Environmental and Microstructural Influence on Fatigue Propagation of Small Surface Cracks

2009 ◽  
pp. 334-334-13 ◽  
Author(s):  
J Petit ◽  
A Zeghloul
Keyword(s):  
Surface Cracks ◽  
Small Surface

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 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

scholarly journals Energy Release Rate Approximation for Small Surface Cracks in Three-Dimensional Domains Using the Topological Derivative

2020 ◽  
Vol 87 (4) ◽  
Author(s):  
Kazem Alidoost ◽  
Meng Feng ◽  
Philippe H. Geubelle ◽  
Daniel A. Tortorelli
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Three Dimensional ◽  
Topological Derivative ◽  
Two Dimensional ◽  
Surface Cracks ◽  
Small Surface ◽  
Refined Meshes ◽  
Boundary Location

Abstract The topological derivative describes the variation of a response functional with respect to infinitesimal changes in topology, such as the introduction of an infinitesimal crack or hole. In this three-dimensional fracture mechanics work, we propose an approximation of the energy release rate field associated with a small surface crack of any boundary location, direction, and orientation combination using the topological derivative. This work builds on the work of Silva et al. (“Energy Release Rate Approximation for Small Surface-Breaking Cracks Using the Topological Derivative,” J. Mech. Phys. Solids 59(5), pp. 925–939), in which the authors proposed an approximation of the energy release rate field which was limited to two-dimensional domains. The proposed method is computationally advantageous because it only requires a single analysis. By contrast, current boundary element and finite element-based methods require an analysis for each crack length-location-direction-orientation combination. Furthermore, the proposed method is evaluated on the non-cracked domain, obviating the need for refined meshes in the crack tip region.

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