Effect Of Slip Distribution Research Articles

The effect of slip distribution on flow past a circular cylinder

A slip boundary has been shown to have a significant impact on flow past bluff bodies. In this work and using a circular cylinder as a model system, the effects of various slip configurations on the passing flow are investigated. A theoretical analysis using matched-asymptotic expansion is first performed in the small-Reynolds number regime following Stokes and Oseen. A slip boundary condition is shown to lead to only higher-order effects (~1/ln(Re)) on the resulting drag coefficient. For higher Reynolds numbers (100–500), the effects of five types of symmetric slip boundary conditions, namely, no slip, fore-side slip, aft-side slip, flank slip, and all slip on the flow field and pertinent parameters are investigated with numerical simulations. Detailed results on the flow structure and force distribution are presented. Flank slip is found to have the best effect for drag reduction with comparable coverage of slip area. For asymmetric slip distributions, torque and lift are found to generally occur.

Deformation and fracture behavior of an Al–Li alloy 8090

Deformation and fracture behavior of an Al–Li alloy 8090

The effect of slip distribution on the monotonic and cyclic ductility of AlLi binary alloys

The monotonic and cyclic properties of three AlLi alloys were correlated with the slip behavior. One alloy was a solid solution with short range order, one had a small volume fraction of shearable precipitates, and one had a large volume fraction of shearable precipitates. Both the monotonic and cyclic ductility were controlled by the degree of strain localization which depended on the extent of work softening on the glide plane. When a large volume fraction of precipitates were present, cracks nucleated at grain boundary ledges during tensile tests and propagated either transgranularly or intergranularly along precipitate free zones. The propagation mechanism depended on the aging treatment. Cracks most often nucleated at slip bands during cyclic deformation, and propagated either by the striated growth mechanism or by slip band decohesion; the path contingent on the extent of strain localization.

The effect of microstructure on the fatigue crack propagation behavior of an Al-Zn-Mg-Cu alloy

The effect of slip distribution on the fatigue crack propagation behavior in vacuum of a high purity Al-5.9Zn-2.6Mg-l.7Cu alloy in various age-hardened conditions has been investigated. The crack propagation resistance was observed to be significantly higher for underaged microstructures containing shearable precipitates in comparison to overaged conditions with nonshearable precipitates. The improved crack propagation resistance is attributed in part to an increased amount of reversed slip in the plastic zone at the crack tip due to a higher degree of planar slip for conditions with shearable precipitates. The observed increase in fatigue crack propagation resistance with decreasing precipitate size for microstructures containing a constant volume fraction of shearable precipitates cannot be explained on the basis of such slip reversibility alone. The variation in ductility for the different microstructures has also to be taken into account. It was found that the enhanced crack propagation resistance can be correlated to the increased ductility with decreasing precipitate size. This explanation was supported by the experimental observation that microstructures containing different volume fractions and sizes of shearable precipitates but exhibiting the same ductility showed approximately the same resistance against fatigue crack propagation.

Effect of slip distribution on the fracture behaviour of magnesium oxide single crystals

Abstract The tensile deformation of chemically polished magnesium oxide crystals has been correlated with the distribution of slip at the onset of plastic flow. If two slip bands, generated on orthogonal {110} planes, happen to intersect to nucleate a crack before other slip bands develop nearby, then the crack so formed is unstable and the crystal completely brittle. If, however, there is a higher density of slip sources cracks can become stabilized by adjacent slip bands and the crystals continue to deform. Sometimes slip is confined to a single slip band which expands laterally to fill the entire gauge length, these crystals are extremely ductile. The fracture behaviour of a given crystal depends critically upon the relative orientation, number, thickness and spacing between slip bands. The density of slip may be increased artificially when dislocation sources are injected into the crystal surface by sprinkling with carborundum before loading. Such crystals are always ductile in tension. A similar treatment for crystals to be bent leads to a profound change in their fracture behaviour.