Practical Applications of Fracture Mechanics to Turbine Engine Rotors

1979 ◽  
pp. 273-302
Author(s):  
J. L. Price
Keyword(s):  
Fracture Mechanics ◽  
Turbine Engine ◽  
Practical Applications ◽  
Engine Rotors

An Application Oriented Gas Turbine Laboratory Experience

2004 ◽  
Author(s):  
Kenneth W. Van Treuren
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Data Set ◽  
Actual Performance ◽  
Turbine Engine ◽  
Practical Applications ◽  
Baylor University ◽  
And Performance ◽  
Technology Level

The gas turbine industry is experiencing growth in many sectors. An important part of teaching a gas turbine course is exposing students to the practical applications of the gas turbine. This laboratory proposes an opportunity for students to view an operating gas turbine engine in an aircraft propulsion application and to model the engine performance. A Pratt and Whitney PT6A-20 turboprop was run at a local airfield and engine parameters typical of cockpit instrumentation were taken. The students, in teams of two, then modeled the system using the software PARA and PERF in an attempt to match the manufacturer’s specifications. This laboratory required students to research the parameters necessary to model this engine that were not part of the data set provided by the manufacturer. The research and modeling encompassed areas such as technology level, efficiencies, fuel consumption, and performance. The end result was a two-page report containing the students’ calculations comparing the actual performance of the engine with the manufacturer’s specifications. Supporting graphs and figures were included as appendices. The same type laboratory could be adapted for co-generation gas turbines. Over 121 colleges and universities have co-generation facilities on campus and that presents a unique opportunity for the students to observe the operation of a land-based gas turbine used for power generation. A 5 MW TB5000 manufactured by Ruston (Alstom) Gas Engines is available on the Baylor University campus and is highlighted as an example. Potential problems encountered with using the Baylor University gas turbine are discussed which include lack of appropriate engine instrumentation.

Gas Turbine Engine Disk Retirement-for-Cause: An Application of Fracture Mechanics and NDE

1980 ◽  
Author(s):  
C. G. Annis ◽  
M. C. VanWanderham ◽  
J. A. Harris ◽  
D. L. Sims
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Cycle Cost ◽  
Energy Savings ◽  
Cost Savings ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Turbine Disks ◽  
Full Life ◽  
Engine Components

Historically, gas turbine engine disks are retired when they accrue an analytically determined lifetime where the first fatigue crack per 1000 disks could be expected. By definition then, 99.9 percent of these components are being retired prematurely. Retirement-for-Cause (RFC) is a procedure, based on Fracture Mechanics, which would allow safe utilization of the full life capacities of each individual disk. Since gas turbine disks are among the most costly of engine components, adopting a RFC philosophy could result in substantial systems life cycle cost savings. These would accrue from reduced replacement costs, conservation of strategic materials such as cobalt, and energy savings.

Three-Dimensional Structural Evaluation of a Gas Turbine Engine Rotor

2014 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Complex Geometries ◽  
Turbine Engine ◽  
Industrial Gas Turbine ◽  
Engine Rotor ◽  
Engine Rotors ◽  
Critical Locations

Engine rotors are one of the most critical components of a heavy duty industrial gas turbine engine, as it transfers mechanical energy from rotor blades to a generator for the production of electrical energy. In general, these are larger bolted rotors with complex geometries, which make analytical modeling of the rotor to determine its static, transient or dynamic behaviors difficult. For this purpose, powerful numerical analysis approaches, such as, the finite element method, in conjunction with high performance computers are being used to analyze the current rotor systems. The complexity in modeling bolted rotor behavior under various loadings, such as, airfoil, centrifugal and gravity loadings, including engine induced vibration is one of the main challenges of simulating the structural performance of an engine rotor. In addition, the internal structural temperature gradients that can be encountered in the transient state as a result of start-up and shutdown procedures are generally higher than those that occur in the steady-state and hence thermal shock is important factor to be considered relative to ordinary thermal stress. To address these issues, the current paper presents the steady-state & quasi-static analyses (to approximate transient responses) of two full 3-D industrial gas turbine engine rotors, SW501F & GE-7FA rotor, comprising of both compressor & turbine sections together. Full 3-D rotor analysis was carried out, since the 2-D axisymmetric model is inadequate to capture the complex geometries & out of plane behavior of the rotor. Both non-linear steady-state & transient analyses of a full gas turbine engine rotor was performed using the general purpose finite element analysis program ABAQUS. The paper presents in detail the FEA modeling technique, overall behavior of the full rotor under various loadings, as well as, the critical locations in the rotor with respect to its strength and life. The identification of these critical locations is needed to help with the repair of the existing rotors and to improve and extend the operational/service life of these rotors.

Damage Tolerance Based Life Prediction in Gas Turbine Engine Blades Under Vibratory High Cycle Fatigue

1997 ◽  
Vol 119 (1) ◽  
pp. 143-146 ◽  
Author(s):  
D. P. Walls ◽  
R. E. deLaneuville ◽  
S. E. Cunningham
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine ◽  
Aspect Ratios

A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a nonresonant mode, with one blade subjected to only the nonresonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution, which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

scholarly journals Damage Tolerance Based Life Prediction in Gas Turbine Engine Blades Under Vibratory High Cycle Fatigue

1995 ◽  
Author(s):  
David P. Walls ◽  
Robert E. deLaneuville ◽  
Susan E. Cunningham
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Resonant Mode ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine

A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a non-resonant mode, with one blade subjected to only the non-resonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

System Identification of Multistage Turbine Engine Rotors

2007 ◽  
Author(s):  
Sang Heon Song ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
System Identification ◽  
Operating Conditions ◽  
Response Analysis ◽  
Component Level ◽  
Modeling Framework ◽  
Turbine Engine ◽  
Reduced Order ◽  
Multistage Turbine ◽  
Systematic Identification ◽  
Engine Rotors

Recently, an efficient approach for modeling the vibration of multistage rotors was developed by the authors [1, 2]. This reduced-order modeling technique employs component mode synthesis, with each stage (bladed disk) treated as a separate component. In addition, the component mode mistuning (CMM) projection technique was extended to multistage systems. In the CMM method, individual blade mistuning is transformed from a basis of cantilevered blade modes to the basis of tuned system modes used for the reduced-order model. In this paper, the component-based modeling framework developed for mistuned multistage turbine engine rotors is utilized for system identification. First, the identification of multistage mode types is considered. Strain energy ratios are used to identify which system modes are confined to mostly one stage and which modes show strong coupling among multiple stages. Simple approximations for these ratios are derived based on data from the component-level free response analysis that are performed during the model construction process. The component-level results are also utilized to identify the dominant nodal diameter number for each multistage mode, even though the multistage system does not possess cyclic symmetry because the stages have different numbers of blades. Second, the modes are further classified as to how much the blades participate in the response relative to the disk for each stage. As a systematic identification procedure, this is applicable to single-stage models as well. For multistage systems, this is used to determine operating conditions where coupled response among blades on adjacent stages is most likely to occur. Third, the application of mistuning identification techniques to multistage systems is considered. It is found that the proposed modal classification methods allow the determination of conditions under which deviations in individual blade properties may be observed indirectly from measurements of the disks and spacer.

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