A Revolutionary Hybrid Pultrusion/VARTM Process for Making Very Large Two-Sided Composite Structures Exhibiting Bending-Twisting Coupling

KaZaK Composites and Stanford University propose to design, develop and demonstrate a prototype bending-twisting-coupled composite rudder for the DDG 51. The Phase I design and process development effort will include classical laminated plate theory,finite element analysis and VARTM mold flow analysis. Test structures will be fabricated by two different methods during Phase I. First, an approximately 1/5-scale rudder structure will be made by a conventional VARTM process modified to produce two smoothouter surfaces. Second, a revolutionary pultrusion / VARTM hybrid process that should result in lower acquisition cost, higher mechanical properties and a greater ability to build-in tailored bending-twisting coupling will be used to fabricate another testarticle. The same basic tool will be used to make both parts. Reduced-scale composite parts will be statically tested to demonstrate that intended, analytically-predicted bending-twisting coupling of the prototype rudder matches behavior measured in tests.Bath Iron Works, a builder of the DDG 51, will work with the KCI/Stanford team to ensure smooth transition from the laboratory development effort to full scale sea trials. It is anticipated that full scale rudder hardware will be built and tested duringPhase II.The composite rudder design and fabrication technology developed and demonstrated during the proposed work, if successful, should help eliminate a chronic problem with cavitation-induced corrosion damage seen with the conventional steel DDG 51Class rudders, as well as eliminate a major cost increase associated with a new, highly-contoured steel replacement. The combination of tailored bending-twisting coupling technology developed in this STTR with a hydrodynamically-optimized, twisted ruddershape should significantly improve the maneuvering performance, weight, acquisition and life cycle costs of DDG 51 rudders. Once proven for a critical military system, the same design and fabrication technology should easily transition to other militaryand commercial vessels. In addition to rudders, there are a multitude of shipboard applications that could benefit from the technology first demonstrated in this project, including low cost two-sided VARTM-like molding (submarine dive planes), hybridpultrusion / VARTM processing (bridge decks and piers), and bending twisting coupling (high performance airfoils).