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In tire development, the dynamic tire-road contact forces are an important indicator to assess structure-borne interior cabin noise. This type of noise is the dominant source in the frequency range from 50-450 Hz, especially when rolling with constant angular velocity on a rough road. The spatial force distribution is difficult or sometimes even impossible to simulate or measure in practice. So, the use of an inverse technique is proposed. This technique uses response measurements in combination with a digital twin simulation model to obtain the input forces in an inverse way. The responses and model properties are expressed in the time domain, since it is specifically aimed to trace back the impact locations from road surface texture indents on the tire. In order to do so, the transient responses of the travelling waves as a result of these impacts is used. The framework expresses responses as a convolution product of the unknown loads and impulse response measurements.

This paper presents the design and experimental results of a novel test setup to measure the road impact response of a rotating tire. The test setup is based on a tire on tire principle and is used to analyse mechanisms of tire/road noise during road impact excitations, such as driving on cobbled roads, joints of a concrete road surface, railroad crossings,… A series of test are performed with different driving speeds, cleat dimensions and inflation pressures. Radiated noise, vibrations of the tire surface and spindle forces are measured on the test setup during impact excitations.

In this paper, singular value decomposition, principle component analysis and multicoherence analysis is used to evaluate the number of important degrees of freedom in acceleration based road load data, which constitute the targets for road reproduction experiments on a hydraulic shaker table. It is therefore important to determine from this road data how many degrees of freedom need to be included in the road reproduction experiments. The multi-axial nature of the input and the suspension response is illustrated based on target data from different road surfaces, acquired on the road and on the road dynamometer, as well as on the reproduction results of these tracks using tire patch and spindle based excitation on the K.U.Leuven high frequency multi-axial shaker table.

Tire noise has become a predominant contributor in many traffic noise situations nowadays and hence, the demand for accurate tire noise prediction models is high. A rolling tire is experimentally characterized by means of the substitution monopole technique: the running tire is substituted by the non-operating tire covered by monopoles. All monopoles have mutual phase relationships and a well defined volume velocity distribution which is derived by means of an inverse Airborne Source Quantification technique; i.e. by combining static transfer function measurements with operational indicator pressure measurements close to the rolling tire. Models with varying amounts and locations of monopoles are discussed.

Prediction of the drive-by noise level in the early design stage of an automotive vehicle is feasible if the source signatures and source-receiver transfer functions may be determined from simulations based on the available CAD/CAE models. This paper reports on the performance of a drive-by noise synthesis procedure in which the transfer functions are numerically evaluated by employing the Fast Multipole Boundary Element Method (FMBEM). The proposed synthesis procedure first computes the steady-state receiver contributions of the sources as appearing from a number of vehicle positions along the drive path. In a second step, these contributions are then combined into a single transient signal from a moving vehicle for each source-receiver pair by means of a travel time correction.

This paper demonstrates the application of a resonant metamaterial concept to tyres in order to reduce structure-borne tyre/road noise. Special attention is given to the frequency range around 220Hz, containing the first acoustic tyre resonances. These resonances are known to transmit high forces to the wheel-knuckle, leading to structural energy propagating into the vehicle’s body and, consequently, causing a tonal noise issue in the vehicle compartment. By adding recycled rubber resonant elements to the inner liner of the tyre, structural stop band behaviour is achieved in the frequency band of interest. Hence, structural vibrations in the tyre are reduced, resulting in a reduction of the excitation of the first acoustic tyre resonances and, consequently, a mitigation of the transmitted forces to the wheel-knuckle. First, the stop band behaviour is designed via unit cell modelling of a section of a tyre mock-up that only accounts for its structural behaviour.