Propeller Damage Tolerance and Nondestructive Inspection Study. Final Report.

摘要

The National Aeronautics and Space Administration Johnson Space Center, in conjunction with Hamilton Sundstrand (HS) and the Federal Aviation Administration Airworthiness Nondestructive Inspection (NDI) Validation Center at Sandia National Laboratories, completed a comprehensive crack growth and fatigue property assessment of the materials used in propeller designs. The test series acquired fracture mechanics data, such as fatigue crack growth rates and threshold values for shot-peened specimens, and surface crack condition specimens made from 7075-T73 and D6AC propeller alloys. Crack growth rates were characterized from threshold to fracture for a range of stress ratio R-values. This work included the development of analyses methods for predicting fatigue crack initiation and growth rates for cracks initiating from different size corrosion pits. The spectrum load test results were then compared with NASGRO analysis results for both interaction and crack retardation model options. This work allowed the team to understand the crack growth behavior of the most frequent types of damage, such as small cracks, scratches, tool marks, and corrosion pitting under conditions relevant to propeller systems.