Nacre‐Inspired Design and Optimal Strategy for Short Carbon Fiber Reinforced Polymer Composites With Improved Strength and Toughness

ABSTRACT Short carbon fiber (SCF) reinforced composite materials have the advantages of low cost, good designability, and good formability, but their poor mechanical performance limits their application as the main load‐bearing structures. Here, an investigation on the mechanical optimization design of SCF‐reinforced polymer composites by mimicking the “brick‐mortar” structure of natural nacre has been carried out. It shows that the strength of the SCF reinforced composites is close to 1000 MPa and its fracture strain can achieve about 13%, providing the possibility for it to be used as a lightweight main load‐bearing structure. Further analysis reveals that there is a size effect of “bricks” in the “brick‐mortar” structure that has a significant impact on the damage, failure, and energy dissipation of the composites. When regulating the mechanical properties of the SCF‐reinforced composites by the size effect, the relationship between strength and toughness of the composites shifts from “mutual promotion” to “mutual constraint.” This size effect has also been successfully validated in the natural nacre and allows the SCF‐reinforced composites to achieve an excellent combination of high strength and high toughness, which are expected to provide useful guidance for the strengthening and toughening design of the internal microstructure of composite materials.