Abstract: Doors will bear great pressure load when civilian aircraft during the flight. With the increasingly stringent requirements of lightweight design, composite doors gradually become a trend. And, doors in the design must meet the stiffness requirement in addition to meet the strength requirement. In order to study the weight loss potential of composite materials applied on the door, and improve the constraint of stiffness, including maximum deformation, waviness, gaps and steps, and the constraint of strength and layout proportion, an optimization design method of multiple stiffness constraints for aircraft composite door is proposed. Taking the front cargo door of airplane for example, according to the constraint of stiffness, strength and layout proportion, by optimizing the skin, beam and frame by using NASTRAN, the purpose of the lightweight design is realized. The result shows that the weight of the front cargo door is reduced by 24.30% after using composite material and structure optimization. This research could provide some useful advices for the application of composite material in aircraft cargo door.

Key words: multiple stiffness constraints, optimization, lay-up proportion, lightweight design