On the influence of damage evolution in an incompressible material with matrix displaying tension-compression asymmetry

A strong difference between the behavior in tension versus compression is observed at the polycrystal level, if either twinning or non-Schmid type slip are contributors to plastic deformation at the single crystal level. Despite recent progress in modeling the effects of this asymmetry in yielding, its influence on damage evolution remains a challenge. In a recent paper [1], we presented a new constitutive model for voided polycrystal that incorporates the effects of the tension-compression asymmetry of the incompressible matrix on the overall dilatational plastic behavior. In this contribution, this model is used to investigate the influence of the tension-compression asymmetry of the matrix on void evolution for uniaxial loading conditions. It is shown that if the matrix tensile strength is higher than its compressive strength, void growth and damage distribution are similar to that in classical materials obeying Gurson's [2] criterion. On the other hand, for certain porous polycrystals in which the matrix tensile strength is lower than its compressive strength, void growth rate is much slower. Damage distribution is significantly different; the location of the zone of maximum porosity shifts from the center of the specimen outwards. Furthermore, the influence of the evolving microstructure on void growth is studied. It is shown that void growth is significantly affected by the rate of change of the matrix strength differential with plastic strain.