Applied Engineering Letters

89-99

Authors: Miloš Pešić, Nikola Jović, Vladimir Milovanović, Danilo Savić, Aleksa Aničić, Miroslav Živković, Slobodan Savić

The safety of the troop in an armored vehicle is paramount. The most serious threat to armored vehicles is a buried charge explosion or an improvised explosive device. The use of numerical approaches in the validation of armored vehicles minimizes the number of prototypes needed and speeds up the design process. This research focuses on blast simulation utilizing the ConWep (which stands for conventional weapon) method for STRENX armor steel used for blast protection in ALM (which stands for antilandmine) vehicles. The plate is modeled as a deformable solid with the Johnson-Cook plasticity model. In this paper protective plates were examined in order to determine which geometry gives the best protective conditions for the troop in an armored vehicle. Three different geometries were numerically tested, and two of them represent combined geometry. The maximal value of the plastic strain and maximal value of the vertical displacement of the central node on the protective plate was chosen as the parameters to represent the obtained results.

108-117

Authors: Yusra Jasim, Ghazwan Alwan, Tahseen Othman

Hydroforming has gained increasing attention in the manufacturing industry in recent years due to the demand for fast yet reliable production for parts, the applications of which accept a wide range of dimensional tolerances. In this study, tube hydroforming in conical dies has been analyzed. The study consists of two parts: computer simulations and experimental work. The simulation results were utilized to find the load paths which produce successful hydroforming for the selected tube specimens. Twelve load paths were identified and implemented with two friction coefficients and three pressure ranges. During the simulation process, the tubes were given an end movement that ranged from a sealing distance to twice that distance. The experimental work was implemented to verify some of the simulation results. The results showed that the best hydroforming limit was reached when the axial feeding was twice as much as the sealing distance. Also, the maximum amount of deformation rate happens shortly after the specimendie interface starts having relative motion, and it is at its slowest when the hydroforming reaches the fully-formed specimen’s shape.

125-131

Authors: Filip Klejch, Eva Schmidová, Tomáš Mejtský

Interstitial Free (IF) steels are nowadays commonly used for stamping complex parts of outer automotive bodies. Current requirements for fast production lead to the need of monitoring the real state of the material after stamping based on its real material conditions. It is desirable to describe and quantify the evolution of microstructure deformation and plastic conditions before and after the stamping process. This paper presents Electron Backscatter Diffraction analyses of deformed and non-deformed IF steel, including the quantitative measurement of the localized plastic response of the real stamped part, using an unconventional indentation method. The effect of strain rate was evaluated using the highspeed tensile tests. The increased ratio of the Low Angle Grain Boundaries was found as a good parameter to quantify the depletion of plasticity.

45-53

Authors: S. Grazion, V. Spiryagin, M. Erofeev, I. Kravchenko, Y. Kuznetsov, M. Mukomela, S. Velichko, A. Ašonja, L. Kalashnikova

The article presents the results of experimental estimation of the possibility of early registration of structural defects using the acoustic-emission method of control, based on the phenomenon of acoustic emission, which is the excitation of elastic vibrations of the material, caused by the formation and development of defects. To confirm the possibility of recording the processes of predestruction, such as the development of crack-like defects and plastic deformation using the acoustic-emission method of control, full-scale tests of the pressure vessel were carried out and the physical model of the shell-and-tube heat exchanger specially designed for this process was verified. It has been determined that the most informative frequency range for recording acoustic emission signals is the range of 100-200 kHz. The relationship of acoustic emission with the characteristics of defect development during plastic deformation has been studied. It was found that for reliable determination of the plastic deformation process, shared usage of amplitude and the count rate of acoustic emission is advisable.

67-73

Authors: M. Vite-Torres, M. Moreno-Ríos, A. Villanueva-Zavala, E. A. Gallardo-Hernández, L. Farfán-Cabrera, D. H. Mesa-Grajales

The phenomenon of cavitation erosion consists of the formation, growth, and collapse of bubbles in liquid media. The bubbles are responsible for the damage generated to metal and non-metal materials. Consequently, there is a pronounced degradation on the material surface, producing a scar in the impact area of the bubbles, and eventually the detachment of material. This experimental work aims to determine the performance of AISI 304 stainless steel base and coated with SiC. The SiC coating was obtained by the Chemical Vapor Deposition technique assisted by plasma. The tests were done through an ultrasonic cavitometer with a frequency of 28 kHz in an aqueous medium using tap water. According to the evidence of mass loss, results indicate that the stainless steel coated with SiC have better wear resistance than stainless steel base. In addition, failure mechanisms as cracking, plastic deformation, pits and others, were identified.

81-88

Authors: A. A. Patil, S. S. Desai, L. N. Patil, S. A. Patil

In the industry, ball bearings are the most widely used machine element. The ball materials may differ in various bearing applications. Wear of the ball and recess after a period of use is the most common cause of ball bearing failure. The present study aims to develop the artificial neural network model for assessing the wear of different ball bearing materials. A wear test method has been followed as suggested by the ASTM-G99 standard. The pin on disc apparatus was selected to conduct numerous trials. L9 array was considered to design the experiments. The factors considered for this study were load, time, and sliding speed. Based on the results obtained, ANN code was proposed to evaluate wear using numerous test parameters. The results obtained from the proposed model are nearly similar to experimental results, which would be evidence for the correctness of the model. The proposed neural network model can be used in numerous applications with given parameters.

1-9

Authors: D. D. Trung

This paper presents a research on investigating the effect of cutting parameters on the surface roughness (Ra) and roundness error (RE) when turning the interrupted surface of 40X steel. The TiN coated high speed steel (HSS-TiN) inserts were used in this research. The cutting parameters include cutting velocity, feed rate, and depth of cut. The Box-Behnken method was applied to develop an experimental matrix with fifteen experiments. The influences of cutting parameters on Ra and RE were found using Pareto chart. Two equations that presented the relationship between Ra, RE and cutting parameters were established. These two equations were used to predict Ra and RE. Genetic algorithm (GA) was also used to determine the optimal values of cutting parameters to simultaneously ensure the minimum values of Ra and RE. The further works of this study was also mentioned in this paper.

17-24

Authors: M. A. Kuznetsov, D. P. Il’yashchenko, E. V. Lavrova, S. A. Solodsky, О. А. Podgornyh, E. V. Verkhoturova

This paper presents the results of working out the modes of obtaining micro range powders according to the developed method. It is based on the navigation on the material of the vortex plasma flows of heterogeneous plasma and synchronized high-frequency impact on the electrode. The formation of powders is derived from individual particles heated and accelerated using a high-temperature gas jet - plasma. It is obtained in a special original plasma generator by blowing the plasma-forming inert gas into an electric arc resulting between two electrodes. The possibility of obtaining powders of various sizes and chemical composition by this method on the developed technology has been established. The design of the executive equipment that implements the studied generation process of the micro-size range is best suited for steel wires. Experimental studies made it possible to determine the optimal modes for wires of various chemical composition (steel wire, with a diameter of 1.2 mm, OK Autrod 347Si with a diameter of 0.8 mm). Range of parameters and modes of actuating equipment: current of 70-80A; Plasma-forming gas pressure 0.7-0.8 atm., Wire feed rate 20-40 mm/s, the frequency of ultrasonic oscillations of 50 MHz and 100 MHz. In these conditions, powders are obtained with a dimension of 50-100 μm.

32-44

Authors: M. Stanojević, R. Tomović, L. Ivanović, B. Stojanović

Planetary gear trains have been applied for a long time in the automotive industry as an irreplaceable part of automatic gearboxes. This paper presents, based on existing research, the kinematic analysis and evaluation of Ravigneaux gear trains, effects of power flow analysis and power loss, evaluation of utility effects of energy utilization through analysis of efficiency. It also illustrates research topics that analyse technical challenges of understanding and predicting dynamics and vibrations of planetary gear trains in the process of design of their configuration, optimization of given gear trains in reference to set criteria and affirmation of validity of their constructions by prototyping and prototype testing on the test stand.

133-147

Authors: P. Taheri, M. J. Taheri

This paper aims to provide a comprehensive feasibility study for the installation of a 100 MW wind power plant using the INVELOX system in Manjil, Gilan, in Northern Iran. In the first part of the paper, we provide a review of the status of wind energy installation in Iran. We then review the mathematical equations involved in wind power calculations. Afterwards, with the environmental data gathered from the corresponding authorities and open‐access sources, we analyzed the INVELOX system with its benefits and drawbacks. Then, based on the derived mathematical formulations, and using simulation software packages, the average wind power density is calculated, and the turbine system is designed accordingly. Finally, the economic profitability of this project was examined using a mathematical economic analysis and the COMFAR software package. In addition to the detailed feasibility study of this specific project, this article aims to provide a comprehensive literature review of the INVELOX system.

157-165

Authors: W. Sriboon, P. P. Pansila, S. Khunthong, S. Sukprasong

Lighting systems are used in all building types and consume large amounts of energy as well as adding to carbon dioxide (CO2) emissions. The aim of this research was to analyze energy consumption in the lighting systems of a new building. This study conducted a preliminary energy consumption audit of the Faculty of Science on the Kasetsart University Sriracha Campus, Thailand. The actual energy consumption in the study period and the specific energy index (specific energy consumption) were assessed. The results showed that the total electric power of all bulbs in the building was 72.13 kW and about 74 % were 20 W lamps. Annual energy consumption and carbon dioxide emissions were 157,753.73 kWh and 89,477.92 kg carbon dioxide for 9 hours use. The total energy consumption accounted for 1.64 % and 4.37 % based on 9 and 24 hours operation, respectively. The specific energy index was higher than the average for this university. Therefore, the energy consumption data obtained are very important in developing energy‐saving measures.

175-183

Authors: Ş. Danişman, E. Ersoy, C. Doğan

Titanium alloys are widely used in the aerospace industry due to their good mechanical properties. Especially Ti6Al4V alloy is preferred in machine parts that require specific strength in aerospace. However, the tribological properties of the Ti6Al4V alloy are poor and need improvement. It is possible to increase the life of Ti6Al4V alloys and improve their surface properties with various heat treatment and surface coating techniques. For this purpose, in this study, plasma nitriding heat treatment was first applied to the samples prepared from Ti6Al4V alloy. Then, TiN coating was carried out by the magnetron sputtering method. Surface roughness and surface hardness were measured before and after coating. Wear tests were performed with dry friction and room temperature conditions on Ti6Al4V alloys using the sliding velocity and normal load as variable parameters. The wear track widths, the weight loss of the samples, and the abrasive disc were measured. The steady‐state sliding regime average friction coefficients were determined from the recorded friction forces depending on the sliding distance. Normal load ‐ wear track widths, normal load ‐ friction coefficient graphics were created. Load wear track width plots showed that the wear track widths on the TiN coated and uncoated samples increased with the load. The fact that the track width values of the uncoated samples with the same load and velocity values were higher than the TiN‐coated samples showed that the TiN‐coated samples had higher wear resistance. In addition, it was observed that the friction coefficient values in the uncoated samples under constant sliding speed were relatively higher than the TiN‐ coated samples.

89-98

Authors: G. Kostadinov, P. Danailov, R. Dimitrova, M. Kandeva, T. Penyashki, V. Kamburov, A. Nikolov, B. Elenov

This paper examines the topography and roughness of coatings of hard alloyed materials deposited by electrospark deposition (ESD) on titanium and nickel alloys with different initial roughness. The influence of the electrode materials and the energy parameters of the ESD process on the roughness parameters Ra, Rt, Rq, Rz, Rmax, on the depth of waviness Wt, the asymmetry Rsk, the excess Rku, on the depth of core roughness Rk and the depth of the reduced picks roughness Rpk was established. The conditions for ESD are indicated, under which the traces of the previous treatment are erased and the characteristics of the initial substrate surface are improved. The numerical values of the roughness parameters for electrospark coatings from five types of hard alloys and one type of TiB2 based electrode with nanosized additives have been established.

105-110

Authors: A. Miteva, A. Petrova, G. Stefanov

Characteristic of the samples based on Al-Si alloys, that we have studied, is their propensity for oxidation at high temperatures. The few number of papers on the oxidation kinetics of aluminium alloys associated with Planar Flow Casting technology (PFC) can be found in the literature. The oxide processes and the properties of the oxide layer formed on the aluminium alloy are mainly considered. The aim of the present work is the kinetics of oxide layer formation on aluminium alloys to clarify whether alloys are suitable for use in space and under specific conditions. The formal kinetics of Nikitin was applied for data processing. The influence of the alloying elements on the formed surface oxide coating is shown.

124-131

Authors: I. Ramadan, M. Tănase

The study on the tubes (made of CuZn36 material) of a condenser used in petrochemical industry revealed that thickness reduction by corrosion is the main factor causing the decrease of the equipment service life. The present paper aims to study, from the experimental point of view, the behavior of the heat exchanger tubes, in the presence of different environments. The experimental program conducted in the article included two directions: evaluation of technical condition of in-service brass tubes after a certain period of operation for a condenser used in petrochemical industry in order to see how the working conditions affect the brass tubes and an experimental study based on simulation of exposure to extreme corrosive environments for samples taken from new CuZn36 tubes. The goal is to establish their influence on the tubes degradations by determining the corrosion rate. The analyzed samples were immersed in different corrosive solutions for 21 days. Another sample was boiled in water and cooled in air in order to simulate the working environment of the tubes in the condenser. All the samples were weighted before and after the exposure in the aggressive environment, thus establishing the corrosion rate for each of them. In order to analyze from mechanical point of view the influence of the environment on the brass tubes, the flattening test was made, comparing the behavior of the exposed samples with that of the unexposed sample.