Shape memory alloys (SMAs) are often used in smart materials and structures as the active components. Their ability to provide a high force and large displacement has been useful in many applications, including devices for damage control, active structural acoustic control, dynamic tuning, and shape control. The paper presents a macroscopic mathematical model which captures the thermomechanical behaviors and the two-way shape memory effect (TWSME) of SMAs, and SMA applications as an actuator to control the shape of a circular composite cylinder where a thin SMA layer actuator is bonded inside the cylinder is investigated numerically. The circular composite cylinder with the thin SMA layer was designed and analyzed to determine the feasibility of such a system for the removal of stiffeners from externally pressurized stiffened composite structures. SMAs start to transform from the martensitic into the austenitic state upon actuation through resistive heating, simultaneously recover the prestrain, and thus cause the composite cylinder to expand in the radial direction. The externally pressurized composite cylinder with the SMA actuators was analyzed using the 3-D finite element method.