Ion Tabacu

Computational modelling of vehicle interior components for impact applications: Thickness analysis

This paper presents some modelling techniques useful for the optimisation of numerical models of vehicle interior parts in terms of improving the structural response in impact applications. A procedure regarding the random distribution of thickness of the elements for a selected area within a user-specified tolerance is presented. Procedures implemented in a custom-written code and the algorithms used for the random distribution are also presented. This was required because the parts presented some deviations from the nominal value (of thickness), probably due to the manufacturing process. With experiments performed with equipment constructed according to ECE R21 regulation, the results obtained using three numerical models are compared and solutions for numerical modelling are presented. Results (accelerations: maximum, average, at peaks; time: peak time, time interval between two peaks; coefficient of restitution) obtained using the numerical models were evaluated and compared with the experimental data.

Plug-In Hybrid Vehicle with a Lithium Iron Phosphate Battery Traction Type

To promote in the academic environment the ways for reducing global warming produced by the Sport Utility Vehicles, the grand hamster—electric way 4WD concept has developed within the University of Pitesti. It is a Plug-in Hybrid Vehicle powered in electric/hybrid modes by a Lithium Iron Phosphate (LiFePO4) traction battery technology, 205 V, 12 kWh. The concept is developed on the Dacia DUSTER crossover vehicle, 4 × 2 series version by implementing an electric propulsion system in the rear axle. The objective of this project is to realize a 4WD environmentally-friendly vehicle maintaining the leisure of driving the vehicle in the city using the continuously variable transmission (CVT) in the electric mode and the diesel motorization outside of the town in the thermal mode. The architecture is parallel type and E-4WD with a standard diesel engine 1,5 dCi FAP, 79 kW(107 bhp) and 6 speed manual gearbox in the front, and an asynchronous electric motor 31 kW (41 bhp) coupled with the reduction and differential gearbox unit at the rear. The traction battery is monitored by a battery monitor and charged by an embarked charger. The charging and discharging of the battery is authorized by the Battery Management System. The paper presents the firsts performances of the vehicle on the road tests.

The evaluation of the overall thermal comfort inside a vehicle

The thermal comfort is one of the most important aspects of the modern vehicles that can influence the safety, the fuel consumption and the pollutions regulation. The objective of this paper is to compare the global and absolute thermal comfort indexes for two vehicles with different distribution air systems inside the car cockpit, one using only front air vents, and the other using both front and rear air vents. The methodology of calculus consists in using the 3D model of the interior vehicle, generally in a CAD format. Then, using a meshing software to create the finite element model of the interior surfaces inside the cockpit and the volume of internal air. Using the obtained finite element geometry, there will be conducted a Theseus FE calculus using the given boundary conditions. The results of the numerical simulation are presented in terms of graphs and figures and also PMV, PPD and DTS thermal comfort indexes. With the obtained results, we will then create the graphs that allows us to evaluate the global and absolute thermal comfort indexes. The results of the evaluation show us that the use of the method allow us to evaluate with a greater accuracy the thermal comfort for the whole vehicle, not only for each passenger, like the standard methods. This shows us that in terms of general and absolute thermal comfort, the vehicle that use front and rear systems is better than the version that use only a front system. The thermal comfort is an important aspect to be taken into account from the beginning of the design stage of a vehicle, by choosing the right air conditioning system. In addition, by using the numerical simulation, we are able to reduce the time needed for preliminary tests and be able to provide the vehicle to the market earlier, at a lower development cost.

Computing Programs for Determining Traffic Flows from Roundabouts

For modeling road traffic at the level of a road network, it is necessary to specify the flows of all traffic currents at each intersection. These data can be obtained by direct measurements at the traffic light intersections, but in the case of a roundabouts, this is not possible directly, and the literature as well as the traffic modeling software offers no way to solve this issue. In the PhD thesis of the first author, this problem is analyzed and even solved: two sets of formulas are proposed by which all traffic flows from the roundabouts with 3 or 4 arms are calculated based on the streams that can be measured by the fixed observers: conflict flows, input flows and right turn flows. This has resulted in a mathematical model whereby all traffic flows from roundabouts can be known - either as measured traffic volumes or as traffic volumes resulting from analytical calculation. The objective of this paper is to develop computational programs to operate with these formulas, both for the determination of all flows at the roundabout and for the case when only the determination of certain traffic flows is desired. For each of the two sets of analytical relations, a computational program was developed in the Java operating language. For the case when it is necessary to determine only certain traffic flows, the calculation programs indicate which measurable flows with fixed observers should be entered as input into the program. Also, computational programs notice the situations where the data input leads to unauthorized (negative) solutions, indicating erroneous input data (caused by measurement errors or operating errors). The obtained results fully confirm the applicability of the calculation programs. The final stage for capitalizing these two programs will be to make them web pages in HTML format (HyperText Markup Language) so that they can be accessed and freely used on the Internet. The achievements presented in the paper are an important step to provide a necessary tool for working in traffic modeling. These computational programs can be easily integrated into specialized software for traffic modeling.

The Estimation of CO2 Emission from Road Vehicles by Traffic Macro-Simulation

Remarkable growth of population and mobility needs in the last century, especially in urban areas, is associated with air pollution. Reducing emissions of greenhouse gases from road vehicles is the main concern about the sustainability of road transport. The main factor derived from anthropogenic activities that contribute to increased greenhouse effect is CO2. This is the main product resulting from the combustion process that occurs during operation of thermal self-propelled vehicle. In this paperwork is estimated the volume of CO2 from road vehicles depending on speed. The case study is conducted for a medium sized city in Romania, Bistrita. The average speed of the vehicles on urban road network, the structure and volume of traffic flow were determined by transport modeling macro-simulation of road traffic using PTV-VISUM specialized software. The variation curves of CO2 volume according to the average speed used in this application has been validated for the structure of national fleet in the document Romania—Technical assistance for the elaboration of the General Transport Master Plan. These were determined according to CORINAIR methodology agreed by European Environment Agency, for the following categories: cars, light trucks, medium trucks and heavy trucks. Applying the methodology of calculation of CO2 based on average travel speed integrated with traffic modeling (knowing the average travel speed and the number of vehicles of existing categories on each segment of road network) allows the estimation of the volume of CO2 from mobile sources (vehicles) on any road network segments analyzed.