Study of 4D primitives' self-transformation

Abstract

4D printing is the process through which a 3D printed object or primitive is transformed into another structure under the influence of external energy input such as temperature, light or other extertal stimuli. The 4th dimension is the time in which the primitive changes its appearance. In most cases, the shape changes. We call this a self-assembly or self-transformation process. In the process of printing a primitive, capable of transforming themselves from one shape to another, we often encounter combinations of one or two thermoplastic materials that have different thermal and physico-mechanical properties. The printed primitive is transformed where the active element is contained. The active element is the basic building block of the self-transforming primitive. For this purpose, it is necessary to choose the appropriate combination of thermoplastic materials, to determine the length of the active element and the number of layers of which it is composed. For the printing of the active element two thermoplastic materials can be selected which differ from each other in their thermal transitions and physico-mechanical properties. The process of transformation under the influence of elevated temperature should be carried out in such a way that the printed primitive is heated above the temperature of the glass transition that the material used on the active elements has. This releases the residual stresses created during the printing process and causes the active material to shrink. In this way, a primitive can be transformed from a flat shape to a final 3D shape. This shape is then maintained by controlled cooling below the glass transition temperature of the active element. In this paper the first research results of the primitive transformation were presented. The appropriate combination of materials and the optimal temperature of the water as external stimuli were determined, and finally the primitives’ shape recovery. In the research we used the active element which consists of a single layer of flexible, elastic thermoplastic material (passive material) and three layers of thermoplastic materials with the properties of shape memory polymers (active material). For printing we used the multitool 3D printer ZMorph which is based on Fused Deposition Modeling (FDM) technology.