Accession Number : AD0740162

Title :   Experimental Observation of a Stress Intensity History Effect upon Fatigue Crack Growth Rate.

Descriptive Note : Technical rept.,

Corporate Author : ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS

Personal Author(s) : Matthews,William T. ; Baratta,Francis I. ; Driscoll,George W.

Report Date : SEP 1971

Pagination or Media Count : 10

Abstract : Experimental results illustrate a previously unreported stress intensity history effect following a step increase in stress intensity. Data for 12 of 24 cases of step increases in stress intensity are presented which show an initially enhanced crack growth rate of two to four times the steady state growth rate. The effect diminishes until the normal rate is reached after 0.025 to 0.150 inch of crack extension and 200 to 600 cycles. An associated study of the causes of this behavior is being undertaken. (Author)

Descriptors :   (*STEEL, CRACK PROPAGATION), (*CRACK PROPAGATION, STRESSES), FATIGUE(MECHANICS), DEFORMATION, HEAT TREATMENT

Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE