Aspects of Strength Testing of Tank Containers in Compliance with the Requirements of the UN Navigation Rules and Regulations

This article deals with the method of computer-aided studies of the results of tank container impact tests to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped test rig or using a railway flat car by impacting a flat car with a striking car, in compliance with the requirements of the UN Navigation Rules and Regulations. It is shown that the main assessed characteristic of the UN requirements is the spectrum of the shock response (accelerations) for the interval natural frequencies of the shock pulse. The calculation of the points of the shock response spectrum curve based on the test results is reproduced in four stages. A test configuration of the impact testing of the railway flat car with a tank container is presented, and the impact is performed in such a way that, under a single impact, the shock spectrum curve obtained during the tests for both fittings subjected to impact repeats or exceeds the minimum shock spectrum curve for all frequencies in the range of 2 Hz to 100 Hz. Formulas for determining the relative displacements and accelerations for the interval natural frequencies of the shock wave are given. The research results are presented in graphical form, indicating that the experimental values of the shock response spectrum exceed the minimum permissible values; the equation of the experimental curve of the shock response spectrum in the frequency range 0–100 Hz is described by power-law dependence. The coefficients of the equation were determined by the statistical method of maximum likelihood with the determination factor being 0.897, which is a satisfactory value; a comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0–100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. A new test configuration is proposed using a tank car with a bulk liquid, the processes in which upon impact differ significantly from other freight wagons under longitudinal impact loads of the tank container. The hydraulic impact resulting from the impact on the tank container and the platform creates an overturning moment that causes the rear fittings to be unloaded.

A New Inverse Method for Determining Uniaxial Flow Properties by Spherical Indentation Test

This study presents a new inverse method to determine tensile flow properties from a single indentation force-depth curves. A database is established to replace the iterative FE calculations in conventional inverse methods and therefore can process the indentation data more quickly and easily. An axisymmetric FE model is constructed to simulate the elastic-plastic response of indention. Assuming the materials follow Ludwic constitutive model, by systematically changing the material parameters, numerous indentation force-depth curves are extracted from simulation results to establish the database. For a given experimental indentation curves, a mean square error (MSE) is designated to evaluate the deviations between the experimental curve and each curve in the database. Then, the relation of deviations versus stresses are investigated to acquire the true stresses at a series of plastic strain. To validate the new method, three different steels, i.e. A508, 316L and 2.25Cr1Mo are selected. Both simulated indentation curves and experimental indentation curves are used as inputs of the database to inversely acquire the flow properties. The result indicates that the proposed approach provides impressive accuracy when simulated indentation curves is used, but is less accurate when an experimental curve is used. This new method can quickly derive tensile properties without iterative calculations that yield a considerable computational costs and are therefore adaptive to engineering application.

ASPECTS OF TANK-CONTAINER TESTS FOR COMPLIANCE WITH THE REQUIREMENTS OF THE UN SHIPPING REGISTER

The article deals the method of calculation studies of impact tests of tank containers to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped stand accredited in the certification system of the Register of Shipping of Ukraine, or using a railway platform and executing an impact force generated by a wagon-striker in accordance with the requirements of the UN Register of Shipping. It is shown that the main estimated characteristic of the UN requirements is the impact response spectrum (accelerations) for the interval natural frequencies of the impact impulse. The calculation of the points of the impact response spectrum curve according to the test results is shown in four stages. The test configuration of a railway platform with a tank-container for impact loads is presented, in which the impact is performed in such a way that the curve of the impact response spectrum obtained during the tests of both fittings under a single impact repeated or exceeded the minimum impact response curve spectrum at all frequencies in the range from 2 Hz to 100 Hz. The matrices of relative displacements and accelerations for the interval natural frequencies of the impact wave are given. The results of the research are presented in graphical form, which shows that the experimental values of the impact response spectrum exceed the minimum allowable values. The equation of the experimental curve of the shock response spectrum in the frequency range 0-100 Hz is described by the power dependence; the coefficients of the equation were determined by the statistical method of the maximum likelihood, with the determination factor being 0.897, which is a satisfactory value. The comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0-100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. It is proposed to use a new test configuration using a tank car with bulk liquid, where the processes occurring under impact significantly differ from other freight cars subjected to longitudinal impact loads of the tank container. The hydraulic shock caused by the impact on the tank container and the platform creates a turning moment, which causes the rear fittings to be unloaded.

Conjugate Direction Particle Swarm Optimization Based Approach to Determine Kinetic Parameters from Part of Adiabatic Data

Due to the limited detection range of the adiabatic equipment, it is difficult to get complete experimental curve of some materials and calculate the kinetic parameters. In this work, the conjugate direction particle swarm optimization (CDPSO) approach, as a global stochastic optimization algorithm, is proposed to estimate the kinetic parameters and complete experimental curve from part of adiabatic calorimetric data. This algorithm combines the conjugate direction algorithm (CD) which has the ability to escape from the local extremum and the global optimization ability of the particle swarm optimization (PSO) which finds the globally optimal solutions. One case was used to verify this method: 20% DTBP in toluene decompositions under adiabatic conditions. Comparing the experimental and calculated complete temperature curve, the accuracy of the fitted kinetic parameters calculated by no less than 70% temperature rise rate proportion of data is verified. The value of TD24 is well-deviated even used 10% proportion of data. The case reasonably proves the effectiveness of CDPSO algorithm in the estimation of kinetic parameters from part of adiabatic data.

Электронное строение и оптическое поглощение фуллеренов как сильно коррелированных систем на примере молекулы C-=SUB=-96-=/SUB=-(C-=SUB=-2-=/SUB=-)

Taking into account the intrasite Coulomb interaction with the parameter U ~ 10 eV in the approximation of static fluctuations, the energy spectrum of the isomer N 181 (C2) of the C96 fullerene is calculated, based on which its optical absorption spectrum is modeled. The obtained curve of the optical absorption spectrum at a good qualitative level coincides with the experimental curve. The same curve obtained in the framework of the traditional model without taking into account the intranode Coulomb interaction differs significantly from the experimental curve. Keywords: fullerene, energy spectrum, optical absorption spectrum, π electron, Hubbard subband, optical transitions.

Theoretical calculation of the exchange coupling constant in some polymeric nickel(II) complexes using range-separated functionals

The magnetic parameters (J, g) of two nickel(II) 1D polymers (Ni(en)(ox) and Ni(ox) (ampy)2; where en = ethylene diamine, ox = oxalate, ampy = 4-amino-pyridine) were calculated using 6-311+G* basis set and six range-separated DFT functionals (CAM-B3LYP, LC-BLYP, wB97, wB97X, wB97X-D3 and B2T-PLYP) together with the hybrid B3LYP method for sake of comparison. We found that the wB97, CAM-B3LYP and wB97X-D3 methods gave approximate value of J for compound 1 and the B2T-PLYP method was found to be the best method for compound 2. The g values were calculated by the coupled perturbed approach. However, we assume that a higher approximation is needed in order to give satisfactory results for g. A new equation has been proposed to relate the experimental susceptibility to the J and g parameters. The Curie-Weiss law was included in this equation resulting in a good explanation of the steep part of the experimental curve below 20 K.