Sem Resumo

The mechanics of chip segmentation is still controversial with regards to its root cause. Whether by thermoplastic instability or damage, chip segmentation is caused by local loss of strength of the chip in the region of primary shear. This work is mainly focused on the discussion of the different theories and the root cause of the phenomenon both by numerical and experimental viewpoints. Numerical experiments deal with the constitutive models that describe softening and damage in finite element simulations, while the experimental part deals with the phenomenon of chip segmentation in a brittle material with anomalous yield behavior, namely an iron aluminide intermetallic. This work concludes that damage mechanics dominate the phenomenon of chip segmentation, at least in materials with limited ductility, and that thermal effects are to be used only as an extension of the theory. In materials with considerable ductility, the numerical models cannot predict chip segmentation without the consideration of thermal effects, where the variables of thermal softening and softening due to damage strongly contribute to the phenomenon.