Numerical/experimental assessment of 3D-printed shape-memory polymeric beams

The main objective of this article is to present different computational tools to replicate thermomechanical shape-memory responses of beam-like structures fabricated by three-dimensional (3D) printing technology. To simulate thermomechanical behaviors of shape-memory polymer (SMP) beams, one-dimensional (1D) finite element model (FEM) building with MATLAB and 3D FEM by means of COMSOL Multiphysics are established. All governing equations are developed based on a 3D thermomechanical SMP constitutive model. 1D FEM is derived on the basis of the Euler-Bernoulli beam theory and linear geometrical assumption. The 3D SMP constitutive model is implemented into geometrically nonlinear COMSOL Multiphysics software through a user-defined material subroutine to provide a powerful 3D simulation tool. Comparative studies on FEMs of MATLAB and COMSOL Multiphysics reveal that geometrically linear assumption is appropriate for models in large/small deformation under tension/bending. 1D analytical solution for deflection of an SMP beam employing Euler-Bernoulli beam theory is also developed. An experiment is conducted to demonstrate a full shape-memory cycle of SMPs. It is experimentally shown that a 3D-printed beam recovers the deformation incurred by external loads upon heating over the transition temperature. The accuracy of the 3D FEM in COMSOL Multiphysics is checked with analytical solutions and experimental data. It is found that simulation results of the program are in good agreement with characteristics observed in the experiment and analytical solutions. The developed computational tools are expected to be instrumental in the design of simple/complicated SMP structures. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47422.