Printed polymer shape memory structures

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Structures with shape memory behavior are the subject of adaptronic research. Certain polymers are able to change their shape under certain conditions. They are easy to produce, program and have a low density. Today's 3D printers make it possible to directly print structures that are able to deform or assemble themselves under energy input directly after printing. Initial experiments show that simple structures printed with commercially available FDM printers from 4 polymer layers of commercially available FDM filaments are capable of changing their geometry under the influence of heat. After activation by heat, the structures can be shaped into any shape while still hot, then cooled and retained in the new shape. Subsequent heating releases the internal stresses in the material and the structure returns to its predefined shape. Cost-effective modifications to the printer, such as a syringe-like second material processing unit, make it possible to combine FDM filaments with metal-containing conductive inks and conductive filaments, which in turn make it possible to achieve the heat input by resistive heating. The data obtained from initial experiments show that the performance of shape variability depends very much on the printing parameters used and the environmental conditions. The project shall provide the proof by systematic investigations. In this project the printing process and its influence on the shape variability shall be investigated in detail. A visual microscope together with a thermal imaging camera will be used to investigate the printing process and the temperature distribution during printing in detail. Special test benches for testing 4D printing structures will be developed together with measurement methods. Performance parameters such as blocking force, fatigue, actuating speed are measured and production parameters are changed. The systematic investigation of the pressure parameters and the distribution of the temperature gradients should lead to a better understanding of the function of the form variability of the printed structures. The experimental investigations together with mathematical models should lead to a very well understood 4D printing process.