Tough, Impact-Resistant Composite Structures for Lightweight Airborne Laser Subsystem

The Airborne Laser (ABL) system is being developed using a Boeing 747 aircraft platform for use in missile defense systems. Current ABL technology demonstration systems and subsystems, such as the ABL-Pressure Recovery Subsystem (ABL-PRS), use heavier materials such as titanium. Weight reductions using advanced composite materials can be substantial, with estimates of over 5,000 pounds savings for the ABL-PRS alone. A key problem in the wide-spread insertion of composites in the man-rated ABL system platform is the lack of data base and thus very conservative design knockdown factors used for composites to ensure positive design margins are achieved on these components for uncertainties such as impact resistance due to mechanical abuse during installation and maintenance of composite components. In the Phase I study, the feasibility of using tough, impact resistant composite materials and a vacuum assisted resin transfer molding (VARTM) low cost manufacturing process were demonstrated for lightweight, low cost ABL composite components in subscale tests. High strain-to-failure carbon fiber reinforced composites were used as surface laminates to provide impact resistance with high strength and modulus carbon fiber reinforced resin matrix composite materials for VARTM manufacturing processes. Mechanical property tests demonstrated that this concept will decrease the design knockdown factors associated with impact damage during installation and maintenance operations for ABL-PRS structural components. Subscale test articles were fabricated using a VARTM process to demonstrate a unitized-construction ABL-PRS subscale component. A Phase II program is proposed to develop and demonstrate full-scale prototype ABL-PRS components using tough, impact resistant composite materials and the VARTM manufacturing process for ABL-PRS components.