A Cumulative Fatigue Damage Model for Gas Turbine Engine Disks Subjected to Complex Mission Loading

The objective of a continuing research program is to develop a low cycle fatigue (LCF) damage model which accurately evaluates the life exhaustion of military gas turbine engine disks subjected to complex loading spectra. This paper reports the results of the first phase of the effort and specifically concerns “cold region” disk bolt holes. A simple cycle LCF model is developed which accounts for nonlinear material behavior and the presence of local surface residual stresses due to machining. Nonlinear cumulative damage is clearly observed in specimen and component testing and is successfully modeled by a “double damage” principle in which an initial crack length need not be known explicitly. Testing of full-scale components under complex loading is used to verify the models.

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Low Cycle Fatigue Life Model for Gas Turbine Engine Disks

Journal of Engineering Materials and Technology ◽

10.1115/1.3224783 ◽

1980 ◽

Vol 102 (1) ◽

pp. 45-49

Author(s):

T. G. Meyer ◽

T. A. Cruse

Keyword(s):

Gas Turbine ◽

Low Cycle Fatigue ◽

Damage Model ◽

Strain Range ◽

Gas Turbine Engine ◽

Cycle Fatigue ◽

Turbine Engine ◽

Mission History ◽

Life Model ◽

Temperature Exposure

A low cycle fatigue (LCF) life exhaustion method is developed for gas turbine engine disks subjected to complex mission history loading. The method is incorporated into an algorithm for LCF life exhaustion prediction as a function of component, material, mission history, and mission ordering. Principal features in the LCF life model include a simple strain range-mean stress correlation model, a predictive model for the effects of strain-hardened surface layers due to machining and the effects of dwell (creep) due to elevated temperature exposure time, a fracture mechanics-based nonlinear, cumulative damage model, and full-scale component verification.

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Modeling of Cyclic Life for Compressor Rotor of Gas Turbine Engine Taking Into Account Production Deviations

Volume 10B: Structures and Dynamics ◽

10.1115/gt2020-16260 ◽

2020 ◽

Author(s):

Alexandr N. Arkhipov ◽

Yury A. Ravikovich ◽

Anton A. Matushkin ◽

Dmitry P. Kholobtsev

Keyword(s):

Gas Turbine ◽

Low Cycle Fatigue ◽

Probabilistic Modeling ◽

Gas Turbine Engine ◽

Critical Zone ◽

Design Stage ◽

Cyclic Life ◽

Engine Operation ◽

Turbine Engine ◽

Compressor Rotor

Abstract The regional aircraft with a turbofan gas turbine engine, created in Russia, is successfully operated in the world market. Further increase of the life and reduction of the cost of the life cycle are necessary to ensure the competitive advantages of the engine. One of the units limiting the engine life is the compressor rotor. The cyclic life of the rotor depends on many factors: the stress-strain state in critical zones, the life of the material under low-cycle loading, the regime of engine operation, production deviations (within tolerances), etc. In order to verify the influence of geometry deviations, the calculations of the model with nominal dimensions and the model with the most unfavorable geometric dimensions (worst cases) have been carried out. The obtained influence coefficients for geometric and weight tolerances are then used for probabilistic modeling of stresses in the critical zone. Rotor speed and gas loads on the blades for different flight missions and engine wear are determined from the corresponding aerodynamic calculations taking into account the actual flight cycles (takeoff, reduction, reverse) and are also used for stress recalculations. The subsequent calculation of the rotor cyclic life and the resource assessment is carried out taking into account the spread of the material low-cycle fatigue by probabilistic modeling of the rotor geometry and weight loads. A preliminary assessment of the coefficients of tolerances influence on stress in the critical zone can be used to select the optimal (in terms of life) tolerances at the design stage. Taking into account the actual geometric and weight parameters can allow estimating the stress and expected life of each manufactured rotor.

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Forecasting low-cycle fatigue life of gas-turbine engine parts by the method of equivalent tests for specimens with stress concentrator under extension-compression

VESTNIK of the Samara State Aerospace University ◽

10.18287/2541-7533-2018-17-2-37-46 ◽

2018 ◽

Vol 17 (2) ◽

pp. 37

Author(s):

S. A. Bukatyy ◽

A. V. Pakhomenkov ◽

G. A. Solntsev ◽

A. S. Bukatyy

Keyword(s):

Fatigue Life ◽

Gas Turbine ◽

Stress Concentrator ◽

Low Cycle Fatigue ◽

Gas Turbine Engine ◽

Cycle Fatigue ◽

Turbine Engine

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Design and Analysis of a New Accessory Gearbox Housing for a Gas Turbine Engine

Volume 6: Structures and Dynamics, Parts A and B ◽

10.1115/gt2011-46747 ◽

2011 ◽

Author(s):

Partha S. Das

Keyword(s):

Gas Turbine ◽

Low Cycle Fatigue ◽

Minimum Weight ◽

Cost Savings ◽

Gas Turbine Engine ◽

Cycle Fatigue ◽

Element Analysis ◽

Turbine Engine ◽

Housing Design ◽

Engine Mount

Accessory Gearbox (AGB) Housing is one of the most critical components of a gas turbine engine that lies between the core engine & the aircraft. The function of the AGB Housing is to provide support for the gear drive assembly that transfers power from the engine to the engine accessories and to the power takeoff drive for the aircraft accessories. The housing also functions as an oil tight container and passageway for lubrication. In addition, the AGB housing provides mount points to attach engine/aircraft support accessories, including the engine mount points to the aircraft. The complexity in predicting AGB housing behavior under the gear loading, engine loading and engine induced vibration is one of the main challenges of designing a new gearbox with minimum weight. To address these issues, the current paper presents for the first time the design-analysis of a new lightweight AGB housing for a turboshaft engine, based on the following three major requirements: i) gear bearing pads strength & stiffness capability, ii) AGB mount pads (for accessories and for engine) load carrying capability, and, iii) vibratory response (mainly high cycle fatigue (HCF) response) of the AGB housing. A 3-D Finite Element Analysis (FEA) model of the AGB housing was developed using the proposed initial design. Various design modifications, involving several interrelated, iterative steps, were then carried out by adjusting and modifying the housing wall thickness, placement & sizes of internal ribs and external gussets, including additional geometric modifications to satisfy the design objectives. The result is a robust, lightweight AGB housing design, eliminating the need for some of the required testing for the qualification of the new gearbox, indicating a significant cost savings. This paper also discusses in detail the methodology for the gear bearing pad strength/stiffness calculation, the FEA modeling techniques for the application of mount loads and gear bearing loads under operating & flight maneuver conditions, and, a methodology for addressing a combined HCF & LCF (Low Cycle Fatigue) response of the housing.

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Low Cycle Fatigue Counter

Aircraft Engineering and Aerospace Technology ◽

10.1108/eb035637 ◽

1980 ◽

Vol 52 (6) ◽

pp. 21-22

Keyword(s):

Gas Turbine ◽

High Speed ◽

Low Cycle Fatigue ◽

Engine Performance ◽

Gas Turbine Engine ◽

Rotating Machinery ◽

Cycle Fatigue ◽

Turbine Engine ◽

On Demand ◽

Long Life

The modern aircraft gas turbine engine produces power on demand hour upon hour and day in, day out. It is one of the most extensively used types of high‐speed rotating machinery as well as one of the most efficient converters of fuel into thrust. Reliability and long life with minimum maintenance depend on efficient monitoring of engine performance and component status.

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