Near threshold fatigue curve based on the dislocation shielding model of fracture

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6418028

Chang, S J; Mura, T

Dislocation pileup along an inclined direction from a crack tip has been observed in metals during tensile deformation in an electron microscope. Dislocations are emitted from the crack tip, move through a dislocation-free zone and pile up in the plastic zone. The problem of inclined pileup of screw dislocations at a crack tip with a dislocation-free zone has been solved by applying the Wiener-Hopf method. Result can be used to calculate the crack tip blunting and the local stress intensity K for the applied stress intensity K/sub 3/. According to the fatigue theory of Laird, the crack propagation per cycle has the order of magnitude of the blunting. The blunting versus K/sub 3/ is then plotted. It has the shape of the near threshold fatigue curve. To plot this curve, the local stress intensity K has been assumed to be the critical value K/sub g/ for the dislocation emission at the crack tip. 19 refs., 3 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6418028
• Report Number(s): CONF-890310-1; ON: DE88011854
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
CRACK PROPAGATION
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
ELECTRON MICROSCOPY
ELEMENTS
EQUATIONS
FAILURES
FATIGUE
FRACTURE PROPERTIES
FRACTURES
LINE DEFECTS
MECHANICAL PROPERTIES
METALS
MICROSCOPY
SCREW DISLOCATIONS
STRESS INTENSITY FACTORS