Effect of Spoke Design and Material Nonlinearity on Non-Pneumatic Tire Stiffness and Durability Performance

Abstract

The non-pneumatic tire (NPT) has been widely used due to its advantages of no run-flat, no need for air maintenance, low rolling resistance, and improvement of passenger comfort due to its better shock absorption. It has a variety of applications in military vehicles, earthmovers, the lunar rover, stair-climbing vehicles, etc. Recently, the Unique Puncture-Proof Tire System (UPTIS) NPT has been introduced for passenger vehicles. In this study, three different design configurations, viz., Tweel, Honeycomb, and newly developed UPTIS, have been compared. The effect of polyurethane (PU) material nonlinearity has also been introduced by applying five different nonlinear PU material properties in the spokes. The combined analysis of the PU material nonlinearity and spoke design configuration on the overall tire stiffness and spoke damage prediction is done using three-dimensional (3D) finite element modelling (FEM) simulations performed in ANSYS 16.0. It has been observed that the Mooney-Rivlin five-parameter model is best to capture the nonlinearity of all five studied PU materials. The effect of material nonlinearity on various spoke designs has been studied. The best combination of spoke design and the use of nonlinear material has been suggested in terms of riding comfort, tire stiffness, and durability performance. This work also shows the relative importance of material damage parameters like strain energy density (SED), maximum principal strain, and maximum octahedral shear strain. The FEM model is validated with experimental vertical stifness results available in the literature of 12N16.5 (Commercial NPT-Tweel) with around 97% accuracy.