Components produced via polymeric additive manufacturing (AM), especially extrusion based methods, possess many weld lines between strands and layers. Thus, the failure of these structures is often dominated either by crack deflection between or crack penetration through individual strands. Two methods to predict the failure mode are those of Cook and Gordan, and of He and Hutchinson. In this work, the applicability of both approaches has been tested on four different polymeric materials. It was observed that the two criteria are quite limited in predicting the correct failure mode. Not only printing temperature also the formation of contact area, the diffusion between the individual strands as well as the resulting morphology of the material were found to play a key role for predicting the crack deflection/penetration problem.
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