Structural performance of composite material for a slotted waveguide antenna stiffened structure under compression

The Slotted Waveguide Antenna Stiffened Structure (SWASS) is an aircraft system that can provide the capabilities of a stiffened panel skin structure and a slotted waveguide radar antenna simultaneously. The system is designed for integration into the fuselage or wing sections of intelligence, surveillance, and reconnaissance (ISR) aircraft and would increase the system performance through the availability of increased area and decreased system weight. Elemental parts of the SWASS structure were tested in compression after preliminary testing was completed for material characterization. Testing included finite element stress and strain field characterization of seven single slot configurations, and results showed the longitudinal 90° slot was the best structural slot by about 30% in terms of maximum von Mises stress. Single waveguides were tested in the non-slotted configuration and a configuration including a five longitudinal slot array in one waveguide wall. The slot array, compared with the unslotted configuration, was determined to have a decrease in nonlinear limit load of 8% using the finite element simulations and 14% using the experimental results and showed good comparisons overall. All waveguides showed the characteristics of local wall buckling with no overall beam buckling.