Accession Number : ADA302323

Title :   Residual Stress Changes in Fatigue.

Descriptive Note : Final rept. Oct 85-Oct 90,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS

Personal Author(s) : Dowling, Norman E. ; Dunn, DeRome O. ; Laurent, M. P.

PDF Url : ADA302323

Report Date : 15 JAN 1994

Pagination or Media Count : 233

Abstract : An investigation of transient time and cycle dependent stress and strain on Ti-6A1-4V titanium and 7475-T651 Al alloys was done to determine how great an effect transients at room temperature would have on fatigue life under cyclic conditions. The mechanical material response was modeled using viscoplasticity constitutive laws and Neuber's rule for notched members. Only small amounts of rate dependence was found, and the viscoplasticity models became stiff when rate dependence was low, causing numerical problems. Experimental verification was done for the local surface stresses in a notched member under load using advanced x-ray stress equipment. An anomalous surface behavior was observed, where the surface yielded before the bulk material. - X-ray measurements for a cycled notched member exhibited relaxation of mean stress and not relaxation of residual stress. (MM)

Descriptors :   *RESIDUAL STRESS, *FATIGUE(MECHANICS), VISCOPLASTICITY, STRESS STRAIN RELATIONS, COMPUTERIZED SIMULATION, MECHANICAL PROPERTIES, FATIGUE LIFE, ALUMINUM ALLOYS, STIFFNESS, X RAY DIFFRACTION, ALLOYS, SURFACE PROPERTIES, AIRFRAMES, CREEP, RELAXATION, HARDENING, AXIAL LOADS, TITANIUM ALLOYS, CYCLIC LOADS, NOTCH TOUGHNESS, NOTCH SENSITIVITY.

Subject Categories : Properties of Metals and Alloys
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE