Abstract

When there are multiple peaks in the design space, it is difficult to obtain the global optimum by mathematical programming. The procedure to obtain the pseudo‐global optimum in the multiple‐peak problem is to select the best solution from many local optimums starting from different initial values. However, this approach requires large computer resources and has difficulty in obtaining the pseudo‐optimum in a problem with many peaks, due to the complicated design space.

We propose more efficient and robust optimization procedures for the multiple‐peak problem. In this approach, a neural network is applied for the approximation of the design space by learning the data when design variables are systematically changed, by employing a design of experiments. Since the neural network can approximate the nonlinear space, it can be applied for the approximation of the complicated design space. Moreover, since the number of analyses is determined by the design of experiments, it is much smaller than that of the mathematical programming. Hence the CPU time for optimization can be decreased by the proposed method. The proposed method is applied to the optimization of tire contact performance and is verified to be effective to improve the handling and wear of a tire.

Abstract

A practical rolling resistance simulation method for tires using a static finite element method is presented that fulfills three requirements: (1) easy input data preparation, (2) shorter computation time, and (3) adequate accuracy. The method implements a static deflection analysis first and the stress and strain thus obtained, together with the loss factors of the materials determined separately, are used to estimate the energy dissipation of a rolling tire.

First, the stress and strain profiles of all element groups that have the same cross‐sectional coordinates and are located along the circumferential direction are obtained. Second, hysteresis loops are computed by introducing a viscoelastic phase lag between the stress and strain profiles. The sum of the areas of the hysteresis loops is regarded as the dissipation energy density of the element group. The loss factors of the rubber materials are experimentally obtained and the effective loss tangents of the fiber‐reinforced rubber are determined by the homogenization theory of dynamic viscoelasticity. The rolling resistance simulation of a passenger radial tire using this approach accurately captures the trends of an actual tire.

Abstract

This study examines treadwear on tires caused by low severity cornering during free roll. The authors previously proposed a method to predict treadwear using rubber pad wear tests. This method required measurements from actual tires to obtain the tread frictional parameters, i.e., the sliding distance, sliding velocity, and contact pressure. The present study proposes an analytical tire model for predicting treadwear that does not require measurements from actual tires. This enables treadwear prediction during the tire design stage, prior to test tire construction. A continuous tread model for lateral tread deformation is described to evaluate the frictional parameters. The treadwear is then predicted from the parameters and the rubber pad wear rate. The predicted treadwear rates are compared with actual treadwear rates and are found to be valid in the tread center area.