Explicit dynamics modeling of blade cutting of thin shells

The finite element simulation of blade cutting is a difficult problem, involving severe nonlinearities of various nature. This type of problems are dominated by the blade sharpness, whose geometric resolution would require extremely fine meshes. To overcome this difficulty, a new crack propagation strategy is here considered, which accounts for the interaction between the process zone and the cutting blade. The strategy is based on the definition of new “directional" cohesive interface elements, which can detect contact against the cutting blade and transmit the cohesive forces in the correct direction. The procedure has been implemented in an explicit dynamics framework. A new selective mass scaling technique has been used to increase the time step, whose size would otherwise be reduced as a consequence of the small shell thickness.