Humidity and thermal triggered Shape Memory Effect - Rheology-based numerical modelling - Thermal Humid Mechanical Cycle

A displacement of s_max = 2.5 mm is performed and fixed. In the same step, the thermal chamber is set to cooling, by setting a lower temperature T_1 = 50 °C, to speed up the cooling process. In the next step the displacement s_max is kept fixed and the temperature is decreased to T_low = 30 °C. Once the sample is in thermodynamic equilibrium, the fixation is released and the stress free recovery step by setting the normal force to F_N = 0 N is performed.

Humidity-dependent recovery of the initial geometry is performed by increasing the relative humidity to RH = 70 %. By performing a THMC, the thermal shape fixation and humidity-dependent shape recovery are captured. Here it can be seen that the programmed shape can also be recovered by higher humidity.