An optimization approach for mass reduction and noise dampening of aircraft closed chamber

Noise level is an important index in closed chamber's design of modern aircraft; by using stiffeners traditional design can reduce noise effectively but results in much heavier structures. Thus, an optimization approach of the structural-acoustic coupling system composed of an aircraft equipment bay is studied aimed at mass reduction under noise constraint. A structural-acoustic coupling finite element model is created; by using the finite element software ACTRAN, the acoustic field in the equipment bay can be calculated, which is then verified and amended by experiments. To reduce structure mass of the equipment bay, the cabin door panel is divided into several areas with internal stiffeners as their boundaries. By conducting the optimization of stiffener sections and the thickness of each area, the total mass of the structure drops substantially. Accordingly, the dynamic stiffness of the structure is better distributed, which reduces the acoustic radiation energy and ultimately reduces the noise within the closed chamber. The work of this paper has important guiding significance in practical engineering, especially in similar structural-acoustic coupling system enclosed by thin plate with stiffeners.