Cristian Andreescu

Some Aspects Concerning the Period of Automotive Air Filters Replacement on the Basis of their Technical Conditions

The engine air supply system is the main source through which impurities from the atmosphere reach inside the kinematic couplings of the engine. The engine protection is ensured by periodically replacement of the air filters. Determining air filters service life is a difficult problem due to different operation conditions of the vehicles. Therefore, air filters are frequently replaced more often than necessary on the principle that a new filter is better than a replaced one. The present paper aims to determine if the air filters replaced during the preventive maintenance activities have reached the end of their service life or they could still be used. The research is based on measuring the pressure restriction and estimating the mass of dust collected by the air filters.

Comparative Study on the Regeneration of Used Motor Oil

Waste oil is a source of global pollution, both in terms of the amount generated and the environmental toxicity. The used motor oils are contaminated by contaminants and impurities resulted from undesirable oxidation processes: sediment, water, metallic particles and degraded additives.

Experimental Researches on the Magneto-Rheological Dampers Response to the Control Parameters

The magneto-rheological (MR) dampers used in automotive suspension improve the energy dissipation capacity for the vertical oscillations of the car body and wheel of the vehicle by increasing the damping force developed by piston motion. The determining of the time constant of the magneto-rheological fluid is essential in order to build a realistic dynamic model of an actuator, needed for implementing a real time control system provided with a comfort feedback. In this paper the authors compare the information collected from the dedicated literature, which currently are relatively restricted, to the results obtained from their own experimental determinations. The final objective of the paper is to help the optimal design a control structure for the assembly of the car magneto-rheological dampers.

Statistical Decision in the Automotive Material Selection

The objective of the research is the ranking of materials applied to an example from the automotive industry (material candidates for the car body construction). The variety of properties/attributes imposes different evaluations for metrical/ordinal scales and the necessary statistical calculus. Heterogeneity of the characteristics imposes the separation of the attributes into mainly two classes: functional (mechanical, physical, etc.), usually with metric scale and technological and environmental attributes with frequently ordinal scale. The paper analyses a practical case of the material for the car body by Multi Criteria Decision Making (MCDM) procedures like primary ranking and preference index value applied to mechanical, technological and ecological, respective all attributes, etc. All these methods are principally based on the variance, viewed as a risk measure. The final comparison has as result the most valuable materials: Titanium sheet, Glass Reinforced Plastics (GRP) and Carbon Fiber Composite.

Modelling and Simulation of the Dynamic Behaviour Automotive’s Suspension By AMESim

The main objective of this paper consists in the preliminary analyse of the dynamic behaviour of an automobile’s suspension using a model built in AMESim simulation program. For the dynamic study of a car suspension the authors have used a full vehicle model with 15 degrees of freedom, hear including the steering system. A strong nonlinear model was used in order to optimize the performance of the suspension by a long series of numerical simulations. The entirely research has shown that AMESim offers a real aid in the suspension study, because it significantly reduces the working time. Once created a model, and validated by experimental measurements, it can be used to study any type of similar suspension.

Experimental Identification of the Automotive Magnetorheological Shock Absorbers

The effectiveness of the shock absorbers in terms of comfort and automotive manoeuvrability is closely linked to the free and forced vibrations generated by the road irregularities and the driver’s orders (acceleration, braking etc.). The passengers mass, the sprung mass parties (car body), the free parties mass (wheels and a part of the suspension), the stiffness and the damping coefficient of the various elements of the car are involved in this process. In the road vehicles’ suspensions field, the dampers control through the valves is an extremely difficult target due to the unpredictable flow’s variation and the pressure difference generated inside them. This was the main reason for developing and using magneto rheological fluids as dampers fluids. The authors have designed and built a complex test bench in order to compare the behaviour of a classical dampers and a magneto rheological one. A high speed National Instruments data acquisition system was used to obtain information about the correlation between the damping force, stroke, and speed, control current, temperature etc. The results were compared with the similar ones supplied by some top level manufacturers.

Maintenance Costs Statistics for Urban Cars

A central economic problem in urban traffic is the total maintenance costs (failure replacements and preventive maintenance), as an important competitive level. The paper has, as main result, the statistical analysis of the dependence between the traffic urban mileage and the total maintenance costs. The variation of these costs depending on the mileage is very useful for any driver and employer. The paper uses some statistical models to evaluate the possibilities of calculation the maintenance costs and their schedule. The most important working tool in the paper is the regression analysis between the independent variable—mileage (measured in kilometres) and the dependent one—the maintenance costs. This statistical function can be used for prognoses and schedules of maintenance costs. Another statistical practical applications used for data modelling are power fit, modified geometric, cubic and normal models; the traffic urban mileage, and respective maintenance costs, has an univariate normal distribution (Shapiro-Wilk test); the derived distribution of both variables is a bivariate Gaussian model (Henze-Zirkler and Royston tests). Numerical adequate examples for automotive operation were processed with specialised software.