Abstract：Mechanical metamaterials (or meta-structures) exhibit extraordinary physical and mechanical properties due to their unique microstructural designs. By combining the design ideas of mechanical metamaterials with intelligent and flexible materials (IFMs), it is possible to create intelligent flexible mechanical metamaterials (IFMMs) with self-sensing and self-actuating capabilities. This paper takes conventional mechanical metamaterials as a starting point and analyzes the fundamental design ideas, deformation mechanisms, and mechanical properties of IFMMs. According to the recent research progress on IFMMs, this novel metamaterial is categorized as mechanical metamaterial based on shape memory polymers (SMPs), hydrogel, magnetoactive soft materials and dielectric elastomers, and we are particularly concerned with the first two types. Based on our previous work, we present the general approach of using analytical methods and numerical simulations to analyze the mechanical properties of negative Poisson's ratio, negative expansion, and multi-stable metamaterials under the assumption of small deformation and large deformation with multi-field coupling, respectively. In the assumption of small deformation, the use of beam theory and energy methods proves to be essential for obtaining fundamental mechanical parameters of the materials. Moreover, accurate constitutive models and numerical implementation under large deformation and multi-field coupling offer the possibility to analyze more complex deformations and structures. In addition, the preparation and performance test of IFMMs remain crucial. Advanced manufacturing techniques have brought new opportunities for the preparation of IFMMs, and currently, various methods are available to effectively prepare these materials. And the performance test of IFMMs includes both experiments applicable to traditional materials and special experiments only for IFMs. Finally, this paper concludes by highlighting some key issues and potential trends of IFMMs. These challenges primarily revolve around material properties, fabrication methods, mechanical models, and structural designs. This review may bring beneficial inspiration for the future development of IFMMs.
2024, Vol. 45 
