Energy-based analysis of temperature oscillation at the shakedown state in shape memory alloys

The upper bound of low cycle fatigue life of pseudoelastic polycrystalline NiTi shape memory alloys

“…Figure 5 gives a schematic of the temperature oscillation of SMAs upon pseudoelastic cycling, which is governed by hysteresis dissipation, latent heat and the heat transfer conditions. In stabilized cycles, the latent heat release during loading and absorption during unloading are identical, and the hysteresis dissipation produced per cycle is completely released to the surroundings [25,34,35]. In this case, the temperature amplitude is governed by the release/absorption of latent heat (marked by 1 ⃝ in figure 5); it increases with the loading frequency and will eventually reach a saturated value (tending to adiabatic condition).…”

“…Figure 5. Thermomechanical coupling at the stabilized cycles [34]: the temperature amplitude is governed by the release/absorption of latent heat (marked by 1 ⃝), while the mean temperature is determined by the hysteresis dissipation (marked by 2 ⃝).…”

“…In fact, most of the local phase transformation events take place instantaneously and the real heat release rate is difficult to be controlled [34]. Nevertheless, the internal ratcheting behavior inside the pseudoelastic loop, as shown in figure 9, provides a possibility to achieve the evolution of cyclic transformation that tends to 0.…”