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.

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.

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.

Engineering Approach to Weld Repairs for Bogie (Truck) Frames

2012 ◽  
Author(s):  
John B. Pearson ◽  
John A. Janiszewski ◽  
Travis M. Nelson
Keyword(s):  
Crack Initiation ◽  
Stress Analysis ◽  
Service Time ◽  
Dynamic Loads ◽  
Structural Components ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Operating Lifetime ◽  
Static And Dynamic Loads ◽  
Induced Defects

As welded rail car truck (bogie) frames become more common than cast frames and as they accumulate more service time and mileage, increasing numbers of service-induced defects are bound to occur. Some items requiring repair or rehabilitation include cracks, accident damage, excessively worn surfaces, and modifications for addition of equipment or mounting brackets. Bogie frames are structural components exposed to severe static and dynamic loads and hence repairs and modifications must consider all aspects of performance. This paper reviews a methodology used by LTK Engineering Services to determine root causes of service-induced defects and to subsequently qualify repairs and modifications to allow the bogie frames to meet their design operating lifetime. The method includes analyses of both the material and the failure itself, to confirm the adequacy of the frame material and to identify the design or fabrication factor(s) contributing to the development of cracks. Stress analysis of varying complexity is utilized to confirm the crack initiation and propagation causes as well as to screen potential repair approaches.

Crack Initiation/Propagation of Perforated Plate Under Displacement-Controlled Fatigue Test at Elevated Temperature

2011 ◽  
Author(s):  
Osamu Watanabe ◽  
Taisuke Akiyama ◽  
Akihiro Matsuda
Keyword(s):  
Stress Concentration ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Test ◽  
Perforated Plate ◽  
Test Results ◽  
Multiple Origins ◽  
Initiation And Propagation ◽  
Estimation Scheme ◽  
Different Diameters

In structures having stress concentration under cyclic loading, a small crack initiates and it grows and propagates. The present paper shows the experimental results of the perforated plate having the different diameters and the prescribed different strain amplitude. In the specimens having a circular hole, a crack initiates at the hole side having the most severe stress concentration in the specimen, and then the other crack also starts to initiate at the opposite hole side. Growth of both cracks is observed from the photographs taken at each cycle to study the relation between crack growth and load decrease. The feature of crack growth initiating from multiple origins will be discussed for fatigue test. The crack initiation is evaluated by referring to the accumulation law using the simplified estimation scheme, and the crack growth is evaluated by referring the increment of J-Integral. The agreement for crack initiation and propagation with these test results will be discussed.

Sign in / Sign up

Export Citation Format

Share Document