Pseudoelastic behaviour of shape memory alloy beams under pure bending: experiments and modelling

The moment-curvature hysteresis loops (for single cycle) under pure bending were experimentally determined for Cu-Al-Be single crystal, Ni-Ti and Cu-Zn-Al polycrystal samples using specially designed device. The comparison with the theoretical loops is presented for linear strain-hardening and ideal pseudoelasticity models discussed in (Int. J. Mech. Sci. 2001;43:1339). All theoretical constants were determined using simple-tension data and thermo dynamical identities. The tensile-compression dissymmetry effect is accounted for and non-linear differential equation describing the motion of neutral plane is derived for beams with arbitrary symmetric cross-section. The evidence of dissymmetry effect in Cu-Al-Zn is provided by application of metallographical and mechanical techniques. But the experiments and modelling have shown that the tension/compression asymmetry has in fact little influence on the moment-curvature responses on SMA beams. (C) 2002 Elsevier Science Ltd. All rights reserved.