Structural Analysis and Life Prediction for Ceramic Gas Turbine Components for the Mercedes-Benz Research Car 2000

1986 ◽  
Author(s):  
H. Hempel ◽  
H. Wiest
Keyword(s):  
Gas Turbine ◽  
Life Prediction ◽  
Subcritical Crack Growth ◽  
Time Dependent ◽  
Relative Importance ◽  
3 Dimensional ◽  
Ceramic Components ◽  
Dimensional Finite Element ◽  
Ceramic Design ◽  
Load Conditions

The paper considers the design and the application of ceramic components in a high temperature gas turbine, which is being developed as an alternative for passenger-car propulsion. Silicon nitride turbine wheels were analyzed using 3-dimensional finite element methods. Calculations of temperatures and stresses were carried out for several steady-state and transient load conditions. Time dependent reliability was also computed using the theory of Weibull including subcritical crack growth. The results of these calculations are presented and discussed. The basic theory for ceramic life prediction methodology is reviewed, including the relative importance of various parameters. From the results, conclusions are derived for ceramic design. Finally some operating-experiences of ceramic turbine wheels are reported.

Lifetime Prediction for Ceramic Gas Turbine Components

1993 ◽  
Vol 115 (1) ◽  
pp. 70-75 ◽  
Author(s):  
G. Stu¨rmer ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Gas Turbine ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Operation Time ◽  
Computer Code ◽  
Experimental Investigations ◽  
Ceramic Components ◽  
Stress States ◽  
Dependent Failure ◽  
Failure Probabilities

At the Institute for Thermal Turbomachinery, University of Karlsruhe (ITS), theoretical and experimental investigations of ceramic gas turbine components are performed. For the reliability analysis by finite element calculations the computer code CERITS has been developed. This code is used to determine the fast fracture reliability of ceramic components subjected to polyaxial stress states with reference to volumetric flaws and was presented at the 1990 IGTI Gas Turbine Conference. CERITS-L now includes subcritical crack growth. With the new code CERITS-L, failure probabilities of ceramic components can be calculated under given load situations versus time. In comparing these time-dependent failure probabilities with a given permissible failure probability, the maximum operation time of a component can be determined. The considerable influence of the subcritical crack growth upon the lifetime of ceramic components is demonstrated at the flame tube segments of the ITS ceramic combustor.

Life Time Prediction for Ceramic Gas Turbine Components

1991 ◽  
Author(s):  
G. Stürmer ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Gas Turbine ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Operation Time ◽  
Life Time ◽  
Computer Code ◽  
Experimental Investigations ◽  
Ceramic Components ◽  
Stress States ◽  
Failure Probabilities

At the Institute for Thermal Turbomachinery, University of Karlsruhe (ITS), theoretical and experimental investigations on ceramic gas turbine components are performed. For the reliability analysis by finite element calculations the computer code CERITS has been developed. This code is used to determine the fast fracture reliability of ceramic components subjected to polyaxial stress states with reference to volumetric flaws and was presented at the 1990 IGTI Gas Turbine Conference. CERITS-L now includes subcritical crack growth. With the new code CERITS-L, failure probabilities of ceramic components can be calculated under given load situations versus time. In comparing these time dependent failure probabilities with a given permissible failure probability, the maximum operation time of a component can be determined. The considerable influence of the subcritical crack growth upon the life time of ceramic components is demonstrated at the flame tube segments of the ITS ceramic combustor.

The Microstructure and Mechanical Properties of Ni-Based Superalloy after Service Exposure in Gas Turbine

2010 ◽  
Vol 654-656 ◽  
pp. 2523-2526 ◽  
Author(s):  
Keun Bong Yoo ◽  
Han Sang Lee
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Mechanical Tests ◽  
Time Dependent ◽  
Second Stage ◽  
Degradation Analysis ◽  
Check Points ◽  
Tcp Phase ◽  
Service Exposure ◽  
High Temperature Tensile

Many investigations about superalloys and coatings have been done in the laboratory, but evaluating the degradation condition of hot section components during service is still important not only for repair and reuse but also for outage prevention. Time dependent degradation for second stage blades of gas turbine was investigated. The degradation analysis for used blades was divided into microstructure changes by position of the blade and mechanical tests of high temperature tensile test. In the microstructure analysis, the rafting and coarsening of γ', MC decomposition and TCP phase formation occurred and progressed with increasing service time, and especially the leading and trailing edge of top layer should be a check points for used blade. High temperature tensile results of 25,000 and 52,000 hrs used blades were also compared with serviced time and position in each blade.

Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures

2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Thermal Changes ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Back Action ◽  
Aggressive Effect

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.

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