PULTRUDED STRUCTURES REDUCE COMPOSITE SHIP CONSTRUCTION COSTS

摘要

KaZaK Composites Incorporated (KaZaK) has developed and demonstrated technology for low cost pultrusion of 8.89 centimeters thick, 3.05 meters wide composite sandwich panels of unlimited length. These panels feature stress-lowering joining details integrated into the panel's long pultruded edges as part of the continuous manufacturing process. While considerable work remains to qualify this technology for shipboard use, KaZaK has worked with Northrop Grumman Shipbuilding (NGSB) to develop techniques for rapid edge-to-edge bonding of long individual pultruded panels. Large multi-panel sections of composite structure were fabricated and tested using these joining techniques. Major labor cost savings were apparent in two areas. First, the pultrusion process was demonstrated to reduce the labor associated with production of composite sandwich panels, including the integrated joint, compared to similar baseline Vacuum Assisted Resin Transfer Molding (VARTM) panels made without these integrated joining details. Pultrusion eliminated costly hand labor associated with other types of composite manufacturing, while providing excellent dimensional accuracy and quality. Second, the integrated joint features (which would be difficult and costly to duplicate with VARTM) enabled the rapid and consistent assembly of individual pultruded panels into much larger sections, ensuring well bonded structural joints with measured mechanical properties matching VARTM panels without a joint. In combination, these technology advances were projected by NGSB to reduce the labor cost of assembled composite structure made in quantities typical of shipbuilding applications by as much as 88% compared to the VARTM-baseline. Significantly, these demonstrated cost savings, together with pultruded joint connectors currently in development, suggest that the finished cost of composite ship structures made from flat pultruded panels could be significantly lower than other approaches to lightweight materials, and that the cost per pound of composite primary ship structure may ultimately become more competitive with conventional steel fabrication.