Passive damping of composites with embedded shape memory alloy wires

NiTi alloy wires were embedded during the infusion processing of woven carbon fibre reinforced plastic (CFRP) composite plates with the purpose to passively increase their damping. Two types of NiTi wires, having the same diameter of 203 mu m, were considered, one superelastic at room temperature, the other one martensitic. For the first one, a martensitic transformation was induced by applying a pre-strain of 2.5% before embedding the wires. The coexistence of austenite and martensite should provide damping through the mobility of boundaries between the two phases. For the second type of wires, the enhancement of damping was based on the presence of martensite.