Topographic study of shape memory alloy wires used as actuators in smart materials

The aim of this work is to characterize the interface between a shape memory alloy wire (SMA) and a resin epoxy matrix. More precisely, we want to associate the roughness of the wire with the adhesion between the fiber/matrix. The effect of various surface treatments applied to SMA NiTi wires on the quality of the fiber/matrix interface is presented and discussed. First, a profilometric study is carried out on the different wires. The parameters, which characterize the vertical distribution of the roughness and the wire morphology, are determined. The topographic study reveals that the surface treatments which are applied strongly modify the external surface of the wire. In the second part of this work the adhesion fiber/matrix is quantified by using a pull-out test. These experimental results are analyzed and compared with the roughness parameters. This comparative study enables us to determine the wire morphology which will guarantee the best adhesion fiber/matrix. The roughness parameters are sufficient for the choice of the wire which will be embedded into the resin.