Design and Manufacture of a Smart Macro-Structure with Changeable Effective Stiffness

Abstract

Smart materials are being utilized in many fields and different external stimuli are used to change specific properties of these materials. In this research, a novel method was developed to design a structure with the desired nonlinear effective Young’s modulus. This method is geometric based where the structures are designed with a gap between them. These structures exhibit nonlinear elastic response. Wide range of structures with desired stress–strain curve can be generated using this approach. First, a unit cell was designed and later used to create a periodic structure. Numerical simulations have been exploited to prove the efficiency of the method. A prototype was manufactured by the Fused Deposition Modeling (FDM) 3D printing method. The compression test was performed on the structure. Both simulations and experimental results proved that the effective Young’s modulus of the structure can be increased up to 142%. Second, the designed unit cell was optimized using Genetic Algorithm (GA) to achieve a cell with desired nonlinear stress–strain curve. This cell was optimized considering five effective geometric parameters to alter the effective Young’s modulus of the cell. Finally, a periodic structure was created by repeating a cell with two different gap’s distances. A structure with a desired stress–strain curve was designed using the same method.