Global recharge of the martian hydrologic system has traditionally been viewed as occurring through basal melting of the south polar cap. We conclude that regional recharge of a groundwater system at the large volcanic provinces, Elysium and Tharsis, is also very plausible and has several advantages over a south polar recharge source in providing a more direct, efficient supply of water to the ...

the cracked brazilian disc (cbd) specimen is widely used in order to determine mode-i/ii and mixed-mode fracture toughness of a rock medium. in this study, the stress intensity factor (sif) on the crack-tip in this specimen is calculated for various geometrical crack conditions using the extended-finite element method (x-fem). this method is based upon the finite element method (fem). in this m...

Rolling contact fatigue tests on 100Cr6 steel were carried out with a ballon-rod tester. Microstructural damage was manifested by gradual hardness changes under the subsurface, and microcracks formed adjacent to inclusions; both being evidence of plastic deformation. The hardness increase appears to be due to the development of residual stress, while the microcracks form as a result of the conc...

Conventional material removal of BK7 optical glass will normally result in brittle fracture at the surface, generating severe subsurface damage and poor surface finish. Subsurface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. However, through ductile mode grinding it is possible to reduce the surface and subsurface cracks. It is m...

A solution is given for the elastic stress field in a half plane containing a plane crack parallel to the surface and subjected to a uniform normal pressure and a concentrated normal load. Frictional slip according to Coulomb's law is permitted between the crack faces. As the load is increased, a slip zone originates and grows either from a crack tip or from an intermediate point. Various arran...

This paper focuses on statistical methods for pre-processing, reconstructing and/or synthesizing hydro-meteorological time series and shrinkage crack aperture signals collected in the galleries of an Underground Research Laboratory in clay rock (Tournemire, France).

the prevalent method of irrigation in paddy fields in iran is continuous ponding, which changes to intermittent method at the time of water shortage. soil cracks are the main problem in intermittent irrigation. in this study, effects of adding rice straw on some soil physical characteristics and cracks were studied in paddy soils of the guilan province of iran. the experiment was performed as s...

This work demonstrates numerically how microplasticity, i.e. the yielding behavior below conventional 0.2% plastic strain threshold, can lead to initiation of cracks at subsurface defects, in rolling contact applications operating under realistic loads. A 3D elasto-plastic finite element model is employed perform shakedown analysis bearing steel around a small spherical void with two different ...

The high-cycle and very-high-cycle fatigue (VHCF) behavior of AlSi10Mg specimens manufactured by selective laser melting with different printing powder sizes was investigated. 20 ?m size contained more defects than those 50 size, the latter have a higher property former. Unmelted powders were detected as main source crack initiation. printed are likely to feature subsurface initiation in VHCF r...