Tire-road noise: an experimental study of tire and road design parameters

It is widely known that road traffic noise has negative influences on human health. Hence, as tire-road noise is considered to be the most dominant cause of road traffic noise above 30-50 km/h, a lot of research is performed by the two involving industries: road authorities/manufacturers and tire manufacturers. Usually, the parameters influencing exterior tire-road noise are often examined separately, whereas it is the tire-road interaction which obviously causes the actual noise. An integral approach, i.e. assessing possible measures to reduce tire-road noise from both the road and the tire point of view, is needed to further reduce traffic noise. In a project Silent Safe Traffic, this tire-road interaction is studied in more detail without focusing on either tire or road but looking at the tire-road system. In this publication we present experimental results of tire and road design parameters influencing tire-road noise from a fixed reference tire-road configuration. The influence of tire tread pattern, compound and construction as well as the influence of road roughness, acoustic absorption and driving speed on the exterior tire-road noise, measured by a CPX-set up, is reported. Keywords: Tire, Road, Measuremen

Transfer path based tyre absorption tests

The development process of a tyre usually involves a combination of simulation and testing techniques focused on characterizing acoustic/aerodynamic and vibrational phenomena. One of the acoustic phenomenon of interest is the absorption of the tyre, which affects the sound radiated. This properties is mainly related to local resonant effects, which can be changed by modifying the geometry of the tyre tread. A procedure is presented to determine the attenuation achieved due to a change in tyre tread configuration. The acoustic transfer path is measured from sound produced at one side of the tyre pavement contact area to the other. A miniature microphone and a small monopole with a known output have been developed to allow measurements inside the tyre grooves. Tyre sections with a circumferential groove only, as well as sections with additional side branches, have been evaluated

Operational modal analysis of a tyre using a PU probe based scanning technique

Tyre vibration can be studied with several experimental and simulation techniques. An important goal for a tyre manufacturer is to “tune” the resonant frequency of the tyre subsystem to reduce the structure-borne noise in the car interior. In this paper, a novel measurement technique is applied to determine the operational tyre deflection shapes under different conditions; i.e. free condition, loaded condition, and rolling condition. The vibrational behaviour of a tyre is studied using a PU probe, which comprises a sound pressure and a particle velocity sensor, and a scanning technique. The relative phase information is obtained using a static reference sensor. The experimental data can be used to validate simulated mode-shapes and resonant frequencies

A source path contribution analysis on tire noise using particle velocity sensors

Road tire noise is an important topic of research where acoustic particle velocity based testing techniques can be expected to bring new insights. Modal analysis can be carried out using non contact particle velocity sensors, and PU sound probes can be used to measure the radiated sound without a need to use anechoic testing conditions. A further breakdown of the overall sound pressure levels measured in to its various sources can be made by applying a source path contribution analysis, using the PU probes to measure velocity, sound intensity and, for determining the reciprocal transfer path, the sound pressure. The concept of using this type of transfer path analysis will be outlined and illustrated by a tire noise case

Engineering tools for interior tyre tread pattern noise

The regular tyre tread pattern design process is often based upon experience and experimental evaluations and may take about 2 years. The use of engineering tooling could improve and speed up this process. The research objective is therefore to develop experimental and simulation tooling by which interior tyre tread pattern noise can be predicted, analysed and optimized.\ud The physics of tyre-road noise is explained in a comprehensive manner as a thorough understanding of the physics is needed to evaluate, measure, analyse or optimize tyres with respect to noise. The first engineering tool developed is an instrumented vehicle with dedicated measurement and processing technologies, enabling quantification of the terminology used in subjective evaluations of tyre-road noise. The three most important tyre tread pattern noise characteristics are: level, tonalness and modulation/drumming.\ud They can be quantified, respectively, by the Sound Pressure Level, the so-called order spectrum and the (bandpass filtered) sound pressure variation during one tyre revolution.\ud While rolling on smooth roads, the tyre tread pattern geometry in the tyre-road contact is considered to be the main origin of contact pressure variations, resulting in vibrations and noise. The second engineering tool is a simulation procedure of this source. In the new source modelling approach, the averaged tread pattern height in contact is calculated. The model predicts (R2 = 0.76) the correct trends of the three tyre tread pattern noise characteristics, by using the trend of their geometrical cause. The model can be used to reduce exterior as well as interior tyre tread pattern noise.\ud From these tyre tread pattern noise characteristics dedicated Sound Quality Metrics are defined: for level the Standard Deviation (STD), for tonalness the Order Prominence (OP) and for modulation the Multi-Order Modulation (MOM). They correspond very well (respectively R2=0.96, 0.60 and 0.80) with the human perception of the noise characteristics. An increase in each of the metrics results in a worse subjective perception of the tyre tread pattern noise. The metrics are applicable for measured and simulated sounds.\ud In the third engineering tool the three metrics are combined to model the human\ud percpetion of tyre tread patternn noise. The human perception model is obtained through a linear regression of these tyre related Sound Quality Metrics on the subjective rating of simulated sounds. The output of the model is called the Sound Quality Preference Index (SQPI) predicting the human perception of tyre tread pattern sounds correctly (R2=0.94).\ud The coupled source - human perception model can be used to speed up and improve the current tyre tread patter design process

Experimental review on interior tire-road noise models

Exterior and interior tire-road noise is a common problem for car and tire manufactures. Exterior tire-road noise is bounded by UN-ECE R117 and EC R661/2009. Interior tire-road noise on the other hand is determined by market requirements. Since the beginning of the last century different model approaches on exterior and interior tire-road noise have been reported. A brief review of these model approaches is given in order to distinguish which approach to model interior tire-road noise is most promising. Some experimental considerations are given as a guide line for this evaluation. The paper concludes that the most efficient model approach is a full interior tire-road noise consisting of a FEM/BEM exterior tire-road noise model combined with measured structure and air-borne transfer paths

Silent and safe roadtraffic-project: An optimization of the tyre-road interaction on noise and wet grip

The tyre-road interaction is responsible for many tyre and road 'characteristics' like rolling resistance, noise, hydroplaning and wet grip. In the EC legislation R1222 the 'tyre characteristics' are measured using 'standard roads'. Whearas 'road characteristics' like noise in the IS011819-2 and skid resistance are often measured using 'standard tyres'. As the standards are often old technology, real innovative steps are hard to achieve. Therefore the project 'Stil Veilig Wegverkeer' is started, translated as 'Silent and Safe Roadtraffic', where the tyre-road interaction is studied in more detail regarding noise and wet grip. With new developed simulation and test methodogies the tyre-road combination is optimized. An overview of the project and the first results will be given