Sergey Ponomarev

The applicability of acoustic emission method to modeling the endurance of metallic construction elements

Acoustic emission method is the most effective nondestructive inspection technique of construction elements. This paper considers the expanded applicability of acoustic emission method to modeling the damage and the remaining operational life of building structures, including the high-ductile metals. The modeling of damage accumulation was carried out to predict endurance using acoustic emission method.

Computer simulation of low-temperature ceramics with a hierarchical structure synthesis

Low-temperature ceramics has been widely used in modern materials production, especially radio engineering and medical supplies. Creation of a comprehensive computer model of the processes of low-temperature ceramics synthesis allows to investigate the kinetics of sintering processes and get the forecast of structural and geometric characteristics.

Development of Microlinear Piezo-Drives for Spacecraft Actuators

The article describes the development and experimental studies of microlinear piezo-drive for control reflective surface devices of large-sized transformable spacecraft antenna reflectors. Research target—experimental investigation of the microlinear piezo-drive to determine stable oscillatory system operating modes which would include improved energy conversion parameters. The following characteristics are briefly presented: test stand construction-design description, identification of oscillatory system resonant and actual frequencies under inertia load. A series of experiments have been conducted for both different preliminary tensions and inertia mass values.

Nondestructive testing method for a new generation of electronics

The implementation of the Smart City system needs reliable and smoothly operating electronic equipment. The study is aimed at developing a nondestructive testing method for electronic equipment and its components. This method can be used to identify critical design defects of printed circuit boards (PCB) and to predict their service life, taking into account the nature of probable operating loads. The study uses an acoustic emission method to identify and localize critical design defects of printed circuit boards. Geometric dimensions of detected critical defects can be determined by the X-ray tomography method. Based on the results of the study, a method combining acoustic emission and X-ray tomography was developed for nondestructive testing of printed circuit boards. The stressstrain state of solder joints containing detected defects was analyzed. This paper gives an example of using the developed method for estimating the degree of damage to joints between PCB components and predicting the service life of the entire PCB.

Simulation of sintering of low-temperature ceramic products formed by additive technology

Computer simulation methods have been applied to study the processes of low-temperature ceramics synthesis corresponding to technological processes. The simulation is performed for micron- and nanosized powders with different morphology. The synthesized composite medium has the characteristics (microlayer thickness, pore volume fraction, etc.) that reflect imperfections in the initial dispersion. The developed model allows one to examine the governing factors of physical and chemical processes in low-temperature ceramics synthesis.

Buckling analysis of large-sized space reflector

This paper presents the buckling analysis of a new large-sized umbrella space reflector and its framework spoke members via finite element method. The main goal is to obtain critical load values for the reflector and its framework spoke members with corresponding buckling modes. In the context of considered method, linear and nonlinear approaches are used. To verify the linear analysis results for spoke the dynamic buckling analysis was applied, including the spoke first natural frequency decreasing under increasing axial loads. In the case of buckling this frequency equals zero. Additionally, according to reflector buckling analysis, it was proved that the safety factor for reflector framework structure is more than eight. Thus, this structure could be considered as reliable in view of buckling.

Durability evaluation method for contact component interconnections in printed circuit boards under thermal loads

In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.

Calculation method for cable-beam shell structures

This paper presents a calculation method suitable for cable-beam shell structures. It is based on both nonlinear finite element and force density methods. The main idea is to define the solution sequence for stress – strain state problem of above mentioned structures by nonlinear finite element method. Every successive solution involves the previous one as an initial estimate in convergent domain. To find an initial estimate for the first solution a force density method is used. The proposed method is tested on a new large space umbrella reflector.

Mathematical model of composite fibre-glass aramide-wired cord rheological properties

This paper describes the rheological properties of composite fibre-glass aramide-wired cords which, in its turn, are applied in large-sized structures for space systems. Based on experimental data a new mathematical model describing creeping and relaxation of composite cords is proposed. This model defines the operation time of the composite cords to be 15 years.

Disturbance impulse effects on large umbrella space reflector dynamics

Large umbrella space antennas are essential for communication, monitoring and observation of Earth and space objects. Despite investigations devoted to space antenna dynamics, the disturbance impulse shape effect on the root mean square error of spacecraft antenna reflecting surface has not been studied. This paper overcomes this gap describing disturbance impulse impact on root mean square error of spacecraft antenna reflecting surface relative to paraboloid via nonlinear finite element method. Based on numerical results root mean square dependency on disturbance time for rectangular and sine impulses was calculated. This approach could be applied in studying antenna reflecting surface response on disturbance impulse for different types of perspective large space antennas.