Speaker
Description
Fragmentation of tempered glass is a dynamic fracture process that is continuously fed by internal residual stresses, where uninterrupted crack propagation, branching, merging of cracks, and formation of fragments take place in a glass pane until complete failure. The simulation of those complex crack patterns using fracture approaches and the finite element method can be challenging, due to the complexity of the underlying phenomena and the sensitivity of the predicted crack paths to spatial discretization, i.e., mesh dependence of the predicted fracture patterns.
In the current contribution, a modelling approach to brittle fracture is presented, where a fracture criterion is developed addressing both a sound emulation of crack related phenomena and numerical remedies, which are applied to reduce the influence of spatial discretization on the predicted crack paths. The main idea is the setting of a local fracture criterion, which is evaluated subdomain-wise and is simultaneously influenced by spatially nonlocal information. A purely local ground-state fracture criterion is initially formulated in terms of crack driving and fracture resistance energies. Subsequently, this local fracture criterion is modified using nonlocally-informed scaling processes. The proposed method allows to take into account the possible influence of surrounding broken material and micro-cracks on the local fracture resistance energy, which is evaluated subdomain-wise. Moreover, it is demonstrated that the approach considers the emulation of crack initiation in a basically sound manner, which excludes predicting unrealistic fracture initiation at regions situated away from crack tips. Besides that, crack merging, which is an important aspect to consider when simulating the formation of fragments, is shown to be properly addressed within the suggested approach. The model implementation constitutes an evaluation of the fracture criterion finite element-wise within the discretized domain, where the associated numerical treatment is similar to the implementation of eigenfracture and eigenerosion methods. A parallel implementation of the framework is undertaken, where associated synchronization algorithms are developed. The plausibility of the fracture modelling approach is evaluated, through simulating complex fracture patterns and fragmentation in tempered glass with an insight into corresponding experimental results.
