Análisis del proceso de fractura en poliamida 6 reforzada con fibra de vidrio corta en condiciones entalladasaspectos microestructurales y determinación de cargas de rotura mediante métodos tensionales y energéticos

Abstract

Since the mid-20th century, fibre reinforced composite materials constitute an important class of technical plastics which are replacing other materials in engineering, industrial and construction components due to their easy fabrication and good mechanical properties. The present PhD Thesis includes a complete analysis of fracture processes in notched Short Glass Fibre Reinforced Polyamide 6 (SGFR-PA6). It is intended to calibrate and validate the use of methodologies such as the Theory of Critical Distances (TCD) and the Strain Energy Density Criterion (SED) that allows the real fracture behaviour of SGFR-PA6 to be estimated, given that Fracture Mechanics does not consider the stress relaxation at the notch tip and, thus, provides over-conservative results. A total amount of 125 fracture tests were performed, combining 5 different fibre contents and 5 notch radii. In addition, this work analyses the effect of the fibre content on the fracture resistance and a complete SEM (Scanning Electron Microscope) analysis of the fracture micromechanisms is performed. Finally, the Failure Assessment Diagrams (FAD) methodology is used for structural integrity assessments, introducing a notch correction provided by the TCD.