Corrosion-Fatigue Life of Aircraft Suspension Materials in Tropical Marine Atmosphere
The work aims to investigate the life of typical aircraft suspension materials under corrosion-fatigue dynamic en-vironments.Statistical analysis was conducted on service environment factors.An accelerated test environment spectrum was designed by the equivalent corrosion acceleration relationship and the conversion factors for typical metal materials.40CrNiMoA alloy steel and 2A12 aluminum alloy were placed in a simulated marine atmosphere environment.A self-made at-mospheric corrosion-dynamic fatigue environment simulation test device was used to conduct corrosion-fatigue synergistic tests.The S-N curves of the two materials were tested to rapidly assess the corrosion-fatigue life of typical aircraft suspension materi-als in a tropical marine environment.In a pH=4 acidic salt solution(5%NaCl+0.05%Na2SO4+0.05%CaCl2),after spraying for 4 hours(t=40℃)and then drying for 4 hours(t=60℃),and repeatedly alternative environment and fatigue tests,the test data of 40CrNiMoA alloy steel and 2A12 aluminum alloy were processed with a linear model.Under the synergistic effect of corrosion and fatigue,the fatigue strength corresponding to 105cycles was 906.2 MPa and 224.6 MPa,respectively,which decreased by two orders of magnitude compared to the strength under pure fatigue.The primary reason was that in the corrosive environment,salt spray corroded the metal surface,forming corrosion pits,which eventually became crack sources and propagated to frac-ture.When the aircraft suspension structure is used in a tropical marine atmosphere,the fatigue strength significantly decreases due to the synergistic effect of corrosion and fatigue.
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