Monolithic Aero Aluminum Structures: The Incorporation of Bulk Residual Stress Models and Measurements into Design and Manufacture

The goal of manufacturing large monolithic structures from aluminum forgings with consistently low residual stress is aided by Alcoa’s finite-element tools to predict the heat treatment quench induced residual stress and its mitigation by compressive cold work stress relief and artificial aging. This predictive capability is integral to the design of Alcoa’s Signature Stress Relief™ forgings. We present validation residual stress measurement work using both the hole drilling and contour methods and applications of the process induced bulk residual stress field maps by OEM’s in design analysis, specifically to address fatigue life and weight optimization. In addition, we present recent progress in cost avoidance in machining aero structures from forgings as aided by residual stress model data.