Fracture Toughness
- Critical value of the stress intensity factor for which crack extensions occurs. The fracture toughness Kc, is a measure of the resistance of a material to the propagation of a crack. It can be measured by loading a sample containing a deliberately-introduced crack of length 2c and then recording the tensile stress σ at which the crack propagates. Fracture toughness is then:
- where
- Y = geometric factor, near unity, which depends on details of the sample geometry.
- Kc has well defined values for brittle materials (ceramic, glasses, many polymers and low toughness metals like cast iron).
- In ductile materials, a plastic zone develops at the crack tip, which introduces new features into the way cracks propagate. This necessitates more complex characterisation.
- Kc has well defined values for brittle materials (ceramic, glasses, many polymers and low toughness metals like cast iron).
| Conversions | ||||||
| 1 ksi in1/2 | = | 1.098843 MPa m1/2 |
See also: Crack, Fracture Stress, Fracture Testing.
Subjects: Mechanical Engineering