Limited reserves of oil and the increasing environmental effect of its usage as a motor fuel repr... more Limited reserves of oil and the increasing environmental effect of its usage as a motor fuel represent global issue related to the constantly increasing number of motor vehicles. Therefore, the reduction of the fossil fuel consumed and the emission produced in internal combustion engines is the primary goal of the development of motor vehicle propulsion systems. In that sense, the present and the future of motor vehicles relies on hybrid drive systems, electric drive systems and drive systems which use hydrogen as a fuel (either by its combustion or by production of electric energy with the help of fuel cells). In this paper, the authors have presented the aforementioned motor vehicle propulsion systems by explaining their function and design, their basic elements and their functions. Authors have also analysed advantages and disadvantages of the mentioned propulsion systems in comparison to conventional internal combustion engine based systems, both technically and environmentally speaking, but also in relation to available infrastructure and energy resources.
Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potenti... more Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potential large number of injuries and fatalities. Therefore, this type of traffic accident became the object of numerous national and international standards and regulations. The aim of this paper is to investigate the possibilities of experimental verification of presented simplified model of the bus body section. For that purpose, completely new multifunctional test bench was presented. The methodology applied for the experimental part was explained. The results provided by the numerical simulation and by the experiment were presented, and appropriate analyses were performed. The key parameters needed for the experimental verification were specified. According to the result analysis, a comparative results review was presented, confirming that the experimental verification of the numerical model was fully acceptable. Also, all of the requirements prescribed by the applied methodology for the achieved results acceptance were fulfilled, providing that numerical simulation, with constant improvements, could be a powerful tool for quick and reliable bus structure analysis in design process.
Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potenti... more Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potential large number of injuries and fatalities. Therefore, this type of traffic accident became the object of numerous national and international standards and regulations. The aim of this paper is to investigate the possibilities of experimental verification of presented simplified model of the bus body section. For that purpose, completely new multifunctional test bench was presented. The methodology applied for the experimental part was explained. The results provided by the numerical simulation and by the experiment were presented, and appropriate analyses were performed. The key parameters needed for the experimental verification were specified. According to the result analysis, a comparative results review was presented, confirming that the experimental verification of the numerical model was fully acceptable. Also, all of the requirements prescribed by the applied methodology for the achieved results acceptance were fulfilled, providing that numerical simulation, with constant improvements, could be a powerful tool for quick and reliable bus structure analysis in design process.
The current state of vehicle technology development has been characterized by the production of a... more The current state of vehicle technology development has been characterized by the production of a very wide range of different types and categories of vehicles. Modern vehicles are characterized by a great complexity of fitted parts and mechanisms. These facts inevitably lead to the intensive development of legislation that cover the entire field of the automotive industry, as well as its harmonization at the international level. From the very beginning of harmonization, Yugoslavia has played a very active role in the development and implementation of the Regulations adopted within the United Nations, the Economic Commission for Europe. As the legal successor, Serbia continued on that path, but due to the situation in the previous 30 years, the activities within the harmonization of regulations have been significantly slowed down, primarily with the European legislation. The paper presents the current state of harmonization of regulations in Serbia with European legislation, as well as certain inconsistencies that occurred during the application of national regulations and performed comparative analysis. Also, an overview of the plan for harmonization of legislation has been given, and some examples of noncompliance are pointed out, which should be overcome with the proposed harmonization plan.
This paper demonstrates the approach to determination of cornering stiffness as the most importan... more This paper demonstrates the approach to determination of cornering stiffness as the most important parameter of motor vehicle steering and stability systems through integration of empirical models and real exploitation parameters. The approach is based on the analysis of a tire mathematical model, identification of key real exploitation parameters and integration of a mechatronic system for tire load monitoring. Measurement of tire load and subsequent integration of measured values into developed software module provide a precise definition of cornering stiffness for a certain vehicle and road contact patch. This research assumes integration of a mathematical model and mechanical, electronic and information technologies with the aim of comprehensive understanding of tire behavior in terms of cornering stiffness determination.
Specific functional requirements for firefighting vehicles have resulted in stricter exploitation... more Specific functional requirements for firefighting vehicles have resulted in stricter exploitation regimes and frequent off-road use. Current practice appoints the problem of the strength of a superstructure’s modules, which are very different in terms of torsional rigidity. It is important to say here that there are no unambiguous manufacturer’s guidelines for bodybuilders to complete a firefighting vehicle. In such circumstances, the identification of the dynamic behaviour of modular firefighting superstructures further gains in importance. Developed numerical-experimental approach for identification, analysis and optimisation of the dynamic behaviour of modular firefighting vehicle superstructures is shown. Experimental part of this method is based on excitation of superstructure physical models with, for this purpose specially developed mechanical exciter. Also, natural frequencies of structures, important in terms of resonant zones, are obtained using bump test and FFT analysis....
Motor vehicle industry is nowadays exposed to numerous serious challenges, mostly related to its ... more Motor vehicle industry is nowadays exposed to numerous serious challenges, mostly related to its influence to environment. Motor vehicles during their life cycles affect the environment in several aspects: through consumption of energy and other resources, through production of waste in design process and usage, and through disposal at the end of their life cycle. First two aspects are in consideration for many years and there is noticeable improvement in reducing the effects, but vehicle disposal at the end of life cycle is relatively new area of research. This paper presents main items of international legislative related to end-of-life vehicle recycling process, as well as responsibilities of all participants in this process, from producers to dismantlers and landfills. Also, current legislation in Serbia is presented, with suggestions and ways for future improvement. At the end, concrete data of recyclability and reusability rates for some vehicle models are given, approving the positive effects of applied legislation on vehicle influence to the environment.
Original scientific paper This paper focuses on the identification of failure causes of a bolted ... more Original scientific paper This paper focuses on the identification of failure causes of a bolted joint used for the bedding of a primary column of an aerial platform. The tests conducted to determine chemical composition and mechanical properties have confirmed the 12.9 grade of the bolts. Also, mechanical properties tests and metallographic examination did not indicate any hidden defects caused by heat treatment (e.g. decarburisation etc.). On the other hand, visual and metallographic examination of cross-section as well as electron microscope scanning confirmed fatigue fracture of the bolts. Therefore, further analyses were done to check the dimensioning and the installation of the bolts. The effects on stress states in the bolts are presented from the standpoint of rated operating regimes, stiffness of joined elements, lubrication conditions of thread surfaces and temperature incompatibility between the bolts and elements being joined. Pre-tightening torque value incompatible with lubrication conditions was found to be the main factor that led to high stress values that initiated and later intensified the fatigue process which ended in fatigue failure of the bolts.
Limited oil reserves and the ecological consequences of its use in motor vehicles impose an incre... more Limited oil reserves and the ecological consequences of its use in motor vehicles impose an increasing need for alternative energy and drives. The use of hydrogen as the fuel of the future is one of the solutions whose commercialization has begun in the past few years. Although its use has no impact on the environment, the production process, which is still expensive, does. Transport and storage of hydrogen, as well as advanced, but expensive technologies for its use, also present additional challenges, which are examined by the authors of this review paper through few topics. The properties of hydrogen, the way it is obtained, stored and transported are presented. Particular attention is paid to the method of obtaining the propulsion energy by combustion or by using different types of fuel cells. The paper also covers some examples of vehicles powered by hydrogen.
Limited reserves of oil and the increasing environmental effect of its usage as a motor fuel repr... more Limited reserves of oil and the increasing environmental effect of its usage as a motor fuel represent global issue related to the constantly increasing number of motor vehicles. Therefore, the reduction of the fossil fuel consumed and the emission produced in internal combustion engines is the primary goal of the development of motor vehicle propulsion systems. In that sense, the present and the future of motor vehicles relies on hybrid drive systems, electric drive systems and drive systems which use hydrogen as a fuel (either by its combustion or by production of electric energy with the help of fuel cells). In this paper, the authors have presented the aforementioned motor vehicle propulsion systems by explaining their function and design, their basic elements and their functions. Authors have also analysed advantages and disadvantages of the mentioned propulsion systems in comparison to conventional internal combustion engine based systems, both technically and environmentally speaking, but also in relation to available infrastructure and energy resources.
Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potenti... more Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potential large number of injuries and fatalities. Therefore, this type of traffic accident became the object of numerous national and international standards and regulations. The aim of this paper is to investigate the possibilities of experimental verification of presented simplified model of the bus body section. For that purpose, completely new multifunctional test bench was presented. The methodology applied for the experimental part was explained. The results provided by the numerical simulation and by the experiment were presented, and appropriate analyses were performed. The key parameters needed for the experimental verification were specified. According to the result analysis, a comparative results review was presented, confirming that the experimental verification of the numerical model was fully acceptable. Also, all of the requirements prescribed by the applied methodology for the achieved results acceptance were fulfilled, providing that numerical simulation, with constant improvements, could be a powerful tool for quick and reliable bus structure analysis in design process.
Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potenti... more Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potential large number of injuries and fatalities. Therefore, this type of traffic accident became the object of numerous national and international standards and regulations. The aim of this paper is to investigate the possibilities of experimental verification of presented simplified model of the bus body section. For that purpose, completely new multifunctional test bench was presented. The methodology applied for the experimental part was explained. The results provided by the numerical simulation and by the experiment were presented, and appropriate analyses were performed. The key parameters needed for the experimental verification were specified. According to the result analysis, a comparative results review was presented, confirming that the experimental verification of the numerical model was fully acceptable. Also, all of the requirements prescribed by the applied methodology for the achieved results acceptance were fulfilled, providing that numerical simulation, with constant improvements, could be a powerful tool for quick and reliable bus structure analysis in design process.
The current state of vehicle technology development has been characterized by the production of a... more The current state of vehicle technology development has been characterized by the production of a very wide range of different types and categories of vehicles. Modern vehicles are characterized by a great complexity of fitted parts and mechanisms. These facts inevitably lead to the intensive development of legislation that cover the entire field of the automotive industry, as well as its harmonization at the international level. From the very beginning of harmonization, Yugoslavia has played a very active role in the development and implementation of the Regulations adopted within the United Nations, the Economic Commission for Europe. As the legal successor, Serbia continued on that path, but due to the situation in the previous 30 years, the activities within the harmonization of regulations have been significantly slowed down, primarily with the European legislation. The paper presents the current state of harmonization of regulations in Serbia with European legislation, as well as certain inconsistencies that occurred during the application of national regulations and performed comparative analysis. Also, an overview of the plan for harmonization of legislation has been given, and some examples of noncompliance are pointed out, which should be overcome with the proposed harmonization plan.
This paper demonstrates the approach to determination of cornering stiffness as the most importan... more This paper demonstrates the approach to determination of cornering stiffness as the most important parameter of motor vehicle steering and stability systems through integration of empirical models and real exploitation parameters. The approach is based on the analysis of a tire mathematical model, identification of key real exploitation parameters and integration of a mechatronic system for tire load monitoring. Measurement of tire load and subsequent integration of measured values into developed software module provide a precise definition of cornering stiffness for a certain vehicle and road contact patch. This research assumes integration of a mathematical model and mechanical, electronic and information technologies with the aim of comprehensive understanding of tire behavior in terms of cornering stiffness determination.
Specific functional requirements for firefighting vehicles have resulted in stricter exploitation... more Specific functional requirements for firefighting vehicles have resulted in stricter exploitation regimes and frequent off-road use. Current practice appoints the problem of the strength of a superstructure’s modules, which are very different in terms of torsional rigidity. It is important to say here that there are no unambiguous manufacturer’s guidelines for bodybuilders to complete a firefighting vehicle. In such circumstances, the identification of the dynamic behaviour of modular firefighting superstructures further gains in importance. Developed numerical-experimental approach for identification, analysis and optimisation of the dynamic behaviour of modular firefighting vehicle superstructures is shown. Experimental part of this method is based on excitation of superstructure physical models with, for this purpose specially developed mechanical exciter. Also, natural frequencies of structures, important in terms of resonant zones, are obtained using bump test and FFT analysis....
Motor vehicle industry is nowadays exposed to numerous serious challenges, mostly related to its ... more Motor vehicle industry is nowadays exposed to numerous serious challenges, mostly related to its influence to environment. Motor vehicles during their life cycles affect the environment in several aspects: through consumption of energy and other resources, through production of waste in design process and usage, and through disposal at the end of their life cycle. First two aspects are in consideration for many years and there is noticeable improvement in reducing the effects, but vehicle disposal at the end of life cycle is relatively new area of research. This paper presents main items of international legislative related to end-of-life vehicle recycling process, as well as responsibilities of all participants in this process, from producers to dismantlers and landfills. Also, current legislation in Serbia is presented, with suggestions and ways for future improvement. At the end, concrete data of recyclability and reusability rates for some vehicle models are given, approving the positive effects of applied legislation on vehicle influence to the environment.
Original scientific paper This paper focuses on the identification of failure causes of a bolted ... more Original scientific paper This paper focuses on the identification of failure causes of a bolted joint used for the bedding of a primary column of an aerial platform. The tests conducted to determine chemical composition and mechanical properties have confirmed the 12.9 grade of the bolts. Also, mechanical properties tests and metallographic examination did not indicate any hidden defects caused by heat treatment (e.g. decarburisation etc.). On the other hand, visual and metallographic examination of cross-section as well as electron microscope scanning confirmed fatigue fracture of the bolts. Therefore, further analyses were done to check the dimensioning and the installation of the bolts. The effects on stress states in the bolts are presented from the standpoint of rated operating regimes, stiffness of joined elements, lubrication conditions of thread surfaces and temperature incompatibility between the bolts and elements being joined. Pre-tightening torque value incompatible with lubrication conditions was found to be the main factor that led to high stress values that initiated and later intensified the fatigue process which ended in fatigue failure of the bolts.
Limited oil reserves and the ecological consequences of its use in motor vehicles impose an incre... more Limited oil reserves and the ecological consequences of its use in motor vehicles impose an increasing need for alternative energy and drives. The use of hydrogen as the fuel of the future is one of the solutions whose commercialization has begun in the past few years. Although its use has no impact on the environment, the production process, which is still expensive, does. Transport and storage of hydrogen, as well as advanced, but expensive technologies for its use, also present additional challenges, which are examined by the authors of this review paper through few topics. The properties of hydrogen, the way it is obtained, stored and transported are presented. Particular attention is paid to the method of obtaining the propulsion energy by combustion or by using different types of fuel cells. The paper also covers some examples of vehicles powered by hydrogen.
Uploads
Papers by Saša Mitić