Innovative Approaches to the Fabrication of Composite Rotary Wing Main Rotor Blade Spars with Option

Sponsored by NAVAIR, Accudyne Systems completed a Phase 1 SBIR program, developing an equipment and process concept for cost-effective fabrication of composite rotary wing main rotor blade spars. The CH-53K spar was the study focus. The recommended work cell concept combines automated tape placement, woven fabric placement, and pick and place of 45° parallelograms to layup plies, then debulk and place packs for two spars fabricated in tandem. All composite material placement, vacuum bag material application, pack-to-tool debulking, and spar revolution is automated. This Phase 2 program develops the stations on the work cell machinery encompassing the material lay-up portion of the proposed work cell, and then demonstrates them for inclusion in a follow-on full design. Special attention will be paid to placing at rates high enough to allow fabrication of 200 spars per year (4 per week). In Phase 2, Accudyne proposes to complete a Requirements Document to detail requirements learned from NAVAIR, Sikorsky, and Hexcel. Then, Accudyne proposes to develop equipment and the process to demonstrate: 1) unidirectional tape placement into plies and on-line debulking to packs, 2) woven fabric placement into plies and on-line debulking to packs 3) bias parallelogram cut, pick, and place and debulking, 4) cutting of unidirectional tape, woven fabric, and bias parallelograms, and 5) a technical trade study encompassing throughput, tolerances, debulking, quality control, machine maintenance, risks, and final implementation. A final report describing the process, equipment, and trade study will conclude Phase 2. The Phase 2-Option program enhances bias ply placement to considerably accelerate spar fabrication. The enhancement is a 3-axis CNC-controlled ultrasonic knife to complete articulate cuts in the bias parallelograms that comprise the bias plies. The noteworthy benefit is that net shape bias packs can be fabricated with the wide ply down with no further cutting. It is intended that the Phase 2-Option run in concert with Phase 2 for maximum synergy.