Buckling and Shape Control of Composite Laminates using Embedded Shape Memory Alloys Wires

Active buckling and shape control through the use of embedded SMA wires is experimentally and numerically investigated. Two different kinds of tests (un-constrained actuation and buckling shape control through actuation) are performed on two different laminates, i.e. carbon- and aramidic-reinforced epoxy. The invasiveness of SMA actuators is evaluated through microscopy analysis and thermography to point out possible resin enrichment, decrease in stress-transfer capability between wires and polymeric matrix and thermal damage at interface due to SMA actuation temperature. The buckling load is measured by means of bifurcation technique, that consists in back-to-back bonding of a couple of strain gauges rosettes on the two surfaces of the specimens. In this way both the increase of the critical buckling load and the alteration of the deflection shape, due to the use of an actuation force of the embedded shape memory alloy wires, can be evaluated. Accurate measurement of characterizing parameters is performed, to be included into an originally-developed algorithm implementing Lagoudas's constitutive law into ABAQUS FEM code. The experimental tests are modeled, for using FEM analyses to predict the buckling shape-control capability of embedded wires.