Fabrication of Mechanical Metamaterials by 3D Printing: Recent Advancements and Current Challenges

Mechanical metamaterials as a class of architected materials have been attracting increasing attention during the last years. This is directly related to the advances in additive manufacturing (AM). Using AM for fabrication of mechanical metamaterials provides environmental adaptation, improved mechanical behavior, and additional functionality. The current paper presents a review on applications of AM in fabrication of mechanical metamaterials made by metals, polymers, and ceramics. Herein, the classification of metamaterials is presented and explained. Then, recent advancements in fabrications of mechanical metamaterials considering single, multi, and composite material are reviewed systematically. Moreover, other types of mechanical metamaterials such as negative thermal expansion and lightweight micro-lattices metamaterials fabricated by AM techniques are explained. In addition, current challenges in this field and future research prospects are outlined. The summarized data can be considered as insight for the researchers to consider the current technological challenges and develop applications of AM in manufacturing geometrically complex mechanical metamaterials.