Mobility and Vehicle Mechanics

1-13

Authors: Jakub Kwapisz, Manuel M. Freitas, Virginia Infante

There are few manufacturers that produce busses and light rail vehicles. Those manufacturers include Bombarider, Siemems, and Solaris among the others. During the case study conducted in one of the manufacturers and presented in this paper, it turned out that potential benefits coming from sharing components between different products are not realized. A great problem for any manufacturer is the engineering effort necessary to produce every set of products for a particular client. One of the solutions for a manufacturer is to use common components in locations not visible for customers and customized elements for product differentiation. Commonality increases quality, prevents resource waste, decreases costs and, most importantly, decreases total development time of the product by eliminating unnecessary development steps of individual components. After a detailed analysis of the car body shell (CBS) components in the light railways and trams, it turned out that there are parts that can be potentially common. The most interesting elements for further study were floor and roof panels. Our hypothesis is that number of profile solutions solution may be reduced and common not only across different rail vehicles, but as well busses. The key problem this research paper investigate is commonality opportunity of reusing the same design for aluminum panels in different light rail and bus applications. Long extrusion is a specific process that takes a long time to set up for final production. The commonality of the aluminum panel concept across different product could lead to decreased development and manufacturing time, and reduce cost. The finite element method (FEM) numerical simulations were performed using the nonlinear commercial finite element software HyperWorks v12 in order to determine properties of different panels already produced by the company and additional optimised panels created during this study. Additional information about panels was gathered from different company division such as industrialization, manufacturing and procurement in order to make final decision which aluminum panel should be shared across different products. The paper is constructed from five chapters. First is an introduction to the problem and conducted research. The second chapter is an industrial case study which was performed in one of the leading manufacturers or railway and road vehicles. The third chapter describes results coming from this case and especially results of the final element analysis. The fourth chapter is a further discussion about commonality possibilities and description of additional information that had to be considered before making a final decision. In the last chapter, there are conclusions coming from this research that can be generalized to other applications. This research paper is very valuable for both academia and practitioners. It present a study area that can be further investigated by different researchers and applied to different companies by practitioners. It turned out that commonality is very beneficial and every company should implement it to some extent. A researcher could collaborate with industry as it was done in our case in order to implement state of art methodologies and solutions together.

29-37

Authors: Branislav Popović, Dragan Milčić, Miodrag Milčić

System for motor vehicle cooling is one of the most important systems for safety of internal combustion engine (IC engine), and engine cooling fan motor is a key subsystem of this system. It ensures that engine operating temperature is within allowed limits and it protects engine from failure of entire internal combustion engine, and vehicle in whole. This engine cooling fan motor is a key subsystem for vehicle air conditioning as well, because it cools air conditioning system cooler at the same time. Radiator cooling fan motor consists from DC engine and radiator cooling fan. DC engine is a subsystem of mentioned systems which has the most important influence on no failure engine cooling fan work, and according to that, on no failure work of engine cooling system and vehicle air conditioning system. The main subject of this paper is development of engine cooling fan from the reliability aspect, in fact, according to required work life of 3000 hours.

53-64

Authors: Rajko Radonjić, Danijela Miloradović, Dragoljub Radonjić

Vehicle’s performance is in relation with its structure, design parameters and interaction with the environment. The domain of the vehicle research is a typical example of interconnectedness and interdependence of theory and experiment. In this paper, problems of combining mathematics - simulation and experimental research of vehicles are considered. The appropriate simulation models are formed and necessary preliminary experiments were carried out. A concept of augmented system with extended Kalman filter is realized and used. Some illustrative results of the research done by this methodology are presented and discussed.

1-18

Authors: Rajko Radonjić Aleksandra Janković

This paper examines contemporary research and educational problems in automotive industry. In terms of perception and better understanding of the complex interdependence of this issue the block diagram is formed of the man-vehicle interaction in three important observation segments: (1) vehicle development through history, (2) phases of creating the vehicle and its life expectancy, (3) influence of the vehicle on human life. Functions of education and research and their complex interdependence are observed within the mentioned second segment of the block diagram – that is, „phase of the life expectancy of the vehicle“. The following is pointed out: multidisciplinarity of this issue, typical vehicle characteristics considering appropriate species of traffic systems, and transfer of knowledge and technologies in the land-air traffic. Within land transport road traffic is especially in focus and the mentioned current problems in the aspect of research and education. Thereby, special attention is given to the problem of the vehicle control in the complex system of the road traffic that is cybernetic system driver-vehicle-roads-surroundings. This problem is illustrated by the results of the specific researches that signal the complexity of the issue, multidisciplinarity, current measurement equipment need, it is also illustrated by the examination of the contemporary disciplines etc. Basing on the general situation and trends in the world and the current problems in Serbia, as well as the approach in this paper, it is possible to critically analyze the past and the current condition in the subject areas with more realistic designs of the future condition and taking the necessary measures in order to improve it.

39-51

Authors: Nenad Miljić, Slobodan J. Popović, Marko Kitanović

Engine speed signal contains valuable and rich content information about the engine working process. Measurement of the engine speed is usually carried out by sensor wheels mounted on the crankshaft. Measurement errors are mostly influenced by geometric tolerances of the engine speed sensor wheel as well as by its radial run-out. In order to avoid the occurrence of this systemic deviation, in the lab and highest accuracy engine speed measurements are usually conducted by means of incremental encoders, radially and axially fixed to the crankshaft with the anti-twist safeguard toward the crankcase. This paper shows how this type of engine speed measurement, which is considered to be the most accurate, is prone to systematic errors as well. The influence of the kinematic parameters of the encoder - crankcase linkage, on the error occurrence is discussed as well as suggested methods for systematic deviation parameters identification and engine crankshaft angular speed error compensation.

63-71

Authors: Mirko Blagojević, Zorica Đorđević, Miloš Matejić, Nenad Kostić, Nenad Petrović

Cycloidal speed reducer is a very complex mechanical system and for studying its dynamic behaviour must be considered all its specifics. On the level of internal dynamic forces very big impact have: manufacturing errors of cycloid disc and other elements of reducer, assembly errors, unequal load distribution, ... On the basis of the models of external and internal gear trains, a dynamic model of a single - stage cycloidal speed reducer is developed in the paper. It is assumed that the values of the stiffness are constant and the excitation force time-variable function. The values of displacement, velocity, and dynamic force for single meshing are presented in this paper. The greatest impact on the dynamic force value has the coefficient of damping and coefficient of stiffness between cycloid disc and the ring gear.

1-10

Authors: Đorđe Vranješ, Branimir Miletić

Traffic accidents present one of the most causes for child injuries in many countries, and almost 50% of all children up to 14 years have been killed in traffic accidents like passenger in vehicle. To prevent that, many car manufactures are developed different protection systems in cars, especially safety belts and child protection seats. Research studies have been investigated the impact of different factors to child restraint systems using level and set different risk levels associated with using or not using protection systems in vehicles. In addition, some studies also investigated how gender, education level, number of passengers, cultural and social characteristics in some areas, length of destination and other factors influenced on child restraint using level. Taking that, in this work we show some important investigation methods, results and recommendations for future investigations which will provide basis for taking measures for improvement of child restraint using systems in vehicle.

19-31

Authors: Duško Pešić, Emir Smailović, Nenad Marković

In the analysis of traffic accidents is one of the many tasks set before an expert traffic engineering profession is properly calculate or estimate deceleration motor vehicles that were involved in the accident. The problem becomes much simpler if done immediately after the accident inspection, and the court records are no data on the measured braking forces. However is not uncommon for a person who performs inspection data is entered on the weight of the vehicle when performing emergency technical inspection. As usual site investigation documentation contains information on vehicle weight, or information on the type of engine and associated equipment, it comes to the situation where the measured brake forces of vehicles, while data on vehicle weight cannot be determined. Considering to the weight of the same brand and type of vehicles can vary more than 500 kg, depending on the type of engine and equipment, it is also the maximum value of the braking coefficient, and therefore the maximum speed of the vehicle to trace braking can differentiate and more than 30 km/h. Depending on the used vehicle weight, will depend on the calculated speed of the braking trace, and therefore possible gaps participant accident.

53-63

Authors: Slobodan Mišanović, Vladimir Spasojević

The consumption of fuel is important indicator and aspect in operation of buses for public transportation. During the tender procedure for the procurement of new buses, fuel consumption is presenting one of the evaluation criteria in order to optimize the operating costs of the vehicle during its life cycle. Since 2009, in the EU as official methodology for measuring the fuel consumption of buses for urban - suburban transport, is used SORT methodology. The methodology is a simulation of real traffic conditions: acceleration, deceleration, stopping, vehicle load, measuring the amount of fuel consumed and processing results on the specially prepared test site for city, intercity and combined cycle. This paper shows the methodology SORT 1 (urban cycle) and the results of tests on five buses of GSP ''Beograd'', brand ''Solaris Urbino 18'', which were conducted in February and March of 2014, on the proving ground ''Santa Oliva'' ( Spain ) by certification body ''Applus Idiada''. Also, will be presented a comparative view of fuel consumption for buses ''Solaris Urbino 18'' in real operating conditions on the routes are served by GSP ''Beograd''.

7-21

Authors: Dragoljub Radonjić

Analysis and comparison of the comparative cycles is of great importance in assessing the effectiveness and efficiency of actual cycles of internal combustion engines. In conventional combustion engines are used the three main comparative cycles: otto, diesel and dual. The development of internal combustion engines, by applications: the new system of mixture formation (GDI, HCCI), variable valve timing, overboost system and aftertreatment of exhaust gases, bring to modification of the real working cycle, but also the need to introduce new comparative cycle such as Atkinson, Miller, Gruden and HEHC cycles. Previous methods of analysis and comparison of the ideal cycle is reduced to the determination of the expression of specific work and thermal efficiency of each cycle as a function of the characteristic parameters, adopting the criteria of comparison and finally, comparison of the specific work and efficiency of the given cycle at different values of the selected parameter. This paper presents a new method of comparison based on the application of the general thermodynamic cycle (GTC), introduced by the author. From the general thermodynamic cycle, in particular procedures can be carried out, all possible cycles for converting heat into work (total: 130), and by determining the expression of specific work and efficiency of this cycle and placing them in appropriate conditions can obtain expressions for the specific work and efficiency of each cycle. On the basis of these procedures has been developed a software package that provides graphical views of the following characteristics of the selected cycle: P-v and T-s diagrams, changes the specific work and thermal efficiency as a function of the desired dimensionless parameter, as well as the comparison of two or more cycles according to proposed criteria.

37-54

Authors: Zoran Nikolić, Zlatomir Živanović

First Electric Vehicle (EV) has been made in in 1837. This type of motor vehicles has dominated throughout the whole 19th century. In the early 20th century the faster and more robust vehicles with Internal Combustion Engine (ICE) overcame them until late 20th century, when ecological and economic problems of further application of these vehicles have emerged. The interest in EV has risen sharply. Researches are working in several directions in order to reduce the need for oil derivatives considering that the EV's are weak primarily due to inferior "reservoir of energy" to fully meet the current driving habits. Savings can be achieved in two ways, by making more economic motor vehicles or by the use of alternative fuels. Combining an electric propulsion and IC engine drives a hybrid vehicle is obtained, with a greater amount of batteries and "plug in" that is to some extent possible to reduce fossil fuel consumption and exhaust emissions. Intensive research work on exploring new battery is still to come. Today promising results with Li - air batteries, fuel cells and super capacitors, as well as the efforts of major car manufacturers indicate that the EV could soon appear massive in the streets of cities. This paper deals with the development of EV, following the development of powertrain and can conclude the fact that in the near future this type of drive could return.

63-77

Authors: Dobrivoje Ćatić, Jasna Glišović, Sandra Veličković, Jasmina Blagojević, Marko Delić

Weibull distribution is one of the most frequently used theoretical models for approximation of empirical distributions of random variables with continuous variation. Procedures for graphical, grapho-analytical and analytical determination of Weibull distribution parameters are described in detail in this paper. Based on the graphical method for determining the position parameters of three-parameter Weibull distribution, the analytical procedure is developed, which is based on the application of the method of least squares. The set of points is approximating with the square parabola, and based on the sign of the second derivative, the information for further proceedings is obtained. For the defined procedure, an algorithm of the computer program for determination of the Weibull distribution parameters is presented in paper. By using the program, based on data from the exploitation related to the operation time until failure, the reliability modelling of wheel’s drum in braking system of light commercial vehicles was performed. The graphical and non-parametric tests were used to test the theoretical model of distribution.