Applied Mechanics and Materials Vol. 430

Abstract: An important contribution to the noise generated by the road transportation means in the environment has the noise produced by the tire-road contact. This paper is concerned with the investigation of the noise produced by the contact between the tire and the rolling surface covered by rubberized asphalt. Initial test performed in the past were performed again in identical conditions in order to assess the durability and absorbent properties of the rubberized asphalt over time in the climate specific to Timisoara. It was found that the rubberized asphalt has not changed its acoustical properties over time, since practically the same values were obtained for the equivalent noise level as well as for the spectral distribution of the noise, which confirm the efficiency of rubberized asphalt to decreasing phonic pollution in urban areas.

Abstract: Today, reduction of industrial noise is a widely used concept for improving the life standard in vicinity of industrial and residential mixed areas. The human ear has a very poor auditory acuity in perceiving sounds produced by sound pressure variations in the very low frequencies or very high frequency range. Noise is, in general interpretation, disturbing sound, annoying or even dangerous, although this perception is subjective. There are at least two kinds of people, one that "adapted" psychological noise and learned to work with it and another which gradually became sensitive to noise. In the current situation of industrial development, and housing, many locations of manufacturing facilities are near residential areas, so it is very important to realize noise levels monitoring. Legislation provides for annual measurements of noise levels to limit industrial properties. This paper describes the monitoring, over a period of several years, the noise sources within a company at the limits of Timisoara.

Abstract: Acoustic power is a measure which must be specified on the outdoor used equipments and its determination depends on several factors: the place where the equipment works (indoor or outdoor), the placement of the microphones for its determination (the distance less or greater from the noise source), the shape of the measurement surface (parallelepiped or hemispherical). This paper aims to analyze the values obtained in these situations and interpret the data to determine the influence that each factor has on the acoustic power compared with the values obtained (permissible) according to Directive regarding noise emission D 2000/14/EC.

Abstract: This paper work presents the model for forecasting the exposure risk of workers to hand-arm occupational vibrations, which has been achieved in the PN 07 45 01 18 Project from within the framework of the NUCLEU/2012-2013 Program.This project is of national and European interest, in order to increase occupational health and safety level and to ensure sustainable environmental quality and comfort at work.

Abstract: The troubles generated by noise represent an issue, unanimously agreed by everybody, and this have numerous psychological and social implications.

Abstract: The paper presents a modeling of the acoustic field emitted by a rig tender located offshore exploration in the Black Sea. Are presented measuring system, experimental context, the types of noise that participate in the overall noise budget and the conditions in which measurements were made, also are mentioned and the project established through were measured the parameters and were defined devices which these measurements were made. Measurement system used is adaptable, allowing dynamic measurements and operative analysis of the acquired data. Measurement methodology was determined by an acoustic project, which was set to be purchased both: sizes and ways of interpreting them. Modeling acoustic field shows that the maximum acoustic impact area, below 120 dB re 1μPa criterion (proposed and accepted by Marine Directive) was extended to 3-5Km distance around the ship. It is expected to produce adverse effects on the marine habitat and on the underwater life.

Abstract: The paper proposes an analysis of vibrations within many Romanian and foreign harvesters provided with tangential threshing unit, watching the influence which these ones have on the human operator's health. The determination of vibrations has been performed on the basis of accelerations measured at various frequencies, on the three directions: x, y and z (by means of the accelerometers mounted on the main working parts of the harvester), tracing the nomographs representing the limits up to which, these are not dangerous for the operator's health. Key words: vibrations, harvester, accelerations, nomogram, frequency.

Abstract: An electric vehicle was subjected to on-road acoustic tests. A specific high frequency tone was perceived in a sound field dominated by wind and road noise. The car was instrumented with microphones which measured the noise inside the passenger compartment and with tachometers to record the motors rotational velocity with respect to time. Waterfall diagrams were generated by tracking the spectrums of noise from fixed time samples against the rpm of the motor. The analysis of the diagrams revealed that high orders, like the 24^th and 48^th were responsible for the sound. These orders represent the acoustic response of the electromagnetic interaction between the stator and the rotor of the electric motor. To analyze the propagation of noise from the source (motor) to the target (driver), a transfer path analysis (TPA), respectively an airborne source quantification (ASQ) were proposed. The TPA focused on the structure borne noise generated by the forces transmitted into the body through the powertrain supports, and the ASQ, on the airborne noise radiated by the surface of the motor and gearbox casing. The conclusion was that the airborne noise is the main contributor to the total pressure level in the passenger compartment, but at lower speeds a strong structure borne noise content is present.

Abstract: The paper presents the result of experimental research of the viscoelastic behavior of the antiseismic elastomeric isolators on stand, in laboratory, where the excitation is given only through harmonic instantaneous displacements. Based on the dynamic response under the form of the elastic and dissipation forces, in the time domain, the hysteresis loops and the stiffness, damping and durability to imposed repeated cycles parameters are determined. In this case, the order I dynamic system is free of added mass which makes the evaluation of its own damping to be estimated as equivalent damping with that of a complete system of 2^nd order with viscous damping.Using elastomeric isolators on site, for a base isolation project, either building or viaduct, imposes corrections of the experimental laboratory values considering the real conditions, function of the dynamic inertial excitation (earthquake, wind gusts, etc.) and of the response in instantaneous displacements.

Abstract: The dissipative function is presented, depending on stiffness and maximum displacement, for a hydraulic damper with silicone oil at an exterior excitation type shock, applied in the time domain. For the same constructive solution, silicone hydraulic oil, the same structural mechanic elements, but with different settings/adjustments, one can model the rheological system Kelvin-Voigt, as well as the Maxwell system. In this context, the main behavioral differences in dynamic response will be presented, as well as the stiffness, dissipation and displacement during the applied shock parameters.