* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Numerical Simulation of Fracture in Viscoelastic Materials Based on
Density of states wikipedia , lookup
Negative-index metamaterial wikipedia , lookup
Nanogenerator wikipedia , lookup
History of metamaterials wikipedia , lookup
Strengthening mechanisms of materials wikipedia , lookup
Deformation (mechanics) wikipedia , lookup
Energy harvesting wikipedia , lookup
Eigenstate thermalization hypothesis wikipedia , lookup
Structural integrity and failure wikipedia , lookup
Spinodal decomposition wikipedia , lookup
Sol–gel process wikipedia , lookup
TaskForceMajella wikipedia , lookup
Work (thermodynamics) wikipedia , lookup
Energy applications of nanotechnology wikipedia , lookup
Work hardening wikipedia , lookup
Fatigue (material) wikipedia , lookup
The Third International Conference on Computational Modeling of Fracture and Failure of Materials and Structures Numerical Simulation of Fracture in Viscoelastic Materials Based on Material Forces K. Özenç∗ , M. Kaliske Institute for Structural Analysis, Technische Universität Dresden, Germany, [email protected] The crack growth mechanism of elastomers is of great importance and interest in engineering applications, however, the correlation between numerical and theorical studies is not well established due to the complexity of the problem. The contribution presents an r-adaptive crack propagation scheme for the description of the viscoelastic fracture response of rubber-like materials at large strains. A similar algorithm is proposed by Miehe et al. [1]. The approach is extended for a generalized finite inelastic continuum by Kaliske et al. [2]. Key feature of this procedure is restructuring the overall system by duplication of crack front degrees of freedom based on minimization of the overall energy via the Griffith criterion. Use of the presented framework enables to study fracture behaviour of elastomers at different deformation rates. The experimental evidence from previous studies favors that the fracture toughness of non-strain-crystallising elastomers shows strong rate-dependency and the energy release rate versus the rate of tearing or crack propagation relation appears to be a fundamental material property [3]. Therefore, in this contribution, a dynamic fracture criterion, which is a function of the rate of crack growth, is shown to be more adequate in numerical simulations. In addition, in previous studies, it is shown that the fracture energy per unit area of crack advancement appears to be the result of two contributions in terms of the change in elastic energy and in terms of the viscous dissipation by a configurational change [4]. In other words, the elastic part is the intrinsic strength of the interface which does not depend on the crack growth rate, whereas the second part, which reflects energy dissipated by viscosity, is a function of the crack growth rate. The separation of the fracture energy is obtained by the global energy momentum balance. To this end, a consistent thermodynamic framework for the combined configurational motion in viscoelastic continua at the finite strain regime is discussed. For the sake of simplicity, all results are obtained neglecting thermoCFRAC 2013 mechanical phenomena and inertia effects. In addition, branching instability triggered by a significantly increased deformation speed is investigated. A crack speed limiter, which is a constant branching velocity, is used in order to explain the phenomenon in elastomers. The Bergstörm-Boyce model is considered to introduce hyperelastic and finite viscoelastic behaviour of rubber-like bulk material. The crack driving force and the crack direction are predicted by the material force approach. The predictive capability of the proposed method is demonstrated by representative numerical examples. In conclusion, experimental and numerical results are discussed in order to clarify the relation between the tearing phenomenon and material force approach in viscoelastic materials. References [1] C. Miehe, E. Gürses, Robust Algorithm for Configurational-Force-Driven Brittle Crack Propagation with R-Adaptive Mesh Alignment, Int J Numer Meth Eng 72 (2007) 127–155. [2] M. Kaliske, K. Ozenc, H. Dal, Aspects of crack propagation in small and finite strain continua, in: Constitutive models for rubber VII : proceedings of the 7th European Conference on Constitutive Models for Rubber, Dublin, 137–142, 2011. [3] G. J. Lake, C. C. Lawrence, A. G. Thomas, High-Speed Fracture of Elastomers: Part I, Rubber Chem Technol 73 (2000) 801–817. [4] B. Näser, M. Kaliske, H. Dal, C. Netzker, Fracture mechanical behaviour of visco-elastic materials: Application to the so-called dwell-effect, Z Angew Math Mech 89 (2009) 677–686. Prague, Czech Republic, 5–7 June 2013