International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The definition of plane stress and strain states plays a crucial role in engineering, as recognizing these states within a structure enables the optimization of its design. This article introduces a novel hybrid wave method for analysing a circular disc geometry, with potential extensions to other geometric configurations. The method involves applying wave forces corresponding to the external loads, which then propagate through the structure and reflect back at the contours to satisfy static equilibrium conditions. The process is conceptualized in two phases while the first phase involves the application of forces where the second phase accounts for the arrival and reflection of waves at the contour boundaries. In each case, the static equilibrium at the contours is maintained by considering the reflection of the stress waves, or return waves. By incorporating these return waves and ensuring the boundary conditions are met, this approach facilitates the determination of stress at any given point within the structure.

Exergy analysis of three cylinder steam turbine segments is performed in this research. The highest mechanical power of 47389.66 kW is developed in the first segment (Seg. I, which actually represents the entire HPC – High Pressure Cylinder). Intermediate Pressure Cylinder (IPC) is the dominant mechanical power producer of all cylinders and it develops 48.95% of cumulative mechanical power produced in the whole turbine. The outlet Low Pressure Cylinder (LPC) segments (Seg. VII and IX) have the highest exergy destructions and the lowest exergy efficiency (equal to 61.27%) of all turbine segments. The best exergy performance shows IPC segments – Seg. V has the lowest exergy destruction (equal to 363.84 kW), while Seg. II has the highest exergy efficiency (equal to 94.04%) of all turbine segments. Outlet LPC segments (Seg. VII and IX) are the most sensitive to the ambient temperature change – their exergy efficiency decreases for 3.19% when the ambient temperature increases from 5 °C to 45 °C.

Laser Powder Bed Fusion (LPBF) is a prominent additive manufacturing process used for fabricating complex metallic structures, but it often encounters challenges related to thermal distortions and residual stresses, particularly in thin-walled structures. These issues compromise the integrity and dimensional accuracy of the parts. Finite Element Analysis (FEA) has been essential in simulating and understanding the thermal and mechanical behaviors during the LPBF process. This study focuses on validating a refined FEA model developed using ANSYS Additive Print (AAP) to predict the thermal distortions in CoCr thin-wall structures. The validation involves comparing simulation results with experimental data to verify the model’s effectiveness. The study demonstrates the integration of advanced simulation techniques in predicting distortions and stresses, thereby enhancing the reliability and accuracy of the manufacturing process.

The article presents the design of a flexible screw sectional working body that will improve the functional and operational characteristics of screw conveyors during the utilization of the removed contaminated soil layer. A mathematical model of the dynamic system of a flexible screw conveyor was created, and dynamic starting torques were calculated at the rated load of the loaded screw and when the system was braked. The analysis of the results shows that with significant damping coefficients, the startup transient process is smooth and the load reaches its nominal value without fluctuations in torque and speed.

The paper examines the dynamic analysis of a hydraulic lift that is used for lifting and lowering vehicles. These lifts are implemented in various servicing facilities for the repair of vehicles. The lifts consist of various mechanical and hydraulic parts and besides lifting and lowering the vehicle, they need to keep the vehicle lifted for a certain amount of time. During the work operations, the lift’s main parts are heavily loaded. The method of analysis consists of 3D modeling of the Hydraulic lift and carrying simulations with software. This enables to analyze the dynamics of motion, identify the forces and stresses in lift parts and the form and intensity of oscillations that can cause failures of parts and concerns about the safety. Conclusions from this paper will be useful regarding the loading dynamics on the Hydraulic Lift during lifting and lowering, and design considerations. Results will be shown in graphical form, in time dependence. The Hydraulic Lift is modeled based on the Data from the standard manufacturer. The software that will be used for modelling and analysis is SimWise 4D.

In this study, an original design was developed to address the issue of insufficient packaging speed, a key challenge in wet wipe production lines. A separator/distributor was developed that enables a single wet wipe machine to work with three packaging units during the transfer of products from the wet wipe preparation unit to the packaging process. The developed separator moves angularly on the vertical axis and can transfer products to conveyor groups leading to three different packaging lines. Additionally, a unique movable upper conveyor was designed to operate across a range of product heights, which applies pressure to the products during movement to prevent them from scattering. One of the primary design criteria for the conveyor is lightweight construction, and this was a key focus during development. To achieve angular motion, a servo-driven flywheel mechanism was designed. The machine is equipped with sensors for Industry 4.0 compatibility, ensuring communication between units. In case one of the packaging machines becomes inactive, the separator automatically redirects the product feeding process to the remaining packaging machines, ensuring uninterrupted production.

Planetary power transmission are characterized through more complex design and kinematics parameters compared to involute gear trains with parallel shafts. It has been established that their components should be measured and monitored more frequently in order to avoid intensive wear. The paper presents a design project of an advanced experimental device for measuring vibration and wear of planetary gear components. As it is well known, approaches to direct measuring of wear and vibration parameters are difficult to be implemented in these gear trains. The application possibilities of a measurement system that includes a micro-electro-mechanical system, a temperature sensor and wireless modules assembled in a planetary gear trains have been considered. The advantages of micro-electro-mechanical measurement systems have been analyzed precisely. The main characteristics of micro-electro-mechanical sensors are low power consumption, small size and good control and monitoring capabilities. A suitable advanced methodology for the experimental study of planetary gears has been created as well. Conclusions and recommendations have been deduced.

The primary task of daytime running lights is for road users to perceive the presence of vehicles, as well as other road users, which is a basic prerequisite for safe traffic. The visibility of the vehicle, as well as of other road users, depends on the light intensity and light beam length of passenger vehicles. As the impact of daytime running lights on improving road safety has not been fully researched, in this paper the lights intensity and length of the light beam in passenger motor vehicles was measured and analysed. The research was done during the technical inspection of the vehicle (at the “Tachograph” technical inspection in Kragujevac). The results show that low beams are more efficient in illuminating the road compared to high beams, while there is no significant difference in light intensity between left and right vehicle headlights.

The article presents the design of a flexible screw sectional working body that will improve the functional and operational characteristics of screw conveyors during the utilization of the removed contaminated soil layer. A mathematical model of the dynamic system of a flexible screw conveyor was created, and dynamic starting torques were calculated at the rated load of the loaded screw and when the system was braked. The analysis of the results shows that with significant damping coefficients, the startup transient process is smooth and the load reaches its nominal value without fluctuations in torque and speed.

This study focuses on the development of modular flue gas waste heat exchangers designed for integration with organic Rankine cycle (ORC) systems within the cement industry. The design and implementation of this system involved comprehensive engineering analyses to address challenges like corrosion and thermal stratification. These heat exchangers, the first of their kind to be produced in Turkey, are compatible with Industry 4.0 standards and offer the capability to convert waste gases into electrical energy without the need for water. This pioneering technology plays a significant role in promoting eco-friendly industrial practices by reducing carbon emissions and supporting the transition to greener energy solutions.

This paper discusses the production and functionality of bladder tanks used in fire protection systems. These tanks, comprising a tank, membrane, and proportioner pressurized through a single line, are designed to mix water and foam concentrate in a controlled manner to create an effective extinguishing medium. The bladder tank technology is renowned for its reliability and precision, making it a popular choice in fixed fire protection systems.

An innovative device and a cost-effective and environmentally friendly technology have been developed to produce porous composite materials by using two types of waste raw materials: residual biomass from agricultural production and municipal waste. Heattreated rice husk and ground waste glass were used as main components. The technological approach presented here allows for the preparation of “breathable” porous materials with the predominant presence of open pores and increased specific surface area. A promising possibility for the application of the developed materials is their use in bulk or in the preparation of various composite building elements based on inorganic binders. Recipes and an adequate technological regime have been developed taking into account the design characteristics of the production facility, the specificity of the waste raw materials used and the intended target performance of the products.