Accession Number:

ADA370422

Title:

Effects of Foreign Object Damage From Small Hard Particles on the High-Cycle Fatigue Life of Ti-6Al-4V

Descriptive Note:

Final rept. Jul 96-30 Sep 99

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH

Personal Author(s):

Report Date:

1999-09-01

Pagination or Media Count:

268.0

Abstract:

Thin rectangular samples of Ti-6Al-4V were damaged by four methods to represent foreign object damage found in turbine engine blades 1 impact with 2 mm and 5 mm diameter glass spheres at 305 ms, 2 impact with 2 mm and 4 mm diameter steel spheres at 305 ms, 3 quasi-static displacement controlled indentation using steel chisels with 1 mm, 2 mm and 5 mm diameter tips and 4 shearing notches with a 2 mm diameter chisel point under a quasi-static loading condition. Finite element analysis was used to study the relationship between the stress state created by the plastic damage and the fatigue strength. A new method of quantifying the amount of plastic damage from multiple methods was developed. The fatigue strength required for crack initiation at 10E7 cycles was found to be a function of the total depth from the edge of the undeformed specimen up to the end of the plastically deformed zone. For damage depths less than 1750 micrometers, the reduction in fatigue strength is proportional to the depth of total damage. For more than 1750 micrometers, there appears to be a threshold value of fatigue strength.

Subject Categories:

  • Aircraft
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE