RELATIVISTIC ENERGY APPROACH AND MANY-BODY PERTURBATION THEORY TO COMPUTING ELECTRON-COLLISION CROSS-SECTIONS OF COMPLEX MULTIELECTRON IONS

An advanced relativistic energy approach combined with a relativistic many-body perturbation theory with ab initio zeroth approximation is used to calculate the electron-collision excitation cross-sections for complex multielectron systems. The relativistic many-body perturbation theory is used alongside the gauge-invariant scheme to generate an optimal Dirac-Kohn-Sham- Debye-Hückel one-electron representation. The results of relativistic calculation (taking into account the exchange and correlation corrections) of the electron collision cross-sections of excitation for the neon-like ion of the krypton are presented and compared with alternative results calculation on the basis of the R-matrix method in the Breit-Pauli approximation, in the relativistic distorted wave approximation and R- matrix method in combination with Dirac-Fock approximation

Substantion of the energy approach to parameter determination of the cyclic ice force against offshore structures

Определение величины силового воздействия ледовых образований на морское ледостойкое основание производится по расчетной формуле, описывающей принятую модель разрушения льда. Лед в контактной зоне ледового поля с сооружением, в зависимости от его температуры и скорости взаимодействия, может разрушаться в широком диапазоне механизмов его разрушения – от вязкого до хрупкого. Здесь представлена разработка модели упруго-хрупкого разрушения льда, учитывающая разрушение кромки ледового поля всеми возможными типами трещин, делящими локальную область массива льда в зоне контакта с сооружением на клиновидные или трапециевидные фрагменты. Предложено все процессы разрушения льда, имеющие различную природу, рассматривать как единообразный, но комплексный процесс, математическое описание которого во времени можно выполнить с использованием универсального энергетического критерия разрушения. Приводятся обоснования закономерности такого подхода, основанные на феноменологическом анализе явления циклического разрушения льда в контактной зоне, на результатах численного моделирования картины развития разрушений в массиве льда у кромки ледовой плиты на контакте с опорой сооружения, а также на данных физического моделирования изучаемого процесса. В качестве универсального критерия в работе рассматривается предельное значение накопленной в единице объема льда перед сооружением потенциальной энергии упругого сжатия – удельной упругой энергии механического разрушения морского льда.

Fatigue strength evaluation of PPGF35 by energy approach during mechanical tests

Thanks to the progress of research on thermoplastic materials, the properties of composite materials have improved considerably. The aim of this study is the evaluation of fatigue strength of glass-fibre-reinforced polypropylene composite (PPGF35) by applying both the Risitano Thermographic Method (RTM) and the new Static Thermographic Method (STM).

Analysis of energy losses in electric transmis-sion taking into account the Sommerfeld – Kononenko effect

The use of an electric drive in modern vehicles allows solving a number of problems related to the issues of environmental and energy security of the country. However, this approach imposes a number of practical limitations. Among them there is such a significant factor as the limitation on the stored energy in the traction batteries and, as a consequence, the limitation of the mileage on one charge. One of the ways to solve this problem is to reduce mechanical losses associated with the appearance of resonance phenomena in rotating transmission elements and having an unbalanced mass. Goal. The goal is to assess the influence of the Sommerfeld – Kononenko effect on energy indicators during the transfer of rotation from the electric motor to the drive wheel of an electric vehicle. To achieve this goal, it is necessary to determine the law of motion of the rotor of an electric motor and a car wheel using the energy approach and a model of complex motion. Methodology. To solve the problem of determining the law of rotation of an electric motor rotor, a dynamic model of an eccentric vibrator is adopted. The study takes into account the fluctuations in the angular velocity of the shaft with Hooke's hinge when the shaft axis deviates from horizontal positions. It is proposed to apply an energy approach using a model of complex motion to determine the law of rotation of an electric motor rotor and a wheel. Results. The dependence of the speed of rotation of the wheel of an electric vehicle is determined in accordance with the dynamic model under the conditions of fluctuations in the angular speed of transmission elements with Hooke's hinge when the wheel axis deviates from the horizontal position. Practical value. An energy approach is proposed for finding losses in a complex motion model to determine the law of rotation of an electric motor rotor and a wheel. An analytical dependence of additional energy losses caused by wheel unbalance on vehicle mileage and wheel unbalance is found.

Shared-Energy Prediction Model for Ship-Ice Interactions

Low- and non-ice-class ship-ice interactions are modelled with a shared-energy approach, which typically models the internal mechanics with nonlinear finite element methods. For applications like the preliminary design phase and quick operational assessments of the ship’s structural capabilities, a finite element shared-energy approach can be time consuming and information intensive, therefore, an analytical share-energy algorithm is proposed. The proposed algorithm applies the upper bound energy methodology by equating the external collision energy, determined with the Popov collision model (Popov, et al., 1967), to the sum of the internal ice and structural response energies. The distribution of the internal energy, between the ice and the structure, is determined by iterating through possible shared contact forces until the sum of the internal response energies equals the external energy introduced into the system. The ice-crushing energy is modelled with Daley’s (1999) energy based ice collision force models, and the internal structural strain energy is modelled through a combination of classical beam theory and design of experiments methodology. The proposed model is benchmarked against a finite element ice wedge-ship grillage structure interaction.