Near-Surface Residual Stress Measurements for Aerospace Structures

It is widely recognized that near surface residual stresses play a significant role in fatigue performance. Tensile residual stresses are of concern because they accelerate fatigue crack initiation and fatigue crack growth relative to what would occur in the absence of residual stress. Compressive residual stresses, on the other hand, have the opposite effect and can be used to improve fatigue performance. To effectively understand and predict residual stress effects on fatigue durability or crack initiation, which accounts for the majority of the total component life under high-cycle applications, accurate and reliable residual stress data are required in the near-surface region. The proposed work plan will develop improvements to a novel near-surface residual stress measurement technique, will demonstrate the effectiveness of this measurement technique under representative conditions, and will develop technology to implement the measurement.