Assessment of the mechanical performance of titanium cranial prostheses manufactured by super plastic forming and single point incremental forming

Cranial implants are custom prostheses characterized by quite high geometrical complexity and small thickness; at the same time aesthetic and mechanical requirements have to be met. Titanium alloys are largely adopted for such prostheses, as they can be processed via different manufacturing technologies. In the present work cranial prostheses have been manufactured by Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF). In order to assess the mechanical performance of the cranial prostheses, drop tests under different load conditions were conducted on flat samples to investigate the effect of the blank thickness. Numerical simulations were also run for comparison purposes. The mechanical performance of the cranial implants manufactured by SPF and SPIF could be predicted using drop test data and information about the thickness evolution of the formed parts: the SPIFed prosthesis revealed to have a lower maximum deflection and a higher maximum force, while the SPFed prostheses showed a lower absorbed energy.