Residual Stress Engineering for Aerospace Structural Forgings

ABSTRACT: Hill Engineering is committed to developing and expanding residual stress engineering technology. The proposed program will develop an approach for quality management of residual stresses in aerospace forgings and will demonstrate important elements of this approach on a representative forged component. The proposed quality management system will combine advanced computational process modeling and residual stress measurement technology to establish a robust system of production control. During Phase I, Hill Engineering will demonstrate the concepts of the quality system using an aerospace forging. The quality system will be evaluated for consistency and reliability and will be validated using independent techniques. BENEFIT: The proposed program offers a logical next-step in the continued improvement of structural engineering methods. Advances in residual stress technology over the past decade (or more) have resulted in improved tools for the analysis of residual stress effects on material performance. Technology is available, for example, to enable engineers to predict fatigue crack growth accounting for residual stress effects. By specifically accounting for residual stress effects in engineering analyses, designs can become more accurate and require lower safety margins. This leads to higher, more aggressive performance. One significant missing ingredient inhibiting the full accounting of residual stress in design is the fact that residual stress levels are typically not certified in the material supply chain. The development of a quality management system for residual stresses in forged aerospace components will enable material suppliers to certify the level of residual stress in their forged product, which will enable end users to specifically account for residual stress effects in design (and will result in significant positive benefit).