6.03 4D printing – 4D printing for the automation sector 

The project 6.6 – 4D printing investigates solutions for 4D printing of programmable materials, considering both polymeric based substrates, such as silicones, polyamides, photocurable resins, and shape memory alloys (SMA) to fabricate elements, at the micro and meso scale, exhibiting actuating and morphing properties.
The main aim is to explore 4D printing strategies relying on the use of time evolving adaptive materials, which are able to change their properties/shape in a controlled manner upon an external stimulus.

The activities include novel 4D design of complex structures, manufacturing of specimens and prototyping by several AM technologies, post processing and surface finishing and a wide-range structural and functional properties investigations. SMA element will be also embedded in thermoplastic polymers for realizing active SMA/polymer composites.

Target applications lie in the automation sector, and include grasping devices and actuators.

The project is composed of two tasks:

6.6.1 Shape changing mechanical systems based on programmable materials
This task will investigate the fabrication of programmable morphologies of flexible electro/magnetic materials, obtained by 3D structuring of polymer composites incorporating magnetic responsive particles or by printing suitable designed conductive patterns on flexible substrates. The magnetic particles can either be magnetically soft, not retaining their magnetization when an applied magnetic field is removed, or magnetically hard, retaining some magnetization.
The capabilities of several 3D printing technologies, such as two photon polymerization, stereolithography, inkjet printing will be investigated to fabricate grasping devices at the micro and meso scale.

6.6.2 AM of low dimension complex structure exhibiting shape memory and superelasticity for actuating and morphing.
In this TASK, AM technologies are applied for manufacturing complex meta structures time evolving under external stimuli, such as temperature change or applied stress. The design of the meta-structures will be supported by numerical simulations (FEA), in order to optimize the cell topology according to the application.
NiTi base alloys will be processed mainly by laser powder bed fusion (LPBF) AM techniques also equipped with different laser sources for evaluating the relative vaporization of elements that strongly affect functional properties of the final components. Both the pre-alloyed powders and pure metals powder approaches will be experimented for reaching high homogeneity AM products. Strategies for real time process monitoring will be implemented. Furthermore, we plan to investigate the feasibility of process chains combining AM and finishing (mechanical, chemical and electrochemical) processes to control the shape memory and superelasticity of Nitinol. Moreover, AM Nitinol elements will be embedded in thermoplastic polymer for realizing active metal/polymer composite devices. Finally, the produced material and components will be tested by a wide range of characterization procedures including microstructural, high cycle and very high cycle fatigue, surface finishing and thermo-mechanical tests for functional testing and process optimizing.