An externally pressurized elliptic composite cylinder stiffened with activated SMA strips

The shape memory alloys (SMAs) are often used in smart materials and structures as the active components. Their ability to provide a high recovery force and a large displacement has been used in many applications such as the devices for damage control, active structural acoustic control, dynamic tuning, and shape control. In this paper the radial displacement of an externally pressurized elliptic composite cylinder where SMA liner or strips actuators are bonded on its inner or outer surface is investigated numerically. The composite elliptic cylinders consisting of an inlet duct system with SMAs are designed and analyzed to determine the feasibility of such a system for the removal of stiffeners from an externally pressurized duct of an aircraft inlet. The deformations caused by prestrained SMAs placed on either surface of an elliptic composite cylinder are studied when thermally activated. The SMAs start to transform from the martensitic phase into the austenitic phase upon actuation by resistive heating, simultaneously recover the prestrain, and thus cause the composite cylinder to expand in the radial direction. The externally pressurized elliptic composite cylinders with the SMA actuators were analyzed using the 3-D finite element method incorporated with 3-D SMA behaviors. The results show that the role of stiffeners may be switched by the activated light SMA actuators.