Magnetism of steel belt in tyres - measurement and related condition assessment

The paper shows the newest findings in measurement techniques of magnetic flux density (induction) of ferromagnetic steel belt in pneumatic tires. The steel belt is complicated and spatially arranged in a sophisticated way, therefore a specially developed approach to its measurement and data transformation is needed in order to extract information about selected properties of a tire. This article discusses measurement techniques, the processing of measurement data, essential data transformations, presentation of results and analysis methods. It is shown that the measurement data is redundant and classic approaches to data presentation are misleading. For data presentation methods with different information reduction are proposed and discussed. It appears, that they can be used for assessing magnetic field changes in time (and distance) and detection of steel belt's anomalies. Application of presentation methods were formulated and summarized in a table. Moreover, the changes in magnetic field of steel belt were related with X-ray photos. Correlation with steel belt magnetics and geometrical state of alignment of rods in steel belt layers and rod's twisting was found. Moreover, evidence was provided for relation with magnetization parameters and mileage. Finally quantitative characteristics were proposed, which allows to determine tires operation time and anomaly detection. The findings can be used for tire properties determination, tires’ degradation and selected structural changes. Overall, the paper demonstrates that proposed measurement, processing technique and analysis method must be used in conjunction to assess for selected tires’ properties.