Simulating loading–unloading hysteretic behaviors of nematic-genesis polydomain nematic elastomers

Abstract

Nematic elastomers (NEs) are lightly cross-linked elastomers with nematic mesogens integrated in their polymer networks. Combination of large deformation capability with nematic-isotropic phase transition enables NEs to be the most promising soft materials for impact attenuation, actuation and soft robotics. In this paper, we focus on nematic-genesis polydomain NEs (N-PNEs) where mesogens are cross-linked at nematic states. N-PNEs are capable of absorbing and dissipating energy and easy to synthesize. We present a Voronoi diagram-based finite element model for specimen-scale N-PNEs, and investigate the cyclic tensile and compressive behaviors of N-PNEs at different strain rates. Our simulations reveal a smooth polydomain-monodomain transition during loading, accompanied by a full recovery of polydomain texture after the load is removed, indicating a memory effect of initial disordered mesogen alignment. The predicted behaviors align well with experimental observations, which validates our model. Furthermore, we assess the energy absorption and dissipation capabilities of N-PNEs compared to monodomain NEs, identifying conditions where N-PNEs exhibit superior performance. This study not only enhances our understanding of polydomain-monodomain transitions in N-PNEs, but also lays the groundwork for the development of N-PNE-based energy absorbers.