Crack Initiation Process for Semicircular Notched Plate in Fatigue Test at Elevated Temperature

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Bopit Bubphachot ◽  
Osamu Watanabe ◽  
Nobuchika Kawasaki ◽  
Naoto Kasahara
Keyword(s):  
Elevated Temperature ◽  
Crack Initiation ◽  
Fatigue Test ◽  
Crack Initiation And Propagation ◽  
Coalescence Process ◽  
Notched Specimens ◽  
Locus Method ◽  
Initiation And Propagation ◽  
Concentration Test ◽  
Circular Notch

Crack initiation and propagation process of fatigue test in semicircular notched plates at elevated temperature were conducted under strain-controlled condition in order to study the crack initiation/propagation/coalescence process and load decrease in structure having stress concentration. Test specimens made of SUS304 stainless steel are tested at 550°C and the geometry of the semicircular notched plate specimens are changed by diameter size of the circular notch in both of single-notched specimens and double-notched specimens. Photographs in all cycles were recorded to investigate crack initiation/propagation/coalescence as a function of number of applied cycle. The typical crack process is predicted by using the simplified method, namely, stress redistribution locus method as well as Neuber’s formula.

Crack Initiation Process for Semi-Circular Notched Plate in Fatigue Test at Elevated Temperature

2008 ◽  
Author(s):  
Bopit Bubphachot ◽  
Osamu Watanabe ◽  
Nobuchika Kawasaki ◽  
Naoto Kasahara
Keyword(s):  
Elevated Temperature ◽  
Crack Initiation ◽  
Fatigue Test ◽  
Video Camera ◽  
Test Results ◽  
Structural Components ◽  
Crack Initiation And Propagation ◽  
Propagation Process ◽  
Initiation Process ◽  
Initiation And Propagation

Crack initiation and propagation process of fatigue test in semi-circular notched plates at elevated temperature were observed by the CCD video camera. Test specimens are made of SUS304 stainless steel, and temperature is kept to be 550°C, and geometry of semi-circular notched plate specimens are changed by diameter size of the circular hole. Photographs in all cycles were recorded to investigate crack initiation process in structural components having stress concentration and obtain number of cycle of crack initiation (Nc). The test results were compared with predictions by Stress Redistribution Locus (SRL) method and Neuber’s rule’s method.

Crack Initiation Process for Semi-Circular Notched Plate in Creep-Fatigue Test at Elevated Temperature

2008 ◽  
Author(s):  
Osamu Watanabe ◽  
Bopit Bubphachot ◽  
Nobuchika Kawasaki ◽  
Naoto Kasahara
Keyword(s):  
Stainless Steel ◽  
Elevated Temperature ◽  
Crack Initiation ◽  
Fatigue Test ◽  
Video Camera ◽  
Test Results ◽  
Crack Initiation And Propagation ◽  
Initiation Process ◽  
Initiation And Propagation ◽  
Creep Fatigue

Crack initiation and propagation in creep-fatigue test were observed on semi-circular notched plates at elevated temperature by the CCD video camera. Test specimens are made of SUS304 stainless steel, and temperature is kept to be 550°C, and geometry of the semi-circular plate specimens are changed by diameter size of the hole. Photographs of all cycles were recorded to investigate crack initiation process in structural component having stress concentration and obtain number of cycle of crack initiation (Nc). The test results were compared with predictions by the Stress Redistribution Locus (SRL) method and the Neuber’s rule’s method.

Notch Effect in Low-Cycle Fatigue at Elevated Temperatures—Life Prediction From Crack Initiation and Propagation Considerations

1986 ◽  
Vol 108 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Masao Sakane ◽  
Masateru Ohnami
Keyword(s):  
Crack Initiation ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Notch Effect ◽  
Cycle Fatigue ◽  
Crack Initiation And Propagation ◽  
Total Strain Range ◽  
Notched Specimens ◽  
Initiation And Propagation

This paper describes the notch effect in low-cycle fatigue of an austenitic stainless steel SUS 304 at 873 K in air. Total strain range-controlled tests were carried out using a round unnotched and three round notched specimens. A prediction method for low-cycle fatigue lives of notched specimens was developed by predicting the crack initiation and propagation periods separately. To predict the former Neuber’s rule was applied and a nominal stress/strain criterion was developed to predict the latter. Failure lives, obtained by adding the two prediction lives, closely agree with observed failure lives.

Acoustic Emission Behavior during Fatigue Crack of API5LX70 Gas Pipeline Steel

2011 ◽  
Vol 80-81 ◽  
pp. 148-152 ◽  
Author(s):  
M.F.M. Yusof ◽  
C.K.E. Nizwan ◽  
Nordin Jamaludin ◽  
S. Abdullah
Keyword(s):  
Acoustic Emission ◽  
Crack Initiation ◽  
Fatigue Test ◽  
Slip Plane ◽  
Pipeline Steel ◽  
Gas Pipeline ◽  
Crack Initiation And Propagation ◽  
Formation Stage ◽  
Initiation And Propagation ◽  
Propagation Stage

This paper present Acoustic Emission (AE) generated during fatigue mechanism of API5LX70 steel which was widely use as gas pipeline materials. Fully reverse (R=-1) constant amplitude fatigue test were done with four different stress amplitudes which were 437.5MPa, 406.25Mpa, 390.6MPa and 359.4MPa respectively. An observation from those tests shows that AE Count gives a significant value during cyclic softening and bauschinger effect. Crack initiation indicated by rapid increase of AE count values at positive peak stress and followed by high AE count values around zero stress which indicate crack closure phenomena. Among all four tests, it was show that AE activity from fatigue test with amplitude of 359.4MPa can be significantly divided into 3 region which correspond to crack incubation stage, microplastic and slip plane formation stage and crack initiation and propagation stage. Further analysis was done by separating AE signals from those 3 regions into 6 different groups. Ten AE signatures from each group were selected to calculate AE RMS and AE kurtosis. Analyses on AE RMS which correspond to overall energy of the signal were useful to indicate the microplastic and slip plane formation stage and crack initiation and propagation stage while AE kurtosis was useful in indicating crack stage including initiation, propagation and closure stage.

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