Mobility and Vehicle Mechanics

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.

1-14

Authors: Barhm Mohamad

Acoustic simulation methods are being increasingly used for practical exhaust system design of automotive. In many practical applications, the sound source emits, partly, a low frequency sound spectrum comprised of superposed discrete tones and partly, a higher frequency broadband spectrum. The turbulent vortices that develop in the boundary layer between the duct wall and the flowing medium are said to generate a self-excited noise, that noise is broadband character. The self-excitation is enhanced when the flow is disturbed by irregularities in the duct wall. Unsteady compressible fluid flow through a duct is often encountered in many engineering applications and has been investigated by many researchers. When a pressure wave generated inside a duct is discharged from an open end of the duct, an impulsive wave that is usually characterized by high sound pressure level of short duration forms at the vicinity of the exit of the duct. Acoustic simulations solve the equations for motion, mass, momentum, and energy and can be divided into two methods, linear and non-linear. Through that literature review, we can analyse the methods and the latest development done on exhaust systems with regard to acoustic performance. The basic theory behind both approaches is explained as well as a source characterization technique that can be used to link the two methods. Some acoustic software tool has been applied to a variety of exhaust systems.

27-43

Authors: Novak Nikolić, Nebojša Lukić, Nikola Milutinović, Aleksandar Nešović

In this paper the energetic and economic performance assessment of residential application of IC engine based cogeneration system in the Serbian climatic conditions using building energy simulation software was performed. The performance of IC based system was compared with the performance of the two other conventional systems for DHW preparation: gas and electric water heater. Comparing the IC based system with gas water heater the period required to return investment costs of IC engine is relatively high (11.7 years). The main barriers for widespread residential application of IC engine cogeneration system are related to the high capital costs and low price of purchased or sold electricity. In this respect, the investment cost reduction in small scale cogeneration systems has to be achieved. In relation to the current price in Serbia the price of purchased and sold electricity (feed-in tariff) should be increased by 37.5% and 67.5%, respectively, in order to achieve the value of payback period of five years. Comparing the IC based system with electric water heater the application of the IC engine is economically feasible since the payback period amounts 3.42 years. According to the simulation results, the IC engine cogeneration system ensured a primary energy saving of 28.81%.

55-68

Authors: Nina Živanović, Gordana Bogdanović

Oscillations of light wheeled vehicle’s centre of gravity, caused by firing weapon integrated on it, are studied through simulation of its axial and angular displacements. Dynamical model of system with three degrees of freedom is used and mathematical model of oscillations is defined using the Lagrange’s equations of second order. Weapon recoil force and resistance force that causes vehicle’s oscillations is calculated according to the internal ballistics data of integrated weapon and chosen system construction. System of differential equations is numerically solved in MATLAB for real firing conditions and vehicle configuration. Coordinates of weapon mount and elevation and azimuth angles are varied and results are analyzed.

1-15

Authors: Valentina Golubović-Bugarski, Snežana Petković, Željko Đurić, Goran Jotić

Research of the human body vibrations, carried out under controlled laboratory conditions, shows that human body is the most sensitive to vibrations in the frequency range that matches the biomechanical resonance. In the vertical direction, the resonance of the body is approximately 5 Hz, while in the horizontal direction the resonance occurs at frequencies less than 2 Hz. The vibrations of the vehicle have been transferred to the driver and passengers over the seats, which have the ability to attenuate or to amplify vibrations which human body is exposed to while driving. One way to determine the vibration behaviour of the seat is to measure the SEAT (seat effective amplitude transmissibility) factor, which represents the ratio between the vibrations measured on the seat and vibration measured directly on the floor under the seat. Measurement of vibrations in these two positions must be performed simultaneously. If the value of SEAT is less than 1, a seat attenuates vibrations and meets vibrational comfort, the value of SEAT greater than 1 indicates that a seat amplifies vibration, reducing vibration comfort. This paper gives results of SEAT factor investigation done on a hybrid vehicle, for different types of road surface and different modes of driving (electric power and internal combustion engine).

29-37

Authors: Nenad Kostić, Nenad Petrović, Vesna Marjanović, Nenad Marjanović

This research allows for a selection of gearbox according to minimal dimensional criteria from automated analytical calculations. An automation of the calculation process for four different analytical approaches from literature. The results achieved in the software are compared according to various criteria, minimal length, height, width, and volume. The automation of the process allows for a selection of gearbox concept depending on the chosen criteria. For specific input values, a verification of the automated software operation was conducted, and the resulting values are compared and discussed. Differences in calculated volumes of gearboxes, depending on choice of calculation, reach over 50%. This approach allows for adequate choice of gearbox for specific cases and speeds up the calculation process.

49-63

Authors: Radivoje Pešić, Saša Milojević, Dragan Taranović, Milan Stanojević

Natural gas and liquefied petroleum gas represent the most practical, realistic and easiest way to reduce pollution coming from road transportation. In practice, natural gas vehicles are as safe as any other vehicles (gasoline, diesel, liquefied petroleum gas, etc.) operating on the roads. However, safety incidents sometimes occur where a natural gas system, primarily storage cylinders, have failed. Recent incidents involving natural gas vehicles have shown that cylinders may explode through compliant with current UN ECE 110R regulation. In the paper are systematized regulations and technical requirements relating to the installation of devices and equipment on vehicles powered by natural gas. The main objective of the research is to present a good practice related to inspection of motor vehicles on natural gas. It was also shown the several options for the reconstruction of vehicles to drive on gas fuel, as well as logistics.