The acoustic and mean flow performance of different configurations of simple expansion chamber mufflers has been considered. The different configurations include extended inlet/outlet pipes and baffles inside the expansion section of the muffler. Both the acoustic and mean flow performance has been evaluated for each muffler. The acoustic CFD model of the muffler uses an axisymmetric grid with no mean flow and a single period sinusoid of suitable amplitude and duration imposed at the inlet boundary. The time history of the acoustic pressure and particle velocity are recorded at two points, one in the inlet pipe and the other in the outlet pipe. These time histories are Fourier transformed and the transmission loss of the muffler is calculated. The mean flow model of the muffler uses the same geometry, but has a finer mesh and has a suitable inlet velocity applied at the inlet boundary and the pressure drop across the muffler is found. The acoustic performance is compared with published experimental results.

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Based on the results of experimental and numerical analyses, we investigate the effects of rotation on tire dynamic behavior. Better understanding of these effects will further improve the ability to control and optimize the noise and vibrations that result from the interaction between the road surface and the rolling tire. The presented work was performed in the framework of the European industry-academia project Tire-Dyn, with partners Goodyear, Katholieke Universiteit Leuven, and LMS International. The effect of rotation on the tire dynamic behavior is quantified for different operating conditions of the tire, such as load and rotation speed. Through combined experimental and numerical analyses, the physical phenomena accounting for the observed rotation influences are described.

Although tire/road noise and tire vibration phenomena have been studied for decades, there are still some missing links in the process of accurately predicting and controlling the overall tire/road noise and vibration. An important missing link is represented by the effect of rolling on the dynamic behavior of a tire. Consequently, inside the European seventh framework program, an industry-academia partnership project, named TIRE-DYN, has been founded between KU Leuven, Goodyear and LMS International. By means of experimental and numerical analyses, the effects of rolling on the tire dynamic behavior are quantified. This paper presents the results of vibration measurements on a rotating tire with an embedded accelerometer. Modal parameters of the rolling tire are estimated from an operational modal analysis. In addition, the dispersion curves, which give detailed insight in the wave propagation behavior of a structure, are analyzed for the rolling tire. The goal of these analyses is to deepen the understanding on the influence of rolling on the tire dynamic behavior.

The driver subjective perception of a vehicle is strongly determined by its Noise, Vibration and Harshness (NVH) behavior. Consequently, the NVH performance has become an important design and marketing criterion for vehicle manufacturers. The low-frequency (0–500Hz) noise and vibration perceived by a passenger are mainly determined by the dynamic behavior of rolling tyres. Besides the increasing awareness for the problems associated with road traffic noise has lead to the demand for more quiet tyres and road surfaces. Computer aided engineering tools play an important role for improving the vehicle vibration behavior at the earliest step of the design. In order to carry out precise modeling of the vehicle and its subsystems, an accurate tyre model is a key element in predicting the performance of the vehicle system with respect to ride comfort, NVH, durability, safety (braking manoeuvre) and tyre/road interaction. To obtain the best possible performance from a tyre model, a number of different measurements are required to support the tyre model parameter identification process. Although tyre vibration and noise behavior has been studied for several decades, there are still some missing links in the process of accurately predicting and controlling the overall tyre/road noise and vibration linked to the difficulty of performing modal testing on a tyre when rotating. This paper deals with the main test benches, experimental activities and modal analysis techniques available nowadays for characterizing the dynamic behavior of a static (unloaded tyre on a fixed hub and loaded tyre on a fixed hub) and a rotating tyre under different boundary conditions. The main results arising from modal analysis of a static and dynamic test on a tyre are highlighted and compared. In particular the effect of rolling speed, inflation pressure, preload, temperature and excitation amplitude on the dynamic response of a rolling tyre will be discussed.