Download or read book Effects of Closure on the Fatigue Crack Growth of Small Surface Cracks in a High-Strength Titanium Alloy written by Jira, JR. and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth experiments were conducted on surface flaws in a high-strength titanium alloy. Surface crack lengths in the range 50-?m to 8 mm were investigated under both increasing and decreasing ?K conditions. Crack length and closure loads were determined from load-displacement data obtained with the aid of a laser interferometric displacement gage, which has resolution capability at 0.01 ?m. Stress ratios of 0.1, 0.5, and -1.0 and net-section stress levels from 0.2 to 0.9 of yield stress were utilized. The applied stress intensity factor range, ?K, correlated crack-growth-rate data for R = 0.1 and R = -1, but all R = 0.5 data fell along a separate band. The effective stress intensity factor range ?Keff determined from closure data, consolidated most of the data into a single band, but some small-crack data fell outside the band. Fracture surface roughness and plasticity were concluded to be the primary features contributing to crack closure.