Dr. Ulf Sandberg is a senior research scientist at the Swedish National Road and Transport Research Institute (VTI) and 2002-2008 an Adjunct Professor at Chalmers University of Technology. His main subject of experience and research is the tyre/road interaction, not the least tyre/road noise and rolling resistance, but he has also worked with other aspects of traffic noise since 1974 when he was enrolled by VTI. Regarding publications, for example, Dr Sandberg is the first author of the 640-page Tyre/Road Noise Reference Book which is used extensively in courses and as a reference. He has recently completed a comprehensive State-of-the-Art review of low noise road surface technology in various parts of the world. Dr Sandberg has been Project Manager of a North-European project "Tyre innovations for lower noise emission and rolling resistance" in which a so-called Composite Wheel has been developed and tested.
His Topic of Materials' Days 2009:
The Composite Wheel – A non-pneumatic integrated tyre/wheel with superior rolling resistance and exterior noise properties
The Composite Wheel (CW) is an invention by a Swedish engineer which was tested by VTI in a first version in 1989. The CW is a tire/wheel construction with a rubber tread mounted on a belt supported by a self-supporting structure (plate and “spokes”) made of composite materials. This early design was found to give 10 dB lower noise than an “average” conventional tire. However, durability was insufficient. In a recent North-European cooperative project led by VTI, new versions of the CW were developed and tested. The first series of new prototypes failed, partly because spokes in the wheel construction created noise emission at the spoke impact frequencies which dominated the noise emission, partly because of insufficient adhesion strength between spokes and belt. In a second series of prototypes, the spoke-related noise was reduced to acceptable levels and lower noise emissions than for any pneumatic tire were measured. Rolling resistance was extremely low, and vehicle handling was reasonably good for being a prototype. There are still some durability problems although much less than before. It is concluded that the CW has very promising features in terms of low noise emission and rolling resistance. The paper presents the latest results measured for this tire/wheel construction.