A normalized damage variable for ductile metals based on toughness performance

▶ An equivalent half-sine model is proposed to describe the plastic stress-strain relationship. ▶ A toughness indicator (ϕ) and the parameter of toughness indicator (A) are introduced to characterize the damage. ▶ The exponential law is concluded to calculate the damage curve with conventional tensile data and the value domain of damage described by toughness indicator is from 0 to 1.