scholarly journals Growth behavior of small surface cracks in coarse and ultrafine grained copper

2009 ◽  
Author(s):  
M. Goto ◽  
S. Z. Han ◽  
Y. Ando ◽  
N. Kawagoishi ◽  
N. Teshima ◽  
...  
Keyword(s):  
Growth Behavior ◽  
Surface Cracks ◽  
Small Surface ◽  
Ultrafine Grained

A study on observation and growth behavior of small surface cracks by remote measurement system

KSME Journal ◽  
1996 ◽  
Vol 10 (4) ◽  
pp. 396-404 ◽  
Author(s):  
Seung Hoon Nahm ◽  
Hae Moo Lee ◽  
Chang Min Suh
Keyword(s):  
Measurement System ◽  
Growth Behavior ◽  
Remote Measurement ◽  
Surface Cracks ◽  
Small Surface

Fatigue Strength of Ultrafine Grained Copper Treated by Post-ECAP Mild Annealing

2011 ◽  
Vol 275 ◽  
pp. 23-26
Author(s):  
Masahiro Goto ◽  
Kazuya Nakashima ◽  
Seung Zeon Han ◽  
Yuji Yokoho ◽  
Kwang Jun Euh ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Annealing Treatment ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Growth Behavior ◽  
Surface Cracks ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Replication Technique

In order to study the effect of post-ECAP (equal channel angular pressing) mild annealing treatment on fatigue strength of ultrafine grained (UFG) copper, the stress-controlled fatigue tests of UFG copper with and without post-ECAP annealing treatment were performed for a wide range of fatigue life. The evolution of surface damage and growth behavior of surface cracks were monitored by plastic replication technique. The effect of post-ECAP annealing on the fatigue strength was discussed through the observation of changes in surface morphological features.

EXPERIMENTAL STUDY ON UNSATURATED DOUBLE-POROSITY SOIL PHENOMENA UNDER VIBRATION EFFECT

2017 ◽  
Vol 79 (4) ◽  
Author(s):  
Loke Kok Foong ◽  
Norhan Abd Rahman ◽  
Ramli Nazir
Keyword(s):  
Water Content ◽  
Soil Sample ◽  
Soil Structure ◽  
Double Porosity ◽  
Dominant Factor ◽  
Response Analysis ◽  
Surface Cracks ◽  
Ground Acceleration ◽  
Small Surface ◽  
Vibration Effect

A physical experiment approach was conducted to observe the deformation of double-porosity soil under vibration effect. The double-porosity soil characteristic was created using kaolin soil. An experiment on a soil sample fitted with accelerometer was conducted on a vibratory table to obtain peak ground acceleration and peak surface acceleration. After the vibration process, the deformable double-porosity soil was verified through field emission scanning electron microscopy tests. As seen in the microscope images, large surface cracks were observed due to the weakness of aggregated kaolin soil structure with its 25% water content. However, the 30% water content soil had small surface cracks due to its stronger soil structure. It was found that the deformable double-porosity soil had more fractured pores compared to the intact soil sample. From the acceleration response analysis, it was seen that both samples had amplification and dis-amplification shaking. In conclusion, the fractured double-porosity, as expected, has high permeability become a dominant factor in fluid migration. Meanwhile, the unconstrained soil and large fracture structure fabric showed significantly different porosity. The percentage of water content plays an important role in the structure of fractured double-porosity soil. 

scholarly journals Crack Growth Behavior in a Residual Stress Field for Vessel Type Structures

2003 ◽  
Author(s):  
P. Dong ◽  
G. Rawls
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Surface Crack ◽  
Growth Behavior ◽  
Welding Parameters ◽  
Crack Growth Behavior ◽  
Butt Weld ◽  
Small Surface ◽  
Longitudinal Residual Stress

Detailed residual stress analysis was performed for a multi-pass butt weld, representing the middle butt-girth weld of a storage tank. The analysis procedures addressed welding parameters, joint detail, weld pass deposition sequence, and temperature-dependent properties. The predicted residual stresses were then considered in stress intensity factor calculations using a three-dimensional finite element alternating model (FEAM) for investigating crack growth behavior for both small elliptical surface and through-wall cracks. Two crack orientations were considered: one is parallel to the vessel girth weld and the other is perpendicular to the girth weld. Since the longitudinal (parallel to weld) and transverse (perpendicular to weld) residual stresses exhibit drastically different distributions, a different crack growth behavior is predicted. For a small surface crack parallel to the weld, the crack tends to grow more quickly at the surface along the weld rather than into the thickness. The self-equilibrating nature of the transverse residual stress distribution suggests that a through-wall crack parallel to crack cannot be fully developed solely due to residual stress actions. For a crack that is perpendicular to the weld, a small surface crack exhibit a rapid increase in K at the deepest position, suggesting that a small surface crack has the propensity to become a through-wall crack. Once the through crack is fully developed, a significant re-distribution in longitudinal residual stress can be seen. As a result, in the absence of external loads there exists a limiting crack length beyond which further crack growth is deemed unlikely.

Nucleation and growth of small surface cracks in aluminium alloy AMg6 as related to discontinuity of the fatigue curve

1991 ◽  
Vol 13 (5) ◽  
pp. 370-376 ◽  
Author(s):  
N GRINBERG ◽  
V SERDYUK ◽  
A GAVRILYAKO ◽  
D LYCHAGIN ◽  
E KOZLOV
Keyword(s):  
Aluminium Alloy ◽  
Fatigue Curve ◽  
Nucleation And Growth ◽  
Surface Cracks ◽  
Alloy Amg6 ◽  
Small Surface
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