Flammability Tests on Hot Surface for Several Hydraulic Fluids

Industrial equipment using hydraulic fluids are design to accept higher load and speed, implicitly higher temperatures, including for fluids. Leakages from enclosures like gear boxes or hydraulic systems could increase the risk of fluid reaching hot surfaces, thus producing fires hard to be controlled and isolated. The designer have to evaluate the flammability of fluids and they should select several solutions for a particular application in order to estimate the costs of different solutions and to mitigate the risk of having accidental fires due to a specific fluid grade. The tests were done with the help of an original equipment allowing a dedicated soft assistance in order to protect the operator and to sustain reproducibility, according to the standard SR EN ISO 20823:2004 Petroleum and related products. The determination of the flammability characteristics of fluids in contact with hot surfaces - Manifold ignition test, There were tested the following grades of hydraulic oil HLP 68 X-Oil, HFC Prista, MHE 40 Prista (100% oil), a rapeseed oil (obtained after a dewaxing process) and an emulsion oil-in-water (5% vol. MHE 40 Prista). There were identified distinct behaviours of these fluids under the test condition

Tribological behavior prediction for an epoxy aramid system based on mechanical and thermal properties analyses

Taking into account that the tribological processes are a combination of many other processes the aim of this paper is building a neural network model based on mechanical and thermal properties for prediction of the tribological behaviour of an Epoxy- Aramidic composite system. The created epoxy based composites with aramidic powders, were tribological tested with diverse parameters in order to obtain follow properties: wear rate and friction coefficient. Bending and compression tests were performed for obtain main mechanical properties. Thermal tests were performed in order to obtain follow properties: specific heat, thermal conductivity and thermal expansions. With all the studied properties was created an Artificial Neural Network (ANN) model. The created ANN model can perform prediction for tribological behaviour of studied composites

A STUDY ON THE PREDICTION OF STABILITY BEHAVIOUR FOR FLEXIBLE ROTOR IN JOURNAL BEARINGS

The influence of the labyrinth seals on the dynamic behaviour of a flexible rotor in journal bearings is investigated. In particular a code which makes possible the determination of the stiffness and damping coefficients and the calculus of the stability threshold in absence of unbalance is carried up. The determination of the oil film pressure in journal bearings and in the labyrinth seal is made using the Warner's hypothesis and the bulk-flow model with two-control-volume, respectively

The Influence of the Relative Sliding on the Surface Quality

This paper presents a study on the surface quality pointing out the influence of relative sliding on the topography parameters. Traditional roughness parameters as Ra and Rq, deal only with relative high of the asperities to the mean line and they give no information on shape, slope and asperities magnitude, on their appearance frequency on the profile length. The authors analysed a set of 3D parameters including the amplitude ones (Sa, Sku, Ssk and St) and functional parameters as Svk, Sk and Spk as calculated with a dedicated soft from the bearing area. Tests were done on roller-roller tribotester lubricated with the grease grade UM185Li2EP (general purpose grease for rolling bearings), the temperature of the environment being kept at 80°C. There was studied the influence of relative sliding speed on the skewness and the kurtosis of the surface topography, but also on common parameters as Sa and St. Such a study may be used for selecting a suitable surface quality and to evaluate the surface topography degradation in time, after tests under severe conditions, very close to the actual ones