We present a phase field‐based framework for modelling fatigue damage in Shape Memory Alloys (SMAs). The model combines, for the first time: (i) a generalized phase field description of fracture, incorporating multiple phase field formulations, (ii) a constitutive model for SMAs, based on a Drucker–Prager form of the transformation surface, and (iii) a fatigue degradation function, with damage driven by both elastic and transformation strains. The theoretical framework is numerically implemented, and the resulting linearized system is solved using a robust monolithic scheme, based on quasi‐Newton methods. Several paradigmatic boundary value problems are addressed to gain insight into the role of transformation stresses, stress‐strain hysteresis, and temperature. Namely, we compute Δε − N curves, quantify Paris law parameters, and predict fatigue crack growth rates in several geometries. In addition, the potential of the model for solving large‐scale problems is demonstrated by simulating the fatigue failure of a 3D lattice structure.

Architected LCE lattices are fabricated with flow‐induced alignment via direct ink writing and systematically characterized their shape morphing, stiffness, and energy absorption behavior across strain rates spanning six orders of magnitude from 10 ⁻³ to 10 ³ s ⁻¹ . It is shown that architected liquid crystal elastomer (LCE) lattices exhibit superior energy absorption compared to their non‐mesogenic (silicone) counterparts. Importantly, the LCE‐to‐silicone energy absorption ratios are up to 18‐fold higher at the highest strain rate tested. A finite element model that captures their shape‐morphing response is developed, which exhibits excellent agreement with the experimental observations. The work opens new avenues for designing and fabricating LCE lattices with programmable alignment, shape morphing, and mechanics.