• Small Angle Light Scattering
• Aneurysms
• Fluid Structure Interaction
• Mock Circulation Loop
• Diffusion Tensor Imaging
• Biaxial Traction

The study reported within this Ph. D. thesis is finalized to the ascending thoracic aortic aneurysm (ATAA) characterization. Different aspects through different techniques were considered in this analysis, including the development of both experimental test benches and computational approaches.
Firstly, the fluid dynamic aspect reproduction was taken into account. The development of an experimental setup for the replica of the correct haemodynamic conditions of the aortic system is presented. The realization of a custom pumping system based on the interpolation of physiologic flow data was achieved. After a first series of validation tests, a full mock circulatory loop for a patient specific case of a complete aortic system was fabricated. The results were compared with physiological flow and pressure values, taken from both in-vivo and in-silico evaluations. As a last step, an additional upgrade of the pumping system was proposed. To include the reproduction of the physiological helicity at ascending aorta level, an 3D printed pneumatic pump replicating the left ventricle movement was designed and its feasibility was demonstrated.
The second activity concerned the mechanical and microstructural evaluation of ATAA tissues. An experimental approach was proposed for the analysis of the fibrous microstructure of aneurysm specimens. This technique is based on diffusion tensor imaging through magnetic resonance scanning of ex-vivo tissues. The mechanical analysis was achieved through the development of a custom biaxial traction machine for soft tissues. The system was adopted to characterize a database of ATAA cases. The resulting data were interpreted through collagen fiber-based constitutive mechanical models. As a last step, the biaxial testing machine was upgraded to obtain the simultaneous microstructural-mechanical characterization of ATAA tissues. An optical system for small angle light scattering characterization was embedded on the biaxial machine. The performances of the new setup were correctly validated and the results on both healthy and ATAA tissues are presented.
At last, a computational analysis of ATAA was presented. In particular, a method for the implementation of the different constitutive models adopted during the mechanical characterization was presented. After the model validation, a patient-specific simulation of a given case was correctly imposed. The fluid dynamic and mechanical conditions were both included in the computational simulation of an ATAA case within the Finite Element environment. The different model effects were discussed by analyzing the patient-specific ATAA simulation.