The behaviour of superelastic springs is investigated in the present work. The goal is to
evaluate the global mechanical device response in large displacement conditions.
Superelastic SMA coil springs have been studied experimentally and numerically considering
uniaxial mechanical load histories both in tension and in compression.
Experimental tests have been performed on three different spring geometrical
configurations. Tested specimens experience a maximum elongation larger than the original
spring axis length. The response is not symmetric and affected in compression by buckling
instability. Nevertheless, results show a very good superelastic behaviour with no damage
and with negligible residual displacements.
Numerical analyses have been performed to reproduce the experimental campaign results.
Main issues in modeling are the material and the geometrical nonlinearities. A simple
finite element model is proposed. Experimental and numerical results agreement is very
good.
The numerical model turns out to be a powerful design tool even in the very complex
geometrical and material nonlinear conditions. Hence, it is proposed as a useful tool for
spring design validation and response prediction.