Ronny Behnke

Analysis of stable crack propagation in filled rubber based on a global energy balance

Stable crack propagation in filled rubber is investigated by means of experimental and finite element analyses. Based on an experimental evaluation of multiple specimens under different loading states, dissipation rates are computed by applying a global energy balance. The dissipation rates calculated analogously from results of a numerical simulation of the multiple specimen method are in good accordance with the experimental findings. A further comparison of simulation results evaluated on basis of the material force method with energy release rates computed by means of an energy balance of two crack states under fixed loading conditions shows that the measured fracture sensitivity values are mainly related to the development and increase of a dissipative zone.

Numerical modelling of tyre–pavement interaction phenomena: coupled structural investigations

This article describes a numerical model for coupled tyre–pavement interaction at static as well as rolling contact condition based on a finite element (FE) formulation. Beneficial of this modelling is that both contacting structures, the tyre as well as the pavement, are modelled under consideration of all relevant structural parts and, therefore, in a realistic manner. The coupled computation is realised by a programme interface that connects tyre and contact simulation in a commercial FE code to pavement simulation in an inhouse FE code. While the coupling for static contact is based on a standard Lagrangian formulation, the coupling of the elastic tyre at steady-state rolling and the inelastic pavement is realised by the introduction of an arbitrary Lagrangian Eulerian (ALE) formulation. A novelty is the implementation of interface elements into the ALE pavement model to describe the layer bonding behaviour. The potential of the coupled modelling for pavement investigations is demonstrated by two examples.

The Extended Non-affine Tube Model for Crosslinked Polymer Networks: Physical Basics, Implementation, and Application to Thermomechanical Finite Element Analyses

This chapter is devoted to a summary of the so-called extended non-affine tube model. First, general model approaches for representation of the behavior of elastomers within numerical simulations are discussed. Second, the extended non-affine tube model is considered in the context of hyperelastic material models. Starting from molecular-statistical considerations, a Helmholtz free energy function is derived and formulated in terms of continuum mechanical quantities of the macroscale. Furthermore, combination with a model approach to represent continuum damage and time-dependent effects is addressed. The free energy function of the model approach is further set into the context of thermomechanics to account for temperature-dependent behavior of elastomers within numerical simulations. Finally, finite element implementation of the extended non-affine tube model and its application to uniaxial and biaxial tension tests performed on elastomer specimens are presented.

Dynamic response of foundations on three-dimensional layered soil using the scaled boundary finite element method

This paper is devoted to the dynamic analysis of arbitrarily shaped three-dimensional foundations on layered ground using a coupled FEM-SBFEM approach. A novel scaled boundary finite element method for the analysis of three-dimensional layered continua over rigid bedrock is derived. The accuracy of the new method is demonstrated using rigid circular foundations resting on or embedded in nonhomogeneous soil layers as examples.

A novel method for constitutive characterization of the mechanical properties of uncured rubber

A novel constitutive characterization method for uncured rubber behaviour has been developed in this article. A systematic measuring procedure was designed to fully investigate the uncured rubber complex stress–strain behaviour under different deformation patterns, which integrated three kinds of tests – the uniaxial tensile, the compression test and the shear test. It can be found from the observed behaviour that the uncured rubber has similar but much pronounced non-elastic stress–strain relationship, which is highly non-linear and highly rate dependent. A generalized Maxwell model with modified Yeoh model is developed to constitutively describe the observed phenomena in which parameters are identified by an evolution optimization scheme. Good agreement can be found between the model and the test data. Another finding is that, similar to vulcanized rubber, multi-test data are needed to obtain compatible constitutive models. The test results, findings and the developed model help rubber engineers deeply understand the uncured rubbers mechanical behaviour and provide a base for rubber manufacturing simulation.