Mobility and Vehicle Mechanics

29-46

Authors: Jasna Glišović Miroslav Demić Jovanka Lukić Danijela Miloradović Jasmina Blagojević Sandra Veličković

It has been proved in literature that there is no generally accepted method for the evaluation of characteristics and output parameters of the disc brake mechanism. This paper presents experimental research of disk brake subsystem with brake fluid pressure in the brake cylinder and disc speed as input quantities and brake torque and brake noise (expressed as sound pressure level) as output quantities. The work of disc brakes during the braking process is defined with physical output parameters: activation force, brake torque, brake noise, thermal load, etc. The aim of this paper was to determine the minimum number of mutually independent physical parameters that represent, with reasonable accuracy, the braking characteristics of disc brakes.

61-77

Authors: Branko Davidović, Miroslav Božović

In October 2013 at the demand of Germany, The European Union postponed the adoption of regulations that stipulate that the average carbon dioxide emission of newly-manufactured passenger vehicles would be reduced from 130 gCO2/km in 2015 to 95 gCO2/km until 2020, which does not understate the importance of the need to reduce the emission of pollutants in road transport. European Automobile Manufacturers Association (ACEA) considers that crediting is necessary and they remind that credits should be used as incentives to technological innovations concerning reduction of carbon dioxide emission. In freight transport more and more carriers deliver monthly reports about carbon dioxide emission and inform their clients about the emission of pollutants and the savings generated in transport. The aims of EU-28 are directed towards the reduction of existing CO2 emission by 20% until 2020 and by 80-95% by 2050 in comparison to 2010. One of the possibilities for CO2 emission reduction is the application of intermodal transport which would meet all basic goals of relevant national and international treaties. Many studies have shown that the application of intermodal transport can reduce CO2 emission in road transport by 13% or more, especially on distances over 250 km long. This paper shows possible reductions of CO2 emission depending on the vehicle load and distance according to various intermodal technologies.

29-53

Authors: Dušan Gruden

For people from ancient times, the world consisted of four elements: air, water, earth and fire. And, although a modern man knows more than 110 chemical elements, his activities in the field of environmental protection are concentrated precisely on these four elements. Further human survival on this planet depends more and more on how much humans care about these elements and their existing reserves. In the early 1970s, after nearly a hundred years of vehicle development, the vehicle’s “eco-development” had started in order to reduce or completely eliminate the negative impact of vehicles on environment. Environmental protection and efficient use of the existing reserves of energy sources and raw materials are in the spotlight of the modern car development for decades and are deeply instilled in overall development of cars. Life cycle assessment, which is carried out with increasing precision, will contribute with new knowledge on possibility for further improvement of the car’s environmental characteristics on its whole journey, from obtaining raw materials for its construction to recycling of end of life vehicles, “from the cradle to the grave”.

69-84

Authors: Marko Kitanović Predrag Mrđa Slobodan Popović Nenad Miljić

Due to Internal Combustion Engines’ (ICE) significant share in global energy demand, primarily through the transportation sector, great efforts are invested in research for solutions that will increase the fuel economy of ICE-powered vehicles. The main objective of the study presented in this paper has been to perform a comparative study of a conventional and a parallel hybrid electric transit bus employing an ultracapacitors-based energy accumulator. A high-fidelity simulation model of the vehicle has been designed in the AMESim multi-domain system analysis software. The conventional powertrain model has been calibrated using data obtained during an acquisition experiment conducted in real-world traffic conditions on a transit bus. This data also served as the basis for defining the driving cycle on which the numerical analyses will be conducted. A simple, sub-optimal control law has been implemented in the hybrid powertrain simulation model. Also, an advanced energy management law based on Dynamic Programming has been derived to assess the ultimate fuel economy improvement potential of the hybrid solution and to make design decisions. Initial study shows that considerable fuel consumption reduction in excess of 30% could be achieved by implementing a regenerative hybrid system employing an ultracapacitor-based accumulator.

19-38

Authors: Giovanni Belingardi, Brunetto Martorana

Vehicle weight reduction (and in turn reduction of fuel consumption, noxious gas and greenhouse gas emissions), manufacturing costs and riding comfort are pushing toward relevant growth the amount of polymeric materials employed in modern cars. At the same time the main performance of the car (and in particular safety and NVH comfort) should be maintained. In order to pursue this trend, it is important to carry out research and innovation on new polymer-based materials, with a high structural performance to weight ratio to replace standard materials, such as mild steel, for structural components. The base costs of composite materials are still relatively too high, therefore research activities are needed to reduce manufacturing costs of composite components. On the other hand the use of composites offer advantages not only in terms of lightweight but also in terms of parts integration, TTM reduction, etc. Innovative components can take advantage from new materials but need for proper design rules and proper manufacturing technologies. Cycle times and production volumes are key factors. The production value chain and the research have to work in order to overtake some technological limits (joining technologies, recyclability, repairing, safety, costs, …) for a wider employment of lightweight materials. This paper is presenting some recent results in the design of vehicle components with composite materials and is also presenting some recent achievements in the use of thermoplastic adhesives, nanomodified by ferromagnetic particles, sensitive to the electromagnetic field finalized to speed up both the manufacturing and the dismounting processes.

55-62

Authors: THE MECHANICAL BEHAVIOUR OF MATERIAL IN AUTOMOTIVE ENGINEERING REINFORCED BY STRONG FIBRES

Laminate is made from layers mutually bonded to form multilayered composite. Composite materials consist two or more constituents such as fibres and matrix. Matrix bond fibres together, gives shape of composite, have role in transfer loads to fibre. Usually fibres are 60-70% of composite volume and they are made of carbon, glass, aramid (such as kevlar) or metal. In the present paper we study wave propagation bulk waves. The properties of these waves are determined by the dependence between the propagation direction and constitutive properties of media. Here we study slowness surfaces, as indicators of dynamical behavior, in order to obtain information about wave propagation in arbitrary directions. The surfaces associated with wave front surfaces are slowness surfaces, with slowness defined by the inverse of the wave front speeds. Constitutive equations are developed for material which is made of unidirectionally reinforced thin sheets, which form model of material. Degrees of wave surfaces deviations depend on the degrees of anisotropy, and may give valuable information about dynamic deformations. The materials used in the present analysis are fibre reinforced materials with two families of continuous elastic and mechanically equivalent fibres, having axes of symmetry along bisectors of the fibre directions and along the normal to the plane tangent to fibres.

17-31

Authors: Slobodan Mišanović

The problem of air pollution, acid rain and the formation of ''greenhouse effect'', as a result of emissions a carbon dioxide (CO2), from vehicles are found in the developed countries of the EU several decades. This problem was got primary importance. EU has chosen a strategy of increase number the vehicles with lower emissions of carbon dioxide (CO2). Introduction of city buses with hybrid (diesel-electric) engines in a growing number of EU cities, are first stage in the implementation of the EU strategy which has defined (Transport policy- White Paper 2011) where is the ultimate goal that of the 2050 year, the cities in the EU will be used only vehicles with zero emissions (CO2). Defined strategy for the EU to promote an ecological clean the bus subsystem of public transport, have accelerated all manufacturers of buses in the European market, to produce buses with hybrid power, which allowed that companies for public transport, are used tender procedures for procurement of hybrid buses pursuant to Directive EC/2009/33. In this paper, is presented experiences in operation of hybrid buses in the some EU cities, which have this type of buses in regular service.

43-55

Authors: Milan Milovanović Miroslav Demić Saša Jovanović

The development of the carrying construction of one producer is an endless process. In addition to the analysis of carrying construction behaviour, it is necessary to take into account the influence of additionally installed drive units onto the carrying construction behaviour. In this paper, the influence of subframe on carrying construction behaviour, is shown. With the aim of presenting the results, behaviour of carrying construction in conditions of quasi-static test has been shown, as well as in conditions of simulation of front impact test.