Effect of the stress triaxiality and Lode angle on the ductile damage evolution

抄録

Damage in a structure is caused by material degradation due to initiation, growth and coalescence of micro-cracks/voids. In the recent years this topic acquired great importance in order to obtain a better design and to prevent the failure of components and structures. The present work aims to consider the influence of the stress triaxiality and the Lode angle effect on the ductile damage evolution, since it has been experimentally proved that the loading conditions highly affect the effective strain (i.e. cumulative plastic strain at failure). An ad hoc Lode angle function is adopted, together with the ductile damage evolution law proposed by Lemaitre, associating the decrease of the Lode angle influence with the generation of large plastic strain. On the other hands the choice of coupling the continuum damage mechanics framework together with an unconventional plasticity model is functional to investigate cyclic loading problems, since conventional plastic algorithms tend to overestimate the material ratcheting, leading to a wrong accumulation of the damage through cycles.