4D printed shape memory alloy metamaterial with tunable energy absorption and vibration isolation

The harmonious integration of energy absorption and vibration isolation strategies in metamaterial design is demonstrated to significantly enhance performance efficiency under complex dynamic loads. A novel metamaterial featuring tunable shape along with controllable energy absorption and vibration isolation capabilities is proposed in this paper, which is developed through 4D printing of shape memory alloys (SMAs) inspired by the collagen fiber structure of knee cartilage. Three distinct configurations (S-1, S-2, and S-3) are designed, representing quasi-zero stiffness, single-stable snap-through, and high-stiffness elastic responses, respectively. Instead of selecting a single optimal design, these configurations collectively enable programmable mechanical responses, allowing the structure to adapt its stiffness, energy absorption, or vibration isolation capability to diverse loading or environmental conditions. The shape recovery and adjustable mechanical behavior of this metamaterial were investigated using a combined approach of theoretical modeling, finite element analysis, and experimental methods. Comprehensive comparisons of stress-strain behavior, energy absorption efficiency, and vibration isolation performance were conducted across various pre-designed configurations height programming and temperature ranges. Adaptive optimization of vibration control and energy absorption is demonstrated to be achievable by adjusting structural parameters, configurations, and thermal conditions. This study will provide theoretical guidance for the potential engineering application of 4D printed SMA metamaterials.