Full-range stress-strain curves for aluminum alloys
Boundary friction of ZDDP tribofilms
The frictional properties of ZDDP tribofilms at low entrainment speeds in boundary lubrication conditions have been studied in both rolling/sliding and pure sliding contacts. It has been found that the boundary friction coefficients of these tribofilms depend on the alkyl structure of the ZDDPs. For primary ZDDPs, those with linear alkyl chains giv...
Collective viscous propulsion of a two-dimensional flotilla of Marangoni boats
A closed-form solution is presented for the collective Marangoni-induced motion of a two-dimensional periodic array, or “flotilla”, of Marangoni boats on deep water at zero Reynolds, capillary and surface P´eclet numbers. The physical set-up is identical to the model of Marangoni propulsion proposed by Lauga & Davis [J. Fluid Mech., 705, (2012)] bu...
Tribological rehydration and its role on frictional behavior of PVA/GO hydrogels for cartilage replacement under migrati...
Graphene oxide (GO) was incorporated into polyvinyl alcohol (PVA) hydrogel to improve its mechanical and tribological performances for potential articular cartilage replacement application. The compressive mechanical properties, creep resistance, and dynamic mechanical properties of PVA/GO hydrogels with varied GO content were studied. The friction...
Effects of dispersant and ZDDP additives on fretting wear
This paper examines the effect of dispersant and anti-wear additives on fretting wear in lubricated bearing steel contacts. Reciprocating sliding ball-on-flat fretting tests with a stroke length of 50 μm have been carried out on steel-to-steel contacts in both dry and lubricated conditions. Wear and friction coefficient have been measured, and surf...
Interaction of void spacing and material size effect on inter-void flow localisation
The ductile fracture process in porous metals due to growth and coalescence of micron scale voids is not only affected by the imposed stress state but also by the distribution of the voids and the material size effect. The objective of this work is to understand the interaction of the inter-void spacing (or ligaments) and the resultant gradient ind...
Rico and the jets: Direct numerical simulations of turbulent liquid jets
This paper is associated with a poster winner of a 2019 American Physical Society's Division of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2019.GFM.P0020.
Elastic local buckling of three-flanged cross-sections
In current structural steel design specifications, the local buckling of cross-sections is typically treated on an element-by-element basis, with the boundary conditions along the adjoined longitudinal edges of the individual plates assumed to be simply-supported. In reality, cross-sections buckle locally as a whole and the individual plate element...
Confined turbulent convection driven by a combination of line and distributed sources of buoyancy
We study the flow and thermal stratification of a closed domain subjected to different combinations of line and distributed surface heating and cooling. Our observations are drawn from a set of direct numerical simulations in which the ratio of the strength of the distributed sources to the localised sources \HfRb is varied and shown to play a deci...
Fracture behaviour and seismic response of naturally fractured coal subjected to true triaxial stresses and hydraulic fr...
Hydraulic fracturing of coalbed methane wells has been widely practised as an effective method to increase drainage efficiency in low-permeability, low-pressure and low-saturated coal seams. To investigate hydraulic fracture performance and associated seismic response in coal, hydraulic fracturing experiments were carried out on two cubic coal bloc...
