Electron Beam Freeform Fabrication of Dissimilar Materials: Cracking in Inconel 625 on GRCop-84
Explore the source record for details and available documents.
Additive manufacturing, electron beam, wire feed, ↗
Engineering topics
Stephen J Hales
Publications and source records attributed to Stephen J Hales.
TPSAS-NF1676L-10936-DND
The current manufacturing process for fiber metal laminates (FML) requires prepreg and an autoclave or press, the part size is limited by the size of the autoclave or press, and the process is expensive. The objective is to reduce the cost of fiber metal laminates by manufacturing by the VARTM process with an ultimate goal of producing FML with the level of quality comparable to those of FML fabricated by autoclave.
Brian J Jensen↗
Advances in Integrally Formed Metallic Structures
NASA Langley Research Center (LaRC) is applying flow forming technology to aerospace aluminum alloys for the manufacture of integrally stiffened cylinders that meet aircraft fuselage or launch vehicle specifications. High-strength 2xxx series alloys, in various temper/product form conditions, are being compared with medium-strength, very formable AA 6061 as the benchmark. Screening of candidate materials traditionally relies on empirical forming trials, but more recently on metrics derived from constant nominal strain rate tensile testing. In this work, the established hierarchy of formability metrics is adopted as the baseline; tensile area reduction, work hardening exponent, and modulus of resilience. The suite of metrics can be expanded based on phenomenological and mechanistic considerations of plastic flow instabilities to incorporate anisotropy ratio, rate of work hardening, and dynamic strain aging effects. Separate research thrusts at LaRC are aimed at formulating a protocol for scalable production of fully formed, defect-free components: 1) quantifying the extended set of formability metrics from constant and jump strain rate tensile tests with digital image correlation (DIC); 2) using statistically designed experiments on a vertical spin/flow forming facility (WF VUD-600®) to isolate the effect of convenient process variables, such as axial feed rate and thickness reduction; and 3) predicting the effect of feed ratio (roller translation relative to mandrel rotation speeds) on material response via process modeling using the DEFORM® simulation software. Current results will be discussed in terms of correlating intrinsic material properties with the bulk workability characteristics to successfully fabricate cylinders with complex cross-sections.
Aluminum↗