A study on the viability of minimum quantity lubrication with water in grinding of ceramics using a hybrid-bonded diamond wheel

With the currently strict environmental law in present days, researchers and industries are seeking to reduce the amount of cutting fluid used in machining. Minimum quantity lubrication is a potential alternative to reduce environmental impacts and overall process costs. This technique can substantially reduce cutting fluids in grinding, as well as provide better performance in relation to conventional cutting fluid application (abundant fluid flow). The present work aims to test the viability of minimum quantity lubrication (with and without water) in grinding of advanced ceramics, when compared to conventional method (abundant fluid flow). Measured output variables were grinding power, surface roughness, roundness errors and wheel wear, as well as scanning electron micrographs. The results show that minimum quantity lubrication with water (1:1) was superior to conventional lubrication-cooling in terms of surface quality, also reducing wheel wear, when compared to the other methods tested.

Wheel-Rail Contact Forces in High-Speed Simply Supported Bridges at Resonance

The response of high-speed bridges at resonance, particularly under flexural vibrations, constitutes a subject of research for many scientists and engineers at the moment. The topic is of great interest because, as a matter of fact, such kind of behaviour is not unlikely to happen due to the elevated operating speeds of modern rains, which in many cases are equal to or even exceed 300 km/h ( [1,2]). The present paper addresses the subject of the evolution of the wheel-rail contact forces during resonance situations in simply supported bridges. Based on a dimensionless formulation of the equations of motion presented in [4], very similar to the one introduced by Klasztorny and Langer in [3], a parametric study is conducted and the contact forces in realistic situations analysed in detail. The effects of rail and wheel irregularities are not included in the model. The bridge is idealised as an Euler-Bernoulli beam, while the train is simulated by a system consisting of rigid bodies, springs and dampers. The situations such that a severe reduction of the contact force could take place are identified and compared with typical situations in actual bridges. To this end, the simply supported bridge is excited at resonace by means of a theoretical train consisting of 15 equidistant axles. The mechanical characteristics of all axles (unsprung mass, semi-sprung mass, and primary suspension system) are identical. This theoretical train permits the identification of the key parameters having an influence on the wheel-rail contact forces. In addition, a real case of a 17.5 m bridges traversed by the Eurostar train is analysed and checked against the theoretical results. The influence of three fundamental parameters is investigated in great detail: a) the ratio of the fundamental frequency of the bridge and natural frequency of the primary suspension of the vehicle; b) the ratio of the total mass of the bridge and the semi-sprung mass of the vehicle and c) the ratio between the length of the bridge and the characteristic distance between consecutive axles. The main conclusions derived from the investigation are: The wheel-rail contact forces undergo oscillations during the passage of the axles over the bridge. During resonance, these oscillations are more severe for the rear wheels than for the front ones. If denotes the span of a simply supported bridge, and the characteristic distance between consecutive groups of loads, the lower the value of , the greater the oscillations of the contact forces at resonance. For or greater, no likelihood of loss of wheel-rail contact has been detected. The ratio between the frequency of the primary suspension of the vehicle and the fundamental frequency of the bridge is denoted by (frequency ratio), and the ratio of the semi-sprung mass of the vehicle (mass of the bogie) and the total mass of the bridge is denoted by (mass ratio). For any given frequency ratio, the greater the mass ratio, the greater the oscillations of the contact forces at resonance. The oscillations of the contact forces at resonance, and therefore the likelihood of loss of wheel-rail contact, present a minimum for approximately between 0.5 and 1. For lower or higher values of the frequency ratio the oscillations of the contact forces increase. Neglecting the possible effects of torsional vibrations, the metal or composite bridges with a low linear mass have been found to be the ones where the contact forces may suffer the most severe oscillations. If single-track, simply supported, composite or metal bridges were used in high-speed lines, and damping ratios below 1% were expected, the minimum contact forces at resonance could drop to dangerous values. Nevertheless, this kind of structures is very unusual in modern high-speed railway lines.

The wagon wheel illusion in movies and reality.

Wheels turning in the movies or in other forms of stroboscopic presentation often appear to be rotating backward. Remarkably, a similar illusion is also seen in continuous light. The occurrence of this perception in the absence of intermittent illumination suggests that we normally see motion, as in movies, by processing a series of visual episodes.

Steering wheel oscillations and vertical movement in 30 mph barrier impacts. Technical report.

Mode of access: Internet.

Occupant response and vehicle acceleration in a 30 mph frontal impact test - 1981 Subaru DL - 4 wheel drive - 4 door wagon - NHTSA 811301. Final report.

National Highway Traffic Safety Administration, Office of Passenger Vehicle Research, Washington, D.C.

A modern, scientific, simplified, step by step, safe method for teaching safety driving in the family car; a text book for behind the wheel driver training, an educational book for better, safer, smoother, driving, a method of driving to end accidents.

Mode of access: Internet.

George at the wheel: or, Life in the pilot-house /

Mode of access: Internet.

An hypothesis which may help to unfold the mystery of Ezekiel's visions; accounting for the form and number of the four creatures, why different from those in the Apocalypse, why they are seen to issue out of the cloud, the reason why wheels were introduced, why they work as a wheel within a wheel, with many particulars unexplained before.

Mode of access: Internet.

Organizational maintenance repair parts and special tools list : pneumatic tires, electric motor, AC, 10 HP, 416V, 3 phase, 60 cycle, 50 ft long, conveyor, belt, 300 tons per hr., wheel mounted 24 in. wide belt, NSN 3910-00-790-2175, Barber-Greene model PG 70.

Includes index.

Direct support and general support maintenance repair parts and special tools lists : pneumatic tires, electric motor, AC, 10 HP, 416V 3 phase, 60 cycle, 50 ft long, conveyor, belt, 300 tons per hr, wheel mounted, 24 in. wide belt, NSN 3910-00-790-2175, Barber-Green model PG 70.

Includes index.

Operator, organizational, field, and depot maintenance manual : conveyor, belt, 300 tons per hr; wheel mounted; pneumatic tires; electric driven; AC, 10 HP, 416 V, 3 phase 60 cycle; 50 ft long; 24 in. belt, (Barber-Greene model PG70), FSN 3910-790-2175.

"July 1961."

Operator, organizational, field, and depot maintenance manual : pump, reciprocating, diaphragm, gasoline driven, wheel mounted, rubber tires' 4 in., 100 GPM at 10 ft. suction lift (Rice Pump and Machine Co. model 4D-327), FSN 4320-829-8434, less MIL STD engine.

Includes index.

Operator and organizational maintenance manual : pump, centrifugal, fresh water; gasoline driven, 2 wheel mounted; 4 in 500 GPM, 30 ft head, (Carver model K400S) FSN 4320-810-7311 (less engine).

Includes index.g