The cyclic shape memory effect of thermo-induced shape memory polymers (TSMPs) is a typical thermo-mechanical process that can be affected by thermo-mechanical loading histories. During the deformation stage of the cyclic shape memory effect, polymer chains exhibit the initial dissociation of sub-entanglements, slipping and orientation with the increase in the deformation. The strain can be recovered with the internal rotation of the dihedral angle due to the enhancing motion of polymer chains during the reheating. Based on the rheological theory, a thermo-viscoelastic model is proposed to capture the cyclic shape memory effect of TSMPs. A temperature-dependent stress threshold value is introduced to reflect the slipping of polymer chains. In order to take into account how orientation affects the cyclic shape memory effect, a relationship between the strain and orientation is constructed and introduced into the evolution equations of elastic modulus, viscosity and irrecoverable strain. By comparing the experimental and simulated results at different loading levels and numbers of cycles, the proposed model is verified. The results show that the proposed model can reasonably predict the cyclic shape memory effect of TSMPs.

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Shape memory behavior of thermo-induced shape memory polyurethane (TSMPU) under proportionally multiaxial loading is investigated experimentally. The shape memory effect is discussed under different axial and torsional loading angles. By comparing the equivalent stress-equivalent strain curves under different loading angles, it is found that the difference in thermo-mechanical behavior is mainly reflected in the shape memory effect. The equivalent characteristic quantities describing the shape memory effect are extracted from the experimental results. By analyzing their evolutions in the strain and stress spaces, it is found that the shape memory effect shows obvious anisotropy under different loading angles, i.e., the equivalent recovery rate of TSMPU increases with the increase of the loading angles. These results are helpful to
establish a thermo-mechanical constitutive model for describing the shape memory

Dual-phase high-entropy alloys (DP-HEAs) have been proved to be a kind of promising materials that exhibit a combination of excellent strength and ductility. Previous studies have emphasized the effect of interface and phase volume fraction on mechanical performance in DP-HEAs. However, the deformation mechanisms such as interplays between dislocations and the constituent phases have not been fully understood. Particularly, the research concerning plastic anisotropy in DP-HEAs is still lacking. Here, molecular dynamics simulations are performed to probe the effect of loading orientation on plasticity in the nano-laminated face-centered cubic (FCC)/hexagonal close-packed (HCP) CoNiCrFeMn DP-HEA. Results reveal that a switch from strengthening to softening and back to strengthening is closely related to the activation of different slip systems when tailoring the inclination angles of the nanolaminates with respect to the tensile direction from 0° to 90°. Slip transfer across phase boundaries, phase transformation and the nucleation of shear bands dominate the plasticity in the samples with low, medium and high inclination angles, respectively. Furthermore, the evolution of microstructures, such as dislocations, stacking faults, and FCC/HCP phase are analyzed to study the underlying deformation mechanisms. These results can help understand the plastic anisotropy of DP-HEAs and design alloys with excellent mechanical properties for engineering applications.