The objective of this project is to develop and validate an improved technology base for the cold-working of high strength aluminum alloys. The improved technology base consists of the following three legs: 1. A test-validated CAD/CAM tool for performing virtual cold-working and for virtual fatigue testing. 2. An improved design mandrel to achieve the full life improvement potential of cold-working. 3. Industry implementation via strategic partnering. The CAD/CAM tool for performing virtual cold-working and virtual fatigue testing will allow models of complex multi-layer joints and control system components to be constructed using drag-and-drop modeling. It will be useful for manufacturing process development by graphically portraying the stresses and strains induced during the mandrel pull-through process, as well as the residual stresses. With such a tool, premature shear or tearing failures during mandrel pull-through in high strength anisotropic alloys or in members with shy e/D can be avoided. The CAD/CAM tool will also be useful as a general design tool for lean manufacturing environments by helping to establish, via analytical simulations, the optimal interference level and the tolerance band for maximizing the fatigue life of the joint while preventing premature failures.
Benefits: Availability of the tool can help prevent the static failures which have occurred during the manufacturing process development for cold-working of high strength aluminum alloys with reduced strengths in the ST direction. It can also help prevent the premature fatigue failures resulting from the use of a non-optimal interference level for the member geometry. With such a tool, the trial-and-error manufacturing and test-based design development process currently required to qualify a cold-worked member can be substantially reduced, leading to shorter cycle times, and lower weapon system acquisition costs.
Keywords: cold-worked fastener hole, CAD/CAM, fatigue, damage tolerance, lean manufacturing
