calculated on the average response over the last two loading cycles and
expressed as the amount of dissipated energy over the elastic energy provided to the sample
during the stretching phase.
As temperature increases, the curves show an increasing steep segment (here referred to as
preload knee) at small deformations (ΔL/L0 < 0.02), i.e. the specimen presents much higher
stiffness at low stretches. This is because the coils start touching each other.
At higher temperatures, the first training cycle is closer to the stabilized response.
• When the RC is kept for 2 s at 50% deformation, slower hysteresis phenomena induce a slight
stress relaxation (see Figure 5).
• Due to hysteresis, during the unloading phase of isothermal tensile cycles at 25 ◦C, the sample
suffers from buckling, i.e, its stress falls to zero, as it approaches the reference configuration.