Principal research areas on mechanical face-seals
Abstract A critical review of world literature on radial face-seals is presented in order to further understanding of seal operation and to obtain some elements of a design method for optimization of their performance. The principal areas examined are hydrostatic, hydrodynamic and boundary lubrication of the faces, and in particular cavitation and the influence of different constructive parameters on the dynamic behaviour of these seals.
Determination of tribological history and wear through visualisation in lubricated contacts using a carbon-based composite
Abstract Friction and wear of a carbon-based composite used for lubricated clutch applications in continuous slipping were studied. Representative simulations with high-resolution visualisations were carried out to identify velocity accommodation mechanisms in this parallel face contact. A new lubricated regime leading to specific changes of the carbon composite during friction was pointed out. In the contact, the load was carried by islands of composite over which the measured film thickness was lower than 0.5 μm. A limited number of islands (called the activated islands) seemed to carry the load at one time. This new lubricated regime, called fractionated lubrication, was characterised by high shear rates (higher than 10 5 s −1 ), unusual local pressures (higher than 500 MPa) over reduced areas of contact, the islands, (about 100 × 100 μm) independent in terms of geometry and of lubricant flow. Various degrees in the morphological changes of the surface of these islands were pointed out, involving a process called tribological history. In this paper, further investigation into the tribological history of the islands is made. The influence of the lubricants and of changing steel counterfaces to glass counterfaces, both under different running conditions, were studied. A morphological examination of the surfaces of the islands was performed after testing from a mechanical point of view and the activated wear phenomena were pointed out. Then the mechanisms involved in the tribological history both in clutch experiments and in simulations were identified as well as the main parameters which governed morphological changes. These results provided a better understanding of the tribological behaviour of the carbon-based composite, allowing one to control and optimise wear in the industrial application.
Women's health in prison: urgent need for improvement in gender equity and social justice.
The needs of women held in detention have received little attention and con-tinue to be neglected by health systems and prison authorities. One reason for this, too readily accepted until now, is that women prisoners are a clear minor-ity group within prisons all over the world. It is only recently that attention has been drawn to the fact that a minor-ity status does not justify the widespread ignorance of women’s basic rights and the considerable gender insensitivity still dominating criminal justice systems.In Europe alone, there are about 100 000 women and girls in prison.