Akademik Veri Yönetim Sistemi
5th European Conference on Constitute Models for Rubber, Paris, Fransa, 4 - 07 Eylül 2007, ss.185-186
Durability and stable quality of rubber products are of vital interest. The components are employed in many fields of engineering with safety relevance and in the design phase of the product, numerical investigations are of great importance. Thus, the finite element method is a commonly used approach in structural analysis. Its application to fracture mechanical problems for rubber material is quite complex. Firstly, filled rubber exhibits nonlinear constitutive characteristics, e.g. elastomers show nonlinear elastic und visco-elastic behaviour at finite strains. Secondly, the specific fracture features need to be determined. Standard approaches of fracture mechanics have been developed for brittle materials or metals. The numerical and analytical formulations are not yet fully derived for elastomers. The present paper employs a new approach of current fracture mechanics research - the so-called method of material forces - to rubber material. With this approach at hand, a very efficient and elegant methodology to evaluate fracture characteristics of rubber components is available. The material force vector at a crack tip yields the J-integral as fracture mechanical parameter. Moreover, a vector quantity, in analogy to a physical force, is obtained that can be identified with the direction of largest crack sensitivity. The fundamental theoretical formulations of this approach are developed for the constitutive time-dependent properties of rubber (finite elasticity, finite visco-elasticity) and moreover, the required developments in the context of the finite element method are shown. The so-called dwell effect is used in this paper to depict the importance to take time-dependent effects into account.