Cracking energy density for rubber materials: Computation and implementation in multiaxial fatigue design

摘要

This article proposes a heuristic model to predict the fatigue life of rubber parts. The developed model is mainly based on the Cracking Energy Density (CED), originally developed by Mars, for the study of rubber parts fatigue. The main contribution consists in the integration of the theoretical framework of the critical plane analysis proposed by Mars with Saintier's experimental research carried out in tension and torsion modes. The CED parameter, derived from the Strain Energy Density (SED), can predict the occurrence of the first crack and its possible orientation depending on the type of loading path. In this context, an analytical analysis of this parameter is carried out for typical loading cases. Furthermore, the variation of CED by SED ratio (W-C/W), as a function of the probable crack angle theta and the principal stretch lambda(1)is investigated. A finite element (FE) model is, then, developed to measure the performance and efficiency for some basic criteria used to investigate rubber fatigue life in literature. The pertinence of such criteria is evaluated in terms of a determination coefficient. The CED parameter can be considered as the most effective criterion for describing the multiaxial fatigue life of rubbers.