What Does Cup and Cone Fracture Mean?
A cup and cone fracture is a type of failure observed in ductile metals and plastics that are subjected to a uniaxial force. It is essentially the separation of a body into two separate pieces due to the application of excessive tensile stress. This mode of fracture gets its name from the resulting shapes at the end of the broken pieces after a failure has occurred. Fractured objects may be more susceptible to corrosive environments.
Corrosionpedia Explains Cup and Cone Fracture
For a cup and cone fracture to occur, the metal subjected to the tensile loading must be ductile, i.e., it must be able to exhibit significant amounts of plastic deformation before rupture. As the tensile stress in the metal approaches its yield strength, a small portion of the material’s cross-sectional area decreases in a process known as necking.
As the load continues to increase, small cavities form at the necked portion of the material. Any further increase in the load causes the cavities to grow in size and eventually coalesce to form an elliptical crack perpendicular to the stress direction.
Eventually, the material fails, and the fractured ends of the material take on the distinctive cup and cone shape.