Airless tyres in the LEON-T project: How can they be modelled?

For more than a century, pneumatic (air-inflated) tyres have totally dominated the market for road vehicle tyres. However, in the recent two decades, interest has grown in developing airless tyres. Some of the authors were involved in design of an early version in composite material 15-30 years ago for passenger cars. Presently, the EU project LEON-T includes a part in which prototypes for innovative heavy goods vehicle (HGV) tyres are developed, with the main purpose to reduce noise emission by 6 dB. To reduce noise that much it is believed that airless tyres are needed. A special challenge is to get a durable design able to carry typical truck tyre loads. This paper introduces the principal design of airless tyres. Airless tyre prototypes are intended to be developed by partner Euroturbine, in cooperation with mainly Applus+ IDIADA, VTI and subcontractor Lightness by Design. The tyre consists of a rim, load-carrying spokes, composite belt and rubber tread. The primary focus is on the modelling of static and dynamic behaviour of the tyre and the corresponding impact on the tyre design. By aid of FE modelling, the tyre static behaviour (radial, lateral and longitudinal stiffness) is analysed. It is found that the radial stiffness of the modelled tyre is within the ranges of that of a conventional pneumatic tyre, however, the longitudinal and lateral stiffnesses are 2.5 and 3 times higher, respectively. The same tyre model is used to study its dynamic behaviour (modal and noise characteristics) which are then compared with that from measurements. For modal studies, the point inertances are used as a reference for test and simulation validation. The same for the noise study is the noise transfer function that is measured at a predetermined location, using a microphone in the vicinity of the tyre.