This paper presents creep buckling finite element modeling of steel beam-type structure. For beams under sustained loads the loss of stability may occur during a period of exploitation of structure even for loads lower than critical buckling load. For that reason stability is characterized by critical buckling time instead the critical buckling load. The simulation is performed using four nodded Kirchoff- Love theory based shell finite elements. For a space frame, as the test example, critical buckling times are calculated for different levels of applied load, temperature conditions and steel chemical composition.
Machines. Technologies. Materials.
Vol. 8 (2014), Issue 2
Table of Contents
The paper presents the results of developmental researches related to determining the influence of application of various systems for LPG on vehicle properties. On model Florida Zastava the following sequential systems were installed: Sequent 24 BRC, Omegas LR, e-G@S, Fast Lovato and Alisei N Zavoli. The results of comparative investigations obtained indicate the advantages of particular systems. The results of individual adjustment have been compared with the results of a production vehicle adjustment.
COMPARATIVE ANALYSIS OF THE BODY VIBRATIONS OF NEW CARS EQUIPPED WITH THREE DIFFRENT TYPE OF ENGINESpg(s) 19-22
The paper presents the results of comparisons tests carried out on one model (Fiat Bravo model 198 produced in 2010) of new cars equipped with three types of engine: Version 54A with the 1.4BZ 90CV CD spark-ignition engine, Version 54G with the 1.4BZ 120CV CD spark-ignition engine equipped with a supercharging system and Version 54W with the 1,6D 105CV diesel engine. The car body vibrations experimentally determined in several specific repeatable points, i.e. behind the front side indicator and behind the passenger handle, were compared. A PSV-400 laser Doppler vibrometer made by Polytec was used to measure vibration velocities. The vibrometer directly measures two quantities: displacement and velocity. In the investigated case, vibration velocity turned out to be the variable supplying better diagnostic information. Vibrations were measured for the car standing on its wheels and for the car jacked up to reduce the influence of the car vibration damping systems on the measurement results. The latter are presented in the form of comparative diagrams. Moreover, the fast Fourier transform was used to determine the frequency distribution. Prior to that the signal was subjected to conditioning operations in time domain, such as parametric windowing and filtering. On the basis of the results the effect of the drive unit on the behaviour of the car body can be assessed for different engine types and rotational speeds. It is shown that the way in which the engine is mounted affects the vibrations of the car.
A COMPARISON OF FUEL CONSUMPTION BETWEEN THE NEW EUROPEAN DRIVING CYCLE TEST AND THE NATURAL OPERATION OF A VEHICLEpg(s) 23-25
There are many changes in the automotive industry which leads to improved to safety and reduce fuel consumption. A new design of vehicles are being modernized, reducing aerodynamic resistances and the weight of vehicle units. However it is forgotten about the same time changing and updating the fuel consumption’s tests. The cars are tested with New European Driving Cycle test which based on directive 91/441/EEC (26 June 1991). It’s been 23 years. NEDC was developed at a time when European vehicles were lighter and less powerful. The test offers a stylized pattern for low speed acceleration (a = 0.89 m / s), speed, ride at idle, but temporary increase is much steeper and more dynamic in practice, in part due to the excess capacity of modern engines.
This paper presents a comparison of fuel combustion Polish users registered on the famous automotive’s forum between factory data vehicles selected. As a result, it is hard for drivers to reach the certified values in practice.
The new version of the driving cycle should be more realistic to the everyday use of additional equipment and gadgets that are installed in modern vehicles.
According to WHO, more than 1.2 million people die in road traffic crashes every year and 50 million are injured or disabled.
Over the last decade nearly all EU countries record a decrease in number of traffic casualties. However, in the same period Montenegro’s figures generally point in opposite direction. The fatality rate on Montenegro’s roads, measured as deaths per capita, is 50% higher than that of EU average; however, car ownership in Montenegro is considerably lower than the EU average. Having traffic safety figures so bad, efforts have been made in recent years to address this issue.
model of charging and discharging of the battery is validated experimentally with a traction battery used in EV / HEV. An interesting feature of this model is the simplicity for extracting of the dynamic parameters of technical specifications of the battery. Only two points on the curve for the discharge of the battery in the steady state are required to obtain the necessary parameters. The model of the battery is included in the simulation using the LabJack U12 in the programming environment LabVIEW2012 for EV / HEV applications. The results show that the model can accurately represent the dynamic behavior of the battery during use of EV / HEV vehicles.
In this paper short reviue about the most important Macedonian foundry companies is given. During prepariation of this work autors visited production units of of the foundry companies and discused with their menegament about the most important things concerning their current work and the plans for the future. It was found that six of the companies are the most important for Macedonian industry. All of them are private companies. They are founded before transition period, and their production is mainly intended for the foreign market. It is important to say that they have very ambitious plans for improvement of technological processes and increase of production.
In current work is made comparison between the differences in structure methods of propulsion and price of two types of motors with permanent magnets and AC drive (PMAC). PMAC is common name of electric motors – permanent magnets synchronous motor (PMSM) and brushless permanent magnet motor (BLDC). On the basis of comparative studies is selected and tested construction and propulsion of low-cost BLDC motor, suitable for hybrid transmission of HEV.
POSSIBILITIES FOR OPTIMIZING MAINTENANCE OF MILITARY VEHICLES ON THE RESULTS OF TRIBOLOGICAL DIAGNOSTICSpg(s) 37-39
Tribological diagnostics is a non-destructive and non-disassembling diagnostic method, that uses lubricating oil as a source of information about processes and changes in mechanical systems, to which it is applied. The paper deals with the mathematical processing, monitoring and analysis of the oil field data obtained from the atomic emission spectrometry in frame of the tribodiagnostic oil tests. The mathematical methods based on a regression analysis and calculations are used in the paper for oil data analysis. The whole assessment procedure and their outcomes serve as identification of a suitable approximation trend. With the same result we are capable of determining in-service operation history as well as giving inputs to maintenance optimisation. Nowadays the system requirements are set up and evaluated in various manners. We would like to keep both preventive and corrective maintenance costs as low as possible. A system design and a maintenance system help to fulfil this task. We propose to use one of the approximations presented in order to track the system operation behaviour.
RESEARCH ON THE INFLUENCE OF THE TYPE OF MICROFILLER ON THE DAMPING CHARACTERISITCS OF POLYMER-CONCRETE COMPOSITESpg(s) 40-43
This research presents the experimental approach and methodics for quantification of the damping characteristics of two groups of polymer-concrete composites. By means of a comparative analysis here it is determined the influence of the type of fine filler material (microfiller) on the damping characteristics of the experimental polymer-concrete composites.
The paper is focused on the analysis of tracked vehicle propulsion mechanism during a movement of the vehicle. Propulsion mechanisms of tracked vehicles are highly loaded by dynamics stress. This stress arises by vehicle movement on a terrain and by vibration of tracks. Analysis of this stress is essential in the process of development or optimization (modernization) of the vehicle. Simulating technology was chosen for analysis of selected vehicle, because analysis of propulsion mechanism stress of tracked vehicle is complex process. Utilization of simulating technologies enables extensive analysis of vehicle behaviour including analysis of stress of main parts of the vehicle.
In this paper the important events in the auto industry all over the world, situation with automobile industry in Serbia, the concern for safety of drivers and other participants in traffic, with special stress on the protection of children in traffic, as well as the obligation of environmental protection are presented. Unfortunately, mortality in traffic is becoming epidemic. The interactive map showing the basic parameters of traffic safety in all countries in the world has been started. Every year on the roads throughout the world even 1.240.000 persons are killed. On the roads in Serbia the most frequent causes of traffic accident with serious consequences are: speeding, driving under the influence of alcohol and not fastening seat belts. Children in traffic are killed mostly as passengers. Reasearch shows that Serbia is positioned very low comparing to European Union countries when it comes to the safe transport of children in vehicles and the use of seat belts. Agency for Traffic Safety in the Republic of Serbia in December 2013 celebrated 4 years from foundation and on that occasion the importance and necessity of connecting and coordination in work of all subjects competent for the field of safety was emphasized.
Multicopters are widely used in a professional manner today in film industry, military applications etc. These vehicles are easy to build which have mechanical and electrical parts. Also autopilots are being sold to control these vehicles. However, mostly these vehicles are being built and used with little knowladge about the system dynamics, performance and stability. Mostly wrong propeller motor battery combinations are used. And mostly these vehicles are being used by different payloads. Every change in payload changes dynamics and stability of the vehicle. Very little of users are eligible at PID tuning and increasing the stability of multirotor vehicles. We aim to provide a test platform and methodoly for system identification and increasing stability of Multirotor Vehicles.
This paper presents the analysis which is based on the parameters of the real device for producing a mixture of hydroxyl (HHO) and similar parameters to the real 2.0 SDI VW Golf MK V engine. Theoretical analysis has been made to principles of cooperation the engine with HHO’s generator. The effects of the gas on the engine and operating economy were established. The analysis was divided into quantitative and qualitative. Quantitative analysis was contained the theoretical and economic calculation of the thermodynamic cycle taking into account the HHO gas. Qualitative analysis was concerned to the quality of combustion in the engine and the impact generator HHO to the quality of the combustion.
Cast zinc alloys are widely used in various industries of national economics, including the manufacturing of products for tribotechnical applications. There are such approaches to solving the problem of improving the tribotechnical characteristics of zinc alloys, as the search for new alloy compositions and optimization of existing ones. However, the capabilities of traditional alloys to achieve the desired properties of products that meet the growing demands almost exhausted at present time. One of the most effective ways to improve the tribotechnical properties of zinc alloys is realization of the principle of reinforced heterophase structure, which is the basis of creation of composite alloys.