A brief review of mechanical designs for additive manufactured soft materials

Additive manufacturing is an arising technology for soft materials and structures with improved complexity and functionality and has gradually become widespread in various fields, including soft robotics, flexible electronics and biomedical devices. Along with the development of material systems and fabrication techniques, mechanical design principles for additive manufactured soft materials have been greatly developed and evolved in recent years and some unique issues that are distinct from conventional manufacturing techniques have emerged. In this short review, we mainly focus on additive manufactured soft materials that are in significant need of mechanical models/simulations to provide design guidelines; therefore, topics such as soft robotics and electronics are not considered here. We first discuss the mechanical design methods for controlling shape distortions and interfacial strength, as they are directly related to the quality and reliability of additive manufactured soft materials. Design principles and manufacturing strategies for bioinspired composites, which represent a large part of current research on additive manufactured soft materials, are then summarized integrally with regards to three aspects. In addition, basic mechanical considerations for additive manufactured four-dimensional shape-changing structures are explained, together with a review of the recent theories and numerical approaches. Finally, suggestions and perspectives are given for future developments in soft material additive manufacturing.