Damage Tolerance of Resin Transfer Molded Composite Sandwich Constructions.

摘要

The objectives of this program were to investigate several innovative sandwich constructions developed by affordable manufacturing process for their impact damage resistance/tolerance. The sandwich composite concepts considered in this study possessed the feasibility to improve the transverse stiffness, provide enhanced damage resistance/tolerance to impact and functionality advantages in comparison to those made from conventional honeycomb and foam cores. The core concepts considered included traditional foam, titanium, steel and E-glass/epoxy pins-reinforced foam, hollow truss/pin core, foam-filled- honeycomb cores, and honeycomb core with hybrid facesheets. Graphite and glass fabric and prepreg facesheets were considered. A number of low cost manufacturing techniques to produce panels included; resin transfer molding (RTM), vacuum assisted resin infusion/transfer molding (VARTM), co-injection VARTM and vacuum assisted compression molding (VACM). Detailed experimental impact studies were performed under three scenarios low velocity, intermediate velocity, and high strain rate loading. Supporting analysis and finite element modeling work were conducted. The various tests and analysis conducted revealed that in terms of failure characteristics, the RTM/VARTM processed sandwich composites yielded similar performance as those manufactured from traditional techniques such as vacuum assisted compression molding. The reinforcement of foam core with stiff pins and/or honeycomb cells was found to provide attractive benefits to suppress/contain damage under low velocity, intermediate velocity and due to high strain rate impact scenarios.