Nonlinear behaviour of pultruded decks due to morphing of tyre loads

Abstract

The spatial profile of the load exerted by a pneumatic tyre on a pultruded glass fibre-reinforced polymer (GFRP) deck varies nonlinearly with the magnitude of the load, owing to changes in the tyre-deck contact zone’s shape, size and pressure distribution. This is a rare problem in which the nonlinearity originates not in constitutive behaviour or large displacements, but in the load’s 3D definition. This paper addresses that problem in three parts. First, a fine grid is overlaid on colour-coded isobars recorded by an electronic pressure sensor in tyre-pultruded deck contact-zones, to obtain a digital record of the spatial pressure distributions defining the patch loads. Second, the digital files are used as tyre loads in experimentally-validated FE analyses of perfect and defective GFRP decks. Third, uniformly-loaded square and circular patch approximations of the tyre patch loads are alternately input to the FE model. Relative to the tyre loads, the square patches enable prediction of similar peak stresses up to 45 kN (relevant for fatigue), while the circular patches enable similar predictability at lower loads, with significant deviation above 25kN. In conclusion, FEA using spatially-defined tyre loads digitally extracted from pressure sensor recordings is recommended for studying other tyres, inflation pressures and deck geometries.