Fatigue in bioengineering: a focus on Thermography and Finite Element Simulation for materials, components and biomechanical systems

The present Ph.D. thesis represents a collection of research activities carried out over three years concerning the study of fatigue phenomena in the biomedical field using energy approaches and numerical simulations. The energy release evaluation into the different applications were studied using experimental and simulation methods. The experimental approach concerns to monitor the surface temperature of materials, component or biomechanical system using Infrared Thermography technique. The Static Thermographic Method and the Risitano Thermographic Method were used for the rapid estimation of fatigue proprieties of plain and notched AISI 304L specimens, and AISI 316L specimens produced by traditional and additive manufacturing. The use of an infrared camera is presented for the study of the effect of heat dissipated during drilling process of titanium dental implants into resin D3 bone-like blocks, and for an analysis of the temperature distribution in the knee area before and after performing an exercise in relation to the weight distribution on the legs. Structural finite element simulations were performed on components, such as hip joint, to optimise the tribological and mechanical properties of the prosthesis, and, on notched specimen and welded details using the Strain Energy Density method, comparing results with codes or thermographic methods. The experimental activities were conducted at the Mechanics Laboratory of the Engineering Department of the University of Messina. Analyses of the microstructure of AISI 316L were performed at the Institute of Physics of Materials in Brno, Czech Republic, during a three-month visit under the supervision of Prof. Ing. Stanislava Fintová. These studies leave room for numerous lines of research that can be further explored in the future.