PhD in experimental mechanics of 3D printed materials @ Ghent University (Belgium)

The approved research project is a collaboration between the companies V!go, Materialise, Devan and Ghent University. It is a feasibility study for 3D printed orthoses, that can be 3D printed and thus tailor-made for every patient. An orthosis (plural: orthoses) is "an externally applied device used to modify the structural and functional characteristics of the neuromuscular and skeletal system".

V!go (http://www.vigogroup.eu/) is a large regional company specialized in technical orthopedics. It develops and distributes orthoses and prostheses for various injuries and many musculo-skeletal problems. This project is focused on the particular ankle-foot orthosis (abbreviation: AFO) that improves mobility and supports rehabilitation for patients with specific ankle/foot related injuries. Such orthoses are quite heavily loaded, because some patients like to practice sports with such an AFO, and even climbing the stairs is an important mechanical load for an AFO.

Currently, ortheses are typically made out of polypropylene and are locally heated to manually reshape them, according to the needs of the specific patient. There is a lot of manual skills involved. It is here that 3D printing can play a role. This technique to deposit molten material layer by layer, only at the locations where the material is needed, is a true hype nowadays. Different media (newspaper, television, internet) highlight the large potential of this recent manufacturing technique. Materialise (http://www.materialise.com/), located in Leuven (Belgium), is a world player in 3D printing software, and worldwide market leader for design-software for 3D printing. They also have a large set of 3D printers in house for printing prototypes. The last industrial partner is Devan. This company is involved for developing anti-microbial coatings for the orthoses, to prevent bad odours and increase the wearing comfort.

Together with three research groups from Ghent University (medical, bio-medical and mechanical groups), it is the goal to investigate if ankle-foot orthoses can be tailor-made by 3D printing, so that no post-processing is necessary and the patient can immediately wear the final orthosis. One of the major challenges is that such orthoses must be completely safe (no sudden or unexpected failure) and must last for several years, so many hundreds of thousands of fatigue cycles. On the other hand, the 3D printing technique is not mature yet and the mechanical properties of 3D printed materials suffer from a larger scatter and weaker fatigue properties than their convential bulk counterparts.

The research tasks of the Mechanics of Materials and Structures research group are:

• mechanical characterization of 3D printed polymers for orthoses
• characterization of the fatigue behaviour of 3D printed polymers and 3D printed orthoses
• development of a material model to describe the elasto-plastic behaviour of these polymers

• development of innovative instrumentation techniques to monitor the mechanical behaviour in fatigue
• find correlations between the production parameters of the 3D printing manufacturing process and the resulting mechanical properties

The research project counts one full-time researcher for 3 years for our research group. A PhD (eventually over 4 years) is possible, but not a necessity. On the other hand, a close interaction and collaboration with V!go and Materialise and the other research groups is mandatory.

The researcher should have a strong background in mechanics and materials. The research is mainly experimental and requires a critical and skilled attitude for setting up mechanical experiments and dedicated instrumentation for measuring strains, deformations, loads, etc. Design of test set-ups is also important.