Environment-Load Interaction Effects on Crack Growth in Landing Gear Steels

摘要

The objective of this program was to investigate chemical environment-load interaction effects on crack propagation. Dry air (<10 percent relative humidity) was used as a reference environment. Alternate immersion in synthetic sea water was used to simulate the aggressive chemical environment to which Navy carrier based aircraft are subjected. Tests were performed to determine the behavior of 300M and HP-9-4-.30 steel in both environments under a variety of stress ratios and load wave shapes. A crack growth prediction capability developed through analysis and test accounts for environment and load interaction effects. A flight-by-flight test stress history was developed for a landing gear of a carrier based Navy aircraft. Crack growth predictions were prepared and tests performed to verify the chemical environment-spectrum loading analysis capability. A comparison of landing gear spectra under Air Force and Navy design conditions is presented. (Author)