Failure Mechanisms

· A typical ductile metallic material shows a neck area reduction of about 50% at fracture and is characterized by a "cup-cone" fracture surface.
· The plastic deformation leading to the neck formation creates internal voids that join as deformation continues. The shear stresses at the edges of the sample cause the final failure along the direction of maximum shear stress.

From: Courtney, "Mechanical Behavior of Materials," McGraw Hill (1990)