Predicting crack deflection angles: An alternative model as key to understand crack bridging quantitatively and measure grain boundary fracture toughnessThursday (29.09.2016) 16:00 - 16:15 Part of:
During crack propagation in ceramics, microstructural geometry and other material parameters, such as residual stress and the fracture toughness of the grain boundary are the key factors determining the macroscopic fracture properties. Despite intense effort, a model allowing quantitative correlation of these parameters to macroscopic fracture behavior has not been established.
Here we introduce a model able to quantitatively predict crack deflections and therefore an effective crack path that allows the correlation of macroscopic fracture behavior to several individual microstructural parameters. The model is based upon angle distributions in the unfractured microstructure and was able to predict an experimental crack deflection histogram recoded from 360 SEM pictures accurately. It serves as an indirect but easy way to measure grain boundary fracture toughness and allows quantitative statements about the crack bridging toughening mechanism as well as critical thoughts on crack deflection toughening.
Composing effective properties out of abstract equivalents of the microstructure is a promising way to incorporate an increasable number of microstructural parameters into one model. Key advantage is the design of the model with interchangeable modular components that allow the incorporation of many other parameters, such as anisotropy, as a step towards accurate description of polycrystalline brittle behavior.