Development of Fatigue and Crack Propagation Design & Analysis Methodology in a Corrosive Environment for Typical Mechanically-Fastened Joints. Volume 4. Phase 2 Test and Fractographic Results

摘要

This report contains the test results and raw fractographic data acquired under Phase II of the corrosion fatigue program for mechanically-fastened joints. The results presented in this volume (4) are evaluated in vol. 3. Variables included in the Phase II test program were material (7075-T7651 and Ti-6A1-4V), environment (dry air and 3.5% NaCl), load spectra (F-16 400 Hr. and F-18 300 Hr.), type loading (strain-controlled, constant amplitude, spectrum), stress level (a base-line stress; three alternayte stresses), specimen conditioning (none; preconditioned), loading frequency (four loading rates), specimen type (strain controlled, compact tension and dog-bone); and bolt load transfer (0%, 20%, 40%). Most of the results are for 7075-T7651 aluminum alloy dog-bone specimens. These results were used to evaluate the corrosion fatigue analysis method for crack initiation and crack propagation in Vol. 3. Ti-6Al-4V alloy results are limited to un-notched strain controlled tests. Further titanium research conducted under Phase II, including experimental results and evaluations, is documented in vol.5.