Eastern-European Journal of Enterprise Technologies

Development and post-processing of mathematical and computer models of contact problems

Tetyana Zaytseva, Ganna Shyshkanova, Yaroslav Honcharov — Wed, 31 Dec 2025 00:00:00 +0200

This study investigates the process of contact interaction between a rigid punch and an elastic half-space under the action of a centrally applied clamping load. The task addressed is automating the processing of results for data analysis.

This paper considers a problem for a punch with complex geometry. The contact zone has a doubly connected shape bounded by concentric ellipses, which complicates the analytical description of the stressed-strained state.

To solve the problem analytically, a perturbation method was applied, using the previously found expansion of the simple layer potential with a small parameter. This makes it possible to reduce the problem to a configuration with a circular ring whose exact solutions are known in the form of a series with recurrent coefficients. The obtained analytical results serve as a reference basis for assessing the accuracy of numerical modeling, for example, when constructing a finite element model. Such mathematical formalization makes it possible to effectively assess the reliability of the results.

Consequently, calculation models were built in the Ansys software environment taking into account features of the punch shape. Special software was developed that enables exporting calculation data to the MATLAB software package with subsequent post-processing to automate data processing. The proposed approach reduced the complexity of post-processing by approximately 45–55%.

It was found that with an increase in the eccentricity of the ellipse, the pressure under the punch increases. In the central zone, a lower pressure is recorded, which increases along the edges of the contact area. The numerical results correlate well with the analytical ones.

The results reported here could be used for strength calculations in engineering practice under conditions of contact interaction between structural elements of mechanical engineering where the contact zone has the shape of an elliptical ring.

Numerical implementation of Richardson extrapolation for dynamic problems of multilayer cylindrical shells

Wed, 31 Dec 2025 00:00:00 +0200

This study considers forced vibrations of a heterogeneous elastic structure in the form of a multilayer cylindrical shell consisting of rigidly connected layers and reinforced with discrete ring elements.

A mathematical model of vibrations of an elastic heterogeneous structure under the action of a non-stationary load has been constructed. The stressed-strained state of a multilayer cylindrical shell with discrete ring ribs was investigated using the geometrically nonlinear theory of Timoshenko-type shells and rods. The presence of a complex right-hand side and discontinuous coefficients in the spatial coordinates in the hyperbolic equations of vibrations of a heterogeneous elastic cylindrical shell (at the locations of the reinforcing ribs) necessitated the use of numerical methods for solving them. A numerical algorithm using Richardson extrapolations has been proposed for studying the constructed model.

For example, a three-layer reinforced cylindrical shell is considered, taking into account the discreteness of the ribs' placement under dynamic loading with rigidly clamped ribs. The proposed numerical algorithm has made it possible to investigate the stressed-strained state of a three-layer reinforced elastic structure of a cylindrical type at any given moment in time. A comparative analysis of the numerical results of the calculations revealed that, according to the standard approach, the discrepancy in the deflection values for n = 40 and n = 160 reached 31%, for n = 80 and n = 160 it was about 5%, according to Richardson's approach for n = 40 ÷ 80 and the standard approach for n = 160, this difference was about 1%.

A distinctive feature of this study is the use of Richardson extrapolation to identify the stressed-strained state of a three-layer reinforced cylindrical shell, which made it possible to increase the accuracy of the solution to the dynamic problem without reducing the calculation step.

The study's results reported in this work could be used for investigating unsteady vibrations of shell structures at research and engineering organizations

Identification of the mechanical performance of finger-jointed laminated merbau timber beams reinforced with carbon fiber reinforced polymer (CFRP)

Lilis Nurhayati, Sri Murni Dewi, Wisnumurti Wisnumurti, Devi Nuralinah — Wed, 31 Dec 2025 00:00:00 +0200

In this research, the mechanical properties and the reinforcement mechanism of finger-jointed laminated Merbau beams processed from wood-industry wastes are investigated and unreinforced specimens and externally U-shaped carbon fiber reinforced polymer (CFRP) strengthened beams are compared. The problem to be solved is the brittle failure and reduced flexural capacity of finger-jointed glulam; hence, it determines the combined impact of joint orientation (face-finger and face-butt), the number of lamination (three and five layers), and CFRP reinforcement on block-assembled beams with randomly distributed finger joints through four-point bending tests. The outcome of the study reveals that the use of CFRP has a huge impact on the flexural performance of the material, with the ultimate load being increased by 27.4–48.8% and the maximum bending moment being raised by 45.3% when compared to non-reinforced beams. The mid-point deflection at the maximum load has also increased by 6.5–51.4%, which shows a higher capacity for deformation and better ductility of the material.

The noted enhancements are credited to the successful shifting of the stress from the timber tension zone to the CFRP, lessening of stress concentration at the fingerjoint discontinuities, and the crack initiation and propagation taking longer time in random locations which together change the structural response from sudden brittle fracture to more stable damage progression leading up to failure. Among the tested configurations, face-butt beams have obtained the highest modulus of elasticity of 20.46 GPa (an 8.8% increase), while the five-lamina face-butt configuration strengthened by CFRP has reached the greatest modulus of rupture of 55.85 MPa (a 33.4% increase). The three-lamina face-finger beams showed the highest increase of MOR after reinforcement, being at 48.30 MPa (a 46.4% increase). Changing lamination from three to five layers raised flexural strength by 18.9%, suggesting a homogenization effect that improves stress distribution in laminated beams composed of blocks. All in all, the collaboration of finger-joint configuration, number of lamination, random block assembly, and CFRP strengthening has opened a door to convert Merbau wood waste into higher-performance engineered timber elements for low-carbon structural applications

Scientific rationale for the use of perforation beams in the bearing structure of a modernized railroad platform car for container transportation

Wed, 31 Dec 2025 00:00:00 +0200

This study investigates processes related to the occurrence, acceptance, and redistribution of loads in the supporting structure of a railroad flat wagon. The task addressed is to improve the technical and economic indicators of the modernized flat wagon for container transportation by reducing its tare.

To this end, the stress distribution fields in the modernized railroad flat wagon structure were determined. It was established that the main longitudinal beams of the frame have a strength reserve, which is due to the underutilization of railroad flat wagon bearing capacity. This leads to an excess sprung mass of its supporting structure. Therefore, it is proposed to introduce perforation in the walls of the main longitudinal beams of a railroad flat wagon. To substantiate this solution, the strength of the bearing structure of a railroad flat wagon was calculated. It was established that the maximum stresses in the bearing structure are 13.6% lower than the permissible ones.

The design service life of a railroad flat wagon is at least 32 years. The biaxiality calculation of the bearing structure showed that its greatest values are reached in the middle parts of girdle beams.

A special feature of the proposed solution is that it makes it possible to improve the technical and economic indicators of the modernized railroad flat wagon with minor capital investments.

The scope of practical application of the results is railroad transport.

A condition for practical use of the results is symmetrical loading of the bearing structure of a railroad flat wagon with cargo.

The results of the research could contribute to improving the efficiency of container cargo transportation along international routes. In addition, the results might prove useful for designing and fabricating new structures of railroad flat wagons, as well as for modernizing existing ones

Effect of wind turbine blade trailing edge modification on aerodynamic noise

Wed, 31 Dec 2025 00:00:00 +0200

This study investigates acoustic processes that occur during the flow of air around the blade segment of a wind turbine. The issue of aerodynamic noise generated by wind turbines is one of the factors that hinders the widespread implementation of wind turbines. Noise reduction is possible by changing the design of the turbine blade to influence the aerodynamic processes during the flow of air around it.

This paper reports an experimental study on the possibility of reducing the aerodynamic noise of wind turbines by modifying the trailing edge of the blade. An original methodology of acoustic experiments in an anechoic chamber is described; the results of experimental studies are given.

Two different modifications of serrated trailing edges of the blade with the NACA0012 aerodynamic profile have been considered: a flat serrated edge and a three-dimensional serrated edge. The results from aerodynamic noise measurements of the prototypes of the blade segments were compared with the noise from the basic original sample. Acoustic measurements were carried out in the range of flow speeds: 7.5–20 m/s and angles of attack 0–15°.

The results demonstrated that both configurations of the serrated trailing edge make it possible to reduce the level of aerodynamic noise compared to the base segment. It was found that the noise reduction occurs at relatively small angles of attack (0–5°) and moderate flow speeds (up to 15 m/s). In the specified range of parameters, the reduction of aerodynamic noise occurred due to a decrease in the sound pressure level in a certain frequency range by up to 4 dB. The segment with flat serrations turned out to be somewhat more effective in terms of noise reduction in the low-frequency range.

Results of this work could be used when designing new generation wind energy systems with reduced noise levels, as well as other aerodynamic devices.

Devising an approach to calculating and optimizing a supersonic nozzle for cold gas-dynamic spraying

Oleksandr Shorinov, Nina Savchenko, Olga Shypul, Ihor Zorik, Serhii Nyzhnyk — Wed, 31 Dec 2025 00:00:00 +0200

This work investigates the process of powder particle acceleration in a supersonic nozzle for cold gas-dynamic spraying (CGS). The task addressed in the study is predetermined by the lack of established patterns in the comprehensive influence of gas parameters and nozzle geometry on the speed of powder particles at the nozzle outlet, which complicates predicting and controlling the spraying process.

A new approach to the design of nozzles for CGS has been proposed and implemented, which allows for targeted optimization of their geometric parameters taking into account the gas parameters at the nozzle inlet. The approach is based on a combination of analytical modeling (isentropic model, particle acceleration model), methods of statistical planning and analysis of experiments (central compositional design, construction of regression equations), and multifactor optimization of nozzle geometry.

Regularities have been established between the velocity of aluminum particles with a size of 25 μm at the nozzle outlet and the gas parameters: braking pressure 0.8–2.5 MPa and braking temperature 300–700°C. The calculations also took into account the influence of the nozzle geometry: critical diameter 1.0–3.0 mm, outlet diameter 5.0–10.0 mm, length of the expansion section 80–150 mm. The resulting nozzle and spraying mode ensure that the particles achieve a velocity at the outlet of 596 m/s, which exceeds the required minimum of 550 m/s, at an air flow rate of 1.0 m³/min.

The proposed approach could be applied to designing new nozzles for mobile and stationary CGS installations operating on compressed air, nitrogen, or helium with a pressure of 0.6 to 4.0 MPa; in particular, for spraying protective and restorative coatings under conditions of limited gas flow. The results lay out the foundation for developing a software tool or an automated system for designing nozzles for CGS in a wide range of initial gas and powder parameters

Defining the transient process of belt lateral runout from a conveyor drum with slight curvature

Аlexandr Gavryukov, Mykhailo Kolesnikov, Andriі Zapriуvoda, Oleg Dedov — Wed, 31 Dec 2025 00:00:00 +0200

A belt conveyor has been investigated in this work. The effect of the angle of the belt axis relative to the drum axis on the lateral runout of the belt was considered. The influence of the belt speed, the load at the point of contact of the belt with the generator drum, the curvature of the generator drum, and the linear mass of the belt on the lateral runout of the belt were also examined. The friction coefficient of the belt sliding on the rollers in the running section of the belt on the drum, the belt tension at the point of running on the drum were investigated.

It was established that lateral runout always occurs in the absence of perpendicularity of the belt axis relative to the drum axis. The belt speed during lateral runout is maximum at the beginning of the transition process and decreases as the displacement increases. During lateral runout of the belt in the zone of its contact with the generator drum, tangential and normal loads occur.

The stationary state is achieved when the belt axis becomes perpendicular to the drum axis.

Tangential loads in the absence of slippage do not depend on normal loads and are caused by the non-perpendicular location of the belt axis relative to the drum axis. Tangential load is proportional to the lateral displacement of the belt. The transient process of belt slippage on a drum with a slight curvature of the generator is described by an equation corresponding to an aperiodic link of the first order.

This study make it possible to determine optimal parameters when designing a system for automatic belt centering on a drum with a curved generatrix. Thus, in the development of the end station of a belt conveyor (Patent of Ukraine No. 98378), a hydraulic pump NSH-10E was used. The magnitude of the drum curvature is limited by the resulting unevenness of belt tension across the width, as well as the possibility of belt slippage, and significantly depends on the stiffness of the belt