Victor Popovici

Finite Element Method for Simulating the Vickers Hardness Test

The purpose of the present paper is to present a different approach to the finite element modeling of the Vickers hardness test measurement, and to establish a numerical correlation between the Young modulus of a material and its hardness. In order to realize this, calculations were based upon the tensions acquired as a result of the hollow caused in the investigated materials by the indenter the maps of stresses. The present work demonstrates that from the results of the simulation based on the finite element method it is possible to compute a material’s hardness.

Procedures for Measuring and Modelling Underwater Acoustic Field Parameters

Considering the pollution acoustics increasingly acute underwater environment, it raises the need for an evaluation, structuring and mapping of underwater noise. It requires a harmonized methodological framework for data collection, field simulation of evolution acoustic characteristics for the modeling and plotting maps of underwater noise. This paper comes to make a contribution on procedures for measuring the characteristics of underwater acoustic field, by developing procedures for measuring and modeling the transmission loss and sound profile. Two scenarios are also presented for the production of underwater noise, that can be used for drawing maps of noise.

Mobile Equipment for Hydro-Acoustic Parameters Measurement

During construction and during exploitation operations of the offshore objectives occurs, inevitably, noise pollution in the marine environment. This paper presents a system for measuring underwater acoustic field. The mobile polygon is described, which is used in noise measurements for the determination of sea noise.

Modeling by Finite Element Method of Thermal Field when Coating with Stellite Welding of Valvetype Parts

The paper presents the optimization results of coating by welding technology of the sealing surfaces of a rod-valve and seat assembly by using finite element programs. The assemblies - rod, valve and seat - are used for closing or opening track heat from heating systems used in power plants. The heat is given by steam that is found at a pressure of 400-450 atm and a temperature range of approximately 500°C. These values determine the use of materials of steels grades that are thermo resistant, alloyed with Cr and Mo, and work surfaces are coated with materials out of stellite grades (Co). To optimize parameters of the welding system and decrease heat loss, by conduction and convection, there were used programs of finite element to simulate the propagation of heat gradient acording to the parameters of welding regime.

Experimental Research and Modeling of the Underwater Sound in Marine Environment

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.