Continuous fatigue crack monitoring of bridges: Long-Term Electrochemical Fatigue Sensor (LTEFS)

2016 ◽  
Author(s):  
Monty A. Moshier ◽  
Levi Nelson ◽  
Ryan Brinkerhoff ◽  
Marybeth Miceli
Keyword(s):  
Fatigue Crack ◽  
Crack Monitoring ◽  
Fatigue Sensor

scholarly journals Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Iryna Danyliuk ◽  
Lyubomyr Poberezhnyi ◽  
Taras Pyrig ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Quantitative Analysis ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Fatigue Cracks ◽  
Preliminary Deformation ◽  
Term Operation ◽  
Steel Pipes

AbstractThe study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

A Novel Fatigue Crack Monitoring Method Based on Nonlinear Dynamic Characteristics of Strain

2019 ◽  
Vol 20 (01) ◽  
pp. 2050016
Author(s):  
Dong Yang ◽  
Dan Li ◽  
K. S. C. Kuang
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Real Time ◽  
Nonlinear Dynamic ◽  
Crack Opening ◽  
Steel Structures ◽  
Monitoring Method ◽  
Strain Measurements ◽  
Crack Monitoring

This paper presents a novel fatigue crack monitoring method for steel specimens based on the smoothness priors method (SPM) and Tsallis entropy (TE) of strain measurements. The aim of the study is to detect initiation of a crack in steel specimens and subsequently to monitor its propagation under the fatigue load, based on real-time strain measurements. The nonlinear dynamic response of the structure was exploited since it degrades due to the initiation and subsequent propagation of the crack under the external dynamic excitation. The proposed method was experimentally validated. Here, the SPM is applied to decomposing the structural strain response into a nearly-stationary (NS) component and a low frequency aperiodic trend (LFAT) component. Features associated with crack initiation can be extracted from the NS component. The LFAT component, on the other hand, can be used to identify crack propagation. To tackle the singularity of the structural responses associated with a crack, the TE of the NS component was used in detection and monitoring of the crack in the steel specimen. Two other techniques, namely, acoustic emission (AE) sensor and crack opening displacement (COD) gauge were used for the purpose of calibration and comparison. The results show remarkable resemblance in terms of crack initiation and propagation identification exhibited by all three types of sensors, highlighting the potential of the proposed method for real-time detection and subsequent monitoring of crack propagation in steel structures.

Kinetics of fatigue crack growth and crack closure effect in long term operating steel manufactured at the turn of the 19 th and 20 th centuries

2017 ◽  
Vol 185 ◽  
pp. 160-174 ◽  
Author(s):  
Grzegorz Lesiuk ◽  
Mieczysław Szata ◽  
José A.F.O. Correia ◽  
A.M.P. De Jesus ◽  
Filippo Berto
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Closure Effect ◽  
Kinetics Of

scholarly journals Degradation in Fatigue Crack Propagation Resistance of a Gas Turbine Vane after Long Term Service

2011 ◽  
Vol 278 ◽  
pp. 375-380
Author(s):  
Masakazu Okazaki ◽  
Motoki Sakaguchi ◽  
Yosuke Sasaki ◽  
Koichi Namba
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Gas Turbine ◽  
Fatigue Crack Propagation ◽  
Trailing Edge ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Turbine Vane ◽  
Edge Part

Degree of long term degradation damage of a retired gas turbine vane made of a Ni-based superalloy which had been operating for about 20000 hrs in a land-based gas turbine, was experimentally evaluated, through an assessment on the change in fatigue crack propagation resistance. For the purpose, a new testing apparatus has been developed to measure the local area fatigue crack propagation resistance, by extracting the miniature size compact tension specimens from the vane, where the specimens were extracted from the leading and the trailing edge, respectively. It was shown, the propagation rate of the crack that grew at the trailing edge part was significantly higher that that at the leading edge part. It was also shown that the crack propagation rates in the miniature specimen were generally higher than those in the standard size specimen. In order to explore an possibility to recover the degradation damage, the effect of a simple reheat treatment on the fatigue crack propagation resistance was also investigated

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