  Four-dimensional (4D) printing, a new technology emerged from additive
manufacturing (3D printing), is widely known for its capability of programming
post-fabrication shape-changing into artifacts. Fused deposition modeling
(FDM)-based 4D printing, in particular, uses thermoplastics to produce
artifacts and requires computational analysis to assist the design processes of
complex geometries. However, these artifacts are weak against structural loads,
and the design quality can be limited by less accurate material models and
numerical simulations. To address these issues, this paper propounds a
composite structure design made of two materials - polylactic acid (PLA) and
carbon fiber reinforced PLA (CFPLA) - to increase the structural strength of 4D
printed artifacts and a workflow composed of several physical experiments and
series of dynamic mechanical analysis (DMA) to characterize materials. We apply
this workflow to 3D printed samples fabricated with different printed
parameters to accurately characterize the materials and implement a sequential
finite element analysis (FEA) to achieve accurate simulations. The accuracy of
deformation induced by the triggering process is both computationally and
experimentally verified with several creative design examples, and the 95%
confidence interval of the accuracy is (0.972, 0.985). We believe the presented
workflow is essential to the combination of geometry, material mechanism and
design, and has various potential applications.
