Percutaneous replacement of the pulmonary valve is a recently developed inter-ventional technique which involves the implantation of a valved stent in the pulmonary trunk. It relies upon careful consideration of patient anatomy for both stent design and detailed procedure planning. Medical imaging data in the form of two-dimensional scans and three-dimensional interactive graphics offer only limited support for these tasks. The paper reports the results of an experimental investigation on the use of arterial models built by rapid prototyping techniques. An analysis of clinical needs has helped to specify proper requirements for such model properties as cost, strength, accuracy, elastic compliance, and optical transparency. Two different process chains, based on the fused deposition modelling technique and on the vacuum casting of thermoset resins in rubber moulds, have been tested for prototype fabrication. The use of anatomical models has allowed the cardiologist's confidence in patient selection, prosthesis fabrication, and final implantation to be significantly improved.

The paper presents a design study for a morphing structural concept, which could be used to obtain a passively actuated high-lift wing configuration. A composite chiral honeycomb core is used to allow large variations of camber at limited strain levels in the structure of the aerodynamic surface. The design hypothesis is first assessed by means of structural analyses, which are performed applying two-dimensional and three-dimensional finite elements schemes. The results confirm the morphing capabilities in the chordwise direction of the structure, which still retains noteworthy axial and torsional stiffness properties. The aeroelastic performances of the morphing airfoil are then optimized, taking into account aeroelastic stability as well as strength constraints. The optimal parameters of chiral network and the required stiffness properties of the covering skin are identified. Overall, the work confirms the promising performances of morphing structures based on chiral topologies and assesses a numerical approach for the design of morphing aerodynamic structures