Mobility and Vehicle Mechanics

1-11

Authors: Milan Blagojević, Miroslav Živković, Marko Topalović

Modern quality control has become unthinkable without optical measuring systems which are intensively used in automotive industry. This paper shows the analysis of preparation of models in terms of proper positioning in relation to the digitized model and the correct interpretation of the results of quality control. Experimental results verifying the method and the theory are shown. Part of tool for pressing and fabricated physical model of passenger car’s suspension control arm is compared to CAD model. Presented results of measurements show that the optical measuring systems are powerful tool for quality control, analysis and discovering of causes of faults.

23-37

Authors: Saša Milojević, Radivoje Pešić, Dragan Taranović

Natural gas as engine fuel is a commercially very attractive option for medium and heavy duty vehicles. A combination of low gas price and incentives for environmentally friendly solutions are key arguments for bus fleet operators to convert to natural gas powered vehicles. From the second side, fuel can be dangerous if handled improperly. Gasoline and diesel are potentially dangerous fuels, but over time we are learned to use them safely. The same is true with liquefied petroleum gas and natural gas, as well as hydrogen. For commercial vehicles both, compressed natural gas and liquefied natural gas are equally relevant options. Recent fire accidents involving natural gas buses have shown that cylinders may explode through compliant with current UN ECE R110 regulation. Such a repeated scenario is certainly not acceptable having in mind the tremendous amount of energy released when a compressed cylinder burst. Recent accidents detailed in this paper highlights potential improvements in current natural gas buses fire safety concepts. Fire safety should not solely rely on cylinder behaviour when exposed to fire but also to additional and upstream fire safety barriers. Thermal fuses cannot be seen any more as an ultimate option to control cylinder burst in case of fire.

51-68

Authors: Ralph Pütz

In the light of the 'megatrends' of electromobility and interconnection the car and commercial vehicle industry is facing dramatic changes which could lead to major upheavals. Triggered by ecological necessity and socially induced paradigm shifts, the understanding of mobility, the status of the environment, limited fossil resources, promising propulsion and fuel technologies as well as the increasing digitalisation and networking of all systems must inevitably be considered within a close system relationship. Sufficient technologies must therefore incorporate a corresponding sustainability in all areas: ecology, economy and social affairs for both subsystems as well as in the overall network context. Thus, for example, electromobility can only succeed in the transition to a comparable internal combustion engine in terms of economic and commercial maturity with a technology leap using post-lithium-ion battery technology. An improved lifecycle assessment can only be achieved in the medium to long term through extensive integration of regenerative energies in the electricity mix. Likewise, the interconnection which, at first glance, is inherent in and, ultimately, overarching within the transport system can probably only succeed in its ultimate aim of autonomous driving by overcoming high safety and regulatory hurdles in the medium to long term. In the context of these developments newly understood mobility and cross sector network synergy effects can be developed in the future on the way to a user perspective. In this respect, market shifts between the classic automobile manufacturers, innovative active suppliers and the IT industry are expected.

1-9

Authors: Nadica Stojanović, Jasna Glišović, Jovanka Lukić, Ivan Grujić

Brake is a device for slowing or stopping the vehicle. The sound that occurs in the process of braking is very irritating for the driver. Brake systems of road vehicles as important factor in overall vehicle noise have attracted great attention. All global brake system manufactures are focused to the quieter brakes. This paper presents an analysis of differentially variants of brake disc, and how the structure itself influencing the occurrence of noise. The weight of analyzed discs is approximately equal to each other. The analysis was performed in the software package ANSYS, while the model was created in CATIA.

31-48

Authors: Dušan Gruden

Regulations of the European Union are demanding that re-use of materials should be taken into account already in the design phase of new vehicles and to provide instructions about exploitation of the old cars. When engineering a car, every part of the vehicle is analysed in terms of ecological criteria: "the possibility of re-use of materials", "convenience for recycling" and "critical materials". The primary principle of "Design for recycling" is using a closed circuit of materials. Recycled material must fully correspond to the new material in all its properties. Analysis of different materials shows that with the increasing application of recycled materials substantial savings in energy consumption and raw materials can be achieved. Selection of plastic materials plays a very important role in the engineering of the car taking into account the recycling. Labelling the plastic allows its clean sorting and re-use. In addition, an important criterion is easy disassembly of the parts to be used again. Car producers are obliged to prepare manuals for disassembling for each vehicle.

63-71

Authors: Gordana Bogdanović, Dragan Milosavljević, Aleksandar Radaković, Dragan Čukanović, Vladimir Geroski

Mechanical behaviour of anisotropic media may be seen the best through its behaviour during bulk wave propagation. Such waves may be decomposed into finite plane waves propagating along arbitrary direction n in solid. Properties of these waves are determined by dependence between propagation direction and constitutive properties of media. Three types of such waves may be distinguished in connection to three displacement vectors, which determine acoustic polarization. The most of dynamical systems are naturally nonlinear; here we are going to write Reimann-Christoffel equation. This equation represents propagation condition of bulk waves as set of three homogeneous linear equations. Materials used in present analysis are fibre reinforced with one or two families of continuous fibres. Often used represent of such materials is epoxy resin carbon fibres composite whose material constants are determined with ultrasound methods.

1-12

Authors: Milan Bukvić, Živojin Petrović, Blaža Stojаnović, Saša Milojević

All systems in the construction of vehicles can be grouped logically, either as a structural system or control system. Structural systems consist of one or more sub-systems, as well as the optional files that define the system. Structural systems do not contain models, but only describe the structure, connecting systems and subsystems. The control systems consist of a model which defines the behaviour of the system and all the files needed to support or calculation of the output value of the system. Models and control systems include mathematical equations that describe the functions of the system or subsystem. Both of these types of systems are arranged in a hierarchical manner in order to define a vehicle that will be simulated. To avoid confusion, the best solution is to replicate the composition of the actual system, as far as possible. For example, small controllers should be grouped with the components they control, at various hierarchical levels wherever possible. Also, only systems that really are in the vehicle should be represented, in other words, there is no need for the unused components or space controllers. In addition to simplifying the construction, this concept will allow easy transfer between users and the system will be fully supported hardware and software, while ensuring effective control of the prototype, according to the needs.

29-38

Authors: Ivan Grujić , Aleksandar Davinić, Nadica Stojanović, Dragan Taranović, Radivoje Pešić

Vehicles are considered to be the biggest polluters of the environment. An alternative to conventional vehicles are hybrid and electric vehicles. Despite the good qualities of these vehicles, they can rarely be seen on the roads. In this paper, economic analysis is performed in order to determine cost effectiveness of the application of these types of vehicles. A comparison between the costs of owning a hybrid, conventional and electric vehicle is considered, in order to determine whether the costs have the greatest impact on the purchase of these vehicles. The costs included: price of a new vehicle, fuel price per km and maintenance price per km. The performed analysis shows that hybrid and electric vehicles do not have better economic indicators than vehicles with IC engines.

53-69

Authors: Zlatomir Živanović

The on-going requirements for reduction of fossil fuels consumption, harmful emissions, and noise in the cities enforced the development of city buses using alternative propulsion systems as a potential answer to these requirements. Even though some improvements, as regards harmfull effects upon environment, have been accomplished by Euro VI diesel engines, no significant developments in this direction can be expected. For this reason transition to electric propulsion systems of city buses having zero emissions, such as batteries or fuel cells buses (FCBs), is imperative for many cities and city operators. The paper presents an analysis of the development of FC buses accomplished by several European projects and points at numerous problems and obstacles that have to be overcome in order to make this technology commercially sustainable. Special attention has been paid to the comparative analysis of FC buses and buses using other propulsion technologies as regards both, fuel economy and operational costs.

1-18

Authors: Mohamed Khalil, Mohamed Ali Emam

The whole world is looking for the energy that it considers the driving forces for any development in the world. On the other hand, it resorted to energy inherent in petroleum and the world felt that this energy will wind up. For this reason, the developed countries directed their research to reduce the fuel consumption of the vehicles in addition to using the renewable energy. This paper proposes a new expert system for optimizing the tyre drawbar pull, especially for off road vehicles. The system depends on measuring the wheel slip to control on the tyre inflation pressure by using the self - inflation pressure system to maximize the drawbar pull for the off road vehicles and accordingly to reduce the fuel consumption.

27-37

Authors: Dragan Ružić, Stjepan Galamboš

Thermal radiation is one mode of the thermal exchange between the passengers and the interior surfaces of the vehicle's cabin, equally important as convection, conduction and latent heat exchange. The parameters that influence radiative heat exchange between the human body and cabin's surfaces are discussed in this paper. The influence of the radiative heat exchange on human thermal sensation is explained. Characteristics of the surrounding surfaces and of the human body surfaces as well quantification of the radiation heat transfer in typical cabin interior conditions are given. The values are based on experimental and numerical researches in motor vehicles. The results show importance of thermal radiation and its high influence on thermal sensation in vehicles.

57-72

Authors: Danijela Miloradović, Jasna Glišović, Jovanka Lukić

Problem of vehicle noise has been observed since the appearance of the larger number of vehicles on the roads. Drivers and passengers are exposed to constant noise and vibration originating from their own vehicles and all other vehicles participating in traffic. This paper reviews development of regulations that impose limits for vehicle noise. Chronological development of vehicle noise regulations is presented in order to observe trends in corresponding noise limits and requirements. Required future activities in formulation of new vehicle noise regulations based on vehicle users’ demands, developments and trends in automotive industry and requisites for vehicle weight reduction and cutting the costs of vehicle production are analysed in the paper.