Journal of Mechanical Engineering Science

Cyclic variations of the important operating characteristics of the twin-land type of oil-control ring have been analysed by considering radial and torsional equilibrium of the ring cross-section. The assumed form of the face profiles of the lands are related to measurements of worn oil-control rings and the analysis includes the effect of surface roughness in the mixed lubrication regime.

The results show that oil-control rings may operate with fluid film, mixed, or boundary lubrication, depending upon the land profiles, the attitude of the ring, and the surface roughnesses on liners and rings. A small height difference between the lands is shown to have a significant effect upon the calculated volume of lubricant passing the ring and the analysis has provided the basis for further rational design of this important machine element.

Additives are used to improve the performance of commercial lubricants. These lubricants behave like non-Newtonian fluids (shear thinning or shear thickening). The effect of the nonlinear behaviour on the performance characteristics of finite width journal bearings is investigated using the Prandtl model. The finite element method, using Galerkin's technique, has been used to solve the Navier-Stokes equations in cylindrical coordinates, representing the flow-field in the clearance space of a bearing using Newtonian fluids, and the non-Newtonian effect is introduced by modifying the viscosity term for the model in each iteration. The results applicable to shear-thinning (pseudoplastic) and shear-thickening (dilatant) lubricants are compared with the established results for Newtonian lubricants.

It has been observed experimentally that when a sphere ricochets off water or sand the critical impact angle depends on the impinging velocity.

To explain this, a model is developed which takes into account the weight of the sphere and the static resistance of the medium into which penetration occurs. The proposed model can also treat processes in which the angle of impact is large and where the velocity of the sphere undergoes considerable change. Projectile trajectories which have been calculated for various conditions are presented and discussed. Numerical results for steel, aluminium alloy, and lead spheres are in good agreement with such experimental results as are available.

An investigation is made of the normal steady drainage of water from horizontal drums freely discharging in a steam atmosphere via vertical drains.

The flow to the drain orifice in a horizontal drum is asymmetric. At the drain the discharge flow may have several forms; however, there are two basic regimes. At low discharge rates it resembles flow over a weir, whereas with increasing flow there is a transition to a form of orifice flow when discharge is as a jet. In both cases the discharging water is free from entrained steam and vortex formation. Correlations are given to determine the regime and, hence, the applicable head/discharge relationship for drain/drum radius ratios from 0–08 to 0–25.

Bless and Barber (1) ‖ have shown that rod projectiles can be affected by the propagation of bending deformation along their lengths when they strike rigid targets at sub-ordnance velocities. Experiments are described in which a range of different modes of deformation are identified for both normally and obliquely incident steel and aluminium rods of length to diameter ratio 24 : 1. The results are discussed from the point of view of classical dynamic structural plasticity.

In the interpretation of the energy sink hypothesis the real body has in the past been approximated by two or more rigid bodies, connected in such a fashion that damping forces acting between them dissipate energy. This approach suffers from several shortcomings, and a more rational treatment of the problem can be achieved by assuming intervalwise rigidity.

The complicated, nonlinear stiffness characteristics of a tensioned plate with a central opening are studied via analogue computer simulation. Associated frequency response characteristics and statistical properties of the response to random excitation are examined using a single degree of freedom model.