Abstract
Designers are still seeking novel, smart and advanced materials. Moreover, a designed geometry for special purposes is also required for structures. In this regard, metamaterials are artificial structures with optimized topology. Furthermore, the multi-material metamaterial (4M) structure could be a frontier technology in different industries, especially in biomechanics, which provides various functions. In this short perspective, 4M structures have been introduced by emphasizing the application of bones and implants. Under cyclic loading, such a smart material should be topology-optimized with the objective of fatigue properties, the fretting fatigue lifetime, reliability, and weight. In addition, the constraint in this finite element modeling-based multi-objective optimization is the strength or the deformation of the structure.