Abstract

A radial automobile tire undergoing steady‐state rotation is analyzed by a finite element method. A special formulation is used which allows the finite element equations to be solved as a quasi‐static problem using static analysis solution procedures, rather than as a dynamic problem requiring solution in the time domain. This is accomplished through a transformation of variable that changes time derivatives, present through inertia, to spatial derivatives. Solution time for the analysis is thereby shortened.

The tire is modeled first as a two‐dimensional ring on an elastic foundation, then in its full three‐dimensional geometry. Rotational speeds are those at which resonance occurs so that the dynamics can be easily visualized and the response easily verified. The models are subjected to point load excitation or ground contact. Point load is used to predict resonance responses of the undamped tire. Results agreed well with experimental measurements. The effect of inertia components and damping on vibrational response of the tire was studied by imposing ground contact at one of the resonance speeds. Damping is included in the model through a two‐element Kelvin‐Voight viscoelastic material model. Responses of the models were similar to standing wave deformations in a tire.

Abstract

A new approach for the complete thermomechanical analysis of a pneumatic tire to estimate cyclic changes in the stresses and strains and obtain the pseudo‐steady state temperature profile in a tire rolling under a load is described. The approach uses a commercially available finite element code and involves a simplified two‐dimensional representation of the tire geometry to reduce computation time. The analysis includes three stages: inflation analysis, contact analysis, and temperature analysis. To handle the large deformations resulting from the inflation and contact loadings, the load is applied in small increments and a linearly elastic deformation is assumed in each increment. The structural and temperature analyses can be coupled through an iterative process to reflect the effect of temperature changes on material properties. Results obtained indicate that in spite of the simplifying assumptions made to reduce computation time, useful approximations to the solution of this complex problem can be obtained.

Abstract

The desire to obtain a higher share for silica in tire compounding has been one motivation in the development of silane coupling agents. This development has reached a stage where at least a partial replacement of semi‐active and active carbon blacks with silane‐modified white fillers is technically feasible although costs are still too high. Nevertheless, silica tires with bis‐(3‐triethoxisilylpropyl)‐tetrasulfide (TESPT) have been built on a development scale and tested under various conditions.

Over the last ten years, the coupling agent TESPT has developed into a special rubber chemical. This is due to its simultaneous capability of forming equilibrium cure systems, polysulfidic crosslinks with extremely high thermal stability, and rubber‐to‐filler bonds to improve silica‐rubber interaction. In conjunction with silica, TESPT gives superior physical vulcanizate properties such as low heat build‐up, better performance under continuous deformation, and better tear and cutting resistance than vulcanizates with carbon black only. Its present main application is in truck, off‐the‐road, and earth‐mover tires to solve specific tire problems.