Elasticity Approach to Predict Shape Transformation of Functionally Graded Mechanical Metamaterial under Tension

The re-entrant structures are among the simple unit cell designs that have been widely used in the design of mechanical metamaterials. Changing the geometrical parameters of these unit cell structures, their overall elastic properties (i.e., elastic stiffness and Poisson's ratio), can be simultaneously tuned. Therefore, different design strategies (e.g., functional gradient) can be implemented to design advanced engineering materials with unusual properties. Here, using the theory of elasticity and finite element modeling, we propose a fast and direct approach to effectively design the microarchitectures of mechanical metamaterials with re-entrant structures that allow predicting complex deformation shapes under uniaxial tensile loading. We also analyze the efficiency of this method by back calculating the microarchitectural designs of mechanical metamaterials to predict the complex 1-D external contour of objects (e.g., vase and foot). The proposed approach has several applications in creating programmable mechanical metamaterials with shape matching properties for exoskeletal and soft robotic devices.

Automated summary

Re-entrant structures are widely used in mechanical metamaterial design, allowing for simultaneous tuning of elastic properties by changing geometric parameters. A fast and direct design approach using elasticity theory and finite element modeling has been proposed, with applications in predicting complex deformation shapes and creating programmable mechanical metamaterials with shape matching properties for exoskeletal and soft robotic devices.