Control of natural frequencies of a clamped–clamped composite beam with embedded shape memory alloy wires

In this study, an analytical model for the evaluation of natural frequencies of glass fibre composite beams with embedded shape memory alloy (SMA) wires, called “SMA composites” is presented. The beams were clamped at both ends and different numbers of SMA actuators were embedded at an interlayer of the composite beams. The changes of tensile modulus, internal recovery stress and strain, and stresses due to the thermal expansion of the beams and wires were considered in the study. The natural frequencies evaluated from the analytical model of the SMA composite beams compared well with experimental measurements. In the study, it was found that the natural frequencies of composite beams decreased with increasing the number of embedded SMA actuators at a temperature below martensite finish temperature, Mf. Although the modulus of the SMA material was relatively higher than glass fibre composites, the decrease of the natural frequencies was due to the increase of the overall density of the SMA composite beams. However, at a temperature above austenite finish temperature, Af, the natural frequencies of the beams with low SMA wire fraction were initially decreased. The frequencies were then increased with continuously increasing the number of SMA wires. These phenomena agree well with the experimental observations.