| Abstract [eng] |
In XXI century, vehicles are a part of many people’s lives. While vehicle driving speeds are increasing more and more often do we see one of the water and tire interaction phenomenon’s – aquaplaning. It is a phenomenon when a tire rolls on a water film and is subjected to a water generated hydrodynamic force. When the force is increasing there is a point upon which tire is lifted from the road and a full tire aquaplaning is reached. Because of the importance of this phenomenon to this day and to driver’s safety this works focus was to analyze parameters that influence aquaplaning speed by using empirical and numerical methods. After literature analysis it was found that parameters that influence critical aquaplaning speed are rut depth, tire pressure, wheel load force, water film thickness, thread design, thread wear and tire stiffness. These parameters were evaluated by creating a finite element model using “Ansys LS-DYNA” software. For this research a finite element model was created where water and tire interactions were described by using smooth particle hydrodynamics (SPH) method and stiff bodies with Lagrangian elements. For this research three different tire models were created: tire with no thread, with longitudinal grooves and a tire with longitudinal and 45 degree lateral grooves. When doing calculations, it was analyzed at what speed the tire will reach critical aquaplaning when using different sets of parameters. After performing numerical and empirical calculations it was found that empirical calculations show higher aquaplaning speed than numerical methods in all instances. That might have been because in empirical calculations rut depth and exact thread design was not considered. After performing numerical calculations, it was found that hydroplaning speed for a tire without groove was the worst at 51,5 km/h while the best aquaplaning speed was reached for a tire with longitudinal and lateral grooves at 62,7 km/h because of better water dissipation. After analyzing parameters that influence aquaplaning speed it was found that the most influence on aquaplaning speed had water film thickness where it was found that decreasing film thickness from 15 to 5 mm increases hydroplaning speed for tire without thread about 33 % and for tire with lateral grooves about 55 %. Also, it was found that wheel load force had a significant influence as well where increasing wheel load force by 1000 N aquaplaning speed increased by up to 15 %. The least influence to aquaplaning speed had tire stiffness where it was found that increasing tire stiffness to all tires yielded only up to 6 % increase in aquaplaning speed. |
