Dual Mode Sensing of Crack Growth in Steel Bridge Structures

2012 ◽  
Author(s):  
Lingyu Yu ◽  
Liuxian Zhao ◽  
Zhenhua Tian ◽  
Victor Giurgiutiu ◽  
Paul Ziehl
Keyword(s):  
Crack Growth ◽  
Damage Index ◽  
Fatigue Cracking ◽  
Fatigue Loading ◽  
Compact Tension ◽  
Crack Growth Behavior ◽  
Steel Bridge ◽  
Dual Mode ◽  
Laboratory Setup ◽  
Bridge Structures

Monitoring of fatigue cracking in steel bridge structures using a combined passive and active scheme has been approached by the authors. Passive acoustic emission (AE) monitoring is able to detect crack growth behavior by picking up the stress waves resulting from the breathing of cracks while active ultrasonic pulsing can quantitatively assess structural defect by sensing out an interrogating pulse and receiving the structural reflections. The dual-mode sensing functionality is pursued by using the R15I ultrasonic transducers. In the paper, we presented the subject dual-mode sensing on steel compact tension (CT) specimens in a laboratory setup. Passive AE sensing was performed during fatigue loading and showed its capability to detect crack growth and location. At selected intervals of loading cycles, the test was paused to allow for active sensing by pulsing the transducers in a round-robin pattern. Plate waves were excited, propagated and interacted within the structure. Several approaches were proposed to analyze the interrogation data and to correlate the data features with crack growth. Root means square deviation (RMSD) damage index (DI) was found as a good indicator for indicating the overall crack development. Short time Fourier transform (STFT) provided both time and frequency information at the same time. Moreover, wave velocity analysis showed interesting results when crack developed across the transmitter-receiver path.

The High Temperature Fatigue Behavior of Inconel-738LC Material Deposited Thermal Barrier Coating

2011 ◽  
Vol 264-265 ◽  
pp. 1409-1414
Author(s):  
Jung Hong Park ◽  
M.S. Ku ◽  
Jeong Suk Kim ◽  
K.H. Lee ◽  
Y.S. Song ◽  
...  
Keyword(s):  
Crack Growth ◽  
Thermal Barrier Coating ◽  
Thermal Fatigue ◽  
Fatigue Behavior ◽  
Compact Tension ◽  
Crack Growth Behavior ◽  
Thermal Barrier ◽  
Vacuum Plasma Spray ◽  
Barrier Coating ◽  
Inconel 738Lc

This work investigated the thermal fatigue behavior of Inconel-738LC material deposited thermal barrier coating by Vacuum Plasma Spray(VPS). The Inconel-738LC material which is widely used as a turbine parts is a CoNi-based superalloy with CoNiCrAlY bond coating and ZrO2-8wt%Y2O3 ceramic top coating. The microstructure of coating layer was analyzed by SEM/EDS and XRD. Thermal fatigue tests were performed using compact tension specimens at 550°C, 750°C, 950°C with the load frequency of 10Hz. The fatigue crack growth behavior was characterized depending on number of cycles. The crack growth rate was found to be greater at lower frequency and higher temperature.

Experimental and Numerical Investigation of Plasticity-Induced Fatigue Crack Closure in Overmatched Welds

2013 ◽  
Author(s):  
Diego F. B. Sarzosa ◽  
Claudio Ruggieri
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Compact Tension ◽  
Cyclic Stress ◽  
Growth Behavior ◽  
Weld Strength ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior

This work provides a numerical and experimental investigation of fatigue crack growth behavior in steel weldments including crack closure effects and their coupled interaction with weld strength mismatch. A central objective of this study is to extend previously developed frameworks for evaluation of crack closure effects on fatigue crack growth rates (FCGR) to steel weldments while, at the same time, gaining additional understanding of commonly adopted criteria for crack closure loads. Very detailed non-linear finite element analyses using 3-D models of compact tension C(T) fracture specimens with square groove, weld centerline cracked welds provide the evolution of crack growth with cyclic stress intensity factor which is required for the estimation of the closure loads. Fatigue crack growth tests conducted on plane-sided, shallow-cracked C(T) specimens provide the necessary data against which crack closure effects on fatigue crack growth behavior can be assessed. Overall, the present investigation provides additional support for estimation procedures of plasticity-induced crack closure loads in fatigue analyses of structural steels and their weldments.

scholarly journals Crack Growth Behavior of Additively Manufactured 316L Steel – Influence of Build Orientation and Heat Treatment

2020 ◽  
Author(s):  
Janusz Kluczynski ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Janusz Torzewski ◽  
Ireneusz Szachogłuchowicz ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Additive Manufacturing ◽  
Crack Growth ◽  
Rolling Direction ◽  
Fatigue Cracking ◽  
Growth Behavior ◽  
Fatigue Properties ◽  
Crack Growth Behavior ◽  
Build Orientation ◽  
Precipitation Heat

The effects of build orientation and heat treatment on the crack growth behavior of 316L stainless steel (SS) fabricated via a selective laser melting (SLM) additive manufacturing process were investigated. Significant growth of available research results of additively manufactured metallic parts still needs to be improved. The most important issue connected with properties after additive manufacturing is properties high anisotropy, especially from the fatigue point of view. The research included crack growth behavior of additively manufactured 316L in comparison to conventionally made reference material. Both groups of samples were obtained using precipitation heat treatment. Different build orientation in additively manufactured samples and rolling direction in reference samples were taken into account as well. Precipitation heat treatment of additively manufactured parts allowed to reach similar microstructure and tensile properties to elements conventionally made. The heat treatment positively affected fatigue properties. Additionally, precipitation heat treatment of additively manufactured elements significantly affected the reduction of fatigue cracking velocity and changed the fatigue cracking mechanism.

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