<p>Four-dimensional (4D) printing has great potential for fabricating patient-specific and stimuli responsive 3D structures for the medical sector. Inspired by these deformations, this paper conducts a systematic research about mechanical behavior based on 4D printing. The anisotropic characteristics of mechanical and shape memory performances induced by different infill strategies via both experimental and theoretical methods are investigated. Uniaxial tensile tests and compressive tests are performed to study the effect of infill patterns on mechanical properties. The deformation mechanism of bilayer structure is proposed, and the structural parameters and related equations of helical structure are introduced. The influence of printing temperature on the storage modulus of polylactic acid test spline is explored by dynamic mechanical analyzer, and the influence of environmental temperature on the stress-strain curve of polylactic acid test spline is explored by stretching machine. In the proposed method, the bilayer structure is fabricated by three-dimension printing and heated in the water bath for a period of time, and then the helical structure is obtained. With the purpose of exploring the shape memory properties including recovery speed, recovery ratio and shape fixity ratio, deformation-recovery tests are conducted under different temperatures and a 2D and 3D convertible structure with programmable Poisson’s ratio are demonstrated.</p>

4D Printed Bilayer Helical Structures Mechanical Behaviors and Shape Memory Effects

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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