Papers by Vladislav Blagojevic
Energies, 2021
During pneumatic control system design, the critical value for choosing the appropriate pneumatic... more During pneumatic control system design, the critical value for choosing the appropriate pneumatic actuator is the weight of the workpiece. In the case of flexible production systems, which are the core part of the Industry 4.0 (I4.0) concept, the weight of the workpieces is often variable, since the crucial feature of this kind of production is its ability to deal with variable parts. Therefore, in order to deal with the variable weight of parts, a pneumatic actuator is chosen according to the heaviest part. However, according to another I4.0 principle, energy efficient operation of machines, the previous criteria for choosing a pneumatic actuator is energy efficient only when handling the heaviest part. In all other cases, operation of the pneumatic actuator is suboptimal in terms of energy efficiency. Aiming to solve this problem, this paper considers the possibility of using a new pressure regulator instead of traditional manually adjusted pressure regulators. This regulator prov...
Passivation of a biomedical grade 316L stainless steel by mean of nitric acid treatment was used ... more Passivation of a biomedical grade 316L stainless steel by mean of nitric acid treatment was used to improve a protective oxide layer on the surface and to increase resistance to pitting corrosion in physiological solution. Both regression analysis and genetic algorithm were employed to reveal the effects of operating parameters of the nitric acid passivation (HNO3 concentration. temperature and passivation period) on the corrosion resistance of AISI 316L stainless steel in Hank's solution. The experiment designed as full factorial with three factors and three levels. The responses were the pitting potential values (Ep) obtained from potentiodynamic tests. Mathematical model was determined by using regression analysis. According to the model, the effects of each variable and interactions between them were calculated. Optimal intervals of the parameters were estimated by mean of genetic algorithm.
Facta universitatis-series: Mechanical …, 2001
Facta universitatis-series: …, 2002
... Simulacijom na računaru ilustrovan je kvalitet rada razmatranog sistema. Ključne reči. pneuma... more ... Simulacijom na računaru ilustrovan je kvalitet rada razmatranog sistema. Ključne reči. pneumatic actuator; variable structure system; digital sliding regimes. Reference. Blagojević, V. (2000) Merenje pritiska u cilindru. Ni: Mainski fakultet, Seminarski rad iz metoda merenja. ...
Facta universitatis - series: Mechanical Engineering, 2013
Abstract. The paper discusses the ternary (three-valued) logic application at the level of the te... more Abstract. The paper discusses the ternary (three-valued) logic application at the level of the technological capacities of the pneumatic components while considering the problem intricacy so far as the logical operation application to the real system is concerned. By using the existing pneumatic components, the circuit of the basic operator of the proposed symmetrical ternary system has been realized so that one of the logical values of variable xi ∈ {-p, 0, p} corresponds to each range. The vacuum induction nozzle is used as the basic component in the scheme realization. The given issues are illustrated by using an example of the integrated ternary system for manipulation within the sequential control.
Abstract. The paper considers the problem of ensuring synchronized movement of several hydraulic ... more Abstract. The paper considers the problem of ensuring synchronized movement of several hydraulic cylinders. The control system for synchronization was designed by applying the variable structure control system theory. The control algorithm is based on the digital sliding mode. Measuring coordinates of the state (positions and velocities) directly on the cylinders is supposed to be possible. It is shown that such a system ensures quick synchronization of cylinders under different initial conditions. The applied algorithm was compared with conventional control algorithms. The quality of work of the considered system was illustrated by computer simulation. Key words: hydraulic cylinder, variable structure system, digital sliding mode, synchronization 1.
In the industrial processes of injection molding, one of the basic requirements is a uniform temp... more In the industrial processes of injection molding, one of the basic requirements is a uniform temperature filed within workpiece and the mold cavities. In the case of simple geometry of workpiece and mold with single cavity achieving a uniform temperature field is not a critical issue. However, if one deals with parts of complex geometries, multi-cavity molds and asymmetric layout of different forms in the mold additional analyses of the runner and cooling system are necessary in order to obtain the required quality and accuracy of end the products. Disposition and dimensions of both runners and cooling channels are directly related to the geometry of finished parts and material properties. In that sense, virtual models and numerical simulations of injection molding processes based on the finite element method are very effective tool which enable accurate prediction of potential problems and significant reduction of trial and error procedure. In this paper, FEM software package Molde...
Facta Universitatis, Series: Mechanical Engineering, 2019
Nowadays, programmable logic controllers (PLC) are widely used in many automated systems, especia... more Nowadays, programmable logic controllers (PLC) are widely used in many automated systems, especially for the control of various actuators. The most common PLC programming is performed by either using a ladder diagram or a structured text. The paper presents the automatic generation of PLC programs for the purpose of sequentially controlling pneumatic actuators. In this paper, the pneumatic actuators are supplied and controlled by 5/2-way as well as 5/3-way bistable pneumatic valves with electric activation. The valve type depends on the number of positions in which the actuator should come, and the position sensors are used for detecting its movement. The characteristic encoding of the movement of actuators, position sensors and control commands is performed. The advantages of the automatic generation of the PLC commands and the entire program described in this paper are illustrated in a real example.
Facta Universitatis, Series: Mechanical Engineering, 2016
Laser cutting is one of the leading non-conventional machining technologies with a wide spectrum ... more Laser cutting is one of the leading non-conventional machining technologies with a wide spectrum of application in modern industry. It order to exploit a number of advantages that this technology offers for contour cutting of materials, it is necessary to carefully select laser cutting conditions for each given workpiece material, thickness and desired cut qualities. In other words, there is a need for process control of laser cutting. After a comprehensive analysis of the main laser cutting parameters and process performance characteristics, the application of the developed software tool “BRUTOMIZER” for off-line control of CO2 laser cutting process of three different workpiece materials (mild steel, stainless steel and aluminum) is illustrated. Advantages and abilities of the developed software tool are also illustrated.
Facta Universitatis, Series: Mechanical Engineering, 2017
Aluminum is a metal that is being increasingly used in the packaging industry in the modern metal... more Aluminum is a metal that is being increasingly used in the packaging industry in the modern metal forming technology, but it also provides a good opportunity for effective advertising and product promotion. Processing technologies for aluminum plastic deformation ensure superior packaging that meets the most rigorous demands in the food, pharmaceutical, chemical, and other industries. It is the case of mass production with very little material loss that offers the possibility of multiple recycling. On the other hand, today's products for general purpose consumers cannot be imagined without aggressive advertising that has a major impact on customers. Modern graphics techniques for printing images and different basic surfaces offer great opportunities that manufacturers use widely in the promotion and sale of their products.
Requirements for increased energy efficiency and lower energy consumption, i.e., efficient and ra... more Requirements for increased energy efficiency and lower energy consumption, i.e., efficient and rational exploitation of energy resources, are today the global imperative which has been a subject of international treaties and standards. Bearing in mind that the compressed air is one of most widely used energy carriers in industry as well as the subject of aforementioned requirements, this paper is a contribution to investigations on the increase of energy efficiency of compressed air systems by reducing unnecessary consumption. In view of this objective, the paper analyzes the effects of the piston rod clamping unit application and its influence on energy efficiency of compressed air systems.
Facta universitatis - series: Electronics and Energetics, 2011
In pneumatic systems, which represent large energy consumers, energy saving is very important. Mo... more In pneumatic systems, which represent large energy consumers, energy saving is very important. Mostly, the costs of the electric power used for feeding the compressors in the production of compressed air amount to around 20% of the overall costs of electrical power for some factory. In order to examine energy efficiency of conventional pneumatic system as well as servo system, no matter on actuator type, in this paper the new experimental model for energy efficiency examination is proposed. It consists of two important parts, such as electric and pneumatic part. The conducted experiments have demonstrated that this new experimental model provides satisfactory results of actuator positioning and energy efficiency as well.
Thermal Science, 2012
Nondestructive testing methods are increasingly in use. With these methods it is possible to obta... more Nondestructive testing methods are increasingly in use. With these methods it is possible to obtain the desired information about the system, without altering or damaging it in any way. This paper examines the possibilities of applying these methods in the quantification of losses incurred by leaking of compressed air from the system in the terms of increasing energy efficiency of the system. The emphasis is on the application of ultrasound detector and IR (infrared) thermographic camera. The potentials and limitations of these technologies are analyzed for leakage quantification on a steel pipe in compressed air systems, as well as the reliability and accuracy of the results thus obtained.
Sadhana, 2013
The issue of energy saving nowadays is very crucial. Pneumatic systems, constituting an important... more The issue of energy saving nowadays is very crucial. Pneumatic systems, constituting an important segment of almost every industry, represent large energy consumers. Also, a significant problem with servo pneumatic actuators is achieving accuracy in positioning. The higher the positioning accuracy, the higher the compressed air consumption is. This paper presents a new solution of the positioning control algorithm which unifies digital control of variable structure and sliding working mode and inter chamber cross-flow. The experiments demonstrated that this control algorithm provides a satisfactory positioning accuracy and robustness of the system, simultaneously reducing compressed air consumption by as much as 29.5%.
Measurement, 2012
ABSTRACT With the leakage elimination in compressed air systems, it is possible to save up to 40%... more ABSTRACT With the leakage elimination in compressed air systems, it is possible to save up to 40% of energy. With appropriate inspection and maintenance of compressed air systems, leakage elimination should be a routine. This paper describes and compares two different noncontact methods for compressed air leakage quantification, ultrasound and infrared thermography. The potentials and limitations of these technologies are analyzed, as well as the reliability and accuracy of results thus obtained. From the results presented in this paper, it can be concluded that thermography offers good results for the leakage quantification from the orifices greater than 1.0 mm and ultrasound should be used for leakage detection for all the dimensions of orifices, but for the quantification purposes only for smaller leaks. As a support for leakage quantification, we proposed diagrams of a leak flow as a function of sound level and as a function of detected temperature change.
Razmatra se zadatak obezbeđenja sinhronog kretanja dva pneumatska cilindra kod maine za savijanj... more Razmatra se zadatak obezbeđenja sinhronog kretanja dva pneumatska cilindra kod maine za savijanje. Upravljački sistem za sinhronizaciju projektovan je primenom teorije sistema upravljanja promenljive strukture. Algoritam upravljanja se bazira na digitalnom kliznom reimu. ...
Facta universitatis-series: Mechanical …, 2005
Electrohydraulic servovalves are very often used as commanding devices in the hydraulic systems. ... more Electrohydraulic servovalves are very often used as commanding devices in the hydraulic systems. For their control many algorithms are developed. This paper gives a control algorithm based upon digital sliding regime. The properties of the proposed algorithm are compared to those of the linear PD controller by computer simulation.
Abstract. The need for energy savings is on the rise. Pneumatic systems, as important parts of an... more Abstract. The need for energy savings is on the rise. Pneumatic systems, as important parts of any branch of industry, are large consumers. The opportunities for saving energy in these systems are great. The paper presents a structure of pneumatic systems while a special emphasis is put on the saving of energy in the execution. A method of recovering energy is also presented.
Control of a pneumatic actuator using pulse width modulation (control) represents a good alternat... more Control of a pneumatic actuator using pulse width modulation (control) represents a good alternative for control of pneumatic actuator that uses proportional valve. Important advantage of pulse width modulation control is fewer consumption of compressed air. In addition, air consumption can be further reduced by the use of inter-chamber cross flow (chamber by-passing). This article discusses joint application of pulse width modulation and by-pass chamber control on the example of pneumatic rodless cylinder which is controlled by programmable logic controller. Saving of compressed air was experimentally determined, as well as the influence of inter-chamber cross flow on the quality of the control. With this application of pulse width modulation and by-pass valve control, pneumatic actuator system shows that 30% of energy can be saved under the same working conditions in comparison to the traditional pulse width modulation control system.
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Papers by Vladislav Blagojevic