine components

1992 ◽  
Author(s):  
KIRK D ◽  
ANDREW VAVRECK ◽  
ERIC LITTLE ◽  
LESLIE JOHNSON ◽  
BRETT SAYLOR
Keyword(s):  
Gas Turbine ◽  
Flexible Manufacturing ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Engine Components

TIMETAL 829

Alloy Digest ◽  
2001 ◽  
Vol 50 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Titanium Alloy ◽  
High Temperature ◽  
High Strength ◽  
Heat Treating ◽  
High Temperature Alloy ◽  
Turbine Engine ◽  
Major Application ◽  
Alpha Titanium ◽  
Engine Components

Abstract TIMETAL 829 is a Ti-5.5Al-3.5Sn-3Zr-1Nb-0.25Mo-0.3Si near-alpha titanium alloy that is weldable and has high strength and is a creep resistant high temperature alloy. The major application is as gas turbine engine components. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness, creep, and fatigue. It also includes information on forming and heat treating. Filing Code: TI-118. Producer or source: Timet.

Life assessment of a high temperature probe designed for performance evaluation and health monitoring of an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Benny George ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Health Monitoring ◽  
Gas Turbine Engine ◽  
Life Assessment ◽  
Exhaust Gas ◽  
Cycle Fatigue ◽  
Creep Life ◽  
Turbine Engine ◽  
Engine Components

AbstractTemperature probes of different designs were widely used in aero gas turbine engines for measurement of air and gas temperatures at various locations starting from inlet of fan to exhaust gas from the nozzle. Exhaust Gas Temperature (EGT) downstream of low pressure turbine is one of the key parameters in performance evaluation and digital engine control. The paper presents a holistic approach towards life assessment of a high temperature probe housing thermocouple sensors designed to measure EGT in an aero gas turbine engine. Stress and vibration analysis were carried out from mechanical integrity point of view and the same was evaluated in rig and on the engine. Application of 500 g load concept to clear the probe design was evolved. The design showed strength margin of more than 20% in terms of stress and vibratory loads. Coffin Manson criteria, Larsen Miller Parameter (LMP) were used to assess the Low Cycle Fatigue (LCF) and creep life while Goodman criteria was used to assess High Cycle Fatigue (HCF) margin. LCF and HCF are fatigue related damage from high frequency vibrations of engine components and from ground-air-ground engine cycles (zero-max-zero) respectively and both are of critical importance for ensuring structural integrity of engine components. The life estimation showed LCF life of more than 4000 mission reference cycles, infinite HCF life and well above 2000 h of creep life. This work had become an integral part of the health monitoring, performance evaluation as well as control system of the aero gas turbine engine.

Life assessment of a high temperature probe designed for performance evaluation and health monitoring of an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Benny George ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Health Monitoring ◽  
Gas Turbine Engine ◽  
Life Assessment ◽  
Exhaust Gas ◽  
Cycle Fatigue ◽  
Creep Life ◽  
Turbine Engine ◽  
Engine Components

Abstract Temperature probes of different designs were widely used in aero gas turbine engines for measurement of air and gas temperatures at various locations starting from inlet of fan to exhaust gas from the nozzle. Exhaust Gas Temperature (EGT) downstream of low pressure turbine is one of the key parameters in performance evaluation and digital engine control. The paper presents a holistic approach towards life assessment of a high temperature probe housing thermocouple sensors designed to measure EGT in an aero gas turbine engine. Stress and vibration analysis were carried out from mechanical integrity point of view and the same was evaluated in rig and on the engine. Application of 500 g load concept to clear the probe design was evolved. The design showed strength margin of more than 20% in terms of stress and vibratory loads. Coffin Manson criteria, Larsen Miller Parameter (LMP) were used to assess the Low Cycle Fatigue (LCF) and creep life while Goodman criteria was used to assess High Cycle Fatigue (HCF) margin. LCF and HCF are fatigue related damage from high frequency vibrations of engine components and from ground-air-ground engine cycles (zero-max-zero) respectively and both are of critical importance for ensuring structural integrity of engine components. The life estimation showed LCF life of more than 4000 mission reference cycles, infinite HCF life and well above 2000 h of creep life. This work had become an integral part of the health monitoring, performance evaluation as well as control system of the aero gas turbine engine.

Diagnosis of Turbine Engine Transient Performance With Model-Based Parameter Estimation Techniques

1994 ◽  
Author(s):  
Jeff W. Bird ◽  
Howard M. Schwartz
Keyword(s):  
Gas Turbine ◽  
Test Data ◽  
Physical Models ◽  
Turbine Engine ◽  
Robustness To Noise ◽  
Linear Effects ◽  
Diagnostic Capabilities ◽  
Engine Components ◽  
And Control ◽  
Parameter Estimation Techniques

This review surveys knowledge needed to develop an improved method of modelling the dynamics of gas turbine performance for fault diagnosis applications. Aerothermodynamic and control models of gas turbine processes are examined as complementary to models derived directly from test data. Extensive, often proprietary data are required for physical models of components, while system identification (SI) methods need data from specially-designed tests. Current methods are limited in: tuning models to test data, non-linear effects, component descriptions in SI models, robustness to noise, and inclusion of control systems and actuators. Conclusions are drawn that SI models could be formulated, with parameters which describe explicitly the functions of key engine components, to offer improved diagnostic capabilities.

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