Papers by Keyword: Distribution Function

Abstract: Experimental densities of intensity distribution for main deformations, as well as the stress strain state of a metal on the side edges of an aluminum strip during its flat rolling, have been determined. Strain, spread and extrusion ratio have been evaluated. The dimensions of the strip cross-section have been chosen in a way that minimizes spreading. Therefore, the deformed state under rolling is close to a flat one. The correlation between the deformation intensity and the stress-strain state of macro-volumes occurred on strip edges has been estimated. The parameters of two-dimensional probability-density function for the joint distribution of deformation intensity and the Nadai-Lode stress-strain parameter have been determined. Distribution densities for longitudinal, transverse deformations and the intensity of main deformations in the zone of strip rolling are bimodal, which corresponds to both forward and backward slip zones under rolling. The results of the work can be used to predict the depletion of plasticity resources during strip rolling.

Abstract: The strain intensity as well as the stress-strain state of grains has been experimentally estimated for aluminum sample in strip rolling. The level of correlation between the intensity of deformation and stress-strain state of individual grains in the sample has been calculated. An experimental two-dimensional function of its joint distribution has been constructed. The parameters of two-dimensional function of probability densities have been defined. A relative number of grains with deformation twice as high as the average deformation of the sample has been obtained. The results allow predicting the plasticity exhaustion in individual grains of the sample during rolling and can be used to estimate the likelihood of defects (micro pores and micro cracks) arising during the rolling of aluminum strips.

Abstract: The high temperature crept tests of T91 steel have been conducted under two different stresses and temperatures. The single crystal electron diffraction is used to identify the precipitated phase structure. The quantity and size of carbides located in boundaries and intragranular area have been obtained by quantitative metallography, respectively. The results showed that the main precipitated carbides in T91 steel are M₂₃C₆(M=Fe,Cr) and V₄C_3, which is located in the grain and at the boundary of prior austenite respectively. In comparison with the carbides at boundary, the average size of intragranular carbides was smaller while the quantity is higher. The distribution of the carbides size crept with different stresses and temperatures is in accordance with a typical Boltzmann distribution.

Abstract: The effect of carbon ion species distribution in arc discharge process becomes significant for the formation of carbon nanomaterial. It is essential to account for the velocity distribution of each carbon ion species to determine the greatest contribution from the kinetic energy possesses by each species that govern the binding energy for carbon formation. The resultant speed of the particle as a result of collisions determines the resultant force exerted by the particles which consider in non-conservative force. The variation of velocity distribution is investigated while the reaction rate for carbon species during kinematic process, the transient condition for carbon species is analyzed. Collision rate of carbon ion species is underway to derive carbon ion motion in electrode gap region where the external electric field is constant. The theoretical development has shown that at constant pressure and temperature, carbon ion species possess the resultant speed due to collision frequency affecting the distribution function quantified for each species.

Abstract: This study has finished the crankshaft fatigue strength test by the rational experimental method. And based on the experimental data, the statistical regression analysis of eight commonly used hypothesis distributions, namely Weibull (two-and three-parameter), normal, lognormal, extreme minimum value, extreme maximum value, and exponential (one-and two-parameter), are developed. Then the degree of fitting effect between the experimental data with the eight statistical distributions is evaluated. The result shows that six kinds of statistical distributions, including Weibull (two-and three-parameter), normal, lognormal, extreme minimum value, extreme maximum value, have good fitting effect. In all distributions, the best one is three-parameter Weibull distribution.

Abstract: We have so far developed continuum mechanical simulation methods of group robots. Taking Hamiltonian with specified exponential function of time has allowed us to deal with motion of robots with friction also in canonical equation framework. We examine in this article results calculated by our continuum mechanical methods. We especially note the presence of collision among robots.

Abstract: Laminar natural heat transfer in the horizontal channel with a heated square cylinder has been studied by using lattice Boltzmann method. Air and water are applied as fluid flow and the walls of channel are adiabatic. Lattice Boltzmann method (LBM) as one of stochastic methods has been used to study the hydrodynamic and thermal behaviours of water and air, with Prantle number 7.01 and 0.71, respectively. Velocity and temperature profiles are achieved near each surface of the square. The results show relation between Prantle number and symmetric degree of streamlines and isotherms profile

Abstract: Statistical analysis of load spectrum is an important part on structural fatigue life and reliability research, it is generally considered that axle’s load spectrum follows Weibull distribution. This paper tested ZL50 loader’s loading history of different working conditions , and obtained the corresponding load spectrum by rain-flow counting method, then analyzed three distributions’ (normal distribution, lognormal distribution, Weibull distribution) fitting degree of load spectrum and effect on the fatigue reliability. Results show that the highest fitting degree of distribution function should be used to fit load spectrum, which can reduce the error in structural fatigue reliability prediction.

Abstract: The process of phase formation at the initial stage of the reaction diffusion and growth of a new phase particles - at the atomic level by applying the Monte-Carlo simulation of the crystalline nanoalloy is presented. The influence of initial composition on the kinetics of phase separation in a binary alloy with the fcc crystal lattice has been analyzed in detail. The dependences of various parameters of tire process - the average size of new-phase particles, volume of new-phase clusters, size distribution function, dispersion and supersaturation - on time have been calculated. The obtained results demonstrate the opportunity of a three-stage separation process at low initial supersaturation values and a two-stage separation at large initial supersaturation values.

Abstract: The influence of thermodynamic constraints like the size, depletion, surface tension and kinetic constraints like energy barrier for diffusion on nonsteady separation kinetics in binary nanopowder is investigated. Here we present a numeric analysis of size hysteresis and its peculiarities using the standard kinetic equation approach.