In this paper, numerical and experimental studies on the influence of the thermal field on behavior of the structure of sandwich plates in three points bending is analysed. Various materials are used so for skins. For the core only extruded polystyrene, with various thicknesses is used. The thermal conductivity n was determined by using the Hilton B480 unit, based on the heat flowmeter method described in ISO 8301:1991. We have been analyzed 12 cases of composite sandwich structures. The results obtained by experimental determination and numerical simulation of all cases of modeling are compared and certain differences occurred on the analyzing of influence of the thermal field on the bending characteristics of sandwich structures.

The mechanical properties of certain flexible core materials of ship structure sandwich panels, having skins made of metallic or composite laminates may be significantly influenced by the temperature variations that may occur during the operational loading. At the same time, the improving knowledge of the behaviour of these panels in terms of bending strength and other stress / strain related aspects in various harsh conditions increases their superiority in terms of weight-to-strength ratio, high stiffness, easy to manufacture, acoustic and thermal insulation. In the paper, the behaviour of the ship structural rectangular sandwich panels to the mechanical and thermal loading are presented. The sandwiches have a special core of 20 mm and skins made out of different materials (glass fiber reinforced polyester, steel and aluminium) with a thickness of 3 mm. Analysis consists of the behaviour of the composite sandwich panels in the bending test at constant speed by the three-point method, for three distances between different supports, by measuring the maximum displacement and force applied to the specimens under various thermal fields. The sandwich structures are also thermally analysed, determining their thermal conductivity by the heat flow measurement method. The experimental results are compared with the results obtained by finite element analysis in numerical simulation of all modelling cases.

The present article is aimed to investigate influence of the heating rate, temperature (T), pressure (P) on the structure and phase transition of amorphous Ni material with heating rate 2 Â 10 5 , 2 Â 10 6 and 2 Â 10 7 K/s at T ¼ 300 K; T ¼ 300, 400, 500, 600, 700, 800, 900 and 1000 K at heating rate 2 Â 10 6 K/s; T ¼ 300, 621 and 900 K at P ¼ 1, 2, 3, 4 and 5 GPa by molecular dynamics simulation method with Sutton-Chen embedded potential and periodic boundary conditions. The structure of amorphous Ni material determined through the radial distribution function, the total energy, the size and the average coordination number. The phase transition and the glass transition temperature determined through the relationship between the total energy and temperature. The result shows that when the heating rate increases, the first peak's position for the radial distribution function is 2.45 Å and a constant, the first peak's height, the total energy and the size increase, the average coordination number decreases from 13 to 12. When temperature increases from 300 to 1000 K at P ¼ 0 GPa, the position decreases from 2.45 Å to 2.40 Å, the average coordination number is 13 and a constant, glass transition temperature is 631 K, the total energy increases, the size increases and happens the phase transition from the amorphous state to the liquid state. When pressure increases from 0 GPa to 5 GPa at T ¼ 300, 621 and 900 K, the position decreases, the height increases, the total energy increases, the size decreases, the average coordination number decreases from 13 to 12, that shows with amorphous Ni material when increasing heating rate, T, P lead to structural change, phase transition of materials is significant.

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The road traffic is one of the main sources of atmospheric pollution in urban areas. This study aims to identify the emissions level for different driving regimes of diesel-powered vehicles that run into urban areas. The study has been performed in laboratory conditions and simulates various driving modes. This paper investigates the effects of vehicle speed, fuel consumption, acceleration, vehicle load on gaseous pollutant emissions (NOx, CO2, CO). The different pollution levels with smoke are also analyzed between idling regimes (maximum opacity index for fast acceleration between minimum and maximum speed) and different loads. The paper states some recommendations concerning the optimal operating regimes of the cars in urban areas, based on the conclusions on the measured levels of pollution.