The coalescence of voids in prestrained notched round copper bars

Notched round copper bars are prestrained to various extents, recrystallize d, and finally strained until fracture. Void nucleation and growth during p restraining cause a decrease in the macroscopic void coalescence strain. Mo delling of this experiment requires a proper account of the changes in void sizes and their interdistances during prestraining. Modelling based on the Gurson-Leblond-Perrin model for void growth and the Thomason model for voi d coalescence is proposed. Comparison with experimental results allows a de monstration of the validity of the Thomason model and the inadequacy of mod els based on a critical porosity value. Porosity at coalescence is found to depend on the initial void volume fraction, the how properties and the str ess state.