Void Coalescence in Metals Involving two Populations of Cavities

Void coalescence is the final stage in the failure of ductile materials. It consists in the localization of the plastic deformation in the intervoid ligament between neighbouring voids. Several experimental evidences obtained from fractographic analyses of broken samples or metallographic analyses of polished samples strained near fracture have shown that a second population of cavities nucleated on small particles significantly affect the damage process controlled by the first population of cavities nucleated on larger particles. Although a second population of voids is considered for a while in the literature as very detrimental for the ductility (e.g. Marini

et al.

[

1

]), only a limited number of studies have been devoted to the modelling of this phenomenon (Tvergaard [

2

], Brocks

et al.

[

3

], Faleskog and Shih [

4

], Perrin and Leblond [

5

], Enakousta

et al.

[

6

]). The aim of this work is to develop a constitutive model for the nucleation, growth and coalescence of voids that incorporate the effect of this second population on the onset of coalescence.