Equivalent Initial Flaw Size Distribution Determination for Gas Turbine Blades Based Upon Inspection Data

2005 ◽  
Author(s):  
W. S. Johnson ◽  
A. C. Wilson ◽  
S. Highsmith
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
Turbine Blades ◽  
Flaw Size ◽  
Fatigue Life Prediction ◽  
Gas Turbine Blades ◽  
Critical Components ◽  
Inspection Data ◽  
Industrial Gas Turbine

A fracture mechanics-based methodology is presented for determining equivalent initial flaw size (EIFS) distributions from field inspection data accounting for different service histories of fracture critical components. The EIFS distribution based on inspection data from a subset of the fleet allows for an assessment of initial material/manufacturing quality and enables a probabilistic fracture mechanics-based fatigue life prediction for the fleet as a whole. The methodology is demonstrated on an industrial gas turbine blade experiencing in-service cracking.

Acoustic Thermography Testing of Industrial Gas Turbine Blades in the Service Stage

2008 ◽  
Author(s):  
Mattias Broddega˚rd ◽  
Christian Homma
Keyword(s):  
Gas Turbine ◽  
Test Object ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Medium Size ◽  
Testing Time ◽  
Testing Technique ◽  
Ir Camera ◽  
Gas Turbine Blades ◽  
Industrial Gas Turbine

Gas turbine blades are operating under very demanding conditions. In modern industrial gas turbines, the rotating blades and the guide vanes of the first stages are hollow to allow internal cooling. This means that there is a possibility of having crack initiation on the internal surface of the components. Due to the complex casting geometry, this type of defects is very difficult to detect with conventional nondestructive testing techniques such as ultrasonic and radiographic testing. Siemens has developed a new non-destructive testing technique based on acoustic thermography, SIEMAT. The test object is energized by an ultrasonic excitation device. Due to the vibrations, a very slight heating will develop at cracks in the test object. The local increase of temperature is captured by a highly sensitive IR camera. The SIEMAT technique is capable of detecting both surface-breaking and internal cracks, including cracks under coatings. The testing time is very short, and the IR sequences are recorded for subsequent analysis. A major advantage for service applications is that the technique is mostly sensitive to closed defects such as cracks, since open defects where no contact between the faces is present, for example pores and scratch marks, will not cause any heat generation. Siemens is currently implementing the SIEMAT technique for assessment of service-exposed turbine blades from medium size gas turbines, which are due for reconditioning. By being able to verify that no internal cracks are present, the reliability of the reconditioned blades will be increased. This paper describes the SIEMAT testing technique, and the results obtained when applied on service-exposed industrial gas turbine blades.

Small-scale specimen testing for fatigue life assessment of service-exposed industrial gas turbine blades

2016 ◽  
Vol 92 ◽  
pp. 262-271 ◽  
Author(s):  
D. Holländer ◽  
D. Kulawinski ◽  
A. Weidner ◽  
M. Thiele ◽  
H. Biermann ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Life Assessment ◽  
Small Scale ◽  
Gas Turbine Blades ◽  
Fatigue Life Assessment ◽  
Industrial Gas Turbine
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