Due to its popularity and high crack sensitivity, 6061 aluminum alloy was selected as a test material for the newly developed double-sided arc welding (DSAW) process. The microstructure, crack sensitivity, and porosity of DSAW weldments were studied systematically. The percentage of fine equiaxed grains in the fully penetrated welds is greatly increased. Residual stresses are reduced. Porosity ...

The residual porosity is an unavoidable phenomenon of the components produced by powder metallurgy process which in turn largely affects the strength property of the same. Now a day it is possible to control porosity of powder metallurgy components and retain them to desired amount when required. The porosity of a powder metallurgy component is greatly depends on the sintering temperature. In t...

The main aim of this survey paper is to give basic information about properties and applications of σ-porous sets in Banach spaces (and some other infinite-dimensional spaces). This paper can be considered a partial continuation of the author’s 1987 survey on porosity and σ-porosity and therefore only some results, remarks, and references (important for infinite-dimensional spaces) are repeated...

The effects of a porous fence with a nonuniform porosity on flow fields are investigated numerically. First, an experiment with a non-uniform porous fence located in a wind tunnel is performed to obtain a reference data set. Then, a numerical model that utilizes the finite volume schemewith a weakly compressible-flowmethod to solve the continuity and momentum equations is developed. The numeric...

To unravel how the microstructure affects the fracture surface roughness in heterogeneous brittle solids like rocks or ceramics, we characterized the roughness statistics of postmortem fracture surfaces in homemade materials of adjustable microstructure length scale and porosity, obtained by sintering monodisperse polystyrene beads. Beyond the characteristic size of disorder, the roughness prof...

Context. In the framework of the coagulation scenario, kilometre-sized planetesimals form by subsequent collisions of preplanetesimals of sizes from centimetre to hundreds of metres. Pre-planetesimals are fluffy, porous dust aggregates, which are inhomogeneous owing to their collisional history. Planetesimal growth can be prevented by catastrophic disruption in pre-planetesimal collisions above...

Monolithic aerogels of high molecular weight polyethylene (Mw= 3x106- 6x106 g/mol) have been prepared by solvent extraction with supercritical carbon dioxide from thermoreversible gels prepared in decalin. These low density and highly porous aerogels present an apparent porosity up to 90%. The aerogel morphology observed by scanning electron microscopy (SEM) is characterized by spherulitic stru...

monolithic aerogels of high molecular weight polyethylene (mw= 3x106- 6x106 g/mol) have been prepared by solvent extraction with supercritical carbon dioxide from thermoreversible gels prepared in decalin. these low density and highly porous aerogels present an apparent porosity up to 90%. the aerogel morphology observed by scanning electron microscopy (sem) is characterized by spherulitic stru...

Continuous-fiber-reinforced ceramic matrix composites (CMC) have been proposed as candidates for high-temperature applications. Their architecture and network of porosity have a strong effect on the mechanical behavior. X-ray tomography is a non-destructive technique that allows studying the volume mesostructure of these porous materials. The volume porosity, the open porosity fraction, the con...

The role of solid obstacle surface roughness in turbulent convection porous media is not well understood, even though it frequently used for heat transfer enhancement many applications. focus this paper to systematically study the influence on microscale flow physics and report its effect macroscale drag Nusselt number. Reynolds-averaged field numerically simulated using realizable k-ε model a ...