Cellular materials have two important properties: structures and mechanisms. This property enables one to design structures with proper stiffness and flexibility. Recent advance in 3D printing technologies enable engineers to manufacture complex cellular structures. In addition, use of smart materials, e.g., shape memory polymers (SMPs), for 3D printing enables us to construct mesostructures actively responsive to environmental stimuli with a programmable function, which may be termed ‘4D Printing’ referring to additional dimension on time-dependent shape change after 3D printing. The objective of this study is to design and synthesize active reconfigurable cellular materials, which enables the advance of technology on intelligent reconfigurable cellular structures with 4D printing. A two-layer hinge of a CPS functions through a programmed thermal expansion mismatch between two layers and shape memory effect of an SMP. Starting with thermo-mechanical constitutive modeling of a compliant porous hinge consisting of laminated elastomer composites, macroscopic behaviors of a reconfigurable compliant porous structure (CPS) will be constructed using the strain energy method. A finite element (FE) based simulation equipped with a user subroutine will be implemented with ABAQUS/Standard to simulate time-dependent thermo mechanical behaviors of a CPS.
The designed CPS with polymers shows an extremely high negative Poisson’s ratio (∼ −120) and negative thermal expansion coefficient (−2,530 × 10−6/C). When programmed with an appropriate thermo-mechanical procedure, the hinge of the CPS bends either in positive and negative sign, which enables to tailor the CPS into desired intermediate and final configurations, ending up with achieving a reconfigurable CPS. This paper demonstrates that actively reconfigurable compliant cellular materials (CCMs) with CPSes can be used for next-generation materials design in terms of tailoring mechanical properties such as modulus, strength, yield strain, Poisson’s ratios and thermal expansion coefficient together with programmable characteristics.
Scalable 3D printing of aperiodic cellular structures by rotational stacking of integral image formation
