Structural Qualification of V-22 EMD Tow-Placed Aft Fuselage

Tow placement technology is being utilized by Boeing Defense & Space Group, Helicopters Division to improve producibility and reduce cost for the V-22 Engineering and Manufacturing Development (EMD) program. The most extensive use of this technology is on the fuselage skin, in which graphite/epoxy tows will replace the fabric system utilized in the Full Scale Development (FSD) program. An extensive experimental program, which included basic material properties, laminate-level allowables and critical elements testing, was initiated to demonstrate equivalency of tow-placed laminate design properties with those established for tape during the FSD program. Thus far, tow-placed laminates have demonstrated notched strengths comparable to those exhibited by tape, with superior performance exhibited for laminate tensile strength. Failure strains have been acceptable with regard to tape design allowables for laminates utilized on the aft fuselage. Relationships between tow lap/gap size and laminate strength were obtained to develop process inspection criteria. A test program using three-stringer shear panels demonstrated the EMD design configuration satisfies strength, stability and durability requirements.