Mobility and Vehicle Mechanics

1-13

Authors: Stefan Milićević

Knowing the limits of transverse handling and vehicle stability is very important from the aspect of designing a system aimed at improving handling and safety. One of the phenomena that have a great impact on vehicle stability and handling is the sideslip angle. Unfortunately, direct measurement of the sideslip angle requires very complex and expensive equipment that is not suitable for installation on ordinary passenger vehicles; therefore, this quantity must be estimated on the basis of measurements of other parameters. As a result of limited information, this parameter is mainly estimated or linearized relative to lateral force when used for calculations though such calculations can be less accurate. In this paper it is concluded that a clear relationship can not be formed between the lateral force and the sideslip angle and that for precise determination of the sideslip angle several parameters need to be known such as tire construction, tire pressure, rim diameter, wheel camber as well as micro and macro road structure.

27-48

Authors: Angelina Pavlović, Goran Bošković, Nebojša Jovičić

Noise is characterized as an environmental problem that represents an exceptional danger to human health. With increased urbanization and motorization, road traffic has been identified as the dominant source of noise in urban areas. The traffic noise originates from vehicle exhaust and braking systems, devices for giving sound signals, engine operation, or as a result of contact between the wheels and the road. In urban areas, the intensity of traffic noise depends on the speed of the vehicle, the flow of traffic, and the surface on which the vehicles are moving. This study aims to monitor traffic noise using the device Brüel & Kjær 2250 on the territory of the city of Kragujevac at specific locations along the roads and during peak hours. Based on the numerical modeling of traffic noise in the Quantum GIS software (abbr. QGIS), it is possible to identify impacts of noise pollution as well as deviations of real noise values from the permissible noise limits. Serbian law regulates that the highest noise level along city roads can be 65 dB (A). The final results obtained by this research can be used to assess the current state of environmental noise pollution, which can be taken into account in the future process of transport planning in the city of Kragujevac.

59-70

Authors: Marian Florin Mitroi

The multitude of high performance equipment, as well as modern technologies integrated in the structure of vehicles, have led to an important change in their area of viability. These changes also have effects on maintenance work. Due to sensitivity of the electronic equipment to environmental, temperature and working conditions, it is necessary to adopt effective solutions to protect them and maintain their state of operation. The major challenge among classic vehicles, but also hybrid or electric is the thermal management of this equipments. IoT is a strategic concept for the future of communications between the various functional systems of society, which will adapt and regulate vehicle traffic in relation to the environment. IoT technology will generate certain job opportunities for predictive vehicle maintenance. The research is a subjective, well-documented analysis, based on which some appropriate measures are proposed for the future, regarding the maintenance process of vehicles. In this direction, the preventive nature of actions and the implementation of 5G / 6G technologies at a global level are pursued. Also, the implementation of hardware and software solutions in the structure of vehicles is considered. They aim to adapt the operation of vehicles to the optimal parameters, by applying preventive corrections.

1-18

Authors: Tarun Kumar, Roger Stephen, Mohammad Zaeimi, Greg Wheatley

The purpose of this report is to investigate the design development and evaluate the structural and functional performance of the proposed system for the 2019 competition. With the review of the literature surrounding rear suspension systems, FSAE standards, analysis techniques and important design parameters, the foundation for the proposed James Cook University (JCU) 2019 rear suspension system is established. This paper is highlighted the development and analysis path undertaken in the construction of rear suspension system befitting a Formula SAE vehicle. Formula SAE is an international student competition centered on the design, construction and racing of an internal combustion vehicle. All parts are designed via SolidWorks and FEA testing is incorporated using ANSYS to test out various loads under different scenarios in racing. Main components including beam axle, trailing arms, brackets, spring and damper are covered in this paper. The design is focused on providing a low cost and easy to manufacture design which operate for infinite life cycles.

33-43

Authors: Saša Milojević, Ivan Miletić, Blaža Stojanović, Ivana Milojević, Marko Miletić

Increase in number of transport vehicles, especially motor vehicles, has negative impact on environment. It refers to air pollution problem due to usage (combustion) of fossil fuels in motor vehicles. Agriculture activities, factories, industry and many other activities additionally contributes to air pollution. Greenhouse gas emission is main cause of global warming and air pollution, and mainly occurs due to industry and transport. In many countries, the adoption of legislation gives priority to the use of electric vehicles due to lower emissions compared to conventionally powered vehicles (diesel or gasoline engines). In this way, goals have been set in the European Union and regulations have been passed which, among other things, require a certain percentage of motor vehicle recycling at the end of their service life. The Directive 2000/53/EC of the European Parliament and of the Council regulates waste management in the vehicle sector. Due to the increased number of electric vehicles, which participate in the transport of goods and people, the paper partially analyzes the problem related to the adaptation of existing recycling centers (for classic vehicles), for the needs of recycling electric vehicles and their specific parts and equipment (such as magnets and electric motors).

55-61

Authors: Mobin Majeed, Greg Wheatley

The aim of this paper is to design the steering system of the formula racing car. This includes the designing of its main components in solidworks, its analysis by calculation and finite element simulation. Load acting on the wheels of formula car are calculated and input in the analysis wherever necessary. The cars steering rack is repositioned to avoid any collision with a-arms. The force acting on the bolts at tie rod, clevis and mounting bracket is found below its yield strength. The clevis attached at the end of the rack is subject to load and fatigue analysis in ANSYS and all results were found satisfactory. Similar analysis is done for rack arm at critical areas and its was found that region where the rack arm can withstand fluctuations ranging for almost whole life till failure. Later the whole steering system was split into three major components (Steering column assembly, steering rack assembly, Tie rod assemblies) and each component is designed separately in SolidWorks and then assembled into whole one. SKF SAKAC 10 M ends are selected rod ends for steering arm assembly allowing rigid force transfer between rack arms and upright assembly as well as vertical motion of wheel assembly in operation. In the assembly 6 x M8 and 4 x M10 exist with the associated washers and nuts. The universal joint connecting the two steering column was machined according to Australian standards with splines at both ends. Two splined steering columns was machined in order to complete the steering column assembly. In order to stop the clevis colliding with the steering with the rack on full lock and to restrict the steering of the vehicle two locking collars were manufactured.

1-12

Authors: Dobrica Milovanović, Dušan Gordić, Vladimir Vukašinović, Mladen Josijević

The design of hydrodynamic torque converter impeller is a complex problem that can be solved if the whole set of individual steps is carried out, starting from input data selection to determination of the model sections of the blade. For that reason, fast as well as efficient solution of inverse flow problem can be carried out only by using numerical techniques to solve fluid flow problems. The method developed in this paper, based on free vortex design, involves the linking of meridional and blade-to-blade solutions. A basic assumption used for predicting flow in the meridional plane of the hydrodynamic transmissions impeller is an axisymmetric flow. In accordance with the Bauersfeld method, the design of the impeller blade is performed in an iterative manner using the relationships between velocity components and geometrical blade parameters. Particular attention in the paper is paid to the determination of a functional law of the energy interchange from the inlet to the outlet in the pump and turbine impeller in hydrodynamic transmissions. Finally, a design example for the pump impeller blade is presented.

31-41

Authors: Vladica Živković , Bogdan Nedić, Stefan Đurić

Independent suspension system of a vehicle allows vertical movements of a wheel, without it affecting the other wheel of the same axle, unlike the solid one. Many elements of the independent suspension systems have been made out of steel in the past, but are recently being replaced by other new materials. Achieving top quality and short cycle times of machining, along with minimising cost per piece have always been key goals for mechanical engineers for technology. Many cutting tool manufacturers make recommendations regarding the selection of machining operations and tools for a range of automotive industry components. These recommendations are presented in this paper and should be kept in mind when designing the technology.

61-71

Authors: Hristo Stanchev, Krasimir Markov

Experimental investigation of a common rail direct injection diesel engine is carried out, when working with diesel fuel in blends with 10% (B10), 15% (B15) and 20% (B20) n- butanol at different loads and speeds. The cetane number of the blends is lower than basic fuel and is corrected to these of the neat diesel fuel. The differences in brake specific fuel consumption (BSFC) and exhaust emissions are compared with the baseline operations (when working with the neat diesel fuel). The cetane improver 2-EthylHexil Nitrate is used. Six types of fuels are investigated: B10 and B10 with cetane improver, B15 and B15 with cetane improver, B20 and B20 with cetane improver. This approach shows that the BSFC for fuel blends with corrected cetane number is closer to this with neat diesel fuel, especially at higher engine speeds. The exhaust smoke (D) for blends with corrected cetane number is lower than the neat diesel fuel and blends without cetane improver. There is no clear trend for NOx emission.

1-12

Authors: Davor Končalović *, Dubravka Živković, Dušan Gordić, Vladimir Vukašinović, Mladen Josijević, Slađana Stević

The subject of this paper are measures for improvement of the energy efficiency of fleets that are in the jurisdiction of the one city in Serbia. Improvement of energy efficiency is proposed thorough following five measures: Data collection, internal benchmarking, transparency, the publication of collected information and rewarding of good practice examples; Creation of a joint fleet, joint driving and driving pairing (car sharing in public institutions); Establishment of eco-driving programs in the City Administration; Tire pressure control and The transition of a part of the petrol fleet to liquid petroleum gas. Here proposed methodology is easily understandable, characterized by transparency and easy adaptation while monitoring the results of the implementation of proposed measures is intuitive and simple.

19-31

Authors: Dušan Gruden

The first transportation means driven by a DC electric motor was a six-passenger boat. Ground vehicles with electric drive have also a longer history than vehicles with IC engines. At the beginning of the 20th century, there were more cars driven by electric motors then those driven by IC engines. During the last 100 years, there have been many attempts to replace the IC engine with supposedly better power units. Experiments with electric vehicles were repeatedly performed. Around 1.1 million electric vehicles or about 0.12% of 947 million of passenger vehicles is used in the world traffic today. In terms of CO2 emissions, electric cars have an environmental advantage after 2 to 4 years of use, only if the electricity for their charging is created by regenerative sources: water, wind, solar energy, high and low tides or nuclear energy (as in France). In China and Germany, where the largest part of the electricity is produced in the coal or gas power plants, the CO2 emissions created by electric cars are significantly higher than those created by cars with IC engines are. It is the opinion of many experts, that vehicles with combined drive via an electric motor and a single, relatively small and optimized IC engine (so-called hybrid drive), present the best solution passenger cars in the future, especially in terms of reduction of toxic emission in the cities, as well as in reduction of fossil fuels consumption. The conclusion of this analysis of electric drives for motor vehicles, can only state the same as it repeats for over half a century: "The piston IC engines will be substituted by the better powertrains during the following 10 to 15 years and the existing oil reserves will be spent in the next 30 to 40 years!"

45-53

Authors: Kjosevski Stevan, Kochov Atanas , Kostikj Aleksandar

The development of new lightweight and strong materials and the design of new products are among the key elements for the development of new advanced construction and vehicle parts for the automotive industry. The use of composite materials in the automotive industry has been popular in recent decades due to the need to reduce vehicle weight, which directly affects fuel consumption and exhaust gases emission. In this way, the development of improved new materials with improved performance is accomplished. Nanocomposites represent a new class of materials that has excellent thermal and mechanical properties. The application of nanocomposites for development of automotive components is reflected in the improvement of the production rate, environmental and thermal stability, and the reduction in weight in the automotive industry, less wear parts, and indirectly to reduce CO2 emissions and environmental pollution. This research paper presents a review of the application of nanocomposites (metal, ceramic and polymeric) in the automotive industry.

1-11

Authors: Aleksandar Jovanović, Dušan Teodorović

Intersections are junctions where at least two roads or streets meet or cross. Consequently, they represent the most critical spots in the city traffic network, in terms of traffic safety. When determining the Level of Service at signalized intersections, the Highway Capacity Manual (HCM) does not take into account the traffic safety factors. In order to overcome this shortcoming, we propose in this paper the multi-criteria approach to the single intersection traffic control problem. The first objective function to be minimized is the average control delay experienced by all vehicles that arrive at the intersection. The second objective function to be minimized is the traffic safety risk index on intersection. These two criteria are in conflict, and the task is to find a good compromise between them. The analysed problem is solved by the combination of dynamic programming, and compromise programming. The proposed approach was tested in the case of the intersection that is controlled with two phases, under over-saturated traffic flows.

25-39

Authors: Dobrivoje Ćatić, Jasna Glišović

Basic concepts and a brief history of the development of Failure Modes, Effects and Criticality Analysis - FMECA are given in the introductory part of the paper. In the present considerations, the quantitative FMECA is based on the assumption that the intensity of the element’s failure is constant and is mainly applied in electronic systems. Based on the current procedure, taking into account the specificity of the mechanical system’s elements in terms of the intensity of the failure, the proposal of the quantitative FMECA of these elements is given. The procedure has been expanded with a step of determining the absolute criticality of the elements from the aspect of reliability and functional safety. The application of the procedure is illustrated through the case of determining the criticality of the elements of the light commercial vehicle’s steering system based on exploitation data.

51-64

Authors: Sandra Veličković, Blaža Stojanović, Lozica Ivanović, Slavica Miladinović, Saša Milojević

The development of new lightweight and strong materials and the design of new products are among the key elements for the development of new advanced construction and vehicle parts for the automotive industry. The use of composite materials in the automotive industry has been popular in recent decades due to the need to reduce vehicle weight, which directly affects fuel consumption and exhaust gases emission. In this way, the development of improved new materials with improved performance is accomplished. Nanocomposites represent a new class of materials that has excellent thermal and mechanical properties. The application of nanocomposites for development of automotive components is reflected in the improvement of the production rate, environmental and thermal stability, and the reduction in weight in the automotive industry, less wear parts, and indirectly to reduce CO2 emissions and environmental pollution. This research paper presents a review of the application of nanocomposites (metal, ceramic and polymeric) in the automotive industry.