Paper Number 5.2
Prediction of Cord-Rubber Composite
and Tire Response Using Nonlinear
Continuum Damage Mechanics Approach
Mahmoud C. Assaad[1]
Ming Du
Tom Ebbott
The Goodyear Tire &
Rubber Company
Email:
The phenomenon of damage observed in
cord-rubber composite regions of the tire is the result of deformation, heat,
chemical degradation and fracture. Initial microcracks and voids grow through
the mechanism of coalescence and generate permanent macroscopic cracks.
A damage approach is proposed to describe the
cumulative effects and damage evolution under cyclic loading, thermal and
chemical impact. The approach parallels the Continuum Damage Mechanics (CDM)
approach advocated by Kachanov and Rabotnov. It is a phenomenological model
which depends on laboratory testing to describe the evolution of the damage
indicator and contains one scalar damage parameter to describe the collective
effect of material degradation.
The following analysis is based on the premise
that the cyclic interlaminar shear strain coupled with the running temperature
at the free edge are the primary cause of damage. The model constants were
derived from an S-N curve at room temperature. The temperature effect on the
material degradation was accounted for by an Arrhenius shift function of the
S-N curve. Numerical simulations of a composite laminate and several tire
models were conducted using the user subroutine UMAT in ABAQUS. The results derived from the
proposed methodology to predict the location of the ensuing damage and the path
of the damage propagation are only valid under well-controlled laboratory
conditions.