Accession Number : ADA182288

Title :   Interaction of Two Slip Planes on Extrusion Growth in Fatigue Band

Corporate Author : CALIFORNIA UNIV LOS ANGELES DEPT OF CIVIL ENGINEERING

Personal Author(s) : Lin, T H ; Lin, S R ; Wu, X Q

PDF Url : ADA182288

Report Date : Jan 1987

Pagination or Media Count : 30

Abstract : Micromechanic theory of fatigue crack initiation by Lin and his associates is reviewed. Intrusions and extensions have been observed in fatigue specimens. An initial stress field favorable for the growth of extrusion or intrusion can be produced by arrays of dislocation dipoles as shown by Lin (1969). These dipoles caused an initial tensile strain giving an elongation which is called the static extrusion growth terminates. Along the direction of an extrusion, tensile strain and tensile stress occurs. The tensile stress caused the resolved shear stress to reach critical and slide in a secondary slip system. The slip causes plastic tensile strain which increases significantly the extrusion growth. Similarly the same mechanism exists for the growth of intrusions. This explains why extrusions grows much more than the static extrusion.

Descriptors :   *CRACKING(FRACTURING), *EXTRUSION, *FATIGUE, *PLASTIC PROPERTIES, *TENSILE PROPERTIES, ARRAYS, DIPOLES, DISLOCATIONS, ELONGATION, GROWTH(GENERAL), INTRUSION, SHEAR STRESSES, STATICS, STRAIN(MECHANICS), STRESSES, TENSILE STRESS

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE