Search Results

Safety on roads strongly depends on appropriate illumination at the foreground of the running vehicle.The head lights projectors should provide good quality visibility of the road surface in normal atmospheric conditions. Unfortunatelly, they do not secure the sufficient quality in night fogs conditions which are inseparable element of our climatical conditions.The low beam lights and fog lights are the most often used typ of projectors in difficult atmospheric conditions. In the paper the results of light calculation and justification of applying the fog projectors as well as comparison of their lighting features in relation to the main low beams lights were presented.

The article demonstrates selected issues related to assessment of computational accuracy in accident analysis. The hereto presented theoretical grounds of the methods make it possible to consider uncertainties in the assessment of input data values. The methods were compared on the basis of their exemplary application in the case of braking process study of a vehicle in rectilinear motion. Also for the aforementioned case, the results obtained by means of various computational methods of vehicle motion (analytical and simulation models) were compared with the outcome of the experimental study.

The paper briefly presents two simulation models which describe the motion and dynamics of biaxial vehicles: a medium class car and 12 tons truck. The road surface may be even or uneven. The main models may be divided into coupled submodels. Their equations of motion can be derived separately. The programs can be run even on personal computers. The models are experimentally verified on even roads for typical manoeuvres recommended by ISO. The paper shows mainly the results of experimental evaluation of simulation models. It also presents steering system submodel in more detail. Its combination with other submodels describe small car motion and dynamics including the influence of steering system freeplay and dry friction.

The temperature influences significantly the braking effectiveness. The paper describes consistency criterions of the brake thermal state in road braking conditions and on the roll-stand. As a result of the vehicle motion simulation, the time histories of the heat fluxes generated on the friction surface of the front and rear disc were determined. They were used as an input data for the model of the heat transfer process in disc brakes. The problem was solved by the use of the finite element method. Time histories of temperatures on the friction surfaces and in the material of the disc were calculated. As a preliminary consistency criterion of the brake thermal state in road and roll-stand braking conditions, a balance of the energy cumulated in the brake rotor was assumed. As the most reliable consistency criterion an equality of average temperatures of the friction surface was assumed.