What is crack tip plasticity?
If plastic deformation occurs, then the elastic stresses are limited by yielding since stress singularity cannot occur, but stress relaxation takes place within the plastic zone. This plastic deformation occurs in a small region and it is called the crack-tip plastic zone.
What is Lefm and Epfm?
LEFM is used for material conditions which are predominantly linear elastic during the fatigue process. • For crack growth or fracture conditions that violate this basic. assumption, elastic-plastic fracture mechanics (EPFM) approaches are used to describe the fatigue and fracture process.
What is crack tip singularity?
The stress singularity at the crack tip is identified as: the infinite stress exists at the crack tip, and the stress components at the crack tip are multivalued.
What are plastic zones?
The region beyond the rupture zone associated with crater formation resulting from an explosion in which there is no visible rupture, but in which the soil is permanently deformed and compressed to a high density. See also rupture zone.
What is plastic zone size?
The plastic zone size along the crack line is less than 5% of the crack length, indicating small-scale yielding prevails at this load level.
What is CTOD test?
CTOD test is one of test methods to determine fracture toughness (fracture resistance) of a material with a crack, and a test to determine crack tip opening displacement to generate unstable fracture (limit CTOD value).
What is a crack theory?
The Griffith theory states that a crack will propagate when the reduction in potential energy that occurs due to crack growth is greater than or equal to the increase in surface energy due to the creation of new free surfaces. This theory is applicable to elastic materials that fracture in a brittle fashion.
What is critical crack size?
Critical crack size is the length at which a crack becomes unstable at certain applied stress. It is very helpful in determining material safety. In an unstable crack, crack propagation, once started, continues spontaneously without an increase in magnitude of the applied stress.