scholarly journals Design of experiments for verification of computational life prediction methods

2019 ◽  
Vol 18 (3) ◽  
pp. 143-154
Author(s):  
O. V. Samsonova ◽  
K. V. Fetisov ◽  
I. V. Karpman ◽  
I. V. Burtseva
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Engines ◽  
Prediction Methods ◽  
Gas Turbine Engines ◽  
Loading Conditions ◽  
Load History ◽  
Strain Behavior ◽  
Before And After ◽  
Two Stages

The failure of heavily loaded rotating parts of aviation gas turbine engines may bring about dangerous consequences. The life of such parts is limited with the use of computational and experimental methods. Computational life prediction methods that are used without carrying out life-cycle tests of engine parts or assemblies should be substantiated experimentally. The best option for verifying the computational methods is to use the results of cyclic tests of model disks. These tests make it possible to reproduce loading conditions and surface conditions that correspond to those of real disks, and the data on the load history and material properties make it possible to simulate stress-strain behavior of disks under test conditions by calculation. This paper shows the process of planning such tests. It is assumed that the tests will be carried out in two stages - before and after the initiation of a low-cycle fatigue crack. A number of criteria are formulated that the geometry of model disks and their loading conditions are to satisfy. Based on these criteria, model disks were designed and the conditions for their testing were selected.

Engine Test Experience and Characterization of Self Sealing Ceramic Matrix Composites for Nozzle Applications in Gas Turbine Engines

2003 ◽  
Author(s):  
Eric P. Bouillon ◽  
Patrick C. Spriet ◽  
Georges Habarou ◽  
Thibault Arnold ◽  
Greg C. Ojard ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Matrix Composites ◽  
Gas Turbine Engines ◽  
Sic Fiber ◽  
Engine Testing

Advanced materials are targeting durability improvement in gas turbine engines. One general area of concern for durability is in the hot section components of the engine. Ceramic matrix composites offer improvements in durability at elevated temperatures with a corresponding reduction in weight for nozzles of gas turbine engines. Building on past material efforts, ceramic matrix composites using a carbon and a SiC fiber with a self-sealing matrix have been developed for gas turbine applications. Prior to ground engine testing, a reduced test matrix was undertaken to aggressively test the material in a long-term hold cycle at elevated temperatures and environments. This tensile low cycle fatigue testing was done in air and a 90% steam environment. After completion of the aggressive testing effort, six nozzle seals were fabricated and installed in an F100-PW-229 engine for accelerated mission testing. The C fiber CMC and the SiC Fiber CMC were respectively tested to 600 and 1000 hours in accelerated conditions without damage. Engine testing is continuing to gain additional time and insight with the objective of pursuing the next phase of field service evaluation. Mechanical testing and post-test characterization results of this testing will be presented. The results of the engine testing will be shown and overall conclusions drawn.

Swedish Navy YS2000 Visby Class Propulsion System Refinements

2006 ◽  
Author(s):  
Kenneth M. Braccio ◽  
Joe Ranero ◽  
Peter B. Nilsson ◽  
Magnus Olsson ◽  
Gerrick Slogar
Keyword(s):  
Power Systems ◽  
Gas Turbines ◽  
Propulsion System ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
Enlisted Men ◽  
Engine Room ◽  
Before And After ◽  
Areas Of Interest

The YS2000 program is a 73 meter length and 10.5 meter width all composite Corvette class vessel. It displaces 640 metric tons when fully equipped and drafts 2.5 meters. It is to be crewed by 18 officers and 25 enlisted men. It is a CODOG propulsion system supplied by Vericor Power Systems, with two MTU 16V 2000 M90 diesels and four TF50A gas turbine engines. Both the diesels and gas turbines are connected to a pair of MA-107 SBS gearboxes that run two 125 SII KaMeWa waterjets. The Visby is designed to be difficult to detect by enemy using radar, infrared, hydro-acoustic monitoring or any other sensor system. The Visby has been in development In Sweden since 1999. To date, four craft have been constructed and sea trailed out of the five totals. The fifth ship is on schedule to complete construction and sea trials later in the 2006 year. Many refinements to the overall propulsion package and related supporting systems have been incorporated since the first ship “Visby” has been sea trailed and since put in service. This paper will review various areas of the propulsion package, explaining the challenges that had to be overcome. The areas of interest will include: the FADEC digital engine control, the exhaust & inlet systems, the turbine engine and starting system, engine room cooling and turbine engine enclosures. The paper will focus on some of the before and after results and attempts to highlight the specific challenges that had to be overcome.

scholarly journals The LCF Behavior of Several Solid Solution Strengthened Alloys Used in Gas Turbine Engines

1990 ◽  
Author(s):  
S. K. Srivastava ◽  
D. L. Klarstrom
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Alloy 617 ◽  
Total Strain Range ◽  
Test Conditions ◽  
Fatigue Characteristics

LCF tests were performed on production plate (16mm thick) materials of HAYNES® alloy No. 230, HASTELLOY® alloy X and INCONEL® alloy 617. The tests were conducted in air at 760, 871 and 982°C under the fully reversed strain controlled mode on materials in the annealed condition. The results showed that 230™ alloy possesses the best low cycle fatigue characteristics followed by alloy X and alloy 617 under all test conditions. The paper presents total strain range-life data, cyclic hardening/softening, and metallographic observations on selected failed samples. It is shown that oxidation plays a key role in fatigue-crack initiation in alloy 617.

Straight-Build Assembly Optimization: A Method to Minimize Stage-by-Stage Eccentricity Error in the Assembly of Axisymmetric Rigid Components (Two-Dimensional Case Study)

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
T. Hussain ◽  
Z. Yang ◽  
A. A. Popov ◽  
S. McWilliam
Keyword(s):  
Central Axis ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axis Ii ◽  
Straight Line ◽  
Third Stage ◽  
Assembly Procedure ◽  
Two Stages ◽  
Eccentricity Error

For assembly of rotating machines, such as machining tools, industrial turbomachinery, or aircraft gas turbine engines, parts need to be assembled in order to avoid internal bending of the geometric axis of the rotor to meet functional and vibration requirements. Straight-build assembly optimization is a way of joining parts together in order to have a straight line between the centers of the components. Straight-build assembly is achieved by minimizing eccentricity error stage-by-stage in the assembly. To achieve minimal eccentricity, this paper proposes three assembly procedures: (i) table-axis-build assembly by minimizing the distances from the centers of components to table axis; (ii) minimization of the position error between actual and nominal centers of the component; and (iii) central-axis-build assembly by minimizing the distances from the centers of components to a central axis. To test the assembly procedures, two typical assembly examples are considered using four identical rectangular components and four nonidentical rectangular components, respectively. Monte Carlo simulations are used to analyze the tolerance build-up, based on normally distributed random variables. The results show that assembly variations can be reduced significantly by selecting best relative orientation between mating parts. The results also show that procedures (i) and (ii) have the most potential to minimize the error build-up in the straight build of an assembly. For these procedures, the variation is reduced by 45% and 40% for identical and nonidentical components, respectively, compared to direct-build assembly. Procedure (iii) provides better performance than direct-build assembly for identical components assembly, while it gives smaller variation at the first two stages and larger variation at the third stage for nonidentical components assembly. This procedure could be used in an assembly with limited stages.

EFFECT OF CASTING DEFECT ON MECHANICAL PROPERTIES OF 17-4PH STAINLESS STEEL

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4463-4468
Author(s):  
JONG-YUP KIM ◽  
JOON-HYUN LEE ◽  
SEUNG-HOON NAHM
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Stainless Steel ◽  
Gas Turbine ◽  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Turbine Engines ◽  
Casting Defects ◽  
Gas Turbine Engines ◽  
Proportional Relationship

Damage and integrity evaluation techniques should be developed steadily in order to ensure the reliability and the economic efficiency of gas turbine engines. Casting defects may exist in most casting components of gas turbine engines, and the defects could give serious effect on mechanical properties and fracture toughness. Therefore, it is very important to understand the effect of casting defects on the above properties in order to predict the safety and life of components. In this study, specimens with internal casting defects, made from 17-4PH stainless steel, were prepared and evaluated and characterized based on the volume fraction of defects. The relation between mechanical properties such as tensile, low cycle fatigue and fracture toughness and volume fraction of defect has been investigated. As a result of the analysis, the mechanical properties of 17-4PH decreased as the defect volume fraction increased with very good linearity. The mechanical properties also showed an inversely proportional relationship to electrical resistivity.

Coating Pre-Cracking Effect in Combined Cycle Fatigue Tests of Superalloys for Gas Turbine Blades

2010 ◽  
Author(s):  
Mauro Filippini ◽  
Stefano Foletti ◽  
Giuseppe Pasquero
Keyword(s):  
Gas Turbine ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Nickel Superalloy ◽  
Combined Cycle ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cycle Fatigue ◽  
Polycrystalline Nickel

In gas turbine engines for aerospace propulsion, the application of coatings on HP and LP stage blading where the highest temperatures are experienced is a common practice to prevent environmental degradation. However, since the strength of the coating is lower than that of the substrate material, upon loading the static strength of the coating may be exceeded and coating cracking may occur. In order to assess the effect of cracking in the coating on polycrystalline nickel superalloy MAR-M002, a number of combined cycle fatigue (CCF) and low cycle fatigue (LCF) tests with and without dwell have been carried out, at temperatures up to 870 °C. In order to experimentally assess the potential detrimental effect of coating cracking, controlled cracking in the coating prior to fatigue testing has been generated by using a special procedure. CCF tests have carried out by superimposing to strain controlled zero to maximum LCF cycles with dwell time stress controlled smaller HCF cycles, simulating the high loading ratio vibrations occurring in the blades. The loading mode applied in the CCF tests, even if much simpler than effective service conditions, is sufficiently representative of the loading experienced by the materials in correspondence of critical geometrical features of the turbine blades, where HCF amplitudes due to blade vibrations are superimposed to major (ground-air-ground) LCF cycles occurring during the regular service of the gas turbine engines. Comparison of the CCF and of the LCF tests with dwell with conventional LCF tests is presented herein, with special consideration of the effect of coating cracking.

On the Accuracy of Rolling Bearing Fatigue Life Prediction

1996 ◽  
Vol 118 (2) ◽  
pp. 297-309 ◽  
Author(s):  
T. A. Harris ◽  
J. I. McCool
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Prediction Method ◽  
Rolling Bearing ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Critical Design ◽  
Bearing Life ◽  
Limit Stress ◽  
Fatigue Endurance

Ball and roller bearings are designed to meet endurance requirements basically determined according to the Standard fatigue life calculation method. This method is based on the Lundberg-Palmgren fatigue life theory as modified by reliability, material, and lubrication factors. As application load and spied requirements have increased, the Lundberg-Palmgren method has resulted in bearings of increased size, adding unnecessarily to the size and weight of mechanisms. This is a critical design situation for weight and size-sensitive components such as aircraft gas turbine engines and helicopter power transmissions. The bearing life prediction method developed by Ioannides and Harris recognizes the existence of a fatigue limit stress. If the stresses an operating bearing experiences do not exceed the limit stress, the bearing can achieve infinite life. In any case, the method tends to predict longer lives than the Lundberg-Palmgren method. This paper evaluates the life prediction accuracies of the Lundberg-Palmgren and Ioannides-Harris methods by comparing lives calculated according to these methods and to those actually experienced in 62 different applications. As a result of the investigation, the Ioannides-Harris method is shown to more accurately predict bearing fatigue endurance.

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