Bastian Näser

Fatigue Investigation of Elastomeric Structures

Abstract Fatigue crack growth can occur in elastomeric structures whenever cyclic loading is applied. In order to design robust products, sensitivity to fatigue crack growth must be investigated and minimized. The task has two basic components: (1) to define the material behavior through measurements showing how the crack growth rate depends on conditions that drive the crack, and (2) to compute the conditions experienced by the crack. Important features relevant to the analysis of structures include time-dependent aspects of rubber’s stress-strain behavior (as recently demonstrated via the dwell period effect observed by Harbour et al.), and strain induced crystallization. For the numerical representation, classical fracture mechanical concepts are reviewed and the novel material force approach is introduced. With the material force approach at hand, even dissipative effects of elastomeric materials can be investigated. These complex properties of fatigue crack behavior are illustrated in the context of ...

Evaluation of Crack-Driving Forces at Finite Viscoelasticity: Theory and Experiment

This contribution presents an approach to determine the fracture mechanical parameters energy release rate and crack-driving force efficiently with the material force method expanded for dissipative materials. A reliable test procedure for the evaluation of these parameters is presented. Another focus lies on the investigation of time-dependent effects in this context induced by viscoelasticity.

Inelastic Fracture Mechanics for Tire Durability Simulations4

Abstract A fully three-dimensional fracture mechanical approach is introduced which may serve as a basis for tire durability simulations utilizing the finite element method. The so-called material force approach is employed as an elegant alternative characterization of the energy release rate or the J-integral to describe discrete cracks. As a vector quantity, it even yields directional information. The method is applicable in the context of finite strains and nonlinear elasticity and inelasticity. Using the shown approach, a physical and efficient modeling of fracture sensitivity of tires is obtained.