Issue 21

C. Maletta et alii, Frattura ed Integrità Strutturale, 21 (2012) 5-12 ; DOI: 10.3221/IGF-ESIS.21.01 10 Recovery energy ratio for indentation loads above 150 mN. This suggests that the greater amount of material stressed reversibly at higher indentation loads, and thus the greater recovery energy available, balances the increased amount of dissipated energy involved in the indentation process at higher indentation loads. Although plastic deformation beneath the indenter reduces the amount of shape recovery this plastically deformed material decreases the stress gradient in the material surrounding the plastically deformed volume favoring the reverse phase transformation. Figure 4 : Single quasi-static indentation tests for different values of maximum load: (a) 50 mN, (b) 150 mN, (c) 300 mN and (d) 450 mN. a) b) Figure 5 . Recovery and residual capability of the SMA after unloading: a) depth recovery and b) energy recovery.