Finite element modelling of crack propagation in carbohydrate extruded starch with open void structure

This study presents a new way of describing the void architecture of a of starch foam to allow the simulation of crack propagation in extruded starch material. In these materials, complex stress distribution takes place upon loading leading to a jagged crack extension. Based on the principle of stress intensity factors, the maximum energy release criterion is implemented and combined with a particular 2-D meshing of the material. The meshing is based on a modification of the element connectivity in a regular grid. A material property is assigned to each element based on grey level of acquired images of the carbohydrate material. The numerical results show that the void structure is responsible for the development of a local mixed mode. Crack propagation exhibits significant changes in the crack path because of the heterogeneous stress distribution. The comparison between numerical and observed crack paths well shows that the predictions are sensitive to grey level distributions and mesh refinement. Finally, the criterion is able to predict nicely the crack extension if the contrast between bright and dark regions is properly addressed.