Simulation of moisture-induced shape changes of fused layer modeling (FLM) 3D printed wood/polylactic acid (PLA) composites

In recent years, the variety of materials for fused layer modeling (FLM) 3D printing has expanded considerably, and new smart materials such as shape memory polymers (SMPs) have been added. Such SMPs enable so-called 4D printing, a programmable shape transformation of FLM 3D printed objects over time due to an external stimulus such as moisture or temperature. This paper addresses the processing of a specially fabricated climate-responsive wood/polylactic acid (PLA) composite using FLM 3D printing and the application of varying print directions for manufacturing programmable shape changing objects. In addition, this study is about developing a two-dimensional mathematical model based on the linear difference method to forecast accurately the moisture-induced deformation behaviour of 4D printed objects. Furthermore, the occurring deformations of the 4D printed objects were recorded using 3D scanning technology and compared with the simulated deformations from the mathematical model for validation purposes. With the help of the developed two-dimensional mathematical model, an exact reproduction of the deformation behaviour of 4D printed objects was made with a deviation percentage of always less than 6.5%.