Experimental and Numerical Study on the Effect of 3D Printing Geometrical Parameters on the Torsional Shape Recovery Behavior of Polylactic Acid

Additive manufacturing is one of the advanced manufacturing processes that is being developed nowadays due to the capability of manufacturing parts with complex structures, speed, and low production cost. 3D printing of shaped memory parts in the form of 4D printing is an emerging phenomenon, which is referred to as the future of additive manufacturing. In this study, the effect of three-dimensional printing fusion layer parameters including layer thickness, print speed, and nozzle diameter on the rate of shape recovery of Polylactic acid was investigated. To reduce the cost and time as well as to increase the validity and accuracy, the Central Composite Design method, one of the subsets of the Response Surface Methodology, was used. Seventeen experiments were performed and a model was obtained to determine the effect of 3D printing geometrical parameters on shape recovery. R 2 and Adj R2 of the model were obtained above of 0.99 and 0.98, respectively, which indicate the high accuracy of the model and the similarity of laboratory data and experimental model. This model showed that the layer thickness, nozzle diameter, and printing speed have a greater effect on the amount of torsional shape recovery, respectively. This process was simulated to investigate the shape recovery behavior. As a result, the relationship between the recovered shape torsion angle and the applied pre-stress was obtained. To validate the model, the effect of 3D printing parameters on the shape recovery, and the relationship between the pre-stress and the rate of shape recovery,...