Tough, aorta-inspired soft composites.

Spatial variations in fiber alignment (and, therefore, in mechanical anisotropy) play a central role in the excellent toughness and fatigue characteristics of many biological materials. In this work, we examine the effect of fiber alignment in soft composites, including both "in-plane" and "out-of-plane" fiber arrangements. We take inspiration from the spatial variations of fiber alignment found in the aorta to three-dimensionally (3D) print soft, tough silicone composites with an excellent combination of stiffness, toughness, and fatigue threshold, regardless of the direction of loading. These aorta-inspired composites exhibit mechanical properties comparable to skin, with excellent combinations of stiffness and toughness not previously observed in synthetic soft materials.