Armored steel sheets have various uses in civil and military industry. For the last one, especially in aeronautics, a better determination of the lifetime for the fatigue and shock loaded parts, is a major challenge. Several methods for fatigue calculus are known: safe-life, fail-safe, crack propagation method. All of this methods are not considering in any way the shocks that can accidentally occur, so in the calculation of lifetime, the role of impact multiplier is null. The authors propose a corrected formula for the calculus of the lifetime for 2P armor steel, based on the internal energy developed into the test specimens, through the impact multiplier.
The formability of tailor welded blanks is significantly reduced compared with the homogeneous blanks. This phenomenon is caused by the fact that there is a severe change in the material property sideways the welding line. Within 2-3 mm, in case of laser welding maybe less, there is a gradient of mechanical characteristics of materials. The research work presented in this paper deals with numerical simulation regarding forming of a cylindrical shaped part made from tailored blanks (TWBs), having the welding line situated symmetrical with respect to the part geometry. Due to dissimilar parent materials of the TWBs, it is difficult to anticipate the maximal depth of the formed part. The presented research is trying to determine the maximal depth of the TWBs part based on the maximal depth of the parts obtained from each parent material partly. To simulate the forming process of the cylindrical part the academically version of the Dynaform 5.8.1 software have been used. The obtained results are presented in the final part of this paper work.
According to the Association of Energy Services Professionals Survey, in the United States there were at least 56 accidents in nuclear power plants until 2010. Tubular branched structures are a common alternative for technological pipe systems, used for transportation of fuel elements and the primary coolant of a nuclear reactor. The tubular branched structures works at 5.1 MPa (or higher) internal pressure. The nuclear plant in Cernavoda is based on the CANDU system (Canada Deuterium Uranium). Tubular branched structures, under specific loads, due to geometrical discontinuities, they show strong concentration of mechanical stresses. The presence of welded surfaces involves a more complicated distribution of the mechanical stress, compared with the corresponding distribution for the typical elements, even at low pressures. There are some studies and researches showing the stress concentrator in the middle of the welding rim, but the authors show in this paper the influence of the geometrical discontinuities in the variation of the stress concentrator in the immediate vicinity. An experimental research was conducted upon the pipelines at 450 branched. The experimental results upon stress and strain were used to validate a numerical model that was used to analyze other angles for branched structures, low pressurized. The consequences of this paper are given by the possibility to determinate the risk of leak due to the crack appearance at buried tubular branched structures with less information: the geometry of the structure and the internal pressure.
The paper analyzes the pollution impact of vibration on the whole human body produced by sorting and washing stations of mineral aggregates, located near inhabited areas, in accordance with national legislation. The imposed limits are correlations between the frequency of vibration with the vibration intensity, measured in vibrars. In the same time, in the EU legislation the imposed limits are given by the daily exposure limit value (acceleration of vibration movement) standardized to an eight-hour reference, measured in m/s2. The authors present a geometrical rim optimization of a mineral aggregates station to diminish the pollution produced by vibrations, that should be taken, in order to align at European legislation. Results are presented in both ways: as maximum vibration intensity and maximum vibration acceleration. Measurements were performed at normal operating capacity of the analyzed plant, based on: direct observations in the field, the existing documentation and information supplied by the business owner.
The paper analyzed the apparent structural viscosity variations of nonlinear viscoelastic non-Newtonian mixtures in function of the revolution of the mixing device and phase's temperature. For the proposed study there were analyzed binary non-Newtonian mixtures by type L-S and S-L with different concentrations obtained in laboratory. The apparent structural viscosity determination was carried out analytically correlating the deformation state of mixing device`s shaft whit the torsion moment value.
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