Accession Number : AD0641990

Title :   DISCONTINUOUS YIELDING OF COMMERCIALLY PURE ALUMINUM,

Corporate Author : TECHNION - ISRAEL INST OF TECH HAIFA MATERIAL MECHANICS LAB

Personal Author(s) : Bodner,S. R. ; Rosen,A.

Report Date : SEP 1966

Pagination or Media Count : 39

Abstract : The discontinuous, repeated yielding of commercially pure aluminum under slowly applied dead weight loading is examined as a dynamic instability problem. The destabilizing factor is shown to be the negative slope of the flow stress-strain rate relation which, for aluminum, is a consequence of rapid strain ageing. The essentials of the phenomenon are illustrated by a dry friction model which incorporates a counterpart of strain hardening. More generalized models show the equivalent of progressive yielding over the specimen length and delayed yielding under incremental loading. A stepped stress-strain curve is derived from the experimental flow stress-strain rate relation which agrees well with the observations in dead weight loading tests. Additional experiments on an Instron testing machine were performed with variable machine flexibility and strain gage recording. These test results support the explanation of the origin of the stepped stress-strain curves. (Author)

Descriptors :   (*ALUMINUM, DEFORMATION), AGING(MATERIALS), LOADS(FORCES), STRESSES, STRAIN(MECHANICS)

Subject Categories : Metallurgy and Metallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE