scholarly journals An efficient electromagnetic and thermal modelling of eddy current pulsed thermography for quantitative evaluation of blade fatigue cracks in heavy-duty gas turbines

2020 ◽  
Vol 142 ◽  
pp. 106781 ◽  
Author(s):  
Zongfei Tong ◽  
Shejuan Xie ◽  
Haochen Liu ◽  
Weixu Zhang ◽  
Cuixiang Pei ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Eddy Current ◽  
Gas Turbines ◽  
Fatigue Cracks ◽  
Thermal Modelling ◽  
Heavy Duty ◽  
Pulsed Thermography

An Integrated Approach With Innovative NDTS for Thermal Barrier Coating Assessment: Optical and Frequency Scanning Eddy Current Testing (F-SECT) Combination With Pulsed Thermography

2006 ◽  
Author(s):  
Claudia Rinaldi ◽  
Letizia de Maria ◽  
Federico Cernuschi ◽  
Giampiero Antonelli
Keyword(s):  
Eddy Current ◽  
Gas Turbines ◽  
Current System ◽  
Field Measurements ◽  
Integrated Approach ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Pulsed Thermography ◽  
Damage Level ◽  
The Right

The components of the hot gas path in gas turbines can survive to very high temperatures because they are protected by ceramic Thermal Barrier Coatings (TBC); the failure of such coatings can dramatically reduce the component life. A reliable assessment of the Coating integrity and/or an Incipient TBC Damage Detection can help both in optimising the inspection intervals and in finding the appropriate remedial actions. In this paper the potential of three different NDT techniques applicable to the metallo/ceramic coatings of hot parts are discussed in the light of both results obtained on laboratory aged specimens and in field measurements on operated components. An investigation of the NDTs capability to detect damage evolution was performed on thermal-cycled specimens coated with TBC (both EB-PVD and pseudocolumnar APS) by means of an F-SECT eddy current system, by an innovative portable Piezospectroscopic system and by pulsed thermography. The observation of metallographic sections of the thermal cycled specimens allowed to give the right interpretation to the results of each NDT methodology and enlightened its specific characteristics and potentiality. Moreover in field applicability is discussed for each technique. Finally it is shown how an integrated approach of suitable coating evolution models and complimentary NDT techniques can provide an interesting assessment of the damage level of the metallo/ceramic coatings of operated rotating blades.

Analysis of field uniformity and quantitative evaluation of subsurface pitting corrosion in conductors via GPEC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 19-29
Author(s):  
Shuting Ren ◽  
Yong Li ◽  
Bei Yan ◽  
Jinhua Hu ◽  
Ilham Mukriz Zainal Abidin ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Eddy Current ◽  
Pitting Corrosion ◽  
Gradient Field ◽  
Uniform Field ◽  
Eddy Current Method ◽  
Optimal Position ◽  
Pulsed Eddy Current ◽  
Field Uniformity ◽  
Processing Algorithms

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.

Detection of internal defects in CFRP strengthened steel structures using eddy current pulsed thermography

2021 ◽  
Vol 282 ◽  
pp. 122642 ◽  
Author(s):  
Jing Xie ◽  
Changwei Wu ◽  
Lemei Gao ◽  
Changhang Xu ◽  
Yinsheng Xu ◽  
...  
Keyword(s):  
Eddy Current ◽  
Steel Structures ◽  
Internal Defects ◽  
Pulsed Thermography

scholarly journals The durability of flexible eddy current array (FECA) sensors in harsh service environments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yujian Song ◽  
Tao Chen ◽  
Ronghong Cui ◽  
Yuting He ◽  
Xianghong Fan ◽  
...  
Keyword(s):  
Eddy Current ◽  
Fatigue Cracks ◽  
Radiation Environment ◽  
The Finite Element Method ◽  
Integrated Sensor ◽  
High Durability ◽  
Vibration Experiment ◽  
Service Environments ◽  
Salt Fog Corrosion ◽  
Salt Fog

AbstractSensors for structural health monitoring (SHM) need to be permanently integrated on structures and withstand the harsh service environments, which has been a big challenge for the application of SHM in aircrafts. This paper focuses on the durability of flexible eddy current array (FECA) sensors in harsh service environments of aircrafts, including vibration environment and several typical exposed environments. First, a kind of FECA sensor is illustrated and its integration method is proposed. Moreover, in order to study the durability of the sensor in vibration environment, the modal analysis is performed by the finite element method. According to the simulation results, the durability experiment in vibration environment is carried out under the fourth order vibration mode, which makes the sensor suffer the harshest vibration loads. During the vibration experiment, output signals of the sensor keep stable and the sensor is well bonded to the structure, which shows the integrated sensor has high durability in vibration environment. Finally, the durability of integrated sensors is separately tested in three exposed environments, including salt fog corrosion environment, fluid immersion environment, as well as hygrothermal and ultraviolet-radiation environment. After these environmental exposure experiments, all sensors are well bonded to structures and can effectively monitor fatigue cracks, which shows great durability. Therefore, FECA sensors can survive in harsh service environments of aircrafts, which provides important support for the engineering applications of FECA sensors.

scholarly journals Investigation of Failure in Gas Turbines: Part 2 — Engineering and Metallographic Aspects of Failure Investigation

1993 ◽  
Author(s):  
Robert E. Dundas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Heavy Duty ◽  
Metallographic Examination ◽  
Fracture Surfaces ◽  
Failure Investigation ◽  
Materials Used ◽  
Component Failures

This paper opens with a discussion of the various mechanisms of cracking and fracture encountered in gas turbine failures, and discusses the use of metallographic examination of crack and fracture surfaces. The various types of materials used in the major components of heavy-duty industrial and aeroderivative gas turbines are tabulated. A collection of macroscopic and microscopic fractographs of the various mechanisms of failure in gas turbine components is then presented for reference in failure investigation. A discussion of compressor damage due to surge, as well as some overall observations on component failures, follows. Finally, a listing of the most likely types of failure of the various major components is given.

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