Multi-functional SMA hybrid composite materials and their applications.

摘要

Shape memory alloy (SMA) materials such as nitinol have unique properties associated with the shape recovery effect and the material's phase changes that have been used in a variety of actuator and sensing applications. By embedding SMA elements into host composite materials, control or modification of the SMA hybrid composite's structural properties can be accomplished in-service, thereby increasing the hybrid composite's structural functionality. Previous studies addressed increasing composite materials' functionality by enabling in-service control of their dynamic response. Utilizing the SMA's substantial recovery stress and capacity to dissipate strain energy to increase the hybrid composite's static functionality is addressed herein. Specific applications for SMA hybrid composites include improving composite material's impact damage resistance and composite cylinder stress and deflection control.; In stress and deflection control of cylindrical structures, SMA actuators are placed within the composite cylinder to form an active compound cylinder. The active SMA elements can significantly reduce the internal pressure-induced radial dilation and creep so that under severe loading, piston to cylinder tolerances may be maintained. Similar to a conventional metallic compound cylinder, the active compound cylinder also reduces peak cylinder hoop stresses.