Material Characterization of Rubber Vulcanizates under Dynamic Conditions Appropriate for Tire Modeling

Abstract

Abstract Material property data used in finite element and other models for tire applications have often been obtained under static or low strain rate conditions at room temperature. In the latter case Williams-Landel-Ferry (WLF) shifts are assumed in order to relate the data to strain rates and temperatures typical of actual tire operation. However, such shifts may not always be appropriate for the highly loaded, diverse elastomer blends used in tires today unless one wishes to go to the trouble of generating the WLF constant for each compound. Data are presented to show that one can directly and easily obtain high quality stress or strain energy density results over wide ranges of strain rates, strain levels, and temperature using techniques developed for fatigue characterization. Thus, material properties can be obtained as a by-product of fatigue testing with little added work, or they can be obtained straightforwardly and quickly if fatigue testing is not required. These data are generated in a dynamic, pulsed loading mode which is especially relevant for those modeling applications which deal with the rolling tire. Results from a high performance tire tread, a sidewall, and an innerliner are presented to illustrate the wide range of compounds that can be accommodated. The primary mode of deformation employed is pure shear. Also, limited data from static simple extension and pulsed simple extension tests are shown for comparison. The pulsed pure shear and simple extension data, obtained over a wide strain range, are an excellent source of basic information on a given compound to fit empirical models, generate Mooney-Rivlin constant, or define material constants for more generalized nonlinear models such as Ogden, Peng, or Peng-Landel. The latter material models are now becoming available in commercial finite element codes to allow studies of tire deformations, rolling resistance, and failure properties under realistic operating conditions.