Flaw Growth in Complex Structure. Volume 3. Summary, Assessments, Conclusions
Final rept. 12 May 1975-12 Sep 1977
LOCKHEED-CALIFORNIA CO BURBANK
Pagination or Media Count:
Fatigue crack growth testing and analysis was conducted to evaluate the effects of initial flaw location and multiplicity on fatigue crack growth life and element failure sequence in multiple element, mechanically fastened metallic structure. The test program, including 68 precracked structural specimens consisting of 26 joints and 42 stringer-reinforced panels, is summarized. The test results and corresponding analytical results are presented and compared. With respect to the test results for precracked joints the following effects are discussed fastener torque, faying surface friction, friction under the fastener head, single and multiple initial flaws, fretting, transverse bending, flush-head and protruding-head fasteners, and spectrum loading effects. With respect to the results for precracked stringer reinforced panels the following are discussed longitudinal splice versus continuous skin, initial flaw locations, single or multiple initial flaws, presence of continuing damage flaws, crack growth in a tee or angle stringer, transverse bending, load shedding effects, spectrum loading, fracture surface marking, stress level, and crack path. Guidelines and recommendations based on the results from this program are discussed.
- Metallurgy and Metallography