Accession Number : ADA321865

Title :   Load Ratio Dependence of Fatigue Threshold in Aermet 100 Steel,

Corporate Author : NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD

Personal Author(s) : Lee, Eun U.

PDF Url : ADA321865

Report Date : 02 OCT 1996

Pagination or Media Count : 23

Abstract : A study was conducted on the fatigue crack growth behavior of AerMet 100 steel at various load ratios in a gaseous dry nitrogen environment. Increasing the load ratio increased the near-threshold fatigue crack growth rate and reduced the threshold stress intensity range for fatigue crack growth, DeltaK sub th. DeltaK sub th decreased with increasing load ratio up to a critical value, R sub cr = 0.5, and then leveled off. The maximum stress intensity at threshold, K sub max, changed little below R sub cr but increased rapidly above R sub cr. The critical threshold stress intensity range, DeltaK sub th and the critical maximum stress intensity, K max were determined to be 2.22 and 3.42 MPa sq root of m, respectively. The fatigue crack growth behavior changed from Class-IIb to Class-IIa with increasing fatigue crack growth rate.

Descriptors :   *THRESHOLD EFFECTS, *LOADS(FORCES), *STEEL, *CRACK PROPAGATION, *FATIGUE(MECHANICS), STRESSES, ENVIRONMENTS, INTENSITY, NITROGEN, GASES, FATIGUE, DRY MATERIALS, STRESS CONCENTRATION.

Subject Categories : Properties of Metals and Alloys
      Inorganic Chemistry
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE