A semi-analytical solution to the stress intensity factors of branched cracks

Crack branching is ubiquitous in engineering practice, and it often takes place when a crack is subjected to dynamic stress fields, or runs into heterogeneous regions. The mechanical analysis of branched cracks is of great significance in safety analysis and crack-path engineering. In this work we developed a theoretical method to calculate the stress intensity factors (SIFs) of branched cracks. By employing both Schwarz-Christoffel mapping and Muskhelishvili approach, we present an asymptotic approximation for the conformal mapping and SIFs of arbitrary branched cracks are then readily derived. We further demonstrate the convenience of this analytical approach to obtain the SIFs of forked crack as well as four-branched cracks. The theoretical solutions are validated by using finite-element simulations. It is shown that the semi-analytical approach agrees well with the FEM calculations on SIFs. The analytical methods supply a general way to solve the SIFs and therefore the energy release rate of branched cracks. It can then be adopted to understand crack splitting and crack network engineering.