Shape memory alloy CuAlBe strands subjected to cyclic axial loads

Structural cables are composed of wires helically wound into strands, which, in turn, are wound around a core. They have high redundancy and can be used to carry large tensile forces in many civil engineering structures. Better dissipation and/or recentering capacity can be expected if the cable is composed of shape memory alloy (SMA) wires in the austenite phase. Tensile tests were performed on strands made of CuAlBe SMA wires to characterize their behavior and demonstrate their potential utility as adaptive or resilient tension elements. In particular, equivalent viscous damping and forward-transformation and maximum stresses were determined for different strain amplitudes. Nearly ideal superelastic properties were obtained up to 3% axial strain. The equivalent damping increased with strain, reaching a value of 4% for a strain amplitude of 5%. Strand experimental results were used to validate a two-dimensional numerical model developed to estimate the strand response to axisymmetric loads within the superelastic deformation range. The model relies on the linearization of the wire geometry and on a multilinear CuAlBe wire stress–strain relationship. The proposed model adequately predicts the maximum strand stress and the residual strains for different strain amplitudes.

► CuAlBe strands show similar behavior to those obtained from a single wire.
► The superelastic limit is 3% strain.
► The equivalent viscous damping reached 4% at a maximum strain equal to 5%.