Experimental Characterization and Numerical Assessment of Cu-Al-Be Shape Memory Alloys for U-Shaped Flexural Plates

This study presents an experimental characterization and numerical assessment of Cu-Al-Be (CAB) shape memory alloys (SMAs) for potential applications in U-shaped flexural plate (UFP) seismic dampers. Six alloy compositions were evaluated through monotonic tensile tests, ASTM F2516 superelastic protocols, and increasing-amplitude cyclic loading to identify the material exhibiting stable superelastic behavior at room temperature. Among the tested materials, alloy CAB4.76-A showed the most favorable response, with high transformation stress, stable pseudoelastic behavior, and strain recovery exceeding 95% for strains up to 2.5%. A phenomenological finite element model based on the Auricchio constitutive formulation was calibrated using experimental data within the validated strain range (ε ≤ 0.025), showing good agreement in stiffness and stress prediction. The calibrated model was subsequently applied to simulate the response of a UFP device under orthogonal cyclic loading. The results indicate a strong dependence on loading orientation due to coupled bending-torsion effects, with the 90° direction exhibiting significantly higher strength and energy dissipation capacity. Comparison with analytical formulations originally developed for steel UFPs showed that these expressions provide approximate estimates when applied to SMA-based devices. The results suggest that Cu-Al-Be alloys are a promising alternative for UFP applications, while highlighting the importance of loading orientation and the need for future experimental validation at a device scale.