SEDL / STP / STP1321-EB / STP12306S

Fracture Toughness Results and Preliminary Analysis for International Cooperative Test Program on Specimens Containing Surface Cracks

Reuter, WG
Consulting Engineer, Idaho National Engineering Laboratory, Lockheed Martin Idaho Technologies Company, Idaho Falls, ID

Elfer, N
Senior staff engineer, Lockheed Martin Corporation, Manned Space System, New Orleans, LA

Hull, DA
Engineer, Engineering Material Research, Downsview, Ontario

Newman, JC
Senior scientist, NASA Langley Research Center, Hampton, VA

Munz, D
Professor, University of Karlsruhe, Karlsruhe,

Panontin, TL
Group leader, NASA Ames Research Center, Moffet Field, CA

Pages: 21    Published: Jan 1997

Download this paper for $25 PDF (448K)          View License Agreement
Abstract

Specimens containing surface cracks were tested in either tension or bending to compare the stress intensity factor at failure with plane strain fracture toughness (K^Ic) in an International Cooperative Test Program. The material was heat treated to σ^ys = 1 587 MPa and K^Ic = 54 MPan^1/2. Because substantial stable crack growth occurred for some specimens, the test plan was modified to include detecting the onset of crack growth. It is shown that P^max and the original fatigue precrack size cannot be employed to calculate K^max for comparison with K^Ic when significant stable crack growth occurs. However, using P^init (load at which stable crack growth is initiated) and the original fatigue precrack size to calculate K^max or K^ϕ=30° provides a very useful comparison with K^Ic. The influence of variations in fatigue precrack configuration on test results are also discussed.