Design of mechanical metamaterials with multiple stable stress plateaus

Existing conventional materials are usually difficult to achieve multiple tunable stress plateau characteristics, which hinders their multifunctional applications. This study proposes a multiple stable stress plateau metamaterial. A theoretical model for predicting stress plateaus was established, and its accuracy was verified by experimental and numerical methods. The proposed material exhibits a three-stage deformation mode owing to sequential snap-through and Euler buckling at the microscopic unit cell level under compression. The effect of geometric parameters on the stress plateau was studied. The results indicated that the first plateau stress can be tuned independently by altering the angle between the inclined thin and thick beams, whereas the third plateau stress can be tuned independently by changing the thickness of the vertical thick beams. The first and second plateau stresses can be tuned by varying the thickness ratio of the inclined and vertical thin beams. Moreover, the total number of stress plateaus and the range of each stress plateau could also be tuned by changing the thickness ratio of the inclined and vertical thin beams and the vertical thick beams. Using the energy efficiency method, we obtained the experimental and numerical plateau stresses for each specimen. Notably, the experimental, numerical, and theoretical results were in good agreement. This study is expected to provide guidance for the design of multifunctional metamaterials with multiple tunable stress plateaus.