Abstract

The molding process is a critical step in the manufacture of pneumatic tires. It affects the design and consequently the performance of the tire. The present paper covers work aimed at analyzing the molding process using the finite element method. Specifically, the finite element code MARC is used to analyze the inflation of a curing bladder inside a rigid tire profile. Incompressible elements are used to model the bladder and GAP elements are used to simulate the contact between the two surfaces. Of primary interest is the bladder‐profile interface, namely how contact occurs at the interface and the magnitude and uniformity of the interfacial pressures. Two different bladder shapes and two different inside tire profiles are studied. Of equal importance is the ability to model this type of contact problem as it is a significant step toward analyzing the tire molding process.

Abstract

A good understanding of the process of adhesion from the mechanics viewpoint and the predictive capability for structural failures associated with adhesively bonded joints require a realistic modeling (both constitutive and kinematic) of the constituent materials. The present investigation deals with the development of an Updated Lagrangian formulation and the associated finite element analysis of adhesively bonded joints. The formulation accounts for the geometric nonlinearity of the adherends and the nonlinear viscoelastic behavior of the adhesive. Sample numerical problems are presented to show the stress and strain distributions in bonded joints.

Abstract

Mechanical losses in rubber compounds per strain cycle are shown to be considerably greater under pulse loading, which simulates tire usage, than under sinusoidal loading. A method is suggested for using data obtained by ordinary laboratory techniques to calculate losses that would occur in an arbitrary anharmonic mode. Some data are given to show how such mechanical losses depend on formulations and processing factors of the rubber. Methods are then discussed for obtaining proper laboratory data on dynamic properties for use in optimizing formulations of tire rubbers.

Abstract

Longitudinal tire forces on four‐wheel drive cars, both with and without a differential gear between the axles, are compared with those on two‐wheel drive cars; tests were made on a curved trajectory.

A “critical speed” may be defined which depends solely on characteristics of the car and test tires; this is usually of the order of a few tens of kilometers per hour. Above that speed, for the lateral accelerations normally reached, the additional longitudinal forces caused by lack of an intermediate differential do not increase the relative tread wear rate relative to that on a two‐wheel drive car. Cars almost always operate above this critical speed. Below it, however, the additional longitudinal forces caused by lack of a differential are much higher and obviously would lead to higher rates of tread wear.